Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEMS AND METHODS FOR USE OF WATER WITH
SWITCHABLE IONIC STRENGTH
FIELD OF THE INVENTION
[0001] The field of the invention is solvents, and specifically an aqueous
solvent
composition that can be reversibly converted between low ionic strength and
higher
ionic strength, and systems and methods of use thereof.
BACKGROUND OF THE INVENTION
[0002] Conventional solvents have fixed physical properties which can lead to
significant limitations in their use as media for reactions and separations.
Many
chemical production processes involve multiple reactions and separation steps,
and
often the type of solvent that is optimum for any one step is different from
that which
is optimum for the next step. Thus it is common for the solvent to be removed
after
each step and a new solvent added in preparation for the next step. This
removal
and replacement greatly adds to the economic cost and environmental impact of
the
overall process. Therefore, there exists a need for a solvent that can change
its
physical properties.
[0003] Solvents are commonly used to dissolve material in manufacturing,
cleaning,
dyeing, extracting, and other processes. In order for a solvent to dissolve a
material
quickly, selectively, and in sufficient quantity, it is usually necessary for
the solvent to
have particular physical properties. Examples of such properties include ionic
strength, hydrophobicity, hydrophilicity, dielectric constant, polarizability,
acidity,
basicity, viscosity, volatility, hydrogen-bond donating ability, hydrogen-bond
accepting ability, and polarity. At some point in such a process after the
dissolution,
separation of the material from the solvent may be desired. Such a separation
can
be expensive to achieve, especially if the solvent is removed by distillation,
which
requires the use of a volatile solvent, which can lead to significant vapor
emission
losses and resulting environmental damage, e.g., through smog formation.
Furthermore, distillation requires a large input of energy. It would therefore
be
desirable to find a non-distillative route for the removal of solvents from
products.
[0004] Water is a particularly desirable solvent because of its low price, non-
toxicity,
nonflammability, and lack of adverse impact on the environment, but the
separation
of water from a product or other material by distillation is particularly
expensive in
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terms of energy because of the high heat capacity of water and the high heat
of
vaporization of water. Therefore the need for a non-distillative route for the
separation of water from products or other materials is particularly strong.
[0005] A common method for separating water from moderately hydrophobic yet
water-soluble materials is "salting out", a method in which a salt is added to
an
aqueous solution that includes a dissolved moderately hydrophobic compound, in
sufficient amounts to greatly increase the ionic strength of the aqueous
portion. High
ionic strength greatly decreases the solubility of some compounds in water;
thus
most of the selected compound or material is forced out of the aqueous phase.
The
compound or material either precipitates (forms a new solid phase), creams out
(forms a new liquid phase) or partitions into a pre-existing hydrophobic
liquid phase if
there is one. This "salting out" method requires no distillation but is not
preferred
because of the expense of using very large amounts of salts and, more
importantly,
because of the expense of removing the salt from the water afterwards.
SUMMARY OF THE INVENTION
[0006] An object of the present invention is to provide systems and methods
for use
of water with switchable ionic strength. In an aspect there is provided a
system for
switching the ionic strength of water or an aqueous solution, comprising:
means for
providing an additive comprising at least one nitrogen atom that is
sufficiently basic to
be protonated by carbonic acid; means for adding the additive to water or to
an
aqueous solution to form an aqueous mixture with switchable ionic strength;
means
for exposing the mixture with switchable ionic strength to an ionizing
trigger, such as
CO2, COS, CS2 or a combination thereof, to raise the ionic strength of the
mixture;
and means for exposing the mixture with raised ionic strength to i) heat, (ii)
a flushing
gas, (iii) a vacuum or partial vacuum, (iv) agitation, or (v) any combination
thereof, to
reform the aqueous mixture with switchable ionic strength. In specific
embodiments,
this system is used to remove water from a hydrophobic liquid or a solvent or
in a
desalination process.
[0007] In another aspect there is provided a system for controlling the
amount, or the
presence and absence, of dissolved salt in an aqueous mixture comprising a
compound which reversibly converts to a salt upon contact with an ionizing
trigger in
the presence of water, the compound having the general formula (1):
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R2
(1)
where R1, R2, and R3are independently:
H;
a substituted or unsubstituted 01 to 08 aliphatic group that is linear,
branched,
or cyclic, optionally wherein one or more C of the alkyl group is replaced by
{-
Si(R10)2-0-} up to and including 8 C being replaced by 8 {-Si(R13)2-0-};
a substituted or unsubstituted CnSim group where n and m are independently
a number from 0 to 8 and n + m is a number from 1 to 8;
a substituted or unsubstituted 04 to C8 aryl group wherein aryl is optionally
heteroaryl, optionally wherein one or more C is replaced by {-Si(R13)2-0-};
a substituted or unsubstituted aryl group having 4 to 8 ring atoms, optionally
including one or more {-Si(R10)2-0-}, wherein aryl is optionally heteroaryl;
a ....(si(R10)2---u)p_
chain in which p is from 1 to 8 which is terminated by H, or is
terminated by a substituted or unsubstituted Ci to 08 aliphatic and/or aryl
group; or
a substituted or unsubstituted (C, to C8 aliphatic)-(C4 to C3 aryl) group
wherein aryl is optionally heteroaryl, optionally wherein one or more C is
replaced by
a {-Si(R13)2-0-};
wherein R1 is a substituted or unsubstituted C1 to C8 aliphatic group, a
substituted or unsubstituted C1 to C8 alkoxy, a substituted or unsubstituted
04 to C8
aryl wherein aryl is optionally heteroaryl, a substituted or unsubstituted
aliphatic-
alkoxy, a substituted or unsubstituted aliphatic-aryl, or a substituted or
unsubstituted
alkoxy-aryl groups; and
wherein a substituent is independently: alkyl; alkenyl; alkynyl; aryl; aryl-
halide;
heteroaryl; cycloalkyl; Si(alkyl)3; Si(alkoxy)3; halo; alkoxyl; amino;
alkylamino;
alkenylamino; amide; amidine; hydroxyl; thioether; alkylcarbonyl;
alkylcarbonyloxy;
arylcarbonyloxy; alkoxycarbonyloxy; aryloxycarbonyloxy; carbonate;
alkoxycarbonyl;
aminocarbonyl; alkylthiocarbonyl; amidine, phosphate; phosphate ester;
phosphonato; phosphinato; cyano; acylamino; imino; sulfhydryl; alkylthio;
arylthio;
thiocarboxylate; dithiocarboxylate; sulfate; sulfato; sulfonate; sulfamoyl;
sulfonamide;
nitro; nitrile; azido; heterocyclyl; ether; ester; silicon-containing
moieties; thioester; or
a combination thereof; and a substituent may be further substituted.,
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wherein when an increase in ionic strength, or the presence of salt, is
desired,
the compound is exposed to the ionizing trigger in the presence of water,
resulting in
protonation of the compound, and
wherein when a decrease in ionic strength, or the absence of salt, is desired,
any ionizing trigger in said mixture is at a level that is insufficient to
convert the
compound to or maintain the compound in protonated form.
[0008] In a further aspect there is provided a system, comprising:
means for providing switchable water which is an aqueous liquid, comprising
an additive, that has switchable ionic strength;
means for exposing the switchable water to an ionizing trigger in the presence
of water thereby protonating the additive to form ionic protonated-additive,
which is
water-miscible or water-soluble, so that the switchable water forms an ionic
aqueous
liquid;
means for exposing the ionic aqueous liquid to i) heat, (ii) a flushing gas,
(iii) a
vacuum or partial vacuum, (iv) agitation, or (v) any combination thereof,
thereby
expelling the ionizing trigger from the ionic aqueous liquid which leads to
deprotonation of the protonated-additive, so that the switchable water forms a
non-
ionic aqueous liquid; and
optionally, means for separating a selected compound from the ionic aqueous
liquid prior to formation of the non-ionic aqueous liquid.
[0009] In a further aspect there is provided a system for removing a selected
compound from a solid material, comprising:
means for contacting a mixture of solid material and selected compound with
switchable water, which comprises a mixture of water and a switchable additive
in its
non-protonated, non-ionic form, so that at least a portion of the selected
compound
becomes associated with the switchable water to form an aqueous non-ionic
solution;
optionally, means for separating the solution from residual solid material;
means for contacting the solution with an ionizing trigger in the presence of
water to convert a substantial amount of the switchable additive from its
unprotonated form to its protonated form, resulting in a two-phase liquid
mixture
having a liquid phase comprising the selected compound, and an aqueous ionic
liquid phase comprising water and the ionic protonated additive; and
means for separating the selected compound from the liquid phase.
[0010] Yet another aspect provides a system for modulating an osmotic gradient
across a membrane, comprising:
a semi-permeable membrane;
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a switchable water comprising an additive having a switchable ionic strength
on one side of said semi-permeable membrane;
means for contacting the semi-permeable membrane with feed stream; and
means for contacting the switchable water with an ionizing trigger to ionize
the
additive and thereby increase solute concentration in the switchable water and
modulate the osmotic gradient.
[0011] An aspect provides a desalination system comprising:
a semi-permeable membrane that is selectively permeable for water;
a draw solution comprising an additive having switchable ionic strength and
water;
means for introducing an ionizing trigger to the draw solution to ionize the
additive;
means for contacting the semi-permeable membrane with a feed stream of an
aqueous salt solution to permit flow of water from the aqueous salt solution
through
the semi-permeable membrane into the draw solution comprising the ionized
additive; and
means for separating the additive from the water.
[0012] Another aspect provides a system for concentrating a dilute aqueous
solution,
comprising:
a semi-permeable membrane that is selectively permeable for water;
a draw solution comprising an additive having switchable ionic strength;
means for introducing an ionizing trigger to the draw solution to ionize the
additive;
means for contacting the semi-permeable membrane with a feed stream of
the dilute aqueous solution to permit flow of water from the dilute aqueous
solution
through the semi-permeable membrane into the draw solution comprising the
ionized
additive; and
optionally, means for separating the additive from the water.
[0013] Another aspect provides a method of separating a solute from an aqueous
solution, comprising combining in any order: water; a solute; CO2, COS, CS2 or
a
combination thereof; and an additive that comprises at least one nitrogen atom
that is
sufficiently basic to be protonated by carbonic acid; and allowing separation
of two
components: a first component that comprises an ionic form of the additive
wherein
the nitrogen atom is protonated and water; and a second component that
comprises
the solute; wherein the solute is not reactive with the additive, CO2, COS,
CS2 or a
combination thereof.
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[0014] In yet another aspect, there is provided a method for modulating ionic
strength, comprising providing an aqueous solution of lower ionic strength
comprising
water and an additive that comprises at least one nitrogen that is
sufficiently basic to
be protonated by carbonic acid; contacting the aqueous solution of lower ionic
strength with CO2, COS, CS2 or a combination thereof, to form a higher ionic
strength
solution; subjecting the higher ionic strength solution to heat, contact with
a flushing
gas, or heat and contact with a flushing gas; and reforming the aqueous
solution of
lower ionic strength.
[0015] In an aspect, there is provided a method for destabilizing or
preventing
formation of a dispersion, comprising combining in any order to form a
mixture:
water; a water-immiscible or water-insoluble ingredient; an additive that
comprises at
least one nitrogen that is sufficiently basic to be protonated by carbonic
acid; and
CO2, COS, CS2 or a combination thereof; and allowing the mixture to separate
into
two components, a first component comprising the water-immiscible ingredient
and a
second component comprising water and an ionic form of the additive.
[0016] It should be understood for all aspects and embodiments thereof that
include
employment of an additive as described in the present application includes
employment of more than one additive.
[0017] In embodiments of the above aspects, the additive is a compound of
formula
(1),
R2
R1NR3 (1)
where R1, R2, and R3are each independently:
H;
a substituted or unsubstituted C1 to C8 aliphatic group that is linear,
branched,
or cyclic, optionally wherein one or more C of the alkyl group is replaced by
{-
Si(R13)2-0-} up to and including 8 C being replaced by 8 {-Si(R10)2-0-};
a substituted or unsubstituted C,,Sim group where n and m are independently
a number from 0 to 8 and n + m is a number from 1 to 8;
a substituted or unsubstituted C4 to C8 aryl group wherein aryl is optionally
heteroaryl, optionally wherein one or more C is replaced by a {-Si(R13)2-0-};
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a ¨(Si(R10)2-0)p¨ chain in which p is from 1 to 8 which is terminated by H, or
is
terminated by a substituted or unsubstituted C1 to C8 aliphatic and/or aryl
group; or
a substituted or unsubstituted (C1 to C8 aliphatic)-(C4 to C8 aryl) group
wherein aryl is optionally heteroaryl, optionally wherein one or more C is
replaced by
{-Si( R10)2-O-};
wherein R1 is a substituted or unsubstituted C1 to C8 aliphatic group, a
substituted or unsubstituted C1 to C8 alkoxy, a substituted or unsubstituted
C4 to C8
aryl wherein aryl is optionally heteroaryl, a substituted or unsubstituted
aliphatic-
alkoxy, a substituted or unsubstituted aliphatic-aryl, or a substituted or
unsubstituted
alkoxy-aryl group; and wherein a substituent is independently: alkyl; alkenyl;
alkynyl;
aryl; aryl-halide; heteroaryl; cycloalkyl; Si(alkyl)3; Si(alkoxy)3; halo;
alkoxyl; amino;
alkylamino; dialkylamino, alkenylamino; amide; amidine; hydroxyl; thioether;
alkylcarbonyl; alkylcarbonyloxy; arylcarbonyloxy; alkoxycarbonyloxy;
aryloxycarbonyloxy; carbonate; alkoxycarbonyl; aminocarbonyl;
alkylthiocarbonyl;
phosphate; phosphate ester; phosphonato; phosphinato; cyano; acylamino; imino;
sulfhydryl; alkylthio; arylthio; thiocarboxylate; dithiocarboxylate; sulfate;
sulfato;
sulfonate; sulfamoyl; sulfonamide; nitro; nitrile; azido; heterocyclyl; ether;
ester;
silicon-containing moieties; thioester; or a combination thereof; and a
substituent may
be further substituted.
[0018] In certain embodiments of the above aspects, the ionic form of the
additive is
a compound of formula (2)
R2
NHO 0
E3CH
(2)
wherein R1, R2, and R3 are as defined for the compound of formula (1) above,
and E
is 0, S or a mixture of 0 and S. As would be readily understood by a worker
skilled in
the art, under appropriate conditions the -E3CH can lose a further hydrogen
atom to
form 2-E3C and, thereby, protonate a second additive. In a specific
embodiment, the
ionic form of protonated additive comprises a bicarbonate ion. In an
alternative
embodiment the ionic form of the additive comprises two protonated amines and
a
carbonate ion. Given that the acid-base reaction is an equilibrium reaction,
both the
carbonate ion and the bicarbonate ion can be present with the protonated
additive
ions.
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[0019] In certain embodiments of the compounds of formulas (1) and (2), one or
more of R1, R2, and R3 comprise one or more nitrogen that is sufficiently
basic to be
protonated by carbonic acid. As would be readily appreciated by the skilled
worker,
each of the one or more nitrogen that is sufficiently basic to be protonated
by
carbonic acid is associated with a corresponding counter ion E3CH- in the
compound
of formula (2).
[0020] In certain embodiments of the compounds of formulas (1) and (2), two of
R1,
R2, and R3, taken together with the nitrogen to which they are attached, are
joined to
form a heterocyclic ring. In some embodiments, the heterocyclic ring has 4 to
8
atoms in the ring. In certain embodiments of formula (1) R1, R2, and R3 may be
H.
R1, R2, and R3 may be a substituted or unsubstituted C1 to C8 alkyl group that
is
linear, branched, or cyclic, optionally containing 1 to 8 {-Si(R13)2-0-}. R1,
R2, and R3
may be a substituted or unsubstituted C2 to C8 alkenyl group that is linear,
branched,
or cyclic, optionally containing 1 to 8 {-Si(R10)2-0-}. RI, R2, and R3 may be
a
substituted or unsubstituted CnSim group where n and m are independently a
number
from 0 to 8 and n + m is a number from 1 to 8. R1, R2, and R3 may be a
substituted
or unsubstituted C5 to 08 aryl group optionally containing 1 to 8 {-Si(R13)2-0-
}. R1, R2,
and R3 may be a substituted or unsubstituted heteroaryl group having 4 to 8
atoms in
the aromatic ring optionally containing 1 to 8 {-Si(R13)2-0-}. R1, R2, and R3
may be a
¨(Si(R10)2-0)p¨ chain in which p is from 1 to 8 which is terminated by H or a
substituted or unsubstituted C1 to C8 alkyl group that is linear, branched, or
cyclic.
R1, R2, and R3 may be a substituted or unsubstituted C1 to C8 alkylene-05 to
08 aryl
group optionally containing 1 to 8 {-Si(R13)2-0-}. R1, R2, and R3 may be a
substituted
or unsubstituted C2 to 08 alkenylene-05 to CB aryl group optionally containing
1 to 8 {-
Si(R10)2-0-}. R1, R2, and R3 may be a substituted or unsubstituted C1 to C8
alkylene-
heteroaryl group having 4 to 8 atoms in the aromatic ring optionally
containing 1 to 8
(-Si(R10)2-0-). R1, R2, and R3 may be a substituted or unsubstituted C2 to 08
alkenylene-heteroaryl group having 4 to 8 atoms in the aromatic ring
optionally
containing 1 to 8 {-Si(R10)2-0-}. R1 may be a substituted or unsubstituted:
Ci to C8
alkyl, C5 to C8 aryl, heteroaryl having from 4 to 8 carbon atoms in the
aromatic ring,
or C to 08 alkoxy moiety.
[0021] In embodiments of the above aspects, the additive is a compound of
formula
(6),
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R2
.rYNN
R1N NR3R4 (6)
where R1, R2, R3, and R4 are independently:
H;
a substituted or unsubstituted C1 to C8 aliphatic group that is linear,
branched,
or cyclic, optionally wherein one or more C of the alkyl group is replaced by
{-
Si(R10)2-0-} up to and including 8 C being replaced by 8 {-Si(R10)2-0-};
a substituted or unsubstituted CflSim group where n and m are independently
a number from 0 to 8 and n + m is a number from 1 to 8;
a substituted or unsubstituted C4 to C8 aryl group wherein aryl is optionally
heteroaryl, optionally wherein one or more C is replaced by {-Si(R10)2-0-};
a substituted or unsubstituted aryl group having 4 to 8 ring atoms, optionally
including one or more {-Si(R10)2-0-}, wherein aryl is optionally heteroaryl;
a ¨(Si(R10)2-0)p¨ chain in which p is from 1 to 8 which is terminated by H, or
is
terminated by a substituted or unsubstituted C1 to C8 aliphatic and/or aryl
group; or
a substituted or unsubstituted (C1 to C8 aliphatic)-(C4 to C8 aryl) group
wherein aryl is optionally heteroaryl, optionally wherein one or more C is
replaced by
a {_si(R10)2-0-};
wherein R1 is a substituted or unsubstituted C1 to C8 aliphatic group, a
substituted or unsubstituted C1 to C8 alkoxy, a substituted or unsubstituted
C4 to C8
aryl wherein aryl is optionally heteroaryl, a substituted or unsubstituted
aliphatic-
alkoxy, a substituted or unsubstituted aliphatic-aryl, or a substituted or
unsubstituted
alkoxy-aryl groups; and
wherein a substituent is independently: alkyl; alkenyl; alkynyl; aryl; aryl-
halide;
heteroaryl; cycloalkyl; Si(alkyl)3; Si(alkoxy)3; halo; alkoxyl; amino;
alkylamino;
alkenylamino; amide; amidine; hydroxyl; thioether; alkylcarbonyl;
alkylcarbonyloxy;
arylcarbonyloxy; alkoxycarbonyloxy; aryloxycarbonyloxy; carbonate;
alkoxycarbonyl;
aminocarbonyl; alkylthiocarbonyl; amidine, phosphate; phosphate ester;
phosphonato; phosphinato; cyano; acylamino; imino; sulfhydryl; alkylthio;
arylthio;
thiocarboxylate; dithiocarboxylate; sulfate; sulfato; sulfonate; sulfamoyl;
sulfonamide;
nitro; nitrile; azido; heterocyclyl; ether; ester; silicon-containing
moieties; thioester; or
a combination thereof; and a substituent may be further substituted.
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[0022] In certain embodiments of the above aspects, the ionic form of the
additive is
a compound of formula (6'):
R2
e E3cH
R1HN NR31R4 (6')
wherein R1, R2, R3 and R4 are as defined for the compound of formula (6)
above, and
E is 0, S or a mixture of 0 and S.
[0023] In embodiments of the above aspects, the at least one nitrogen being
sufficiently basic to be protonated by carbonic acid is the at least one
nitrogen having
a conjugate acid with a pKa range from about 6 to about 14, or about 8 to
about 10.
[0024] In certain embodiments of the above aspects, the additive is MDEA (N-
methyl
diethanol-amine); TMDAB (N, N, N', N'-tetramethy1-1, 4-diaminobutane); THEED
(N,
N, N', N'-tetrakis(2-hydroxyethyl) ethylenediamine); DMAPAP (1-[bis[3-
(dimethylannino)]propyl]amino]-2-propanol); HMTETA (1,1,4,7,10,10-hexamethyl
triethylenetetramine) or DIAC (N',Ar-(butane-1,4-diy1)bis(N,N-
dimethylacetimidamide.
[0025] In an embodiment of certain aspects, the dilute aqueous solution is
wastewater.
[0026] In certain embodiments of the aspect of a method for destabilizing or
preventing formation of a dispersion, the combining in any order comprises
forming a
mixture by adding the additive to an aqueous solution that comprises the
solute; and
contacting the mixture with CO2, COS, CS2 or a combination thereof. In another
embodiment, the combining in any order comprises forming a mixture by adding
the
solute to water or an aqueous solution; contacting the mixture with CO2, COS,
CS2 or
a combination thereof; and adding the additive. In yet another embodiment, the
combining in any order comprises forming a mixture by adding the solute to an
aqueous solution that comprises the additive; and contacting the mixture with
CO2,
COS, CS2 or a combination thereof. In another embodiment, the combining in any
order comprises adding a mixture comprising the solute and the additive to an
aqueous solution that comprises CO2, COS, CS2 or a combination thereof. In
another embodiment, the combining in any order comprises forming a mixture by
adding the solute to an aqueous solution that comprises CO2, COS, CS2 or a
combination thereof, and adding the additive.
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[0027] In certain embodiments of this aspect, the solute comprises a product
of a
chemical reaction. The first component may further comprise a water-soluble
catalyst. The solute may comprise a catalyst. In another embodiment of certain
aspects, combining further comprises combining the water, the solute, the
additive,
and the CO2, COS, CS2 or a combination thereof, with a hydrophobic liquid,
wherein
after the separating step the second component comprises the hydrophobic
liquid.
[0028] In certain embodiments, a mixture of water, the solute, and the
additive is a
homogeneous liquid. In other embodiments, a mixture of water and the ionic
form of
the additive is a homogeneous liquid. In yet another embodiment, a mixture of
water
and the ionic form of the additive is a suspension. In another embodiment, a
mixture
of water and the ionic form of the additive is a solid. In certain embodiments
the
solute is soluble or miscible in low ionic strength aqueous solutions and is
insoluble
or immiscible in high ionic strength aqueous solutions.
[0029] Some embodiments further comprise isolating the first component, and
subjecting it to a trigger to form an aqueous solution comprising the
additive, wherein
the trigger is heat, bubbling with a flushing gas, or heat and bubbling with a
flushing
gas. In certain embodiments, isolating includes centrifuging, decanting,
filtering, or a
combination thereof. In certain embodiments, the additive is water-soluble or
water-
miscible in both its ionized form and its non-ionized form. In certain
embodiments,
only the ionized form of the additive is water-soluble or water-miscible and
the non-
ionized form is water insoluble or immiscible.
[0030] In certain embodiments of the above aspects, number of moles of water
in the
aqueous solution and number of moles of basic nitrogen in the additive in the
aqueous solution is approximately equivalent. In other embodiments of the
above
aspects, number of moles of water in the aqueous solution is in excess over
number
of moles of basic nitrogen in the additive in the aqueous solution.
[0031] In an embodiment of the aspect regarding a method for destabilizing or
preventing formation of a dispersion, the dispersion is an emulsion and the
water-
immiscible ingredient is a liquid or a supercritical fluid. In other
embodiments, the
dispersion is a reverse emulsion and the water-immiscible ingredient is a
liquid or a
supercritical fluid. In yet another embodiment of this aspect, the dispersion
is a foam
and the water-immiscible ingredient is a gas. In other embodiments of this
aspect,
the dispersion is a suspension and the water-immiscible ingredient is a solid.
In
embodiments of the aspects described herein, a mixture may further comprise a
surfactant.
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[0032] In an embodiment of the aspect regarding the method for modulating
ionic
strength, the method is used as a sensor of CO2, COS or CS2; a detector of
CO2,
COS or CS2; a chemical switch; a surfactant deactivator; or to conduct
electricity.
[0033] In further embodiments of the aspect regarding a method of separating a
solute from an aqueous solution, the aspect regarding modulating ionic
strength, and
the aspect regarding a method for destabilizing or preventing formation of a
dispersion are used to remove water from a hydrophobic liquid or a solvent.
[0034] In further embodiments, methods of these aspects are used in a
desalination
process or a wastewater treatment process.
[0035] Another aspect provides a system having a modulatable osmotic gradient
across a membrane, comprising:
a semi-permeable membrane;
a switchable water located on one side of said semi-permeable membrane,
said switchable water comprising water and an additive switchable between a
first
form and a second form, wherein said second form of the additive includes at
least
one ionized functional group that is neutral in said first form of the
additive, such that
switching the additive from the first form to the second form increases the
osmotic
pressure of the switchable water;
means for contacting the semi-permeable membrane with a feed stream on
the other side of said permeable membrane; and
means for contacting the switchable water with an ionizing trigger to ionize
at
least one functional group in the additive and thereby increase the ionic
strength of
the switchable water and modulate the osmotic gradient across the membrane.
[0036] Another aspect provides a system for destabilization of a suspension,
comprising:
a mixture of water or an aqueous solution and one or more particle solids that
are substantially insoluble in water;
a switchable water comprising water and an additive switchable between a
first form and a second form, wherein said second form of the additive
includes at
least one ionized functional group that is neutral in said first form of the
additive, such
that switching the additive from the first form to the second form increases
the ionic
strength of the switchable water; and
means for contacting the switchable water with an ionizing trigger to ionize
at
least one functional group in the additive and thereby increase the ionic
strength of
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the switchable water to stop the formation of a suspension of the one or more
particle
solids or destabilize a suspension of the one or more fine particle solids.
[0037] Another aspect provides a method for destabilizing a suspension or
preventing formation of a suspension, comprising:
combining, in any order, to form a mixture:
water or an aqueous solution and one or more particle solids that are
substantially insoluble in water;
an additive switchable between a first form and a second form,
wherein said second form of the additive includes at least one ionized
functional
group that is neutral in said first form of the additive; and
an ionizing trigger to ionize the at least one functional group in the
additive and thereby increase the ionic strength of the mixture to stop the
formation
of a suspension of the one or more particle solids or destabilize a suspension
of the
one or more particle solids; and
allowing the mixture to separate into two components, a first component
comprising the particle solids and a second component comprising water and an
ionic form of the additive.
[0038] Another aspect provides a method for removing a solute from an aqueous
solution or concentrating a dilute aqueous solution, comprising the steps of:
providing a semi-permeable membrane that is selectively permeable for water
and has on one side a draw solution that is a switchable water comprising
water and
an additive switchable between a first form and a second form, wherein said
second
form of the additive includes at least one ionized functional group that is
neutral in
said first form of the additive;
contacting the draw solution with an ionizing trigger to switch the additive
to
the second form before or after association with the semi-permeable membrane,
thereby increasing the osmotic pressure of the draw solution;
contacting the semi-permeable membrane with a feed stream of the aqueous
solution to permit water to flow from the aqueous solution through the semi-
permeable membrane into the increased ionic strength draw solution; and
optionally, removing the additive from the resulting diluted draw solution.
[0039] Another aspect provides a system and method for modulating viscosity of
an
aqueous solution or mixture. The system for modulating viscosity of water or
an
aqueous solution, comprises:
water or an aqueous solution having a first viscosity in combination with an
additive switchable between a first form and a second form, wherein said
second
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form of the additive includes at least one ionized functional group that is
neutral in
said first form of the additive, such that switching the additive from the
first form to
the second form increases the ionic strength of the switchable water; and
means for contacting the combination with an ionizing trigger to ionize at
least
one functional group in the additive and thereby increase the ionic strength
of the
switchable water and change the viscosity of the combination to a second
viscosity.
[0040] The method for modulating viscosity comprises:
adding to the water or aqueous solution an additive that is switchable
between a first form and a second form to produce a mixture, wherein said
second
form of the additive includes at least one ionized functional group that is
neutral in
said first form of the additive, such that switching the additive from the
first form to
the second form increases the ionic strength of the switchable water; and
contacting the mixture formed in step (a) with an ionizing trigger to ionize
at
least one functional group in the additive and thereby increase the ionic
strength of
the switchable water and change the viscosity of the mixture to a second
viscosity.
[0041] Another aspect provides a system for homogeneous catalysis, comprising:
a hydrophilic catalyst;
an organic solvent;
a switchable water comprising water and an additive switchable between a
first form and a second form, wherein said second form of the additive
includes at
least one ionized functional group that is neutral in said first form of the
additive, such
that switching the additive from the first form to the second form increases
the ionic
strength of the switchable water; and
means for contacting the switchable water with an ionizing trigger to ionize
at
least one functional group in the additive and thereby increase the ionic
strength of
the switchable water,
wherein the organic solvent is miscible with the switchable water when the
additive is
in the first form and immiscible or poorly miscible with the switchable water
when the
ionic strength is increased by switching the additive to the second form.
[0042] Another aspect provides a method for homogeneous catalysis, comprising:
forming a homogeneous reaction mixture by combining, in any order: a
hydrophilic catalyst; one or more reactants; an organic solvent; water or an
aqueous
solution; and an additive in a first form, wherein the additive is switchable
from the
first form to a second form that includes at least one ionized functional
group that is
neutral in said first form of the additive;
allowing the reactants to react to form one or more products; and
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subsequently contacting the homogeneous mixture with an ionizing trigger to
switch the additive to its second form, by ionizing at least one functional
group in the
additive, and increase the ionic strength of the mixture to salt out the
organic solvent
and the one or more products,
wherein the organic solvent is miscible with water when the additive is in the
first
form and immiscible or poorly miscible with water when the ionic strength is
increased by switching the additive to the second form.
[0043] Another aspect provides a system for modulating ionic strength of an
aqueous solution comprising:
a switchable water comprising water and an additive switchable between a
first form and a second form, wherein said second form of the additive
includes at
least one ionized functional group that is neutral in said first form of the
additive, such
that switching the additive from the first form to the second form increases
the ionic
strength of the switchable water; and
means for contacting the switchable water with an ionizing trigger to ionize
at
least one functional group in the additive and thereby increase the ionic
strength of
the switchable water,
wherein the additive is a polymer.
[0044] Another aspect provides a method for modulating the ionic strength of
an
aqueous solution, comprising:
contacting a switchable water comprising water and an additive switchable
between a first form and a second form, wherein said second form of the
additive
includes at least one ionized functional group that is neutral in said first
form of the
additive, such that switching the additive from the first form to the second
form
increases the ionic strength of the switchable water with an ionizing trigger
to ionize
at least one functional group in the additive and thereby increase the ionic
strength of
the switchable water,
wherein the additive is a polymer.
[0045] In accordance with certain embodiments of all the above aspects, the
switchable water additive is a monoamine, a diamine, a triamine, a tetraamine
or a
polyamine, such as a polymer or a biopolymer.
[0046] In accordance with another aspect there is provided a polymer that is:
a functionalized branched or linear polyethyleneimine, such as a methylated
polyethyleneimine ("MPEI"), an ethylated polyethyleneimine ("EPEI"), a
propylated
polyethyleneimine ("PPEI"), or a butylated polyethyleneimine ("BPEI");
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a functionalized polymethyl methacrylate ("PMMA") based polymer, such as
3-(dimethylamino)-1-propylamine functionalized PMMA;
a functionalized polyacrylic acid ("PAA") polymer, such as, 3-(dimethylannino)-
1-propylamine functionalized PAA;
an amine-containing polyacrylic acid salt;
a functionalized poly(methyl methacrylate-co-styrene) ("PMMA/PS"), such as
a 3-(dimethylamino)-1-propylamine functionalized PMMA/PS; or
a polymer synthesized form amine-containing monomers, such as a
polydiethylaminoethylmethacrylate ("PDEAEMA").
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] Embodiments of the invention will now be described, by way of example,
with
reference to the accompanying drawings.
[0048] Figure 1 shows a chemical reaction equation and a schematic of the
switching reaction between differing ionic strength forms of an aqueous
solution of an
amine.
[0049] Figure 2 presents the chemical structures of various tertiary amines
useful as
additives in the present invention.
[0050] Figure 3 shows multiple 1H NMR spectra from switchability study of MDEA
carried out in D20 at 400 MHz. Spectrum A was captured with no CO2 treatment,
spectrum B was captured after 20 minutes of CO2 bubbling, and spectrum C was
captured after 300 minutes of N2 bubbling. This is discussed in Example 4
below.
[0051] Figure 4 shows multiple 1H NMR spectra from a switchability study of
DMAE
carried out in D20 at 400 MHz. Spectrum A was captured with no CO2 treatment,
spectrum B was captured after 30 minutes of CO2 bubbling, and spectrum C was
captured after 240 minutes of N2 bubbling. This is discussed in Example 4
below.
[0052] Figure 5 shows multiple 1H NMR spectra from a switchability study of
HMTETA carried out in D20 at 400 MHz. Spectrum A was captured with no CO2
treatment, spectrum B was captured after 20 minutes of CO2 bubbling, and
spectrum
C was captured after 240 minutes of N2 bubbling. This is discussed in Example
4
below.
[0053] Figure 6 shows multiple 1H NMR spectra from a switchability study of
DMAPAP carried out in D20 at 400 MHz. Spectrum A was captured with no CO2
treatment, spectrum B was captured after 20 minutes of CO2 bubbling, and
spectrum
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C was captured after 120 minutes of N2 bubbling. This is discussed in Example
4
below.
[0054] Figure 7 shows conductivity spectra for the responses of water and 1:1
v/v
H20: DMAE; 1:1 v/v H20: MDEA; and 1:1 w/w H20: THEED solutions to a CO2
trigger over time. This is discussed in Example 5 below.
[0055] Figure 8 shows conductivity spectra for the responses of 1:1 v/v H20:
DMAE;
1:1 v/v H20: MDEA; and 1:1 w/w H20: THEED solutions, which had been switched
with a CO2 trigger, to the removal of CO2 by nitrogen bubbling over time. This
is
discussed in Example 5 below.
[0056] Figure 9 shows a plot of the degree of protonation of 0.5 M solutions
of DMAE
and MDEA in D20 and a 0.1 M aqueous solution of THEED in D20 resulting from
exposure to a CO2 trigger over time. This is discussed in Example 6 below.
[0057] Figure 10 shows a plot of the degree of deprotonation of 0.5 M
solutions of
DMAE and MDEA in D20 and a 0.1 M solution of THEED in D20 which have been
switched with a CO2 trigger to the removal of the trigger by nitrogen bubbling
over
time. This is discussed in Example 6 below.
[0058] Figure 11 shows conductivity spectra for the responses of 1:1 v/v H20:
amine
solutions to a CO2 trigger over time, in which the amine is TMDAB (o), HMTETA
(11),
and DMAPAP (A). This is discussed in Example 7 below.
[0059] Figure 12 shows conductivity spectra for the responses of 1:1 v/v H20:
amine
solutions, which have been switched with a CO2 trigger, to the removal of the
trigger
by nitrogen bubbling over time, in which the amine is TMDAB (*), HMTETA (o),
and
DMAPAP (A). This is discussed in Example 7 below.
[0060] Figure 13 shows five photographs A-E representing different stages of
an
experiment exhibiting how the switchable ionic strength character of amine
additive
TMDAB can be used to disrupt an emulsion of water and n-decanol. This is
discussed in Example 8 below.
[0061] Figure 14A-C schematically depict studies performed to monitor clay
settling
in switchable water according to various embodiments (Fig. 14A; Study 1 of
Example
12; Fig. 14B Study 2 of Example 12; and Fig. 14C Study 3 of Example 12).
[0062] Figure 15A-D shows the results of mixing a switchable water with
kaolinite
clay fines and treatment with CO2 followed by treatment with N2 (Fig. 15A clay
+ 1
mM TMDAB; Fig. 15B clay + 1 mM TMDAB after 1 hour CO2; Fig. 15C clay + 1 mM
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TMDAB - CO2 by addition of N2 for 1 h; and Fig. 15D photographs of mixtures +
TMDAB, after CO2, and after N2).
[0063] Figure 16A-B shows the results of mixing a switchable water with
kaolinite
clay fines and treatment with CO2 in the presence of clay (Fig. 16A clay + 1
mM
TMDAB after 1 hour CO2; and Fig. 16D photographs of mixtures + TMDAB after
CO2,
and after N2).
[0064] Figure 17A-C shows the results of mixing a CO2 treated filtrate
(obtained from
a mixture of switchable water with kaolinite clay fines) with clay (Fig. 17A
lh CO2
filtrate + clay; Fig. 17B CO2 blank + clay (control); Fig. 170 photographs of
mixtures
CO2 filtrate + clay and CO2 blank + clay (control)).
[0065] Figure 18 depicts a standard system for seawater desalination using
forward
osmosis.
[0066] Figure 19 depicts a system and process for desalination by forward
osmosis
followed by reverse osmosis using a switchable water ("SW on" refers to the
bicarbonate form of the switchable water and "SW off' refers to the non-
ionized form
of the switchable water).
[0067] Figure 20 depicts an alternative system and process for desalination by
forward osmosis followed by removal of CO2 (by heat or bubbling of a non-
acidic
gas) causing separation of much or all of the additive from the water, using a
switchable water ("SW on" refers to the bicarbonate form of the switchable
water and
"SW off' refers to the non-ionized form of the switchable water). In such a
process, if
the separation of the switchable water additive from the water is incomplete,
reverse
osmosis or nanofiltration can be used to remove the remaining additive from
the
water.
[0068] Figure 21 depicts a system that includes means for reversibly
converting a
non-ionized form of switchable water to an ionized form of the switchable
water.
[0069] Figure 22 depicts a system for obtaining at least one compound from a
mixture of compounds using switchable water that is reversibly switched from
its non-
ionic form to an ionized form.
[0070] Figure 23A shows the results of mixing a switchable water, comprising a
BPEI, MW 600, switchable additive at low concentration, with montmorillonite
in the
absence of 002.
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[0071] Figure 23B shows the results of mixing a switchable water, comprising a
BPEI, MW 600, switchable additive at low concentration, with montmorillonite
in the
presence of CO2.
[0072] Figure 24 shows a photograph of the results of mixing switchable water,
comprising a EPEI, MW 600, switchable additive at low concentration, with
montmorillonite in the absence (left) and presence (right) of 002.
[0073] Figure 25 shows the results of mixing a switchable water, comprising an
amine functionalized FM MA, MW 120 K, switchable additive at low
concentration,
with montmorillonite in the presence of CO2.
[0074] Figure 26A shows the results of mixing a switchable water, comprising 3-
(dimethylamino)-1-propylamine functionalized PMMA/PS (10mor/o styrene,
MW=10,600-15,900) switchable additive at low concentration, with
montmorillonite in
the absence of CO2.
[0075] Figure 26B shows the results of mixing a switchable water, comprising 3-
(dimethylamino)-1-propylamine functionalized PMMA/PS (10mol /0 styrene,
MW=10,600-15,900) switchable additive at low concentration, with
montmorillonite in
the presence of 002.
[0076] Figure 27 shows a photograph of the results of mixing switchable water,
comprising 3-(dimethylamino)-1-propylamine functionalized PIV1MA (MVV=120,000)
switchable additive at low concentration, with kaolinite in the absence (left)
and
presence (right) of CO2.
[0077] Figure 28A shows the results of mixing water and polyacrylamide, 6000
K,
with montmorillonite in the absence of CO2.
[0078] Figure 288 shows esults of mixing water and polyacrylamide, 6000 K,
with
montmorillonite in the presence of 002.
[0079] Figure 29 depicts a schematic of a method and system using switchable
water in process for the hydroformylation of styrene.
[0080] Figure 30 shows the results of hydroformylation of styrene using DMEA
as a
switchable water additive. (Left) All reagents mixed before reaction or CO2
treatment.
(Centre) After completion of the hydroformylation reaction. (Right) After CO2
treatment for 45 minutes. From Top to Bottom: Cycles 1 to 3 using the same
catalyst
and aqueous phase.
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[0081] Figure 31 shows the settling profile of CO2-treated kaolinite
suspension in a
blank, 1 mM, 10 mM, and 100 mM TMDAB solutions.
[0082] Figure 32 graphically shows the results of mixing a switchable water,
comprising a TMDAB, switchable additive, with kaolinite in the presence of
CO2.
[0083] Figure 33 is a photograph showing the results of mixing a switchable
water,
comprising a TMDAB, switchable additive, with kaolinite in the presence of
CO2.
[0084] Figure 34 shows supernatant from kaolinite settling experiment after 2
hours.
From left to right: no treatment, CO2 blank, 0.01 mM, 0.1 mM, 1 mM, 10 mM, and
100
mM TMDAB. All suspensions with TMDAB were subjected to CO2 treatment.
[0085] Figure 35 shows the zeta potentials of kaolinite clay particles under
different
treatment conditions.
[0086] Figure 36 shows the particle size of kaolinite clay under different
treatment
conditions.
[0087] Figure 37 shows the settling profile of CO2-treated kaolinite
suspension with
different clay loadings.
[0088] Figure 38 shows the effect of kaolinite clay loading on the turbidity
of the
supernatant water after settling in the presence of either CO2 or both 1 mM
TMDAB
and CO2.
[0089] Figure 39 shows settling profiles of a kaolinite suspension treated
with 1 mM
TMDAB and CO2 and two different controls (pH and ionic strength adjusted).
[0090] Figure 40 shows settling profiles of a kaolinite suspension treated
with 10 mM
TMDAB and CO2 and two different controls (pH and ionic strength adjusted).
[0091] Figure 41 depicts turbidity measurements of kaolinite settling
experiments
with different concentrations of TMDAB and three controls (pH and ionic
strength
adjusted) and CO2 blank.
[0092] Figure 42 depicts zeta potentials of kaolinite settling experiments
with
different concentrations of TMDAB and three controls (pH and ionic strength
adjusted) and CO2 blank.
[0093] Figure 43 shows chemical force titration curve showing the tip-sample
adhesive force as a function of pH between an Au-coated AFM tip terminated
with a
SAM of 12-phenyldodecylthiol or 12-mercaptododecanoic acid and (a) silica
substrate or (b) mica substrate. The forces measured between the silica
substrate
and the acid tip are scaled by a factor of 10 relative to other three sets of
data. The
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error bars represent the 95% confidence interval in the adhesion force as
measured
from an average of at least 1000 force-distance curves.
[0094] Figure 44 shows a schematic of a switchable surfactant (C8) in neutral
form
(left) and surfactant form (right).
[0095] Figure 45 shows a schematic of a switchable amidine (C4) in the absence
of
CO2 (left) and in the presence of CO2 (right).
DETAILED DESCRIPTION OF THE INVENTION
[0096] Definitions
[0097] Unless defined otherwise, all technical and scientific terms used
herein have
the same meaning as commonly understood by one of ordinary skill in the art to
which this invention belongs.
[0098] As used in the specification and claims, the singular forms "a", "an"
and "the"
include plural references unless the context clearly dictates otherwise.
[0099] The term "comprising" as used herein will be understood to mean that
the list
following is non-exhaustive and may or may not include any other additional
suitable
items, for example one or more further feature(s), component(s) and/or
ingredient(s)
as appropriate.
[00100] As used herein, "aliphatic" refers to hydrocarbon moieties that
are
linear, branched or cyclic, may be alkyl, alkenyl or alkynyl, and may be
substituted or
unsubstituted. "Alkenyl" means a hydrocarbon moiety that is linear, branced or
cyclic
and contains at least one carbon to carbon double bond. "Alkynyl" means a
hydrocarbon moiety that is linear, branced or cyclic and contains at least one
carbon
to carbon triple bond. "Aryl" means a moiety including a substituted or
unsubstituted
aromatic ring, including heteroaryl moieties and moieties with more than one
conjugated aromatic ring; optionally it may also include one or more non-
aromatic
ring. "05 to 05 Aryl" means a moiety including a substituted or unsubstituted
aromatic
ring having from 5 to 8 carbon atoms in one or more conjugated aromatic rings.
Examples of aryl moieties include phenyl.
[00101] "Heteroaryl" means a moiety including a substituted or
unsubstituted
aromatic ring having from 4 to 8 carbon atoms and at least one heteroatom in
one or
more conjugated aromatic rings. As used herein, "heteroatom" refers to non-
carbon
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and non-hydrogen atoms, such as, for example, 0, S, and N. Examples of
heteroaryl
moieties include pyridyl tetrahydrofuranyl and thienyl.
[00102] "Alkylene" means a divalent alkyl radical, e.g., ¨CfH2f- wherein
f is an
integer. "Alkenylene" means a divalent alkenyl radical, e.g., ¨CHCH-.
"Alkynylene"
means a divalent alkynyl radical. "Arylene" means a divalent aryl radical,
e.g., ¨
C6H4-. "Heteroarylene" means a divalent heteroaryl radical, e.g., ¨05H3N-.
"Alkylene-aryl" means a divalent alkylene radical attached at one of its two
free
valencies to an aryl radical, e.g. ,-CH2-C6H5. "Alkenylene-aryl" means a
divalent
alkenylene radical attached at one of its two free valencies to an aryl
radical, e.g., ¨
CHCH-C81-15. "Alkylene-heteroaryl" means a divalent alkylene radical attached
at one
of its two free valencies to a heteroaryl radical, e.g., ¨CH2-05H4N.
"Alkenylene-
heteroaryl" means a divalent alkenylene radical attached at one of its two
free
valencies to a heteroaryl radical, e.g., ¨CHCH-05H4N-.
[00103] "Alkylene-arylene" means a divalent alkylene radical attached at
one
of its two free valencies to one of the two free valencies of a divalent
arylene radical,
e.g., ¨CH2-C6H4-. "Alkenylene-arylene" means a divalent alkenylene radical
attached
at one of its two free valencies to one of the two free valencies of a
divalent arylene
radical, e.g., ¨CHCH-C61-14-. "Alkynylene-arylene" means a divalent alkynylene
radical
attached at one of its two free valencies to one of the two free valencies of
a divalent
arylene radical, e.g., ¨C
[00104] "Alkylene-heteroarylene" means a divalent alkylene radical
attached at
one of its two free valencies to one of the two free valencies of a divalent
heteroarylene radical, e.g., ¨CH2-05H3N-. "Alkenylene-heteroarylene" means a
divalent alkenylene radical attached at one of its two free valencies to one
of the two
free valencies of a divalent heterarylene radical, e.g., ¨CHCH-05H3N-.
"Alkynylene-
heteroarylene" means a divalent alkynylene radical attached at one of its two
free
valencies to one of the two free valencies of a divalent arylene radical,
e.g., ¨C
[00105] "Substituted" means having one or more substituent moieties whose
presence does not interfere with the desired reaction. Examples of
substituents
include alkyl, alkenyl, alkynyl, aryl, aryl-halide, heteroaryl, cycloalkyl
(non-aromatic
ring), Si(alkyl)3, Si(alkoxy)3, halo, alkoxyl, amino, alkylamino,
alkenylamino, amide,
amidine, hydroxyl, thioether, alkylcarbonyl, alkylcarbonyloxy,
arylcarbonyloxy,
alkoxycarbonyloxy, aryloxycarbonyloxy, carbonate, alkoxycarbonyl,
aminocarbonyl,
alkylthiocarbonyl, phosphate, phosphate ester, phosphonato, phosphinato,
cyano,
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acylamino, imino, sulfhydryl, alkylthio, arylthio, thiocarboxylate,
dithiocarboxylate,
sulfate, sulfato, sulfonate, sulfamoyl, sulfonamide, nitro, nitrile, azido,
heterocyclyl,
ether, ester, silicon-containing moieties, thioester, or a combination
thereof.
Preferable substituents are alkyl, aryl, heteroaryl, and ether. It is noted
that aryl
halides are acceptable substituents. Alkyl halides are known to be quite
reactive,
and are acceptable so long as they do not interfere with the desired reaction.
The
substituents may themselves be substituted. For instance, an amino substituent
may
itself be mono or independently disubstitued by further substituents defined
above,
such as alkyl, alkenyl, alkynyl, aryl, aryl-halide and heteroaryl cycloalkyl
(non-
aromatic ring).
[00106] "Short chain aliphatic" or "lower aliphatic" refers to C1 to C4
aliphatic.
"Long chain aliphatic" or "higher aliphatic" refers to C5 to C8 aliphatic.
[00107] As used herein, the term "unsubstituted" refers to any open
valence of
an atom being occupied by hydrogen. Also, if an occupant of an open valence
position on an atom is not specified then it is hydrogen.
[00108] As used herein, the term "polymer" means a molecule of high
relative
molecular mass, the structure of which essentially comprises multiple
repetition of
units derived from molecules of low relative molecular mass. Included within
the term
"polymer" are biopolymers. The term "bio-polymer," as used herein, refers to a
naturally occurring polymer. Naturally occurring polymers include, but are not
limited
to, proteins and carbohydrates. The term "bio-polymer" also includes
derivatised
forms of the naturally occurring polymers that have been modified to include
one or
more pendant amines. As used herein, the term "oligomer" means a molecule of
intermediate relative molecular mass, the structure of which essentially
comprises a
small plurality of units derived from molecules of low relative molecular
mass. A
molecule can be regarded as having a high relative molecular mass if the
addition or
removal of one or a few of the units has a negligible effect on the molecular
properties. A molecule can be regarded as having an intermediate relative
molecular mass if it has molecular properties which do vary significantly with
the
removal of one or a few of the units. (See IUPAC Recommendations 1996 in
(1996)
Pure and Applied Chemistry 68: 2287-2311.)
[00109] The term "switched" means that the physical properties and in
particular the ionic strength, have been modified. "Switchable" means able to
be
converted from a first state with a first set of physical properties, e.g., a
first state of a
given ionic strength, to a second state with a second set of physical
properties, e.g.,
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a state of higher ionic strength. A "trigger" is a change of conditions (e.g.,
introduction or removal of a gas, change in temperature) that causes a change
in the
physical properties, e.g., ionic strength. The term "reversible" means that
the
reaction can proceed in either direction (backward or forward) depending on
the
reaction conditions.
[00110] "Carbonated water" means a solution of water in which CO2 has
been
dissolved. "002 saturated water" means a solution of water in which CO2 is
dissolved to the maximum extent at that temperature.
[00111] As used herein, "a gas that has substantially no carbon dioxide"
means that the gas has insufficient CO2 content to interfere with the removal
of CO2
from the solution. For some applications, air may be a gas that has
substantially no
CO2. Untreated air may be successfully employed, i.e., air in which the CO2
content
is unaltered; this would provide a cost saving. For instance, air may be a gas
that
has substantially no CO2 because in some circumstances, the approximately
0.04%
by volume of CO2 present in air is insufficient to maintain a compound in a
switched
form, such that air can be a trigger used to remove CO2 from a solution and
cause
switching. Similarly, "a gas that has substantially no 002, CS2 or COS" has
insufficient 002, CS2 or COS content to interfere with the removal of CO2, CS2
or
COS from the solution.
[00112] As used herein, "additive" refers to a compound comprising at
least
one amine or amidine nitrogen that is sufficiently basic that when it is in
the presence
of water and CO2 (which form carbonic acid), for example, the amine or amidine
nitrogen becomes protonated. When an aqueous solution that includes such a
switchable additive is subjected to a trigger, the additive reversibly
switches between
two states, a non-ionized state where the nitrogen is trivalent and is
uncharged, and
an ionized state where the nitrogen is protonated making it a positively
charged
nitrogen atom. In some cases such as protonated amidines, the positive charge
may
be delocalized over more than one atom. For convenience herein, the uncharged
or
non-ionic form of the additive is generally not specified, whereas the ionic
form is
generally specified. The terms "ionized" or "ionic" as used herein in
identifying a form
the additive merely refer to the protonated or charged state of the amine or
amidine
nitrogen. For example, in certain examples, the additive includes other
functional
groups that are ionized when the amine or amidine nitrogen(s) is in the
uncharged or
non-ionic form.
24
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[00113] As would be readily appreciated by a worker skilled in the art,
since
few protonation reactions proceed to completion, when a compound is referred
to
herein as being "protonated" it means that all, or only the majority, of the
molecules
of the compound are protonated. For example, when the additive has a single N
atom, more than about 90%, or more than about 95%, or about 95%, of the
molecules are protonated by carbonic acid.
[00114] As used herein, "amine additive" (see compound of formula (1)
below)
refers to a molecule with a structure R1R2R3N, where R1 through R3 are
independently
hydrogen or aliphatic or aryl, which includes heteroaryl, as discussed below.
The
ionic form of an amine (see compound of formula (2) below) is termed an
"ammonium salt". The bicarbonate salt of an amine (see compound of formula (3)
below) is termed an "ammonium bicarbonate".
[00115] As used herein, "amidine additive" refers to a molecule with a
structure R1N=C(R2)-NR3R4, where R1 through R4 are independently hydrogen or
aliphatic or aryl, which includes heteroaryl, or siloxyl, as discussed below.
The ionic
form of an amidine (see compound of formula (6') below) is termed an
"amidinium
salt".
[00116] As used herein, the term "a basic nitrogen" or "a nitrogen that
is
sufficiently basic to be protonated by carbonic acid" is used to denote a
nitrogen
atom that has a lone pair of electrons available and susceptible to
protonation.
Although carbonic acid (CO2 in water) is mentioned, such a nitrogen would also
be
protonated by CS2 in water and COS in water. This term is intended to denote
the
nitrogen's basicity and it is not meant to imply which of the three trigger
gases (CO2,
CS2 or COS) is used.
[00117] "Ionic" means containing or involving or occurring in the form of
positively or negatively charged ions, i.e., charged moieties. "Nonionic"
means
comprising substantially of molecules with no formal charges. Nonionic does
not
imply that there are no ions of any kind, but rather that a substantial amount
of basic
nitrogens are in an unprotonated state. "Salts" as used herein are compounds
with
no net charge formed from positively and negatively charged ions. For purposes
of
this disclosure, "ionic liquids" are salts that are liquid below 100 C; such
liquids are
typically nonvolatile, polar and viscous. "Nonionic liquids" means liquids
that do not
consist primarily of molecules with formal charges such as ions. Nonionic
liquids are
available in a wide range of polarities and may be polar or nonpolar; they are
typically
more volatile and less viscous than ionic liquids.
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[00118] "Ionic strength" of a solution is a measure of the concentration
of ions
in the solution. Ionic compounds (i.e., salts), which dissolve in water will
dissociate
into ions, increasing the ionic strength of a solution. The total
concentration of
dissolved ions in a solution will affect important properties of the solution
such as the
dissociation or solubility of different compounds. The ionic strength, I, of a
solution is
a function of the concentration of all ions present in the solution and is
typically given
by the equation (A),
/ =1
2 " (A)
in which ci is the molar concentration of ion i in mol/dm3, zi is the charge
number of that ion and the sum is taken over all ions dissolved in the
solution. In
non-ideal solutions, volumes are not additive such that it is preferable to
calculate the
ionic strength in terms of molality (mol/kg H20), such that ionic strength can
be given
by equation (B),
2
= 1 - Zi
2 (B)
in which m, is the molality of ion i in mol/kg I-120, and zi is as defined in
the
previous paragraph.
[00119] A "polar" molecule is a molecule in which some separation occurs
of
the centres of positive and negative charge (or of partial positive and
partial negative
charge) within the molecule. Polar solvents are typically characterized by a
dipole
moment. Ionic liquids are considered to be polar solvents, even though a
dipole may
not be present, because they behave in the same manner as polar liquids in
terms of
their ability to solubilize polar solutes, their miscibility with other polar
liquids, and
their effect on solvatochromic dyes. A polar solvent is generally better than
a
nonpolar (or less polar) solvent at dissolving polar or charged molecules.
[00120] "Nonpolar" means having weak solvating power of polar or charged
molecules. Nonpolar solvents are associated with either having little or no
separation
of charge, so that no positive or negative poles are formed, or having a small
dipole
moment. A nonpolar solvent is generally better than a polar solvent at
dissolving
nonpolar, waxy, or oily molecules.
26
[00121] "Hydrophobicity" is a property of a molecule leading it to be
repelled
from a mass of water. Hydrophobic molecules are usually nonpolar and non-
hydrogen bonding. Such molecules tend to associate with other neutral and
nonpolar molecules. The degree of hydrophobic character of a molecule, or
hydrophobicity, can be quantified by a logP value. The logP is the logarithm
of the
lipid-water partition coefficient, P, of a molecule. The lipid-water partition
coefficient
seeks to determine the ratio of solubilities of a molecule in a lipid
environment and a
hydrophilic aqueous environment. The lipid-water partition coefficient is the
equilibrium constant calculated as the ratio of the concentration of the
molecule in the
lipid phase divided by the concentration of the molecule in the aqueous phase.
[00122] "Moderately hydrophobic" is used herein to refer to compounds
that
are moderately or completely soluble in aqueous solutions of low ionic
strength but
that are much less soluble or essentially insoluble in aqueous solutions of
high ionic
strength. Such compound may be liquids or solids; they may be organic or
inorganic.
An example of a moderately hydrophobic compound is tetrahydrofuran.
[00123] Partition coefficients can be determined using n-octanol as a
model of
the lipid phase and an aqueous phosphate buffer at pH 7.4 as a model of the
water
phase. Because the partition coefficient is a ratio, it is dimensionless. The
partition
coefficient is an additive property of a molecule, because each functional
group helps
determine the hydrophobic or hydrophilic character of the molecule. If the
logP value
is small, the molecule will be miscible with (or soluble in) water such that
the water
and molecule will form a single phase in most proportions. If the logP value
is large,
the compound will be immiscible with (or insoluble in) water such that a two-
phase
mixture will be formed with the water and molecule present as separate layers
in
most proportions.
[00124] It is possible to theoretically calculate logP values for many
organic
compounds because of the additive nature of the partition coefficient arising
from the
individual functional groups of a molecule. A number of computer programs are
available for calculating logP values. The logP values described herein are
predicted
using ALOGPS 2.1 software, which calculates the logP value for a given
molecule
using nine different algorithms and then averages the values. This
computational
method is fully described by Tetko I. V. and Tanchuk V. Y. in J. Chem. inf.
Comput.
Sc., 2002, 42, 1136-1145 and in J. Comput. Aid. Mol. Des., 2005, 19, 453-463.
27
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[00125] In contrast to hydrophobicity, "hydrophilicitV' is a property of
a
molecule allowing it to be dissolved in or miscible with a mass of water,
typically
because the molecule is capable of transiently bonding with water through
hydrogen
bonding. Hydrophilic molecules are usually polar. Such molecules may thus be
compatible with other polar molecules. Hydrophilic molecules may comprise at
least
one hydrophilic substituent which can transiently bond with water through
hydrogen
bonding. Hydrophilic substituents include amino, hydroxyl, carbonyl, carboxyl,
ester,
ether and phosphate moieties.
[00126] "Insoluble" refers to a poorly solubilized solid in a specified
liquid such
that when the solid and liquid are combined a heterogeneous mixture results.
It is
recognized that the solubility of an "insoluble" solid in a specified liquid
might not be
zero but rather it would be smaller than that which is useful in practice. The
use of
the terms "soluble", "insoluble", "solubility" and the like are not intended
to imply that
only a solid/liquid mixture is intended. For example, a statement that the
additive is
soluble in water is not meant to imply that the additive must be a solid; the
possibility
that the additive may be a liquid is not excluded.
[00127] "Miscibility" is a property of two liquids that when mixed
provide a
homogeneous solution. In contrast, "immiscibility" is a property of two
liquids that
when mixed provide a heterogeneous mixture, for instance having two distinct
phases (i.e., layers).
[00128] As used herein, "immiscible" means unable to merge into a single
phase. Thus two liquids are described as "immiscible" if they form two phases
when
combined in a proportion. This is not meant to imply that combinations of the
two
liquids will be two-phase mixtures in all proportions or under all conditions.
The
immiscibility of two liquids can be detected if two phases are present, for
example via
visual inspection. The two phases may be present as two layers of liquid, or
as
droplets of one phase distributed in the other phase. The use of the terms
"immiscible", "miscible", "miscibility" and the like are not intended to imply
that only a
liquid/liquid mixture is intended. For example, a statement that the additive
is
miscible with water is not meant to imply that the additive must be a liquid;
the
possibility that the additive may be a solid is not excluded.
[00129] As used herein, the term "contaminant" refers to one or more
compounds that is intended to be removed from a mixture and is not intended to
imply that the contaminant has no value.
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[00130] As used herein, the term "salt" refers to an ionic compound that
is not
a zwitterion. This may include sodium chloride (traditional table salt), other
inorganic
salts, or salts in which the anion(s), the cation(s), or both are organic. The
term
"salty" means comprising at least one salt.
[00131] As used herein the term "emulsion" means a colloidal suspension of
a
liquid in another liquid. Typically, an emulsion refers a suspension of
hydrophobic
liquid (e.g., oil) in water whereas the term "reverse emulsion" refers to a
suspension
of water in a hydrophobic liquid.
[00132] As used herein the term "suspension" means a heterogeneous
mixture of fine solid particles suspended in liquid.
[00133] As used herein the term "foam" means a colloidal suspension of a
gas
in a liquid.
[00134] As used herein the term "dispersion" means a mixture of two
components, wherein one component is distributed as particles, droplets or
bubbles
in the other component, and is intended to include emulsion (i.e., liquid in
liquid,
liquid in supercritical fluid, or supercritical fluid in liquid), suspension
(i.e., solid in
liquid) and foam (i.e., gas in liquid).
[00135] "NMR" means Nuclear Magnetic Resonance. "IR spectroscopy"
means infrared spectroscopy. "UV spectroscopy" means ultraviolet spectroscopy.
[00136] The term "DBU" means 1, 8-diazabicyclo-[5.4.0]-undec-7-ene. The
term "DMAE" means N, N-(dimethylamino)ethanol. The term "MDEA" means N-
methyl diethanol-amine. The term "TMDAB" means N, N, N', N'-tetramethy1-1, 4-
diaminobutane. The term "TEDAB" means N, N, N', N'-tetraethyl-1, 4-
diaminobutane. The term "THEED" means N, N, N', N'-tetrakis(2-hydroxyethyl)
ethylenediamine. The term "DMAPAP" means 1-[bis[3-
(dimethylamino)]propyl]amino]-2-propanol. The term "HMTETA" means
1,1,4,7,10,10-hexamethyl triethylenetetramine. Structural formulae for these
compounds are shown in Figure 2.
[00137] The term "wastewater" means water that has been used by a
domestic or industrial activity and therefore now includes waste products.
[00138] As used herein, "PEI" means branched or linear polyethyleneimines
of
various molecular weights, including, but not limited to, methylated
polyethyleneimine
("MPEI") ethylated polyethyleneimine ("EPEI"), propylated polyethyleneimine
("PPEI"), and butylated polyethyleneimine ("BPEI").
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[00139] As used herein, "PMMA" refers to polymethyl methacrylate based
polymers including, but not limited to, 3-(dimethylamino)-1-propylamine
functionalized PMMA of various molecular weights.
[00140] As used herein, "PAA" refers to polyacrylic acid based polymers
including, but not limited to, 3-(dimethylamino)-1-propylamine functionalized
PAA of
various molecular weights.
[00141] As used herein, "PMMA/PS" refers to poly(methyl methacrylate-co-
styrene), which may be functionalized with, for example, 3-(dimethylamino)-1-
propylamine.
[00142] US Patent Application Publication No. 2008/0058549 discloses a
solvent that reversibly converts from a nonionic liquid mixture to an ionic
liquid upon
contact with a selected trigger, such as CO2. The nonionic liquid mixture
includes an
amidine or guanidine or both, and water, alcohol or a combination thereof.
[00143] Zhou K., et al, "Re-examination of Dynamics of Polyelectrolytes
in
Salt-Free Dilute solutions by Designing and Using a Novel Neutral-Charged-
Neutral
Reversible Polymer" Macromolecules (2009) 42, 7146 ¨7154, discloses a polymer
that can undergo a neutral-charged-neutral transition in DMF with 5% water.
The
transition between the neutral and charged state is achieved by alternately
bubbling
CO2 and N2 through a mixture containing the polymer.
[00144] Switchable Water
[00145] Provided herein is a liquid mixture comprising an aqueous
component
in which the ionic strength can be reversibly varied from a lower ionic
strength to a
higher ionic strength by subjecting the mixture to a trigger. Put simply, such
aspects
provide water that can be reversibly switched between water-with-substantially-
no-
salt and salty-water, over and over with little or substantially no energy
input. The
term "switchable water" is used herein to refer to the aqueous component which
is
pure water mixed with an additive, or an aqueous solution mixed with an
additive,
wherein the additive can switch between an ionic form and a non-ionic form in
order
to increase or decrease the ionic strength of the water or aqueous solution,
respectively.
[00146] Traditionally, once a salt was added to water, high energy input
was
required to recapture the water (e.g., since the salted water had to be heated
to its
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boiling point). Accordingly, certain aspects of this application provide
methods of
separating a compound from a mixture by solubilizing the compound in an
aqueous
solution of a first ionic strength (a switchable water) and then isolating the
compound
by switching the medium to a solution of a second ionic strength. Such methods
use
non-ionic aqueous solutions and ionic liquids. Switchable water can be reused
over
and over in the extraction of a desired or selected compound.
[00147] Aqueous mixtures including switchable water as described herein
are
useful for extraction of a solute from a mixture, a solution, or a matrix.
After use in its
lower ionic strength form for example, for extraction of a water soluble
solute, the
switchable water is triggered to switch to its higher ionic strength form, to
cause the
precipitation or separation of the solute. The switchable water can then be re-
used
by switching it back to the lower ionic strength form. Solutes for extraction
are either
pure compounds or mixtures of compounds. They include both contaminants and
desired materials. Such solutes can be extracted from various compositions,
including, without limitation, soil, clothes, rock, biological material (for
example, wood,
pulp, paper, beans, seeds, meat, fat, bark, grass, crops, fur, natural fibres,
cornstalks, oils), water, equipment, or manufactured materials (for example,
machined parts, molded parts, extruded material, chemical products, refined
oils,
refined fuels, fabrics, fibres, sheets, and like materials, whether made of
metal,
mineral, plastic, inorganic, organic, or natural materials or combinations
thereof).
Desired solutes to be extracted include, without limitation, medicinal
compounds,
organic compounds, intermediate compounds, minerals, synthetic reagents, oils,
sugars, foods, flavorants, fragrances, dyes, pesticides, fungicides, fuels,
spices, and
like materials.
[00148] Other non-limiting examples of selected solutes include the
following:
plant extracts (e.g., lignin, cellulose, hemicellulose, pyrolysis products,
leaf extracts,
tea extracts, petal extracts, rose hip extracts, nicotine, tobacco extracts,
root extracts,
ginger extracts, sassafras extracts, bean extracts, caffeine, gums, tannins,
carbohydrates, sugars, sucrose, glucose, dextrose, maltose, dextrin); other
bio-
derived materials (e.g., proteins, creatines, amino acids, metabolites, DNA,
RNA,
enzymes); alcohols, methanol, ethanol, 1-propanol, 1-butanol, 2-propanol, 2-
butanol,
2-butanol, t-butanol, 1,2-propanediol, glycerol, and the like; products of
organic
synthesis (e.g., ethylene glycol, 1,3-propanediol, polymers, poly(vinyl
alcohol),
polyacrylamides, poly(ethylene glycol), poly(propylene glycol)); industrially
useful
chemicals (e.g., plasticizers, phenols, formaldehyde, paraformaldehyde,
surfactants,
soaps, detergents, demulsifiers, anti-foam additives); solvents (e.g., THF,
ether,
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ethyl acetate, acetonitrile, dimethylsulfoxide, sulfolene, sulfolane,
dimethylformamide,
formamide, ethylene carbonate, propylene carbonate, dimethylacetamide,
hexamethylphosphoramide); fossil fuel products (e.g., creosote, coal tar, coal
pyrolysis oil components, crude oil, water-soluble components of crude oil);
colorants
(e.g., dyes, pigments, organic pigments, stains, mordants); undesired
compounds
and mixtures (e.g., dirt or stains on clothing or equipment).
[00149] Selected compounds that may be suited to extraction methods
described herein include compounds that are soluble to different degrees in
water of
lower ionic strength and water of higher ionic strength. Certain selected
solutes are
more soluble in aqueous solutions as described herein that have lower ionic
strength
and include an amine additive than they are in neat water. Because the
following
description is about a reversible reaction that proceeds from low ionic
strength to
high ionic strength and back again, over and over, one must choose one of
these two
states to begin the process. However, this choice is arbitrary, and as
described
below, one could start with either state depending on the specific
application.
[00150] Switchable Additive
[00151] The exemplary description provided below starts with the low
ionic
strength switchable water, which comprises water and a switchable additive in
its
non-ionic form that is substantially soluble in water. The switchable water
with the
non-ionic form of the additive has a lower ionic strength than the switchable
water
with the ionic form of the additive. In specific embodiments, where the
switchable
additive does not contain other ionized functional groups, the switchable
water with
the non-ionic form of the additive has little to no ionic strength.
[00152] The switchable water can be used as a solvent to dissolve
compounds
that do not react with the additive. When it is desirable to separate
dissolved
compounds from the non-ionic switchable water, a trigger is applied and the
additive
is converted to its ionic form. The resultant ionic switchable water has a
higher ionic
strength.
[00153] In accordance with one example, both the non-ionic and the ionic
forms of the switchable additive employed in this reversible reaction are
soluble with
water, such that where a liquid mixture separates into two phases, a
hydrophobic
phase and an aqueous phase, substantially all of the additive remains in the
aqueous
layer, no matter whether it is in its non-ionic form or its ionic form. In
this example, in
contrast to the additive, certain compounds will no longer be soluble in the
higher
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ionic strength solution, and they will separate into a phase that is distinct
from the
ionic aqueous phase. This distinct phase may be a pre-existing hydrophobic
liquid
phase (non-aqueous solvent).
[00154] In accordance with an alternative example, only the ionic form of
the
switchable additive is substantially soluble in water, such that when the
additive is
converted to its non-ionic form, two phases are formed, with the non-ionic
form of the
additive being largely or completely in the non-aqueous phase. The non-aqueous
phase can include only the non-ionic form of the switchable additive, or it
can include
a solvent that is not soluble or miscible with water, such as a pre-existing
hydrophobic liquid phase (non-aqueous solvent). In many cases, the non-aqueous
phase will comprise some water, although in many applications the amount of
water
in the non-aqueous phase would preferably be as low as possible.
[00155] The switchable additive (also referred to herein as an
"additive") is a
compound comprising an amine nitrogen that is sufficiently basic that when it
is in the
presence of water and CO2 (which form carbonic acid), for example, it becomes
protonated. When an aqueous solution that includes such a switchable additive
is
subjected to a trigger, the additive reversibly switches between two states, a
non-
ionic state where the amine nitrogen is trivalent and is uncharged, and an
ionic state
where the amine nitrogen is protonated making it a 4-coordinate positively
charged
nitrogen atom. Accordingly, the charged amine moiety has a negatively charged
counterion that is associated with it in solution. The nature of the
counterion
depends on the trigger used and will be described below. An aqueous solution
comprising the additive in its ionic state is distinguishable from an aqueous
solution
comprising the compound in its non-ionic state by comparing the ionic
strengths.
[00156] The switchable additive is at least partially soluble in water
when in its
ionic form. Specifically, the switchable additive must be sufficiently soluble
in water
when in its ionic form to impart an increase in ionic strength in comparison
to the
ionic strength of the water (or aqueous solution depending on the application)
without
the ionic form of the additive present.
[00157] In certain embodiments, the switchable water comprises water and
an
amine additive that is peralkylated. The term "peralkylated" as used herein
means
that the amine has alkyl or other groups connected to nitrogen atoms that are
sufficiently basic that they are protonated by carbonic acid, so that the
molecule
contains no N-H bonds. Amine compounds of formulae (1) and (4) which do not
have any N-H bonds are preferred because most primary and secondary amines are
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capable of carbamate formation during switching with CO2. Removal of carbamate
ions in water by heating and bubbling with a flushing gas to switch the salt
back to
the amine form can be difficult. This is evident from comparative example 2,
in which
it was determined that it was not possible to switch certain primary and a
secondary
amine additives in ionic form back to the corresponding non-ionic amine forms
using
low energy input triggers. Thus, carbamate formation is undesirable because it
can
decrease the efficiency of reverting an ionic solution back to an aqueous
solution of
amine (non-ionic form). This concern about formation of carbamate ions is not
relevant if the amine is an aniline (i.e., an aryl or heteroaryl group is
attached directly
to a nitrogen atom); in such a molecule, an N-H bond is not considered
unpreferred.
[00158] Stable carbamate formation can be greatly reduced by using bulky
substituents on primary and secondary amines to provide steric hindrance
(Bougie F.
and IIHuta M.C., Chem Eng Sci, 2009, 64, 153 ¨ 162 and references cited
therein).
Steric hindrance allows for easier CO2 desorption. Tertiary amines are
preferred
since their ionic forms do not include carbamates but rather are bicarbonates
anions.
However, in some embodiments, primary and secondary amines that have bulky
substituents are preferred because the switching process may be faster than
that
observed with tertiary amines. As demonstrated in Example 22 below, the
inventors
reasonably expect that efficient reversible switching is possible between non-
ionic
and ionic forms with primary and secondary amines that have bulky
substituents.
The inventors also reasonably expect that the presence of a small amount of a
secondary or primary amine that is capable of carbamate formation, in addition
to a
switchable additive compound of formula (1), would not inhibit switching of
the
additive. In some embodiments, the presence of a small amount of secondary or
primary amine may increase the rate of switching of the additive between its
ionic
and non-ionic forms.
[00159] In one embodiment, a primary amine additive can be used. However,
the reversion of the ionic form of the primary amine additive to the non-ionic
form is
too difficult to be of practical use in application where reversion is
required. Rather, a
primary amine additive can be valuable in situations in which reversal of the
additive
ionization is unnecessary. Alternatively, a primary amine additive can be
valuable in
situations in which the use of higher temperatures, longer reaction times or
other
more severe conditions to force the reversion to take place are acceptable.
[00160] In another embodiment, a secondary amine additive can be used. As
demonstrated in Example 22, certain secondary amine additives are reversibly
switchable between an ionized and a non-ionized form.
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[00161] Useful additives can comprise more than one nitrogen centre. Such
compounds are called, for example, diamines, triamines, tetraamines or
polyamines.
Polyamines include polymers with nitrogens in the polymer backbone. Polyamines
also include polymers with nitrogens in pendant groups, for examle,
biopolymers and
derivatives thereof. Polyamines also include polymers with nitrogens in the
polymer
backbone and with nitrogens in pendant groups. Polyamines also include small
molecules (i.e., not polymers) that have more than one nitrogen atom. Examples
of
polyamines include poly(vinylamine), poly(N-vinyl-N,N-dimethylamine),
poly(allylamine) poly(N-allyl-N,N-dimethylamine), 1,2,3,4,5,6-hexakis(N,N-
dimethylaminomethyl)benzene (e.g., C6(CH2NMe2)6 ) and 1,2,3,4,5,6-hexakis(N,N-
dimethylaminomethyl)cyclohexane (e.g., 06H6(CH2NMe2)6).
[00162] In a specific example, the additive is a biopolymer comprising
one or
more amine nitrogens that are sufficiently basic that when in the presence of
water
and CO2 (which form carbonic acid), for example, it becomes protonated.
Examples
of suitable biopolymers for use as a switchable additive include, but are not
limited to,
collagens (including Types I, II, Ill, IV, V and VI), denatured collagens (or
gelatins),
fibrin-fibrinogen, elastin, glycoproteins, polysaccharides such as, but not
limited to,
alginate, chitosan, N-carboxymethyl chitosan, 0-carboxymethyl chitosan, N,0-
carboxymethyl chitosan, hyaluronic acid, chondroitin sulphates and
glycosaminoglycans (or proteoglycans), oxidized polysaccharides such as, but
not
limited to oxidized chondroitin sulphate, oxidized alginate and oxidized
hyaluronic
acid. In each case, the biopolymer can be derivatised to incorporate amine
nitrogens
that are sufficiently basic that when in the presence of water and CO2 (which
form
carbonic acid), for example, it becomes protonated.
[00163] An example of a method to prepare polyamine additive includes
reacting homopolymers of propylene oxide or ethylene oxide with maleic
anhydride
under free radical conditions either in solution or in solid state to yield
grafted
material. As an alternative to homopolymers, random or block copolymers of
propylene oxide and ethylene oxide can be used. Once prepared, the grafted
material is reacted with a diamine (e.g., 3-dimethylamino-1-propylamine) to
form a
polyamine additive that is useful as an additive in embodiments of the
invention
described herein. In some embodiments, ratios of the ethylene oxide and
propylene
oxide repeating units of the polyamine are controlled such that, at a given
temperature and pressure, the additive in its "off' state is substantially
insoluble in
water and in its "on" state is soluble in water.
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[00164] Another example of a method to prepare polyamine additive
includes
reacting a polymer of acrylic acid (or a corresponding ester) with a diamine
(e.g., 3-
dimethylamino-1-propylamine) to form the additive via amide bond formation. As
an
allternative to acrylic acid polymer, another polymer that comprises
carboxylic acid
(or a corresponding ester thereof) can be used. An example of such a polymer
includes a random or block co-polymer of polystyrene and a polymer comprising
carboxylic acid and/or ester. The amide bond is formed, for example, via
dehydration, alcohol elimination, alkoxide elimination, acid chloride
reaction,
cataytically, or the like. Any secondary or primary amide nitrogen atom can be
alkylated to further tune solubility properties of the additive. In some
embodiments,
ratios of the components of the polyamine are controlled such that, at a given
temperature and pressure, the additive in its "off" state is substantially
insoluble in
water and in its "on" state, after exposure to CO2 and H20, is soluble in
water.
[00165] Specific, non-limiting examples of amine containing polymers
useful
as switchable water additives are: branched or linear polyethyleneimines
("PEls") of
various molecular weights, including, functionalized PEls such as, methylated
polyethyleneimine("MPEI"), ethylated polyethyleneimine ("EPEI"), propylated
polyethyleneimine ("PPEI"), and butylated polyethyleneimine ("BPEI");
functionalized
polymethacrylate ("PMA") polymers of various molecular weights; functionalized
poly(methyl acrylate) ("PMeA") polymers of various molecular weights;
functionalized
polynnethyl methacrylate ("PMMA") polymers including, but not limited to, 3-
(dimethylamino)-1-propylamine functionalized PMMA of various molecular
weights;
functionalized polyacrylic acid ("FAA") polymers including, but not limited
to, 3-
(dimethylamino)-1-propylamine functionalized FAA of various molecular weights;
and
functionalized poly(methyl methacrylate-co-styrene) ("PMMA/PS") copolymers
including, but not limited to 3-(dimethylamino)-1-propylamine functionalized
PMMA/PS of various molecular weights and mol% styrenic units. The term
"functionalized", as used herein with reference to polymers, means polymers
that
comprise one or more functional groups, such as, but not limited to,
substituted or
unsubstituted aliphatic groups. In certain embodiments the polymers are
functionalized to include protonatable nitrogen atoms. As would be well
understood
by a worker skilled in the art, a functionalized polymer can be synthesized by
functionalizing a polymer at pendant reactive groups (e.g., acid groups) to
add the
desired functional group or groups. In a specific example of this alternative,
polymers
are further functionalized at existing primary amines to form secondary or
tertiary
amines. Alternatively, the functionalized polymer can be synthesized from
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monomers, or mixture of monomers, that contain the desired functional group or
groups.
[00166] When referring to polymers herein, the terminology used refers to
"functionalized" polymers without specifying the bonds formed as a result of
incorporation of the functional groups in the polymer. For example, the
polyacrylamide formed from the reaction of a PAA with an amine is, for
simplicity,
referred to herein as a "functionalized PAA".
[00167] In certain embodiments the additive is immiscible or insoluble, or
poorly miscible or poorly soluble, in water but is converted by a trigger to a
form that
is ionic and is at least partially soluble or miscible with water. In order to
function as a
switchable additive, the additive must be sufficiently soluble in water or an
aqueous
solution when in the "on" or "ionized form" so that the ionized additive
imparts an
increase in ionic strength of the water or aqueous solution without the
additive or with
the additive in the "off' or "non-ionized" form. The immiscibility or
insolubility of the
additive in its non-ionized form is advantageous in some applications because
the
additive can be readily removed from the water, when such removal is desired,
by
the removal of the trigger. TEDAB is an example of an additive that functions
according to this embodiment.
[00168] Also provided herein are ionic polymers, which are salts formed
from a
simple acid-base reaction between a polymer having pendant acidic groups and
amine or amidine-containing molecules having an accessible basic group (for
example a diamine- or triamine-containing compound). The "non-ionized", or
"off'
form of these ionic polymers is actually partially ionized, which can result
in increase
water solubility of the "non-ionized" form of these polymers, in comparison to
the non-
ionized form of the functionalized polymers described above. For example, a
basic
diamine can undergo an acid-base reaction with a polymer containing an acidic
side
group to yield a singly ionic polymer in the off form. This polymer can then
undergo a
second reaction with carbonic acid, for example, to give a doubly ionic
polymer in the
on form.
[00169] In certain embodiments, the water solubility or miscibility of a
polymeric additive in water can be switched by taking advantage of the upper
and/or
lower critical solution temperatures of the polymeric additive. In the present
situation
the lower critical solution temperature (or LCST) is the critical temperature
below
which the polymer is soluble or miscible in water or an aqueous solution and
the
upper critical solution temperature (or UCST) is the critical temperature
above which
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the polymer is soluble or miscible in water. For those polymeric additives
that have
an LCST in the non-ionized form, temperature can be used to facilitate removal
of the
additive from water. After the polymeric additive is switched from its ionized
form to
its non-ionized form, the temperature is raised to above the LCST such that
the
polymeric additive either precipitates or becomes immiscible with the water or
aqueous solution of the system. The polymeric additive can then be removed
from
the water using standard techniques such as filtration or decanting.
[00170] In certain aspects the additive is a compound of formula (1),
R2
R11\1R3 (1)
where R1, R2, and R3are independently:
H;
a substituted or unsubstituted Ci to C8 aliphatic group that is linear,
branched,
or cyclic, optionally wherein one or more C of the alkyl group is replaced by
a {-
Si(R13)2-0-} unit up to and including 8 C units being replaced by 8 {-Si(R13)2-
0-} units;
a substituted or unsubstituted Sim group where n and m are independently
a number from 0 to 8 and n + m is a number from 1 to 8;
a substituted or unsubstituted C4 to C8 aryl group wherein aryl is optionally
heteroaryl, optionally wherein one or more C is replaced by a {-Si(R13)2-0-}
unit;
a substituted or unsubstituted aryl group having 4 to 8 ring atoms, optionally
including one or more {-Si(R10)2-0-} unit, wherein aryl is optionally
heteroaryl;
a ¨(Si(R10)2-0)p¨ chain in which p is from 1 to 8 which is terminated by H, or
is
terminated by a substituted or unsubstituted C1 to C8 aliphatic and/or aryl
group;
a substituted or unsubstituted C1 to C8 aliphatic-C4 to C8 aryl group wherein
aryl is optionally heteroaryl, optionally wherein one or more C is replaced by
a {-
Si(R10)2-O-} unit; or
wherein R13 is a substituted or unsubstituted C1 to C8 aliphatic group, C1 to
C8
alkoxy, or 04 to 08 aryl wherein aryl is optionally heteroaryl.
[00171] A substituent may be independently: alkyl; alkenyl; alkynyl;
aryl; aryl-
halide; heteroaryl; cycloalkyl (non-aromatic ring); Si(alkyl)3; Si(alkoxy)3;
halo; alkoxyl;
amino, which includes diamino; alkylamino; alkenylamino; amide; amidine;
hydroxyl;
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thioether; alkylcarbonyl; alkylcarbonyloxy; arylcarbonyloxy;
alkoxycarbonyloxy;
aryloxycarbonyloxy; carbonate; alkoxycarbonyl; aminocarbonyl;
alkylthiocarbonyl;
phosphate; phosphate ester; phosphonato; phosphinato; cyano; acylamino; imino;
sulfhydryl; alkylthio; arylthio; thiocarboxylate; dithiocarboxylate; sulfate;
sulfato;
sulfonate; sulfamoyl; sulfonamide; nitro; nitrile; azido; heterocyclyl; ether;
ester;
silicon-containing moieties; thioester; or a combination thereof. The
substituents may
themselves be substituted. For instance, an amino substituent may itself be
mono or
independently disubstitued by further substituents defined above, such as
alkyl,
alkenyl, alkynyl, aryl, aryl-halide and heteroaryl cyclyl (non-aromatic ring).
[00172] A substituent may be preferably at least one hydrophilic group,
such
as Si(C1-C4-alkoxy)3, 01-C4-alkoxyl, amino, C1-C4-alkylamino, C2-C4-
alkenylamino,
substituted-amino, C1-04-alkyl substituted-amino, C2-C4-alkenyl substituted-
amino
amide, hydroxyl, thioether, C1-C4-alkylcarbonyl, C1-C4-alkylcarbonyloxy, C1-C4-
alkoxycarbonyloxy, carbonate, C1-C4-alkoxycarbonyl, aminocarbonyl, C1-C4-
alkylthiocarbonyl, phosphate, phosphate ester, phosphonato, phosphinato,
acylamino, imino, sulfhydryl, C1-04-alkylthio, thiocarboxylate,
dithiocarboxylate,
sulfate, sulfato, sulfonate, sulfamoyl, sulfonamide, nitro, nitrile, Cl-
Cralkoxy-
alkyl, silicon-containing moieties, thioester, or a combination thereof.
[00173] In some embodiments, compounds of formula (1) are water-soluble or
water-miscible. In alternative embodiments, compounds of formula (1) are water-
insoluble or water-immiscible, or only partially water-soluble or water-
miscible.
[00174] In certain embodiments, each of 1:21, R2 and R3 may be substituted
by
a tertiary amine, which is optionally sufficiently basic to become protonated
when it is
in the presence of water and CO2 (which form carbonic acid).
[00175] The present application further provides an ionic solution
comprising
water and a salt additive of formula (2) where R1, R2, and R3 are as defined
for the
compound of formula (1) and E is 0, S or a mixture of 0 and S,
R2
NHO
E3cH
R3 (2).
[00176] In some embodiments, a compound of formula (2) is prepared by a
method comprising contacting a compound of formula (1) with CO2, CS2 or COS in
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the presence of water, thereby converting the compound to the salt of formula
(2). In
some embodiments, a compound of formula (2) is water soluble.
[00177] Any of R1, R2, and R3 of the salt of formula (2) may be
optionally
substituted as discussed for the compound of formula (1). However, should the
optional substituent comprise a nitrogen of sufficient basicity to be
protonated by
carbonic acid, it can be present in its protonated form as it may be
protonated by the
ionizing trigger. For instance, if the optional substituent is an amino group,
such as a
tertiary amino group, this may exist as a quaternary ammonium moiety in the
salt of
formula (2).
[00178] The present application further provides a switchable water
comprising water and a salt of formula (3). In a preferred embodiment, in the
presence of water and CO2, an amine compound of formula (1), converts to an
ammonium bicarbonate, depicted as a salt of formula (3) as shown below
R2
0
NH e03CH
(3)
where R1, R2, and R3are as defined above. In some embodiments, a compound of
formula (3) is water soluble. There may be some carbonate anions present, in
addition to bicarbonate anions. As would be readily understood by a worker
skilled in
the art, under appropriate conditions the -03CH can lose a further hydrogen
atom to
form 2-03C (carbonate) and, thereby, protonate a second additive. In a
specific
embodiment, the ionic form of protonated additive comprises a bicarbonate ion.
In an
alternative embodiment the ionic form of the additive comprises two protonated
amines and a carbonate ion. Given that the acid-base reaction is an
equilibrium
reaction, both the carbonate ion and the bicarbonate ion may be present with
protonated additive ions.
[00179] Should an optional substituent comprise a basic nitrogen, it may
be
present in protonated form if it can be protonated by carbonic acid. For
instance, if
the optional substituent is an amino group, such as a tertiary amino group,
this may
exist as a quaternary ammonium moiety in the salt of formula (3).
[00180] A water-soluble additive of formula (1) can provide a switchable
water
that is a single-phase mixture and can function as a solvent for water-soluble
substances. Although in theory an aqueous solution of the water-soluble
compound
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of formula (1), in the absence of other components, will have an ionic
strength of zero
since no charged species are present; in practice, the ionic strength might be
small
but higher than zero due to some impurities such as dissolved air or small
amounts
of salts. Because of the zero or small ionic strength, a switchable water
comprising a
water-miscible compound of formula (1) is particularly useful as a solvent for
substances which are miscible or soluble in low ionic strength aqueous
solutions.
[00181] In some embodiments, both the non-ionic additive of formula (1)
and
the salt additive formula (2) are water-soluble and can each, therefore, form
a single
phase aqueous solution when dissolved in water. This means that the non-ionic
compound of formula (1) and the salt of formula (2) can remain in aqueous
solution
as a single phase with water after switching. Switching a non-ionic switchable
water
comprising the compound of formula (1) to an ionic switchable water comprising
the
salt of formula (2) increases the ionic strength of the switchable water.
Increasing
the ionic strength of the switchable water can be used to expel a dissolved
substance
which is insoluble in such an increased ionic strength solution without the
need for
distillation or other energy intensive separation techniques.
[00182] Alternatively water-insoluble, or poorly soluble, additive of
formula (1)
can provide a switchable water that is a two-phase mixture. Although in theory
the
water in the two-phase mixture, in the absence of other components, will have
a zero
or very low ionic strength because no charged species are present in
significant
quantities (charged species present in small concentrations may include the H4
and
Oft ions that one would expect from the dissociation of water and the amount
of
protonated additive formed by the reaction of additive with water); in
practice, the
ionic strength might also be slightly increased by the presence of some
impurities
such as dissolved air or small amounts of salts. Because of the zero or small
ionic
strength, a switchable water mixture comprising a water-immiscible, or poorly
miscible additive of formula (1) is particularly useful as a solvent for
substances
which are miscible or soluble in low ionic strength aqueous solutions.
[00183] In some embodiments, the non-ionic additive of formula (1) is
water-
insoluble, or poorly soluble, and the salt additive formula (2) is water-
soluble such
that a single phase is formed only when the additive is switched to its ionic
form.
Switching a non-ionic switchable water comprising the compound of formula (1)
to an
ionic switchable water comprising the salt of formula (2) increases the ionic
strength
of the switchable water. In this embodiment, the fact that the non-ionic form
of the
additive is water-insoluble or immiscible, can be useful in situations where
it is
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beneficial to remove the additive from the aqueous phase following switching
to the
non-ionic form.
[00184] In accordance with either embodiment, the salt of formula (2) can
be
switched back into a non-ionic additive of formula (1) by removal of the
ionizing
trigger, such as CO2, or by addition of a non-ionizing trigger. This is
advantageous
because it allows the re-use of the switchable water.
[00185] In certain embodiments, at least one of R1, R2 and R3 can be
replaced
by one or more further tertiary amine groups. For instance, R1 may be
substituted
with a tertiary amine, which may itself be further substituted with a tertiary
amine.
Thus, the present invention includes the use of an aqueous solution comprising
water
and a compound of formula (4),
R5 R2
<1\1'R4-1----- R3
a (4)
where R2, and R3, are independently as defined for the compound of formula
(1);
R5 and R6 are independently selected from the definitions of R1, R2 and R3 of
formula (1);
R4 is a divalent bridging group selected from a substituted or unsubstituted
to C8 alkylene group that is linear, branched or cyclic; a substituted or
unsubstituted
C2 to C8 alkenylene group that is linear, branched or cyclic; a substituted or
unsubstituted -CnSim- group where n and m are independently a number from 0 to
8
and n + m is a number from 1 to 8; a substituted or unsubstituted C5 to C8
arylene
group optionally containing 1 to 8 {-Si(R10)2-0-} units; a substituted or
unsubstituted
heteroarylene group having 4 to 8 atoms in the aromatic ring optionally
containing 1
to 8 {-Si(R16)2-0-} units; a ¨(Si(R10)2-0)p- chain in which "p" is from 1 to
8; a
substituted or unsubstituted C1 to C8 alkylene-05 to C8 arylene group
optionally
containing 1 to 8 {-Si(R16)2-0-} units; a substituted or unsubstituted C2 to
C8
alkenylene-05 to C8 arylene group optionally containing 1 to 8 {-Si(R16)2-0-}
units; a
substituted or unsubstituted C1 to C8 alkylene-heteroarylene group having 4 to
8
atoms in the aromatic ring optionally containing 1 to 8 {-Si(R16)2-0-} units;
a
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substituted or unsubstituted 02 to C8 alkenylene-heteroarylene group having 4
to 8
atoms in the aromatic ring optionally containing 1 to 8 {-Si(R10)2-0-} units;
I:21 is a
substituted or unsubstituted Ci to C8 alkyl, C5 to 08 aryl, heteroaryl having
from 4 to 8
carbon atoms in the aromatic ring or C1 to C8 alkoxy moiety; and "a" is an
integer. In
some embodiments, compounds of formula (4) are water-soluble. Additives with
large values of "a" are likely to be more effective in increasing the ionic
strength when
they are in their ionic forms but may suffer from poor solubility in water
when they are
in their non-ionic forms. For the avoidance of doubt, it is pointed out that
when "a">
0, in a repeat unit ¨N(R5)-R4-, R4 and R5 may have a different definition from
another
such repeat unit.
[00186] In some embodiments, the additive is an oligomer or a polymer
that
contains one or more than one nitrogen atom(s) that is sufficiently basic to
be
protonated by carbonic acid in the repeating unit of the oligomer or polymer.
In
accordance with one embodiment, the nitrogen atoms are within the backbone of
the
polymer. The additive of formula (4) is a specific example of such a polymer
in which
the nitrogen atom(s) are within the backbone of the polymer. In alternative
embodiments, the additive is an oligomer or polymer that contains one or more
than
one nitrogen atom(s) that is sufficiently basic to be protonated by carbonic
acid in a
pendant group that is part of the repeating unit, but that is not situated
along the
backbone of the oligomer or polymer. In some embodiments, some or all of the
nitrogen atom(s) that are sufficiently basic to be protonated by carbonic acid
are
amidine groups. Such amidine groups may be part of the backbone of the
oligomer
or polymer or may be in pendant group s that are part of the repeating unit.
[00187] Example polymer additives having formulae (5a-g) are shown below.
In these formulae, "n" refers to the number of repeat units containing at
least one
basic group and "m" refers to the number of repeat units containing no basic
group.
Additives with large values of "n" are likely to be more effective in
increasing the ionic
strength when they are in their ionic forms but may have poor solubility in
water when
they are in their non-ionic forms. It is not necessary that the backbone of
the polymer
be entirely made of carbon and hydrogen atoms; in some embodiments, the
backbone may comprise other elements. For example, the polymer may have a
polysiloxane backbone with amine-containing side groups, a polyether backbone
with
amine-containing side groups, or the backbone can itself comprise amine
groups. In
some embodiments, it is preferably to have a backbone or side groups that is
reasonably hydrophilic or polar. Without wishing to be bound by theory, it is
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contemplated that a hydrophilic or polar backbone or side groups can help the
charged form of the additive from precipitating.
NR2
R2N
(5a) (5b) (5c)
0 /mX
0
R2N R
in
NR2
(5d) (5e)
NIMe2 (--NNMe2 -
Me2NNMe2
)-n
Me2N-)\INMe2
(5f)
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r-N r NH2 NH2
N- NH2
H2NNNH2
(5g)
[00188] R1 can be substituted with a tertiary amine, which may itself be
further
substituted with a tertiary amine, as shown in the compound of formula (4).
Such
tertiary amine sites may be protonated when contacted with CO2, CS2 or COS in
the
presence of water. Thus, in certain embodiments the present invention provides
an
ionic solution comprising water and a salt of formula (4).
[00189] It will be apparent that when the polymer additive is in its
ionized form,
in order to balance the positive charges on the quaternary ammonium sites in
the
cation, a number of anions equivalent to the number of protonated basic sites
should
be present. For example, in the ionized form of the polymer additive of
formula (4),
there will be (a+1) --E3CH anionic counterions for each cation having (a+1)
quaternary ammonium sites in the salt of formula (4). Alternatively, some of
the
E3CH ions are replaced by anions of formula 0E32-.
[00190] Each of R1, R2, and R3 in the compound of formula (1) can be
substituted with a tertiary amine which may itself be further substituted with
a tertiary
amine. Such tertiary amine sites may be protonated when contacted with CO2,
CS2
or COS in the presence of water. However, not all amine compounds having more
than one amine site (i.e. polyamines) may be capable of protonation by the
trigger at
every amine site. Thus, amine compounds of formula (4) may not be protonated
at
every tertiary amine site when contacted with CO2, COS or CS2. Consequently,
it
should not be assumed that all basic sites must be protonated in order to
effectively
raise the ionic strength of the switchable water.
[00191] Furthermore, the pKaH (i.e. the pKa of the conjugate acid (i.e.,
ionic
form)) of the amine compound of formula (1) should not be so high as to render
the
protonation irreversible. In particular, the ionic form of the additive should
be capable
of deprotonation through the action of the non-ionizing trigger (which is
described
below to be, for example, heating, bubbling with a flushing gas, or heating
and
bubbling with a flushing gas). For example, in some embodiments, the pKaH is
in a
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range of about 6 to about 14. In other embodiments, the plc., is in a range of
about
7 to about 13. In certain embodiments the pKaH is in a range of about 7.8 to
about
10.5. In some embodiments, the pKaH is in a range of about 8 to about 10.
[00192] Additives useful in a switchable water can have higher aliphatic
(05-
05) and/or siloxyl groups. Monocyclic, or bicyclic ring structures, can also
be used.
A higher number of aliphatic groups can cause a compound to be waxy and water-
immiscible at room temperature. As described above, this may be advantageous
if it
means that the non-ionic form of the additive is water-immiscible, but the
ionic form is
water miscible.
[00193] In certain embodiments, the additive is liquid at room
temperature.
[00194] It is preferred that the aliphatic and/or siloxyl chain length is
1 to 6,
more preferably 1 to 4. A siloxyl group contains {-Si(R10)2-0-} units; where
R1 is a
substituted or unsubstituted C1 to C8 alkyl, C5 to C8 aryl, heteroaryl having
from 4 to 8
carbon atoms in the aromatic ring or Ci to C8 alkoxy moiety. Conveniently, in
some
discussions herein, the term "aliphatic/siloxyl" is used as shorthand to
encompass
aliphatic, siloxyl, and a chain which is a combination of aliphatic and
siloxyl units.
[00195] Optionally the additive comprises a group that includes an ether
or
ester moiety. In preferred embodiments, an aliphatic group is alkyl. Aliphatic
groups
may be substituted with one or more moieties such as, for example, alkyl,
alkenyl,
alkynyl, aryl, aryl halide, hydroxyl, heteroaryl, non-aromatic rings,
Si(alkyl)3,
Si(alkoxy)3, halo, alkoxy, amino, ester, amide, amidine, guanidine, thioether,
alkylcarbonate, phosphine, thioester, or a combination thereof. Reactive
substituents
such as alkyl halide, carboxylic acid, anhydride and acyl chloride are not
preferred.
[00196] Strongly basic groups such as amidines and guanidines may not be
preferred if their protonation by carbonic acid is difficult to reverse.
[00197] In other embodiments of the invention, substituents are lower
aliphatic/siloxyl groups, and are preferably small and non-reactive. Examples
of such
groups include lower alkyl (C1 to C4) groups. Preferred examples of the lower
aliphatic groups are CH3, CH2CH3, CH(C1-13)2, C(CH3)3, Si(CH3)3, CH2CH2OH,
CH2CH(OH)CH3, and phenyl. Monocyclic, or bicyclic ring structures, may also be
used.
[00198] It will be apparent that in some embodiments substituents R may
be
selected from a combination of lower and higher aliphatic groups. Furthermore,
in
certain embodiments, the total number of carbon and silicon atoms in all of
the
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substituents R1, R2, R3 and R4 (including optional substituents) of a water-
soluble
compound of formula (1) may be in the range of 3 to 20, more preferably 3 to
15.
[00199] Referring to Figure 1, a chemical scheme and schematic drawing
are
shown for a switchable ionic strength solvent system of a water-miscible amine
additive of formula (1) and water. The chemical reaction equation shows an
additive
(non-ionic form) which is an amine compound of formula (1) and water on the
left
hand side and an ionic form of the additive as an ammonium bicarbonate salt of
formula (3) on the right hand side. This reaction can be reversed, as
indicated. The
schematic shows the same reaction occurring in the presence of tetrahydrofuran
(THF) wherein a single-phase aqueous solution of an amine additive (e.g., a
compound of formula (1)) that is water-miscible, water and THF is shown on the
left
side under a blanket of N2. A two phase (layered) mixture is shown on the
right side
under a blanket of CO2. The two phases being an aqueous solution of the salt
of
formula (3) comprising ammonium bicarbonate and water, and THF.
[00200] Referring to Figure 2, structures of a number of compounds of
formula
(1) are provided. DMEA or DMAE is N,N-(dimethylamino)ethanol, which in formula
(1) has R1 is methyl; R2 is methyl; and R3 is C2H4OH). MDEA is N-methyl
diethanolamine, which in formula (1) has R1 is methyl; R2 is C2H4OH; and R3 is
C2H4OH). Both compounds, DMEA and MDEA, are monoamines having a single
tertiary amine group. TMDAB is N,N,NN4etramethyl-1, 4-diaminobutane, which in
formula (1) has R1 is methyl; R2 is methyl; R3 is C4H8N(CH3)2). THEED is
AI,N,N,A1-
tetrakis(2-hydroxyethyl) ethylenediamine, which in formula (1) has R1 is
C2H4OH; R2
is C2H4OH; and R3 is C2H4N(C2H4OH)2). Compounds TMDAB and THEED are
diamines having two tertiary amine groups. Compound DMAPAP is a triamine,
having three tertiary amine groups, 1-[bis[3-(dimethylamino)]oropyl]amino]-2-
propanol, which in formula (1) has R1 is methyl; R2 is methyl; and R3 is
C3H6N(CH2CH(OH)CH3)C3H6N(CH3)2). Compound HMTETA is a tetramine, having
four tertiary amine groups, 1,1,4,7,10,10-hexamethyl triethylenetetramine,
which in
formula (1) has R1 is methyl;R2 is methyl; and R3 is
C2H4N(CH3)C2H4N(CH3)C2H4N(CH3)2). These compounds are discussed further in
the working examples.
[00201] Referring to Figure 3, multiple 1H NMR spectra are shown from a
MDEA switchability study carried out in D20 at 400 MHz. This is discussed in
Example 4 below.
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[00202] Referring to Figure 4, multiple 1H NMR spectra are shown from a
DMAE switchability study carried out in D20 at 400 MHz. This is discussed in
Example 4 below.
[00203] Referring to Figure 5, multiple 1H NMR spectra are shown from a
HMTETA switchability study carried out in D20 at 400 MHz. This is discussed in
Example 4 below.
[00204] Referring to Figure 6, multiple 1H NMR spectra are shown from a
DMAPAP switchability study carried out in D20 at 400 MHz. This is discussed in
Example 4 below.
[00205] Referring to Figure 7, conductivity spectra are shown for the
responses to a CO2 trigger over time the following solutions: 1:1 v/v
H20:DMAE; 1:1
v/v H20:MDEA; and 1:1 w/w H20:THEED. Experimental details are discussed in
Example 5 below.
[00206] Referring to Figure 8, conductivity spectra are shown for the
responses of 1:1 v/v H20:DMAE; 1:1 v/v H20:MDEA; and 1:1 w/w H20:THEED
solutions, which had been switched with a CO2 trigger, to the removal of CO2
by
nitrogen bubbling over time. Experimental details are discussed in Example 5
below.
[00207] Referring to Figure 9, a plot of the degree of protonation of 0.5
M
solutions of DMAE and MDEA in D20 and a 0.1 M aqueous solution of THEED in
D20 resulting from exposure to a CO2 trigger over time is shown. This is
discussed
in Example 6 below.
[00208] Referring to Figure 10, a plot of the degree of deprotonation of
0.5 M
solutions of DMAE and MDEA in D20 and a 0.1 M solution of THEED in D20, which
have been switched with a CO2 trigger, to the removal of the trigger by
nitrogen
bubbling over time is shown. This is discussed in Example 6 below.
[00209] Referring to Figure 11, conductivity spectra for the responses of
1:1
v/v H20: amine solutions to a CO2 trigger over time, in which the amine is
TMDAB
(+), HMTETA (a), and DMAPAP (A), is shown. This is discussed in Example 7
below.
[00210] Referring to Figure 12, conductivity spectra for the responses of
1:1
v/v H20: amine solutions, which have been switched with a CO2 trigger, to the
removal of the trigger by nitrogen bubbling over time, in which the amine is
TMDAB
(o), HMTETA (a), and DMAPAP (A), are shown. This is discussed in Example 7
below.
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[00211] Referring to Figure 13, five photographs A-E representing
different
stages of an experiment exhibiting how the switchable ionic strength character
of
amine additive TMDAB can be used to disrupt an emulsion of water and n-decanol
are shown. This is discussed in Example 8 below.
[00212] In accordance with an alternative aspect, the switchable additive
is an
amidine having formula (6):
R2
RlNNR32 (6)
where R1, R2, and R3are each, independently, as defined above. The ionized
form of
the additive of formula (6) is:
R2
RI HN t 0 = NR32
(8 E3CH)n
where n is a number from 1 to 6 sufficient to balance the overall charge of
the
amidinium cation, and E is 0, S or a mixture of 0 and S.
[00213] Ionizing and Non-ionizingTriggers
[00214] As used herein, a trigger is a change that leads to a chemical
reaction
or a series of chemical reactions. A trigger can either be an ionizing
trigger, which
acts to effect conversion of the additive to its ionic form (e.g.,
protonated), or a non-
ionizing trigger, which acts to effect conversion of the additve to its non-
ionic form
(e.g., deprotonated).
[00215] As the skilled person will know, there are several ways to
protonate a
compound in the presence of water. Likewise, there are several ways to
deprotonate
a compound in the presence of water. In accordance with some embodiments, a
non-reversible switch between a non-ionic (e.g., deprotonated amine) state and
an
ionic (protonated) state is sufficient. In accordance with other embodiments,
a non-
reversible switch between an ionic (e.g., protonated amine) state and a non-
ionic
(deprotonated) state is sufficient. In preferred embodiments the switching
between
ionic and non-ionic states is reversible. Accordingly the following discussion
will
describe several triggers.
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[00216] An example of a non-ionizing trigger for converting the ionic
state
(e.g., protonated amine) to the non-ionic state (e.g., deprotonated amine) in
an
aqueous solution that has little or no dissolved CO2, is addition of a base to
the
aqueous solution. An example of an ionizing trigger for converting the non-
ionic state
(e.g., deprotonated amine) to the ionic state (e.g., protonated amine) in an
aqueous
solution, is addition of an acid to the aqueous solution.
[00217] The compound of formula (1) can advantageously be converted, in
the
presence of water, from a water-soluble non-ionic amine form to an ionic form
that is
also water-soluble. The conversion occurs when the aqueous non-ionic solution
is
contacted with an ionizing trigger that is a gas that liberates hydrogen ions
in the
presence of water. Hydrogen ions protonate the amine nitrogen of the non-ionic
compound to form a cation and, in the case of a CO2 trigger, bicarbonate anion
acts
as a counterion and a salt form is formed. This aqueous salt solution is a
single-
phase ionic aqueous solution. More particularly, the ionic form is an ammonium
salt.
One skilled in the art will recognize that a small amount of carbonate anions
will also
form and may act as counterions to the protonated ammonium cations.
[00218] In the example in which the additive is immiscible or insoluble,
or
poorly miscible or poorly soluble, in water, it can be converted, in the
presence of
water, to an ionic form that is more water-soluble. For example the conversion
can
occur when the mixture of non-ionic additive and water is contacted with a
trigger gas
that liberates hydrogen ions in the presence of water. Hydrogen ions protonate
the
amine nitrogen of the non-ionic compound to form a cation and, in the case of
a CO2
trigger, bicarbonate anion acts as a counterion and a salt form is formed.
This
aqueous salt solution is a single-phase ionic aqueous solution. More
particularly, the
ionic form is an ammonium salt. One skilled in the art will recognize that a
small
amount of carbonate anions will also form and may act as counterions to the
protonated ammonium cations.
[00219] As used herein, "gases that liberate hydrogen ions" fall into two
groups. Group (i) includes gases that liberate hydrogen ions in the presence
of a
base, for example, HCN and HCI (water may be present, but is not required).
Group
(ii) includes gases that when dissolved in water react with water to liberate
hydrogen
ions, for example, CO2, NO2, SO2, SO3, CS2 and COS. For example, CO2 in water
will produce HCO3- (bicarbonate ion) and C032- (carbonate ion) and hydrogen
counterions, with bicarbonate rather than carbonate being the predominant
anionic
species at pH 7. One skilled in the art will recognize that the gases of group
(ii) will
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liberate a smaller amount of hydrogen ions in water in the absence of a base,
and will
liberate a larger amount of hydrogen ions in water in the presence of a base.
[00220] Preferred gases that liberate hydrogen ions are those wherein the
salt
form switches to its non-ionic (amine) form when the same gas is expelled from
the
environment. CO2 is particularly preferred. Hydrogen ions produced from
dissolving
CO2 in water protonate the amine. In such solution, the counterion for the
ammonium ion is predominantly bicarbonate. However, some carbonate ions may
also be present in solution and the possibility that, for example, two
ammonium
molecules, each with a single positive charge, associate with a carbonate
counterion
is not excluded. When CO2 is expelled from the solution, the ammonium cation
is
deprotonated and thus is converted to its non-ionic (amine) form.
[00221] Of group (ii) gases that liberate hydrogen ions, CS2 and COS
behave
similarly to CO2 such that their reaction with amine and water is fairly
easily reversed.
However, they are not typically preferred because their use in conjunction
with water
and an amine could cause the formation of highly toxic H2S. In some
embodiments
of the invention, alternative gases that liberate hydrogen ions are used
instead of
CO2, or in combination with CO2, or in combination with each other.
Alternative
gases that liberate hydrogen ions (e.g., HCI, SO2, HCN) are typically less
preferred
because of the added costs of supplying them and recapturing them, if
recapturing is
appropriate. However, in some applications one or more such alternative gases
may
be readily available and therefore add little to no extra cost. Many such
gases, or the
acids generated from their interaction with water, are likely to be so acidic
that the
reverse reaction, i.e., converting the ammonium salt to the amine form, may
not
proceed to completion as easily as the corresponding reaction with CO2. Group
(I)
gases HCN and HCl are less preferred triggers because of their toxicity and
because
reversibility would likely require a strong base.
[00222] Contacting a water-soluble compound of formula (1) with a CO2,
CS2
or COS trigger in the presence of water may preferably comprise: preparing a
switchable water comprising water and a water-soluble additive of formula (1);
and
contacting the switchable water with a CO2, CS2 or COS trigger. Alternatively,
the
contacting a water-soluble compound of formula (1) with CO2, CS2 or COS in the
presence of water may comprise: first preparing an aqueous solution of CO2,
CS2 or
COS in water; and subsequently mixing the aqueous solution with a water-
soluble
additive of formula (1) to form a switchable water. Alternatively, contacting
a water-
soluble additive of formula (1) with CO2, CS2 or COS in the presence of water
may
comprise: dissolving CO2, CS2 or COS in a water-soluble additive of formula
(1) that
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is in a liquid state to provide a liquid; and mixing the non-aqueous liquid
with water to
form a switchable water.
[00223] Contacting a water-insoluble compound of formula (1) with a CO2,
CS2
or COS trigger in the presence of water may preferably comprise: preparing a
switchable water comprising water and a water-insoluble additive of formula
(1); and
contacting the switchable water with a CO2, CS2 or COS trigger. Alternatively,
the
contacting a water-insoluble compound of formula (1) with CO2, CS2 or COS in
the
presence of water may comprise: first preparing an aqueous solution of CO2,
CS2 or
COS in water; and subsequently mixing the aqueous solution with a water-
insoluble
additive of formula (1) to form a switchable water. Alternatively, the
contacting a
water-insoluble additive of formula (1) with CO2, CS2 or COS in the presence
of water
may comprise: dissolving CO2, CS2 or COS in a water-insoluble additive of
formula
(1) that is in a liquid state to provide a liquid; and mixing the non-aqueous
liquid with
water to form a switchable water.
[00224] Depletion of CO2, CS2 or COS from a switchable water is obtained
by
using a non-ionizing trigger such as: heating the switchable water; exposing
the
switchable water to air; exposing the switchable water to vacuum or partial
vacuum;
agitating the switchable water; exposing the switchable water to a gas or
gases that
has insufficient CO2, CS2 or COS content to convert the non-ionic state to the
ionic
state; flushing the switchable water with a gas or gases that has insufficient
CO2, CS2
or COS content to convert the non-ionic state to the ionic state; or any
combination
thereof. A gas that liberates hydrogen ions may be expelled from a solution by
simple heating or by passively contacting with a nonreactive gas ("flushing
gas") or
with vacuum, in the presence or absence of heating. Alternatively and
conveniently,
a flushing gas may be employed by bubbling it through the solution to actively
expel
a gas that liberates hydrogen ions from a solution. This shifts the
equilibrium from
the ionic ammonium form to non-ionic amine. In certain situations, especially
if
speed is desired, both a flushing gas and heat can be employed in combination
as a
non-ionizing trigger.
[00225] Preferred flushing gases are N2, air, air that has had its CO2
component substantially removed, and argon. Less preferred flushing gases are
those gases that are costly to supply and/or to recapture, where appropriate.
However, in some applications one or more flushing gases may be readily
available
and therefore add little to no extra cost. In certain cases, flushing gases
are less
preferred because of their toxicity, e.g., carbon monoxide. Air is a
particularly
preferred choice as a flushing gas, where the CO2 level of the air (today
commonly
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380 ppm) is sufficiently low that an ionic form (ammonium salt) is not
maintained in
its salt form. Untreated air is preferred because it is both inexpensive and
environmentally sound. In some situations, however, it may be desirable to
employ
air that has had its CO2 component substantially removed as a nonreactive
(flushing)
gas. By reducing the amount of CO2 in the flushing gas, potentially less salt
or amine
may be employed. Alternatively, some environments may have air with a high CO2
content, and such flushing gas would not achieve sufficient switching of ionic
form to
non-ionic amine form. Thus, it may be desirable to treat such air to remove
enough
of its CO2 for use as a trigger.
[00226] CO2 may be provided from any convenient source, for example, a
vessel of compressed CO2(g) or as a product of a non-interfering chemical
reaction.
The amines of the invention are able to react with CO2 at 1 bar or less to
trigger the
switch to their ionic form.
[00227] It will be understood by the skilled person in the art that
regeneration
of a water-miscible compound of formula (1) from an ionic aqueous solution of
a salt
of formula (2) can be achieved by either active or passive means. The
regeneration
may be achieved passively if an insufficient concentration of an ionizing
trigger, such
as CO2, is present in the surrounding environment to keep the additive
switched to
the ionic form. In this case, an ionizing trigger such as CO2 could be
gradually lost
from the aqueous solution by natural release. No non-ionizing trigger, such as
heating or active contacting with flushing gases would be required. Heating or
contacting with flushing gases would be quicker but may be more expensive.
[00228] In studies described herein (see example 7), efficient contact
between
gas and solution was obtained using a fritted glass apparatus. Heat can be
supplied
from an external heat source, preheated nonreactive gas, exothermic
dissolution of
gas in the aqueous ionic solution, or an exothermic process or reaction
occurring
inside the liquid. In initial studies, the non-ionizing trigger used to expel
CO2 from
solution and to switch from ionic form to amine was heat. However, CO2 was
expelled, and the salt was converted to the amine by contacting with a
flushing gas,
specifically, nitrogen. It is also expected that CO2 can be expelled from the
ionic
solution merely by passively exposing the solution to air.
[00229] In some embodiments the amine additive in its non-ionic state is
a
liquid, in other embodiments the amine additive in its non-ionic state is a
solid.
Whether liquid or solid, they may be miscible or immiscible with water.
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[00230] In some embodiments the ionic form of the additive (e.g.,
ammonium
bicarbonate) is a liquid, in other embodiments the ionic form of the additive
is a solid.
Whether liquid or solid, they may be miscible or immiscible with water.
[00231] It is not significant whether neat ammonium bicarbonate salt is a
solid
or a liquid as long as it is water soluble such that a single phase solution
is provided
of the ionic aqueous solution. It will be apparent that at least a molar
equivalent of
water is required to react with the CO2 to provide the carbonic acid to
protonate a
nitrogen site(s) of the amine group of the compound of formula (1) to form the
ammonium cation.
[00232] In embodiments where a neat ammonium bicarbonate of formula (3)
is
a solid and not a liquid, more than a molar equivalent of water relative to
the number
of nitrogen sites should be present in the aqueous solution to ensure the
complete
dissolution of the salt in the ionic aqueous solution. In some embodiments,
the
amount of water is 1 or more weight equivalents relative to the compound of
formula
(1).
[00233] In some embodiments, the mole ratio of water and basic nitrogen
sites
in the amine capable of protonation is at least about equimolar. It will be
apparent to
one skilled in the art that when the ionic form is prepared from this mixture,
there will
remain little or no unreacted reactant(s), and thus little or no water after
conversion to
the salt form.
[00234] In other embodiments, the ratio of non-gaseous reactants is
greater
than equimolar, i.e., the number of moles of water is greater than the number
of
moles of basic nitrogen sites in the amine capable of protonation. This
provides
additional, unreacted water which is not consumed in the switching reaction.
This
may be necessary to ensure a single phase liquid mixture should the neat
resulting
salt be a solid, thereby providing a single phase aqueous solution. In some
embodiments, a very high ratio of moles of water to moles of non-ionic
additive
(amine) is preferred so that the cost of the aqueous solvent can be decreased;
it is
assumed that the amine additive is more expensive than the water. It is
preferred
that sufficient water is present to dissolve the salt formed after switching
so that an
ionic aqueous solution is obtained.
[00235] If insufficient water is present to solubilize a solid ammonium
bicarbonate formed after switching, unsolubilized salt will be present as a
precipitate.
For instance, should the ratio of (moles of water) to (moles of basic nitrogen
sites in
the amine capable of protonation) be equimolar, substantially all the water
would be
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consumed in a complete switching reaction. If the salt was a solid rather than
an
ionic liquid, this solid would form as a precipitate. The formation of the
salt as a
precipitate may be advantageous in some circumstances because it is easily
recoverable, for instance by filtration.
[00236] Systems and Methods Employing Switchable Water
[00237] As described briefly above, an aspect provided herein is a method
and
system for switching the ionic strength of water or an aqueous solution. The
method
comprises the step of mixing water or an aqueous solution with a switchable
additive,
before, after or simultaneously with the introduction of an ionizing trigger
to ionize the
switchable additive and consequently raise the ionic strength of the mixture
of the
water or the aqueous solution and the switchable additive. Optionally, the
method
additionally comprises the step of introducing a non-ionizing trigger to
reverse the
ionization of the switchable additive.
[00238] Also provided is a switchable water system that comprises: means
for
providing a switchable additive comprising at least one nitrogen that is
sufficiently
basic to be protonated by carbonic acid; means for adding the additive to
water or to
an aqueous solution to form an aqueous mixture with switchable ionic strength;
means for exposing the water or aqueous solution to an ionizing trigger, such
as
CO2, COS, CS2 or a combination thereof, to raise the ionic strength of the
aqueous
mixture with switchable ionic strength; and, optionally, means for exposing
the
mixture with raised ionic strength to a non-ionizing trigger, such as (i)
heat, (ii) a
flushing gas, (iii) a vacuum or partial vacuum, (iv) agitation, (v) or any
combination
thereof, to reform the aqueous mixture with switchable ionic strength. As will
be
appreciated, the means for exposing the water or aqueous solution to the
ionizing
trigger, can be employed before, after or together with the means for adding
the
additive to the water or the aqueous solution.
[00239] Figure 21 provides an example of a switchable water system as
described above. In the system embodiment depicted in Figure 21, the system
includes means for contacting the non-ionized form of a switchable water with
the
ionizing trigger, which, in this example is CO2. Following contact with the
ionizing
trigger, the switchable water is reversibly converted to its ionic form. As
also depicted
in Figure 21, the system in this example further comprises a means for
introducing a
non-ionizing trigger to the ionized form of the switchable water. In this
example, the
non-ionizing trigger is air.
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[00240] The following is a non-limiting list of applications of systems
and
methods employing switchable water:
1. In Osmosis (either by Forward Osmosis (FO) or by Forward Osmosis followed
by Reverse Osmosis (FO/RO))
a. For production of freshwater by desalination of seawater or brackish
water.
b. For partial dewatering of wastewater, process water, or other industrial
aqueous solutions (whether waste or in a process). The osmosis
concentrates the wastewater/process water/industrial aqueous
solution and produces a purified water stream that can be directly
recycled or disposed of, or further purified or processed for recycling
or disposal.
2. In Forcing Immiscibility
a. For the drying of (i.e., removal of water from) organic liquids by forcing
the water-content in the organic liquid to form a second liquid phase.
b. For the recovery of organic liquids from water by forcing the organic
content in the water to form a second liquid phase.
c. For forcing two immiscible aqueous phases to form (for separating
water-soluble polymers such as polyethylene glycol (PEG) from salts
or for concentrating solutions of water-soluble polymers such as
PEG).
3. In Forcing Insolubility
a. For recovering a solid compound or compounds (such as an organic
product, e.g., an active pharmaceutical ingredient (API) or a
contaminant) from water or from an aqueous mixture. The recovered
solid compound or compounds can be the target compound or
compounds or an undesired compound or compounds (such as
contaminants or by-products). This can be useful, for example, after
an organic synthesis in water; after the extraction of an organic into
water; for recovering proteins from water; for decontaminating
contaminated water; for causing a coating, dye or mordant to come
out of aqueous solution and attach itself onto a solid.
b. For adjusting the solubility of salts in water (i.e., the solubility of the
salt would be different in the ionic switchable water than in the non-
ionic switchable water). Possibly useful in mining or in separations
involving salts.
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c. For adjusting the partition coefficient of solutes between an aqueous
phase and an organic liquid phase. Certain systems and methods
employing switchable water are useful in catalysis, extractions,
washing of products, separations of mixtures, etc.
4. In Breaking Dispersions
a. For breaking emulsions. Can be useful, for example, in the oil
industry during or after enhanced oil recovery, during or after
pipelining of heavy crudes or bitumen, during or after wastewater
treatment, in the treatment of rag layers.
b. For breaking suspensions. Can be useful, for example, in removal of
suspended solids/particles from water (e.g., wastewater or storm
water). For example, the present methods and systems can be used
in oil sands processing and tailings ponds, in mining, in the treatment
of wastewater from mining, in minerals processing and separation, in
treatment of wastewater from other industries, in latex preparation,
handling and precipitation, in
emulsion/microemulsion/miniemulsion/suspension polymerization. In a
specific example, the methods and systems can be used in removal of
fine clay particles from water.
c. For breaking foams and froths. Can be useful, for example, in the oil
industry for suppressing foams, in mineral separations, in the
treatment of aqueous streams after mineral separations.
5. In Causing Other Properties of Aqueous Solutions to Change
a. For modifying density. The density of the ionic form of a switchable
water is expected to be different from the density of the non-ionic
version. This density change can be useful in the separation of solid
materials like polymers because some would float and some would
sink at each density and modifying the density could allow the
separation of different polymers at different densities.
b. For modifying conductivity, for example, in sensors, liquid switches.
c. For modifying viscosity. The viscosity of the ionic form of a switchable
water solution is different from the non-ionic version.
[00241] In specific embodiments, this system and method are used, for
example:
¨ to remove water from a hydrophobic liquid or a solvent;
¨ to remove water from a hydrophilic organic liquid such as an alcohol;
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¨ to remove or isolate a solute from an aqueous solution;
¨ to remove or isolate a hydrophobic liquid or solvent from an aqueous
mixture;
¨ to remove salt and/or generate fresh water in a desalination process;
¨ to destabilize or disrupt micelles and/or to deactivate a surfactant;
¨ to provide a switchable antifreeze, a switchable electrolyte solution, a
switchable conducting solution, or an electrical switch; or
¨ to provide a CO2, COS, CS2 sensor.
[00242] In one embodiment, there is provided a method of extracting a
selected substance from a starting material(s) that comprises the selected
substance. In some embodiments, the selected substance is soluble in an
aqueous
solution comprising the non-ionic form of a swichable water (comprising the a
non-
ionic form of the switchable additive) with zero or low ionic strength, and
the selected
substance is insoluble in an aqueous solution comprising the ionic form of a
switchable water (comprising the ionized form of the additive), which has a
higher
ionic strength. For instance, the starting material may be a solid impregnated
with
the selected substance. For another instance, the starting material may be a
liquid
mixture of the selected substance and a hydrophobic liquid. This method of
extracting a selected substance is particularly effective if the selected
substance is
soluble in the non-ionic aqueous solution. The selected substance, which may
be a
liquid or a solid, dissolves in the non-ionic aqueous solution comprising an
additive of
formula (1) and can thereby be readily separable from any water-insoluble
remaining
starting material (e.g., by filtration) and can be separated from the
hydrophobic liquid
(e.g., by decantation). Once the non-ionic aqueous solution comprising the
selected
compound is isolated, the selected substance can be separated from the aqueous
phase (i.e., "salted out") by converting the non-ionic aqueous solution to an
ionic
aqueous solution. The selected substance will then separate out and can be
isolated.
[00243] Using methods and systems described herein it is possible to
separate certain water-soluble selected compounds from an aqueous solution.
Once
the selected compounds are dissolved in an aqueous solution, and optionally
separated from other non-soluble compounds by, for example, filtration, the
selected
compounds can be isolated from the aqueous solution without having to input a
large
amount of energy to boil off the water. Conveniently, this separation is done
by
increasing the ionic strength (amount of charged species) in the aqueous
solution
(more commonly referred to as "salting out") resulting in a separation of the
selected
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compound from the distinct aqueous phase. The selected compound can then be
isolated from the aqueous solution be decanting it or filtering it, as
appropriate. Thus,
an aqueous solution whose ionic strength is altered upon contact with a
suitable
trigger can dissolve or separate from a selected compound in a controlled
manner.
Importantly, this method of salting out is readily reversible, unlike the
conventional
method of salting out (e.g., adding NaCI to water). A system for employing
such a
method includes, in addition to the components set out above, means for
mechanical
separation of solids from a liquid mixture.
[00244] In an embodiment, the invention provides a method of removing
water
(i.e., drying) from hydrophobic liquids such as solvents. As described in
detail herein,
additives form a salt in the presence of water and CO2, COS or CS2.
Accordingly,
additives added to wet solvent and an ionizing trigger gas (in any
combination) cause
any water that was in the wet solvent to separate out as a distinct ionic
component in
an aqueous phase. A system for employing such a method includes, in addition
to
the components set out above, means for extracting a water immiscible liquid
phase
from an aqueous solution.
[00245] A conceptual model of such a system is shown in Figure 1, which
shows the reversible separation of tetrahydrofuran (THF) from an aqueous
solution of
a compound of formula (1). This figure shows that when THF is mixed with a non-
ionic aqueous solution, THF is miscible with the non-ionic aqueous solution,
providing a single phase. As discussed in working examples 1 and 2, THF was
experimentally shown to be miscible with the non-ionic aqueous solution.
Further,
THF was isolated from the mixture by switching the additive in the solvent
from its
non-ionic form to its ionic form (ammonium bicarbonate) in order to increase
the ionic
strength and force THF from the aqueous solution.
[00246] Specifically, as discussed in working examples 1 and 2, the
aqueous
solution was contacted with CO2 to switch the amine to its ammonium
bicarbonate
form (ionic form) as shown by formula (3). The contacting was carried out by
treating
a miscible mixture of THF, water and water-soluble amine compound of formula
(1)
with carbonated water or actively exposing the mixture to CO2. The THF then
formed
a non-aqueous layer and the ammonium bicarbonate remained in an increased
ionic
strength aqueous layer ("water + salt (3)"). The non-aqueous and aqueous
layers
are immiscible and formed two distinct phases, which can then be separated by
decantation, for example. Once separated, the non-aqueous and aqueous layers
provide an isolated non-aqueous phase comprising THF and an isolated aqueous
phase comprising the ammonium bicarbonate form of additive in the switchable
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solvent. In this way, the solvent is separated from the THF without
distillation. While
it is unlikely that every single molecule of THF will be forced out of the
aqueous
phase, a majority of the THF can be forced out by this method. The amount of
THF
that remains in the aqueous phase will depend on several factors, including
nature
and concentration of additive, temperature, effect of other species in
solution,
amount of CO2 (or other gas(ses) that releases protons in water) in the water,
and
the number of basic sites on the additive that are protonable by carbonic
acid.
[00247] The ammonium bicarbonate salt of formula (3) in the aqueous phase
was switched back to its non-ionic form. The aqueous solution of salt (3)
which has
been switched back to a non-ionic aqueous solution can then be used to
dissolve or
extract further THF.
[00248] Note that the ability of the liquid mixture of water and amine
additive
(e.g., compound of formula (1)) to dissolve a selected compound may be greater
than the ability of pure water to dissolve the same selected compound because
the
additive may help the desired compound to dissolve in the aqueous solution.
This
may be because of a polarity-lowering effect of the amine, because of
preferential
solvation of the molecules of the desired compound by the molecules of the
amine
additive, and/or because of a miscibility-bridging effect in which the
addition of a
compound of intermediate polarity increases the mutual miscibility between a
low-
polarity liquid and a high-polarity liquid.
[00249] When the aqueous solutions with switchable ionic strength are
switched between their lower ionic strength state and their higher ionic
strength state,
characteristic of the solution are changed. Such characteristics include:
conductivity,
melting point, boiling point, ability to solubilise certain solutes, ability
to solubilise
gases, osmotic pressure, and there may also be a change in vapour pressure. As
discussed herein, the switchable ionic strength also affects surfactants by
changing
their critical micelle concentration and by affecting their ability to
stabilize dispersions.
Variation of such characteristics can be used, for example, the reversibly
switchable
ionic strength solution can be a reversibly switchable antifreeze, a
reversibly
switchable electrolyte solution, or a reversibly switchable conducting
solution.
[00250] A further aspect provides a non-ionic switchable water mixture
that is
largely nonconductive (or only weakly conductive) of electricity, that becomes
more
conductive when it is converted to its ionic form, and that this change is
reversible.
Such a conductivity difference would enable the mixture to serve as an
electrical
switch, as a switchable medium, as a detector of 002, COS or CS2, or as a
sensor of
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the presence of CO2, COS or CS2. This ability of the ionic liquid to conduct
electricity
can have applications in electrochemistry, in liquid switches and in sensors
and/or
detectors. Common, affordable CO2 sensors are typically effective at 2-5% CO2.
CO2 sensors that work between 2-100% are usually large and prohibitively
expensive. A chemical approach based on switchable ionic strength solutions
can
cost much less.
[00251] Further provided is a method for maintaining or disrupting
miscibility of
two liquids where the first liquid is miscible with low ionic strength water
but is
immiscible with higher ionic strength water and the second liquid is the
reversible
switchable ionic strength aqueous solvent described herein. In a mixture of
the first
and second liquids, they are miscible when the switchable solvent is in its
non-ionic
form. To disrupt the miscibility, a trigger is applied, causing the ionic
strength of the
switchable solvent to increase and the newly-immiscible liquids to separate.
Alternatively, the first liquid may be a liquid that is miscible with aqueous
solutions of
high ionic strength and immiscible with aqueous solutions of low ionic
strength. In
such a case the ionic and non-ionic forms of the switchable solvent should be
used to
maintain and disrupt the miscibility, respectively.
[00252] Another aspect is a method for "salting-in" of solutes that are
more
soluble in water of high ionic strength than in water of low ionic strength.
For
example, an aqueous solution of switchable additive at high ionic strength is
used as
a solvent for a solute, and the switching of the solution to low ionic
strength causes
the solute to form a second phase or precipitate or to partition into an
existing second
phase.
[00253] Another aspect provides a method of deactivating surfactants.
Surfactants (also known as detergents and soap) stabilize the interface
between
hydrophobic and hydrophilic components. In aqueous solutions, detergents act
to
clean oily surfaces and clothing by making the (hydrophobic) oil more soluble
in
water (hydrophilic) by its action at the oil-water interface. Once a cleaning
job is
finished, soapy water with hydrophobic contaminants remains. To recover the
oil
from the soapy water, salt can be added to the water and most of the oil will
separate
from the salt water. With the switchable ionic strength aqueous solution of
the
present invention, after a cleaning job, the oil can be recovered from the
soapy water
solution merely by applying a trigger to reversibly increase the solutions
ionic
strength. The trigger causes the ionic strength to increase, thereby
deactivating the
surfactant. Many surfactants are unable to function properly (effectively
stabilize
dispersions) at conditions of high ionic strength. The oil then separates from
the
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aqueous phase, and can be decanted off. Then the aqueous solution can be
triggered to decrease the ionic strength. Regenerated soapy water can then be
reused, over and over.
[00254] Another aspect provides switchable water of switchable ionic
strengths that are used to stabilize and destabilize emulsions, which may
include
surfactant-stabilized emulsions. Emulsions of oil and water that include
surfactants
are used in oil industries to control viscosity and enable transport of oil
(as an
emulsion) by pipeline. Once the emulsion has been transported, however, it is
desirable to separate the surfactant-supported emulsion and recover oil that
is
substantially water-free. In its non-ionized form, amine additive does not
significantly
interfere in the stability of an emulsion of water and a water-immiscible
liquid (e.g.,
hexane, crude oil). However, once switched to its ionic form, the increased
ionic
strength of the solution interferes with the stability of the emulsion,
resulting in a
breaking of the emulsion. In surfactant-stabilized emulsions, the higher ionic
strength
solution may interfere with the surfactant's ability to stabilize the
emulsion. This
reversible switch from lower to higher ionic strength is preferable over
destabilizing
emulsions by traditional means (i.e., increasing the ionic strength by adding
of a
traditional salt such as NaCI). This preference is because the increase in
ionic
strength caused by the addition of a traditional salt is difficult to reverse
without a
large input of energy.
[00255] Creating an emulsion is possible, for example by adding a water-
immiscible liquid to the lower ionic strength switchable aqueous solution as
described
previously, to form two phases. Then, a surfactant that is soluble in the
aqueous
phase should be added to a concentration above the critical micelle
concentration of
the surfactant. Shear or mixing of the mixture then creates an emulsion. As
discussed above, the resultant emulsion can be destabilized by treatment with
an
ionizing trigger, such as by bubbling it with CO2, COS or CS2 to raise the
ionic
strength of the aqueous phase. Subsequent removal of CO2, COS or CS2 by
treatment with a non-ionizing trigger, such as by bubbling the mixture with a
flushing
gas and/or by heating it lowers the ionic strength allowing the system to
return to the
initial conditions.
[00256] Non-limiting examples of emulsions include mixtures of water
with:
crude oil; crude oil components (e.g., gasoline, kerosene, bitumen, tar,
asphalt, coal-
derived liquids); oil (including oil derived from pyrolysis of coal, bitumen,
lignin,
cellulose, plastic, rubber, tires, or garbage); vegetable oils; seed oils; nut
oils; linseed
oil; tung oil; castor oil; canola oil; sunflower oil; safflower oil; peanut
oil; palm oil;
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coconut oil; rice bran oil; fish oils; animal oils; tallow; or suet. Other non-
limiting
examples of emulsions include water with colloidal particles, colloidal
catalysts,
colloidal pigments, clay, sand, minerals, soil, coal fines, ash, mica,
latexes, paints,
nanoparticles including metallic nanoparticles, nanotubes.
[00257] Another aspect provides aqueous solutions of switchable ionic
strength, or switchable water, which are used to stabilize and destabilize
reverse
emulsions.
[00258] A suspension is a finely divided solid that is dispersed but not
dissolved in a liquid. In an aspect of the invention, aqueous solutions of
switchable
ionic strength are used to stabilize and destabilize suspension of solids in
water,
which may include surfactant-stabilized suspensions. In its non-ionized form,
amine
additive does not interfere in the stability of a suspension. However, once
the
additive is switched to its ionic form, the increased ionic strength may
significantly
destabilize a suspension and/or it may inhibit the ability of a surfactant to
stabilize
such a suspension, resulting in coagulation of the solid particles. This
reversible
switch from lower to higher ionic strength is preferable to destabilizing a
suspension
by adding traditional salts (e.g., NaCl) because the increase in ionic
strength caused
by the addition of a traditional salt is difficult to reverse without a large
input of
energy. Typical examples of such suspensions may include polymers (e.g.,
polystyrene), clays, minerals, tailings, colloidal dyes, and nanoparticles
including
metallic nanoparticles. Increasing the ionic strength of the solution by
applying a
trigger, causes small solid particles to aggregate or coagulate to form larger
particles
that settle to the bottom of the solution. Application of a trigger to convert
from higher
ionic strength to lower ionic strength (e.g., removal of CO2) allows for
redispersion of
the particles, regenerating the suspension.
[00259] In an alternative aspect there is provided, aqueous solutions
comprising switchable water of switchable ionic strength that are used to
stabilize
and destabilize foam (i.e., gas-in-liquid), which may include surfactant-
stabilized
foams. In its non-ionized form, the switchable additive does not interfere in
the
stability of a foam. However, once the additive is switched to its ionic form,
the
increased ionic strength interferes with the stability of the foam and/or
inhibits a
surfactant's ability to stabilize a foam, resulting in the breaking of the
foam. This
reversible switch from lower to higher ionic strength is preferable to
destabilizing
foams by adding a traditional salt (e.g., NaCI) because the increase in ionic
strength
caused by the addition of a traditional salt is difficult to reverse without a
large input
of energy.
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[00260] A gas in liquid emulsion can exist in the lower ionic strength
aqueous
solution that includes an amine additive. When a trigger is applied to
increase the
solution's ionic strength the foam is destabilized. The application of a
trigger to
convert it from the higher ionic strength solution to the lower ionic strength
solution
leads a newly generated foam to be stabilized in the solution. In this
situation, a non-
ionizing trigger to release CO2, COS or CS2 would preferably be application of
a
flushing gas (e.g., N2, air). In an embodiment of the method of separating a
solute
from an aqueous solution, instead of separating the solute in a neat form, it
is
possible to add a water immiscible liquid (e.g., n-octanol) to the mixture. In
the lower
ionic strength form, the solute has a given partitioning between the aqueous
phase
and the hydrophobic phase. With application of a trigger, the aqueous phase
converts to a higher ionic strength solution, which causes more of the solute
to
partition into the hydrophobic phase. In this embodiment, rather than the
solute
forming its own phase, the solute is dissolved in the hydrophobic phase. If
desired,
another trigger (e.g., removal of CO2) lowers the ionic strength allowing the
solute to
return to the aqueous phase. A system for employing such a method would
include,
in addition to the components described above, means for providing the water
immiscible liquid and means for extracting a water immiscible liquid phase
from an
aqueous solution
[00261] In another aspect there is provided, aqueous solutions of
switchable
ionic strength that are used to create aqueous/aqueous biphasic systems. A
lower
ionic strength aqueous solution with amine additive and a water-soluble
polymer
(e.g., poly(ethylene glycol) exists as a single phase. With application of a
trigger, the
aqueous phase converts to a higher ionic strength solution, which causes the
mixture
to form two separate phases. Specifically, the phases are the polymer and
water that
it carries with it since is quite water soluble and the aqueous solution of
higher ionic
strength. If desired, another trigger (e.g., removal of CO2) lowers the ionic
strength
causing the system to recombine into a single aqueous phase.
[00262] In an embodiment of this aspect, there are two solutes in the
aqueous
solution of switchable ionic strength that comprises a water-soluble polymer
(e.g.,
poly(ethylene glycol). The two solutes may be, for example, two different
proteins.
Each protein will separate from higher ionic strength aqueous solution (i.e.,
"salt out")
at a distinct and specific ionic strength. If a trigger increases the ionic
strength of the
switchable solution such that only one of the two proteins separates from the
higher
ionic strength aqueous phase, the one protein will partition into the water
and water-
soluble-polymer layer so that it is separated from the other protein. As
described
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above, with another trigger to reduce the ionic strength, the aqueous solution
can be
used over and over again. In another embodiment of this aspect, a solute may
partition from the higher ionic strength aqueous solution into the water with
water-
soluble-polymer layer in the form of a solid.
[00263] Another aspect of the invention is a method of drying hydrophobic
liquids by separating the hydrophobic liquid from its water contaminant. As
described
herein, this separation is effected by adding an additive that forms a salt in
the
presence of water and CO2, COS or CS2. The salt can then be isolated from the
hydrophobic liquid thereby removing its water contaminant. Non-limiting
examples of
hydrophobic liquids include solvents, alcohols, mineral oils, vegetable oils,
fish oils,
seed oils. In some embodiments of the invention the liquid that needs to be
similarly
dried is a hydrophilic liquid such as a smaller alcohol.
[00264] Yet another aspect of the invention provides a method of
reversibly
lowering an aqueous solution's boiling point. Another aspect of the invention
provides a method of reversibly increasing an aqueous solution's boiling
point.
[00265] Another aspect of the invention provides a method and system for
altering the viscosity of an aqueous solution or mixture. It has been found
that the
use of switchable water to alter the ionic strength of an aqueous solution
also results
in an alteration in the viscosity of the aqueous solution. In one embodiment,
the
method and system for switching the viscosity of an aqueous system facilitates
a
reversible small change in viscosity. Such a method and system makes use of
lower
molecular weight swichable water additives. The dissolution in water of a
lower
molecular weight switchable water additive, in its non-ionic form, will
generate a
modest increase in viscosity over water alone. However, it has been found that
addition of CO2 to such a system still causes a decrease in viscosity making
it
valuable in those situations that require only small changes in viscosity.
[00266] In another embodiment, the method and system for switching the
viscosity of an aqueous solution facilitates a relatively large reversible
change in
viscosity. Such a method and system makes use of higher molecular weight
switchable water additives. The dissolution in water of a higher molecular
weight
switchable water additive, in its non-ionic form, will generate a significant
increase in
viscosity over water alone. As will be appreciated by a worker skilled in the
art, the
large molecular weight switchable water additive must be sufficiently soluble
in water,
when the additive is in its non-ionic form, to generate the large increase in
viscosity
over water alone. When a suitable ionizing trigger is introduced, the ionic
form of the
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high molecular weight switchable water additive is generated, leading to a
relatively
large decrease in the viscosity of the solution.
[00267] A system and method for reversible alteration of viscosity would
be
useful, for example, in point to point transport of an otherwise viscous
material in
which its application calls for a higher viscosity, such as in conventional
waterflooding
techniques. Conventional waterflooding techniques are used for enhanced oil
and
gas recovery operations. Low viscosity, ionic form, polymer solutions could be
injected into oil and gas wells at pressures lower than conventional polymer
additives, at which point the solutions could be switched to a higher
viscosity by use
of a suitable trigger, which may help promote oil flow towards collection
points. Once
operations are complete it may be possible to lower the viscosity of the
solution by
switching on the polymer additive to it's ionic form, at which point the ionic
form of the
polymer additive solution could be pumped out of the well.
[00268] Another aspect of the invention provides a method and system for
reversibly lowering an aqueous solution's boiling point. Another aspect of the
invention provides a method of reversibly increasing an aqueous solution's
boiling
point.
[00269] An aspect of the invention provides a reversibly switchable
antifreeze.
[00270] An aspect of the invention provides a reversibly switchable
electrolyte.
[00271] An aspect of the invention is a method for reversibly controlling
the
attractive and repulsive forces existing in a multiphase mixture such as oil
sands
(also known as tar sands or bituminous sands). For example, in some
embodiments,
the high ionic strength aqueous solution of switchable additive could make
some or
all of the interactions between components become attractive, while some or
all of
the interactions would be less attractive or even be repulsive in the presence
of low-
ionic strength aqueous solution. Repulsive forces, for example between clay
and
bitumen, between clay particle and another clay particle, or between clay and
sand
particles, are accetable or even desired in the separation of oil sands into
bitumen
and tailings, while, in contrast, repulsive forces are acceptable or even
desired in the
treatment and settling of tailings.
[00272] In preferred embodiments, conversion of the compound of formula
(1)
to the salt is complete. In certain embodiments, the conversion to salt is not
complete; however, a sufficient amount of the amine is converted to the salt
form to
change the ionic strength of the liquid. Analogously, in some embodiments, the
conversion of ionic form back to the amine compound of formula (1) that is
water-
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miscible may not be complete; however a sufficient amount of the salt is
converted to
the amine compound of formula (1) that is water-miscible to lower the ionic
strength
of the solution.
[00273] An advantage of switchable water described herein is that it can
facilitate syntheses and separations by eliminating the need to remove and
replace
water or an aqueous solution after each reaction step. With triggers that are
capable
of causing a drastic change in the ionic strength of the water or aqueous
solution
while it is still in the reaction vessel, it may be possible to use the same
water or
aqueous solution for several consecutive reaction or separation steps. This
would
eliminate the need to remove and replace the solvent water or aqueous
solution. For
example, a chemical reaction that requires an aqueous solvent could be
performed
using the switchable water while in its amine form as the solvent. Once the
reaction
is complete, the solvent could be switched to its higher ionic strength form
which is
substantially incapable of dissolving a product and/or side-product of the
reaction.
This would force the product to precipitate, if solid, or become immiscible,
if liquid.
The solvent could then be separated from the product by physical means such
as, for
example, filtration or decantation. The solvent could then be switched back to
its
lower ionic strength form by switching the ionic form to the water-miscible
amine and
reused. This method allows the use of an aqueous solvent without the
requirement
for an energy-intensive distillation step to remove the solvent. Such
distillation steps
may be complex because both the solvent and the product may have similar
boiling
points.
[00274] Reuse and recycling of solvents of the invention provide both
economic and environmental benefits. The time required to switch between the
higher and lower ionic strength solvents is short as demonstrated by studies
described in Examples 6 and 7. In Example 6, an incomplete switch between an
additive in ionic form and nonionic form can occur in 300 minutes with
heating.
Example 6 also shows that in excess of about 90% of the ionic forms of MDEA
and
THEED were converted back to their non-ionic forms. THEED was 98%
deprotonated after 120 minutes of heating (75 C) and bubbling with N2 using a
single
needle. As shown in Figure 12 and described in Example 7, conductivity of
TMDAB
was reduced approximately 95% in 90 minutes when heated at 80 C and N2 was
bubbled through a glass frit. This result demonstrated a dramatic ionic
strength
reduction.
[00275] It is advantageous to convert from non-ionic amine form to ionic
form
and then back again (or vice-versa). The solvent comprising water and the
additive
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in its amine form could be miscible with another liquid, and then the solvent
could be
switched to increased ionic strength form to allow for separation of the
resulting two
liquid components. The liquid components may or may not appear as distinct
layers.
Methods for separation of the components may include decanting, or
centrifuging
followed by decanting. After separation, it is desirable to convert an ionic
form of the
additive back to its non-ionic amine form in water. Thus the solvent can be
reused.
[00276] In accordance with a specific embodiment, there is provided a
system,
as depicted in Figure 22, for isolating or purifying one or more compounds
from a
mixture. The system includes a means, 10 (denoted in Figure 22), for
introducing a
non-ionic switchable water to a mixture of compounds. In this example, the
first
compound is miscible in the non-ionic form of switchable water and the second
compound is insoluble. Accordingly, the system additionally comprises means,
20
(denoted in Figure 22), for mechanically collecting the second compound that
is
insoluble in the non-ionic switchable water. For example, the system can
include
means for collecting or removing the second compound by filtration thereby
leaving a
mixture, 30 (denoted in Figure 22), that includes the non-ionic switchable
water and
the first compound. The system depicted in Figure 22 further comprises means
for
contacting mixture, 30 (denoted in Figure 22), with an ionizing trigger (e.g.,
CO2) to
increase the ionic strength of the switchable water and generate a two-phase
mixture
,40 (denoted in Figure 22), in which the first compound is no longer miscible
with the
switchable water. The system shown in Figure 22 additionally comprises means,
50
(denoted in Figure 22), for collecting the immiscible first compound. For
example, the
system can include means for decanting or otherwise collecting the top layer
of
mixture, 40 (denoted in Figure 22), which top layer includes the first
compound.
Optionally, this system further includes means for reversing the ionic
strength
increase of the switchable water by introducing a non-ionizing trigger, such
as air, to
reform the non-ionic form of the switchable water, 60 (denoted in Figure 22).
[00277] Switchable water can also be useful in water/solvent separations
in
biphasic chemical reactions. Separation of a liquid from a switchable solvent
can be
effected by switching the switchable solvent to its higher ionic strength
form. This
ability to separate solvents may be useful in many industrial processes where,
upon
completion of a reaction, the solvent can be switched to its higher ionic
strength form
with the addition of a trigger allowing for facile separation of the two
distinct phases.
Thus a switchable ionic strength solvent may be used in its lower ionic
strength form
as a medium for a chemical reaction. Upon completion of the reaction, the
chemical
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product is readily separated from solution by switching the solvent to its
higher ionic
strength form. The switchable water solvent can then be recovered and reused.
[00278] To gain a better understanding of the invention described herein,
the
following examples are set forth. It should be understood that these examples
are for
illustrative purposes only. Therefore, they should not limit the scope of this
invention
in any way.
[00279] In the following Working Examples, a variety of tertiary amines
have
been studied for their properties as switchable additives in switchable ionic
strength
aqueous solutions (i.e., switchable water).
[00280] Results presented in the working examples, figures and tables
show
that six tertiary amines, selected from monoamines, diamines, triamines,
tetraamines
exhibited reversible switching ionic strength behavior. All of these compounds
were
miscible with water in aqueous solution, and in the presence of CO2 switched
to
ammonium bicarbonate salt forms which were soluble in the aqueous phase. In
addition, the working examples, figures and tables show polyamines that were
successfully used to reversibly switch ionic strength behavior of aqueous
systems.
[00281] Variations to the structure of these amine compounds are well
within
the skill of the person of ordinary skill in the art pertaining to the
invention. These
include minor substitutions, varying the length of a hydrocarbon chain, and
the like.
[00282] As described in the working examples, several salts of formulae
(2)
and (3), and of polyamines have been formed according to the invention by
reacting
CO2 with aqueous solutions of water-miscible amine compounds of formulae (1)
and
(4). The water system advantageously provides a rapid rate of reaction to form
the
ammonium bicarbonate compounds from the water-miscible compounds of formulae
(1) and (4), and allows the dissolution of the ammonium bicarbonate compounds
should they be solid at the temperature of the separation.
WORKING EXAMPLES
[00283] The following chemicals were used as received: ethanolamine, 2-
(methylamino) ethanol, chloroform-d (99.8+ atom%d), D20 (99.9+ atom%d),
acetonitrile-d3 (99.8+ atom%d), methanol-d4 (99.8+ atom%d), 1,4-dioxane
(99+%),
DMAE, MDEA, TMDAB, THEED, DMAPAP and HMTETA (Sigma-Aldrich of Oakville,
Ontario, Canada, or ICI of Portland, Oregon, USA); THF (99+%) and ethyl
acetate
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(99.5+ c1/0) (Caledon Laboratories, Ontario, Canada); hydrochloric acid (-12
M,
Fischer Scientific, Ottawa, Ontario, Canada); and DMSO-d6 (99.9+ atom%d)
Cambridge Isotope Labs, St Leonard, Canada).
[00284] Diethyl ether was purified using a double-column solvent
purification
system (Innovative Technologies Incorporated, Newbury Port, USA). Compressed
gasses were from Praxair (Mississauga, Ontario, Canada): 4.0 grade CO2
(99.99%),
5.0 grade Ar (99.999%), supercritical grade CO2 (99.999%, H20 <0.5 ppm),
nitrogen
(99.998%, H20 <3 ppm) and argon (99.998%, H2O < 5 PPn1).
[00285] Unless otherwise specified, water used in studies described
herein
was municipal tap water from Kingston, Ontario, Canada that was deionized by
reverse osmosis and then piped through a MilliQ Synthesis A10 apparatus
(Millipore
SAS, Molsheim, France) for further purification.
[00286] DBU (Aldrich, Oakville, Ontario, Canada, 98% grade) was dried by
refluxing over CaN2 and distilled under reduced pressure onto 4A molecular
sieves
and then deoxygenated by repeated freeze/vacuum/thaw cycles or by bubbling
with
CO2 followed by filtration to remove any bicarbonate precipitate.
[00287] 1H NMR and 13C NMR spectra were collected at 300 K on a Bruker
AV-400 spectrometer at 400.3 and 100.7 MHz, respectively.
[00288] COMPARATIVE EXAMPLE 1: Amidine and water system
[00289] A bicyclic amidine DBU (1,8-diazabicyclo-[5.4.0]-undec-7-ene),
having
the following structure, was investigated as an additive to provide switchable
ionic
strength aqueous solutions.
3 2
4 1 N 10
9
[00290] DBU in non-ionic amidine form was soluble in water to provide a
single phase aqueous solution. It was found to be capable of switching to a
water-
soluble amidinium bicarbonate salt form in the presence of water and a CO2
trigger.
[00291] Initial experiments with a solution of DBU in water confirmed
that
compounds THF and 1,4-dioxane were miscible with the aqueous solution of DBU
(non-ionic form) in the absence of CO2, and were immiscible with the aqueous
solution in the presence of CO2 in which the amidine had been switched into
its
amidinium bicarbonate ionic form. However, it was found that it was not
possible to
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liberate CO2 from the ionic solution with moderate heating. The two-phase
mixture of
non-aqueous THF and aqueous amidinium bicarbonate that had been generated
from exposure to CO2 could not be converted to a single-phase aqueous solution
of
DBU (non-ionic form) and THF.
[00292] Specifically, a 1:1:1 (v/v/v) mixture of DBU, water and compound
was
added to a six dram vial containing a magnetic stirrer and fitted with a
rubber septa.
To introduce gas to the solution, a single narrow gauge steel needle was
inserted
and gas was bubbled through. A second narrow gauge steel needle was inserted
to
allow venting of the gaseous phase.
[00293] When the compound was THF, a single phase miscible liquid mixture
was observed. After CO2 was bubbled through the solution for 15 min, the
mixture
separated into two phases, an aqueous phase comprising a solution of the
amidinium
bicarbonate salt of DBU and a non-aqueous phase comprising THF. Bubbling N2
through the mixture for several hours at 50 C failed to cause the phases to
recombine.
[00294] Similarly, a 1:1:1 (v/v/v) mixture of DBU, water and 1, 4-dioxane
was
observed to be a single phase miscible liquid mixture. After CO2 was bubbled
through the solution for 60 min, the mixture separated into two phases, an
aqueous
phase comprising a solution of the amidinium bicarbonate salt of DBU and a non-
aqueous phase comprising 1, 4-dioxane. Bubbling N2 through the mixture for
several
hours at 50 C failed to cause the phases to recombine.
[00295] Thus, although an aqueous solution of the amidine DBU can be
switched from a lower ionic strength form to a higher ionic strength form in
order to
force out THF or 1, 4-dioxane from the solution, the switching was not found
to be
reversible at the given experimental conditions. It is likely that with high
energy input
such as high temperatures, reversible switching would be possible.
[00296] COMPARATIVE EXAMPLE 2: Primary and secondary amine and
water systems
[00297] A primary amine, ethanolamine, and a secondary amine, 2-
(methylamino) ethanol were investigated as additives to provide switchable
ionic
strength aqueous solutions. Six dram vials comprising 3:3:1 (v/v/v) mixtures
of H20,
amine, and compound were prepared as described for comparative example 1.
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[00298] A 3:3:1 (v/v/v) mixture of H20, ethanolamine, and THF was
observed
to be a single phase solution. This solution separated into two phases after
CO2 was
bubbled through the liquid mixture for 30 minutes, with an aqueous phase and a
non-
aqueous phase comprising THF. However, the two separate phases did not
recombine into one miscible layer even after N2 was bubbled through the liquid
mixture for 90 minutes at 50 C.
[00299] A 3:3:1 (v/v/v) mixture of H20, ethanolamine, and DIVISO was
observed to be a single phase solution. This solution did not separate into
two
phases after CO2 was bubbled through the liquid mixture for 120 minutes,
however
turbidity was observed.
[00300] A 3:3:1 (v/v/v) mixture of H20, 2-(methylamino)ethanol, and THF
was
observed to be a single phase solution. This solution separated into two
phases after
CO2 was bubbled through the liquid mixture for 10 minutes, with an aqueous
phase
and a non-aqueous phase comprising THF. However, the two separate phases did
not recombine into one miscible layer even N2 was bubbled through the liquid
mixture
for 90 minutes at 50 C.
[00301] Thus, in preliminary studies, certain primary and secondary amine
additives did not exhibit reversible switchable of ionic strength character.
Although
they switched from lower ionic strength to higher ionic strength, they were
not
successfully switched from higher to lower ionic strength forms using the low
energy
input conditions of bubbling N2 through the liquid mixture for 90 minutes at
50 C. It is
noted that higher temperatures were not used due to the limitation posed by
the
boiling point of THF of 66 C. Bubbling N2 at a higher temperature may have led
to
the reverse reaction; however, THF evaporation would have been a problem.
Although not wishing to be bound by theory the inventors suggest that this
irreversibility may be as a result of carbamate formation arising from the
reaction of
available N-H groups in the primary and secondary amines with CO2. The removal
of
carbamate ions in water to give non-ionic amines by heating and bubbling a
nonreactive gas can be difficult.
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[00302] EXAMPLE 1: Reversible solvent switching in tertiary amine/water
systems
[00303] Three tertiary amines, DMAE, MDEA and THEED were investigated
as additives for switchable ionic strength solutions. DMAE and MDEA are
monoamines, and THEED is a diamine.
[00304] Six dram vials containing a magnetic stirrer and fitted with a
rubber
septa were prepared with 1:1:1 w/w/w solutions of water, THF, and an additive
of
tertiary amine compound of formula (1). To introduce gas to the solution, a
single
narrow gauge steel needle was inserted and gas was bubbled through. A second
narrow gauge steel needle was inserted to allow venting of the gaseous phase.
[00305] The solutions were tested for switchable ionic strength character
by
bubbling CO2 through the mixtures. The time necessary to observe separation of
the
THF from the aqueous solution of the ionic bicarbonate salt was recorded and
is
shown in Table 1 below. It was determined that it typically takes 30 min of
bubbling
with CO2 to separate out THF from the aqueous phase.
Table 1. Duration of CO2 bubbling required to separate THF from aqueous
phase comprising additive, and duration of N2 bubbling required to recombine
THE
and the aqueous phase
Additive Time of CO2 bubbling to get Time of N2 bubbling to get
phase separation at 25 C RT phase recombination at 50 C
(min) (min)
DMAE , ¨30 ¨90
MDEA ¨30 ¨30
THEED ¨30 ¨60
[00306] After separation of the THF into a distinct non-aqueous phase was
observed, nitrogen was then bubbled through the two-phase solutions at a
temperature of 50 C in order to remove CO2 from the aqueous phase and switch
at
least a portion of the ionic bicarbonate salt form back to the non-ionic
tertiary amine
form. If the switching reaction was sufficiently reversible to reduce the
ionic strength
of the aqueous phase to a level allowing miscibility with the THF, conversion
of the
two-phase mixture to a single aqueous phase was observed.
[00307] As shown in Table 1, all of the tested tertiary amine additives
could be
switched back from their ionic forms allowing recombination of the two phase
mixtures to a single phase.
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[00308] EXAMPLE 2: Quantitative determination of the separation of
compound and additive upon switching
[00309] The three switchable aqueous solution systems of Example 1 were
further investigated by 1H NMR spectroscopy to quantify the amount of THF
separated from the aqueous phase upon switching of the additive to its higher
ionic
strength ammonium bicarbonate form, and to quantify the amount of additive
retained
in the aqueous solution after switching.
[00310] To measure the extent of THF being forced out of an aqueous phase
by an increase in ionic strength, and the amounts of amine which remained in
the
aqueous phase, 1:1:1 w/w/w solutions of water, THF, and amine additive were
prepared in graduated cylinders and the cylinders were capped with rubber
septa.
After 30 minutes of bubbling CO2 through the liquid phase at a flow rate of 3-
5 mL
miril)as measured by a J&W Scientific ADM 2000 Intelligent Flow Meter, from a
single narrow gauge steel needle, a visible phase separation was observed. The
volumes of each phase were recorded. Aliquots of the non-aqueous and aqueous
layers were taken and dissolved in d3-acetonitrile in NMR tubes. A known
amount of
ethyl acetate was added to each NMR tube as an internal standard.
[00311] 1H NMR spectra were acquired on a Bruker AV-400 NMR
spectrometer at 400.3 MHz for several replicate solutions of each mixture, and
through integration of the ethyl acetate standard, a concentration of THF or
additive
was calculated and scaled up to reflect the total volume of the aqueous or non-
aqueous phase giving a percentage of the compound being forced out or
retained.
The results are shown in Table 2 below.
Table 2. Amount of THF separated out of aqueous phase comprising additive and
amount of additive retained in the aqueous phase
Additive Amount of THF separated Amount of additive retained
(mol%) (mol%)
DMAE 76 1.7 % 73.5 2.0 %
MDEA 74 3.0 % 90.7 1.5 %
THEED 67 5.0 % 98.6 0.2 %
[00312] The choice of tertiary amine additive was found to determine the
amount of THF separated from the aqueous phase upon switching with CO2 as
shown in Table 2. When the tertiary amine was MDEA, 74 mol% of the THF was
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separated from the aqueous phase after bubbling CO2 through the solution,
while
90.7 mol% of the additive (in ionic form) was retained in the aqueous phase.
[00313] In some embodiments, it is preferred that substantially all of
the
additive remains in the aqueous phase, rather than going into the non-aqueous
phase. This is because the utility of such solutions as reusable solvent
systems
would be increased if losses of the additive from the aqueous phase could be
minimised. In the case of MDEA, 90.7 mol% of the MDEA remained in the aqueous
phase. Thus, 9.3 mol% of the MDEA was transferred into the non-aqueous phase
comprising THF. Interestingly, THEED had the best retention in the aqueous
phase
at approximately 98.6 mol%, even though it was least successful in forcing
about
67.7 mol% of the THF out of solution.
[00314] Subsequent bubbling of N2 through the mixture lowered the ionic
strength and allowed the THF and aqueous phases to become miscible and
recombine. At 50 C, this took about 30 minutes for the MDEA/THF/water mixture
(Table 1). The rate of recombination would increase at higher temperatures,
but this
was not attempted in this case because of the low boiling point of THF
(boiling point
66 C).
[00315] These experiments were also conducted using air rather than
nitrogen
as the nonreactive gas to drive off CO2 from the aqueous solution and switch
at least
a portion of the additive from ionic form to non-ionic form. The time taken
for the
recombination of the aqueous and non-aqueous phases was approximately the same
for air as it was for N2 for each additive.
[00316] EXAMPLE 3: Quantitative determination of the separation of
compound and additive upon switching at different additive loadings
[00317] Reversible solvent switching in amine/water systems were explored
for different loadings of five additives, while keeping the ratio of THF:water
at a
constant 1:1 w/w. The additives were all tertiary amines selected from
monoamines
DMAE and MDEA, diamine TMDAB, triamine DMAPAP and tetramine HMTETA.
[00318] To measure the extent of THF being forced out of an aqueous phase
by an increase in ionic strength, and the amounts of amine which remained in
the
aqueous phase, 1:1 w/w solutions of water:THF were prepared in graduated
cylinders and the appropriate amount of amine additive added. The graduated
cylinders were capped with rubber septa. This comparison involved bubbling CO2
through a single narrow gauge steel needle for 30 min at a rate of 3-5 mL min
1 as
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measured by a J&W Scientific ADM 2000 Intelligent Flow Meter to switch the
tertiary
amine in aqueous solution with THF to ionic form. A second narrow gauge steel
tube
was provided to vent the gaseous phase. A visible phase separation into two
liquid
phases occurred, resulting in a non-aqueous and an aqueous phase. Aliquots of
the
non-aqueous and aqueous layers were taken and were spiked with a known amount
of ethyl acetate to act as an internal standard and the amounts of THF and
additive
were quantified by 1H NMR integration as discussed in Example 2. The results
are
shown in Table 3 below.
Table 3. Comparison of relative amounts of amine additive to the separation of
THF
from 1:1 w/w solutions of THF and H20 and retention of amine in aqueous phase
when reacted with CO2.
Additive THF:H20:Additive % THF Separated[al `)/0 Additive
Retainedral
(w/w/w)
DMAE 1:1:1 76 1.7 % 73.5 2.0 %
DMAE 3:3:1 85 2.2 % 93.9 2.1 %
DMAE 5:5:1 74 5.6 % 91.7 2.6 %
DMAE 10:10:1 75 0.3 % 98.3 0.4 %
MDEA 1:1:1 74 3.0 % 90.7 1.7 %
MDEA 3:3:1 74 3.8 % 95.7 1.5 %
MDEA 5:5:1 72 0.3 % 95.2 1.5 %
MDEA 10:10:1 66 3.0 % 96.6 0.6 %
TMDAB 3:3:1 87 1.3 % 87.1 2.1 %
TMDAB 5:5:1 87 0.6% 99.6 0.1 %
TMDAB 10:10:1 80 0.5 % 99.4 0.1 %
TMDAB 15:15:1 74 0.9% 98.4 0.4 %
DMAPAP 3:3:1 78 6.1 % 87.1 7.3 %
DMAPAP 5:5:1 81 1.0 % 98.4 0.4%
DMAPAP 10:10:1 69 1.4% 96.0 0.8%
DMAPAP 15:15:1 62 1.1 % 94.4 1.1 %
HMTETA 3:3:1 80 4.0 % 95.6 1.5 %
HMTETA 5:5:1 80 3.0 % 98.4 1.2 %
HMTETA 10:10:1 70 1.3 % 98.0 1.0%
HMTETA 15:15:1 65 4.9% 98.2 0.3%
Eal Determined by 1H NMR spectroscopy as discussed in Example 2.
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[00319] It is apparent that an increase in the loading of the additive
generally
resulted in an increase in the % THE separated from the aqueous solution after
switching, as would be expected. It can also be seen that the diamine compound
TMDAB at a 9 wt% loading (i.e. 5:5:1 THF:H20:amine) forced 87 % of the THE out
of
the aqueous phase after switching while 99.6 % of the additive was retained in
the
aqueous phase. Even at a 3 wr/o loading of TMDAB (15:15:1 THF:H20:amine), 74
% of the THE was forced out after switching. In comparison, the monoprotonated
additives DMAE and MDEA were only effective at higher loadings and had greater
losses of the additive to the THF phase (Table 3).
[00320] In all experiments, the effect of the increase in ionic strength
upon
switching with CO2 could be reversed; such that the THE phase recombined with
the
aqueous phase to regenerate a one phase system when the mixture was heated and
sparged with N2 or air to remove 002.
[00321] EXAMPLE 4A: Qualititative determination of the separation of
selected
compound (THE) and additive (amine) upon switching at equivalent
additive loadings
[00322] A qualitative comparison of reversible solvent switching in the
five
amine/water systems of Example 3 was undertaken at equivalent additive
loadings to
determine by 1H NMR spectroscopy the relative effectiveness of switching each
additive from non-ionic amine to ionic ammonium bicarbonate and back to non-
ionic
amine forms. Aqueous solutions (0.80 molal) of DMAE, MDEA, TMDAB, THEED,
DMAPAP, HMTETA additives were added to 1:1 w/w solutions of THF:D20 in NMR
tubes, which were sealed with rubber septa. 1H NMR spectra were acquired for
each
sample prior to any gas treatment, and are shown as the A spectra in Figures
4, 5, 6,
and 7 for DMAE, TMDAB, HMTETA and DMAPAP respectively. Two narrow gauge
steel needles were inserted and the trigger gas was gently bubble through one
of the
needles into the solution at a rate of 4-5 bubbles per second. The second
needle
served as a vent for the gas phase, which was maintained at a positive
pressure
above atmospheric by the bubbling.
[00323] CO2 was used as the trigger to switch the amine from its non-
ionic to
ionic form. 1H NMR spectra were acquired for each sample after switching with
CO2.
[00324] The spectrum obtained after switching DMAE by 20 minutes of
bubbling at 25 C with a CO2 trigger is shown as spectrum B in Figure 4.
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Subsequently, the additive was switched back to non-ionic form by bubbling a
nitrogen gas trigger through the solution for 300 minutes at 75 C and the
spectrum is
shown as spectrum C in Figure 4.
[00325] The spectrum obtained after switching TMDAB by 30 minutes of
bubbling at 25 C with a CO2 trigger is shown as spectrum B in Figure 5.
Subsequently, the additive was switched back to non-ionic form by bubbling a
nitrogen gas trigger through the solution for 240 minutes at 75 C and the
spectrum is
shown as spectrum C in Figure 5.
[00326] The spectrum obtained after switching HMTETA by 20 minutes of
bubbling at 25 C with a CO2 trigger is shown as spectrum B in Figure 6.
Subsequently, the additive was switched back to non-ionic form by bubbling a
nitrogen gas trigger through the solution for 240 minutes at 75 C and the
spectrum is
shown as spectrum C in Figure 6.
[00327] The spectrum obtained after switching DMAPAP by 20 minutes of
bubbling at 25 C with a CO2 trigger is shown as spectrum B in Figure 7.
Subsequently, the additive was switched back to non-ionic form by bubbling a
nitrogen gas trigger through the solution for 120 minutes at 75 C and the
spectrum is
shown as spectrum C in Figure 7.
[00328] EXAMPLE 4B: Quantitative determination of the separation of
selected compound (THF) and additive (amine) upon switching at
equivalent additive loadings
[00329] To measure the amount of THF being separated out of an aqueous
phase by increasing its ionic strength, and the amounts of amine which
remained in
the aqueous phase, 1:1 w/w solutions of THF and water were prepared in
graduated
cylinders. The appropriate mass of amine additive to result in a 0.80 molal
solution
was added and the cylinders were capped with rubber septa. After 30 minutes of
bubbling CO2 through the liquid phase from a single narrow gauge steel needle,
a
visible phase separation was observed. The two phases were a non-aqueous phase
comprising THF, which was forced out of the increased ionic strength aqueous
solution, and an aqueous phase comprising the additive in ionic form. The
volumes
of each phase were recorded. Aliquots of the non-aqueous and aqueous layers
were
taken and dissolved in d3-acetonitrile in NMR tubes. A known amount of ethyl
acetate was added to each NMR tube as an internal standard. 1H NMR spectra
were
acquired as for the fully protonated additives, and through integration of the
ethyl
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acetate standard, a concentration of THF or additive was calculated and scaled
up to
reflect the total volume of the aqueous or non-aqueous phase giving a
percentage of
the compound being forced out or retained. The results are shown in Table 4
below.
Table 4. Comparison of abilities of 0.80 molal aqueous solutions of amine
additives
to separate THF from 1:1 w/w solutions of THF and H20 and retention of amine
additive in the aqueous phase when reacted with CO2
Additive % THF Separated] % Additive Retained[al
DMAE 70 0.6 % 98.0 0.2 %
MDEA 61 0.6 % 99.0 1.3 %
TMDAB 82 0.6 % 99.2 0.4 A
DMAPAP 79 1.2 % 98.8 0.4 %
HMTETA 78 0.9 % 99.3 0.4 %
[a] Determined by 1H NMR spectroscopy as discussed in Example 1.
[00330] Diamine TMDAB, triamine DMAPAP and tetramine HMTETA additives
exhibited superior THF separation compared to monoamine additives DMAE and
MDEA. This observation can be explained due to the increase in ionic strength
as a
result of the increased charge on the quaternary ammonium cations resulting
from
the protonation of multiple basic nitrogen centres in the diamine, triamine
and
tetrannine. It is apparent from equation (C) that for an equimolal
concentration of
additive, an increase in the charge on the cation of the salt from +1 to +2
should give
rise to a tripling in ionic strength.
[00331] It should be noted that although TMDAB and DMPAP contain more
than two tertiary amine centres, only two of the basic sites in each molecule
are
capable of protonation as a result of switching with CO2. This means that
equimolal
solutions of the protonated salts of TMDAB, DMAPAP and HMTETA should each
exhibit a similar ionic strength, and thus similar % THF separations, as is
apparent
from Table 4.
[00332] EXAMPLE 5: Reversible protonation of amine additives in H20 as
monitored by conductivity
[00333] Protonation of aqueous solutions of three tertiary amine
additives,
DMAE, MDEA, and THEED, in response to the addition of a CO2 trigger was
performed and monitored by conductivity meter.
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[00334] Aqueous solutions of an additive with distilled, deionised H20
were
prepared (1:1 v/v H20 and DMAE, 1:1 v/v H20 and MDEA and 1:1 w/w H20 and
THEED) in sample beakers. 1:1 w/w H20 and THEED was used because a 1:1 v/v
solution was too viscous to pour accurately. A trigger gas chosen from CO2,
air or
nitrogen was bubbled at identical flow rates through the solution via a narrow
gauge
steel tube and the conductivity of the solution was measured periodically
using a
Jenway 470 Conductivity Meter (Bibby Scientific, NJ, US) having a cell
constant of
1.02 cm 1.
[00335] Results of bubbling a CO2 gas trigger through the solutions of
additives in water at room temperature are depicted in Figure 7. As shown in
this
Figure, the conductivity of each of the additive solutions rose as the amine
was
converted to its ionic form as it was contacted with the CO2 trigger. The
aqueous
solution of DMAE showed the largest rise in conductivity.
[00336] It is noted that conductivity is not simply a function of salt
concentration; conductivity is also strongly affected by a solution's
viscosity. Thus,
even if two separate additive solutions have identical numbers of basic sites
which
can be fully protonated and have identical concentrations in water, they may
have
different conductivity levels.
[00337] The deprotonation reactions of the ionic solutions of additives
in water
were monitored in a similar manner, and the conductivity plot is shown in
Figure 8.
Nitrogen gas was flushed through the solution at 80 C to switch salts back to
their
non-ionic tertiary amine form. The residual levels of conductivity exhibited
show that
none of the additives were completely deprotonated by this treatment within 6
h.
[00338] EXAMPLE 6: Reversible protonation of amine additives in D20 as
monitored by 1H NMR spectroscopy
[00339] The degree of protonation of tertiary amine additives upon
contact
with a CO2 trigger was investigated by 1H NMR spectroscopy. Two monoamines,
DMAE and MDEA, and the diamine THEED were chosen for study.
[00340] In order to establish the chemical shifts of the protonated
bases, molar
equivalents of several strong acids, including HCI and HNO3, were added to
separate
solutions of the amines dissolved in D20. 1H NMR spectra were acquired on a
Bruker AV-400 NMR spectrometer at 400.3 MHz for three replicate solutions of
each
amine. An average value of each chemical shift for each protonated base was
calculated along with standard deviations. If the bases when reacted with the
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to ionic form showed chemical shifts within this error range, they were
considered to
be 100% protonated within experimental error. The 1H NMR chemical shifts of
the
unprotonated amines were also measured.
[00341] The extent of protonation by CO2 of each additive at room
temperature
at 0.5 M (except THEED was at 0.1 M) in D20 was monitored by 1H NMR. The
amine was dissolved in D20 in an NMR tube and sealed with a rubber septa. The
spectrum was then acquired. Subsequently, two narrow gauge steel needles were
inserted and gas was gently bubbled through one of them into the solution at
approximately 4-5 bubbles per second. The second needle served as a vent for
the
gaseous phase.
[00342] Firstly CO2 was bubbled through the solution for the required
length of
time and then the spectrum was re-acquired. This process was repeated. The %
protonation of the amine was determined from the observed chemical shifts by
determining the amount of movement of the peaks from the normal position for
the
unprotonated amine towards the position expected for the fully protonated
amine.
[00343] The results shown in Figure 9 indicate that DMAE and MDEA are
fully
protonated (the peaks fell within the standard deviation of the HCI and HNO3
salts)
within 20 minutes when CO2 was bubbled through the solution. THEED is one half
protonated (49%) by 10 minutes, meaning that only one of the two nitrogen
atoms of
this diannine has been protonated.
[00344] The reverse reaction was monitored in a similar manner and the
results shown in Figure 10. Nitrogen gas was flushed through the solution at
75 C.
The spectra showed that none of the additives were completely deprotonated by
this
treatment within 5 hours, (2 hours for THEED), with the ionic form of THEED
reacting
the fastest of the three, and with DMAE being the slowest. THEED was 98 %
deprotonated (i.e., the ionic strength of the solution dropped twenty-five
fold) after 2
hours of N2 bubbling.
[00345] The observed rates of switching, as represented by the
protonation
and deprotonation processes, are affected by the manner in which the CO2 or
sparging gas was introduced (e.g., its rate of introduction and the shape of
the vessel
containing the solution). For example, a comparison of Figure 7 with Figure 9
shows
that the rate of the reaction in the 1H NMR experiment was faster than that in
the
conductivity experiment. This rate difference is due to the difference in
equipment.
The 1H NMR experiment was performed in a tall and narrow NMR tube, which is
more efficiently flushed with CO2 than the beaker used in the conductivity
tests.
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Furthermore, it is very likely that the rate of deprotonation and thus
reduction in the
ionic strength of the solution could be increased if the N2 sparging were done
in a
more efficient manner than simple bubbling through a narrow gauge tube.
[00346] Thus, a 1:1 v/v mixture of MDEA and water can be taken to 100%
protonated and returned back to about 4.5% protonation by bubbling/sparging
with
N2. It is possible to calculate an approximate ionic strength of the 100% and
4.5%
degrees of protonation of the amine additive. The density of MDEA is 1.038
g/mL, so
a 1 L sample of this mixture would contain 500 g of water and 519 g (4.4 mol)
MDEA.
Therefore the concentration of MDEA is 4.4 M. The ionic strength, assuming an
ideal
solution and assuming that the volume does not change when CO2 is bubbled
through the solution, is 4.4 M at 100% protonation and 0.198 M at 4.5%
protonation
(using equation (A) above).
[00347] EXAMPLE 7: Reversible protonation of amine additives in H20 as
monitored by conductivity
[00348] Three tertiary polyamine additives were selected for further
investigation of additives for switchable ionic strength aqueous solutions.
TMDAB is
a diamine, DMAPAP is a triamine, and HMTETA is a tetramine.
[00349] 1:1 v/v solutions of the various additives and distilled,
deionised water
were prepared in six dram glass vials and transferred to a fritted glass
apparatus
which acted as a reaction vessel. The fritted glass apparatus consisted of a
long
narrow glass tube leading to a fine glass frit having a diameter of
approximately 4
cm. The other end of the glass frit was connected to a cylindrical glass tube
which
held the solution of the additive during contacting with the trigger gas. This
apparatus allowed a multiple source of trigger gas bubbles to contact the
solution,
compared to the single point source of Example 5.
[00350] A trigger gas chosen from CO2, air or nitrogen was bubbled
through
the solution via the glass frit at a flow rate of 110 mL min-1 as measured by
a J&W
Scientific ADM 2000 Intelligent Flowmeter (CA, USA). For each conductivity
measurement, the solution was transferred back to a six dram vial, cooled to
298 K
and measured in triplicate. Conductivity measurements were performed using a
Jenway 470 Conductivity Meter (Bibby Scientific, NJ, US) having a cell
constant of
1.02 cm-1.
[00351] Figure 11 shows a plot of the conductivity changes resulting from
bubbling CO2 through the three solutions at 25 C. It is apparent that HMTETA
(0)
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and DMAPAP (A), the tetramine and triamine respectively, exhibit lower
conductivities than TMDAB (*), the diamine. In addition, TMDAB exhibits the
highest
rate of conductivity increase.
[00352] The reverse reaction was monitored in a similar manner and the
results shown in Figure 12. Nitrogen gas was flushed through the solution at
80 C.
It is apparent that the conductivity of the solution of HMTETA (m) in ionic
form returns
to close to zero after 20 minutes, indicating substantial removal of CO2 from
the
solution and reversion of the additive to its non-ionic form. The rate of
conductivity
decrease is highest for TMDAB (s), the diamine, indicating it can be
reversibly
switched between non-ionic and ionic forms at a higher rate than HMTETA and
DMAPAP (A)
[00353] The observed rates of switching, as represented by the changes in
conductivity, appear to be affected by the manner in which the CO2 or sparging
gas
was introduced (e.g., its rate of introduction and the shape of the vessel
containing
the solution). For example, a comparison of Figure 11 with Figure 7 shows that
the
rate of the reaction utilising the fritted gas apparatus appears to be faster
than that
the delivery of the trigger via a narrow gauge steel tube, although it is
accepted that
different additives are being compared. This may be because the fritted glass
apparatus is more efficiently flushed with CO2 than the beaker used in the
conductivity tests.
[00354] EXAMPLE 8: Emulsion formation and disruption of solutions
comprising a surfactant and switchable amine additive
[00355] Three vials were prepared, each containing 0.462 g N,N,N',N'-
tetramethy1-1,4-diaminobutane (TMDAB) in 4 mL water (giving a 0.80 molal
solution)
and 20 mg SDS (sodium dodecyl sulfate, a nonswitchable surfactant) at 0.50 wt%
loading. To each vial n-decanol (0.25 mL) was added and the vials were capped
with
rubber septa. Figure 13, photograph "A" shows the three vials at this stage in
the
experiment. In each vial, there are two liquid phases. The lower liquid
aqueous
phase has a larger volume and is transparent and colourless. The upper liquid
n-
decanol phase has a smaller volume and is also colourless though is is not as
transparent. n-Decanol is not miscible with neat water.
[00356] The three vials were then shaken by hand for 30 seconds. Figure
13,
photograph "B" shows the appearance after the shaking. All three vials show an
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opaque liquid mixture with cloudiness and foaming typical of an emulsion,
which is as
expected because of the presence of the known surfactant SDS.
[00357] Gases were then bubbled through the solutions for 30 min via a
narrow gauge steel needle inserted through the septum and down into the liquid
mixture. For each vial, gas was allowed to vent out of the vial via a short
second
needle inserted into the septum but not into the liquid phase. The gas was CO2
for
the left vial and N2 for the centre and right vials. Figure 13, photograph "C"
shows
the appearance after the treatment with gas. Only the right two vials show the
cloudiness typical of an emulsion. The liquid in the left vial is now clear
and free of
foam, showing that the conversion of the aqueous solution to its high-ionic
strength
form has greatly weakened the ability of the SDS to stabilize emulsions and
foams.
The liquid contents of the centre and right vials still show the cloudiness
and
foaminess typical of an emulsion, indicating that bubbling N2 gas through the
solution
does not have the effect of weakening the ability of SDS to stabilize
emulsions and
foams. This is because N2 had no effect on the ionic strength of the aqueous
phase.
[00358] While the left vial was allowed to sit for 30 min without further
treatment, CO2 gas was bubbled through the liquid phase of the centre vial for
30 min
and N2 was bubbled through the right vial. Figure 13, photo "D" shows the
appearance of the three vials after this time. The liquids in the left and
centre vials
are now largely clear and free of foam, showing that the conversion of the
aqueous
solution to its high-ionic strength form has greatly weakened the ability of
the SDS to
stabilize emulsions and foams. The emulsion and foam still persist in the
right vial.
[00359] N2 gas was bubbled through the liquid phases of the left and
centre
vials for 90 min in order to remove CO2 from the system and thereby lower the
ionic
strength of the aqueous solution. The two vials were then shaken for 30 min.
During
this gas treatment and shaking, the right vial was left untouched. Figure 13,
photograph "E" shows the appearance of the three vials after this time. All
three
exhibit the cloudiness typical of an emulsion, although foaminess in the left
two vials
is not evident, presumably because the conversion of the aqueous solution back
to a
low ionic strength is not complete. In practice, substantial conversion to low
ionic
strength is not difficult. However, it can be more difficult to achieve
complete
conversion.
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[00360] EXAMPLE 9: Description of ionic strength
[00361] The ionic strength of an aqueous solution of the salt will vary
depending upon the concentration of the salt and the charge on the ammonium
ion.
For example, an amine B having n sites which can be protonated by carbonic
acid to
provide a quaternary ammonium cation of formula {BH';+] , may have a switching
reaction shown in reaction (1):
B + nH20 + nCO2 [BH"++ n[03CH] reaction (1)
[00362] If the molality of the amine in aqueous solution is m, the ionic
strength
I of the ionic solution after switching can be calculated from equation (C):
I =1/2 m (n2 + n) (C)
[00363] Thus, for a given molality m, the ionic strength of a
diprotonated
diamine (n=2) will be three times that of a monoprotonated monoamine (n=1).
Similarly, the ionic strength of a triprotonated triamine (n=3) will be six
times that of
that of a monoprotonated monoamine and the ionic strength of a tetraprotonated
tetramine (n=4) will be ten times that of a monoprotonated monoamine. Thus, by
increasing the number of tertiary amine sites in the compound of formula (1)
which
can be protonated by the trigger, the ionic strength of a solution comprising
the
corresponding salt of formula (2) can be increased, for a given concentration.
[00364] Not all the basic sites on a compound of formula (1) may be
capable
of protonation by a gas which generates hydrogen ions in contact with water.
For
instance, when the gas is CO2, the equilibrium between CO2 and water and the
dissociated carbonic acid, H2CO3 is shown in reaction (2):
CO2 + H20 H+ + HCO3¨ reaction (2)
[00365] The equilibrium constant, Ka for this acid dissociation is
calculated
[H+] _HCCc
from the ratio 2at equilibrium ¨ in dilute solutions the concentration of
water is essentially constant and so can be omitted from the calculation. The
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equilibrium constant Ka is conventionally converted into the corresponding pKa
value
by equation (D):
pKa = -log Ka (D)
[00366] The pKa for reaction (2) is 6.36. The corresponding equilibrium
for the
dissociation of a protonated amine base BR (i.e. the conjugate acid) is
provided by
reaction (3),
BH H + B reaction (3)
[00367] The equilibrium constant KaH , for the conjugate acid BH+
dissociation
[B][H+ ]
is calculated by the ratio [Bil] . The equilibrium constant KaH is
conventionally
converted into the corresponding pl<E4 value analogously to equation (D). From
the
foregoing, it will be apparent that the equilibrium constant for the switching
reaction
shown in reaction (1) above in which n=1 can be calculated from the ratio
[BH + ][HCO3-1 K K
[B][CO2] , which is equivalent to KaR . The ratio K
I-1 can also be expressed
1 PKõH¨PKõ
in terms of the corresponding pK values as 0 . Thus, in the case of the
dissociation of CO2 in water, if the pKaH value of the conjugate acid BH+
exceeds
[BH+][HC031
]
6.36, the ratio [B][CO2 is greater than 1, favoring the production of
ammonium bicarbonate. Thus, it is preferred that a salt as used herein
comprises at
least one quaternary ammonium site having a pKaH greater than 6 and less than
14.
Some embodiments have at least one quaternary ammonium site having a pKaH in a
range of about 7 to about 13. In some embodiments the salt comprises at least
one
quaternary ammonium site having a pKaH in a range of about 7 to about 11. In
other
embodiments, the salt comprises at least one quaternary ammonium site having a
pKaH in a range of about 7.8 to about 10.5.
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[00368] EXAMPLE 10: Synthesis of Diamine and Triamine Switchable
Additives
[00369] Example 10A: Synthesis of N,N,N',N'-tetraethyl-1,4-diaminobutane
(TEDAB)
[00370] 4.658 g (63.4 mmol) diethylamine was dissolved in 100 mL
dichloromethane and cooled to 0 C. 2.339 g (15.1 mmol) succinyl chloride was
added dropwise to the solution. The solution was warmed to room temperature
and
stirred for 18 hours.
[00371] An aqueous solution 0.80 mL concentrated HCI and 25 mL H20 was
added to the mixture to wash the organic layer. The organic layer was then
removed
and dried with MgSO4. The solvent was removed in vacuo to yield 3.443 g of
N,N,N',N'-tetraethylsuccinamide in 99% yield. 1H NMR (400 MHz CDCI3) ¨ .5:
3.37 (q,
= 7 Hz, 8H), 2.69 (s, 4H), 1.20 (t, J = 7 Hz, 6H), 1.11 (t, J = 7 Hz, 6H).
[00372] 3.443 g (15.1 mmol) of N,N,N',N'-tetraethylsuccinamide is
dissolved in
100 mL THF, degassed with N2 and cooled to 0 C. 61.0 mL of 2.0M LiAIH4 in THF
solution (122 mmol) was added dropwise to the solution. The solution was then
refluxed for 6 hours.
[00373] The solution was then cooled to 0 C and the excess LiAIH4 was
quenched by adding 4.6 mL H20, 4.6 ml, 15% NaOH, and 13.8 mL H20. The solution
was warmed to room temperature and stirred for 12 hours. The precipitate was
filtered off and washed with THF. The washings were combined with the original
THF
solution and dried with MgSO4. The solvent was removed in vacuo to yield 2.558
g of
a brown liquid resulting in a 84.6 A yield of N,N,N',N'-tetraethy1-1,4-
diaminobutane.
1H NMR (400 MHz CDCI3) ¨ 5: 2.55 (q, = 7 Hz, 8H), 2.41 (t, J = 7 Hz, 4H), 1.43
(t, J
= 7 Hz, 4H), 1.02 (t, J = 7 Hz, 12H).
[00374] All other straight chain diamines, N,N,N',N'-tetrapropy1-1,4-
diaminobutane and N,N'-diethyl-N,N'-dipropy1-1,4-diaminobutane, were
synthesized
in a similar fashion utilizing the appropriate starting materials. Succinyl
chloride,
diethylamine, dipropylamine, lithium aluminum hydride solution were all
purchased
from Sigma Aldrich and used as received. N-ethylpropylamine was purchased from
Alfa Aesar and the solvents and MgSO4 were purchased from Fisher and used as
received.
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[00375] EXAMPLE 10B: Synthesis of 1,1',1"-(cyclohexane-1,3,5-
triy1)tris(N,N,-
dimethylmethanamine) (CHTDMA)
[00376] 1.997 g (9.2 mmol) 1,3,5-cyclohexane-tricarbboxylic acid was
taken
up in 40 mL dichloromethane to create a suspension. 3.84 g (29.8 mmol) oxalyl
chloride and one drop of DMF were added to the solution. The solution was
refluxed
for 3 hours, giving a yellow solution with white precipitate. The mixture was
cooled to
room temperature and the solvent was removed in vacuo resulting in 2.509 g of
a
solid which contained both the desired 1,3,5-cyclohexane tricarbonyl
trichloride and
unwanted salts. 1H NMR (400 MHz CD0I3) -6: 2.88 (t, J = 9 Hz, 3H), 2.69 (d, J
= 13
Hz, 3H), 1.43 (q, J = 13 Hz, 3H).
[00377] 2.509 g of the solid mixture was taken up in 50 mL THF and cooled
to
0 C. 34.5 mL of a 2.0 M dimethylamine solution in THF (69 mmol) was added. The
solution was warmed to room temperature and stirred for 18 hours. The solvent
was
then removed in vacuo leaving a yellow solid. The solid was taken up in a
solution of
2.081 g (37.1 mmol) KOH in 20 mL H20. Organic contents were then extracted
with 3
x 40 mL chloroform washings. The organic washings were collected and the
solvent
removed in vacuo to yield 1.930 g of a yellow liquid, N,N,N',N',N",N"-
hexamethylcyclohexane-1,3,5-tricarboxamide in 70.2 `)/0 yield. 1H NMR (400 MHz
CDCI3) - 6: 3.06(s, 9H), 2.92 (s, 9H), 2.65 (q, J = 15 Hz, 3H), 1.86 (t, J = 8
Hz, 6H).
[00378] 1.930 g (6.5 mmol) of N,N,N',N',N",N"-hexamethylcyclohexane-1,3,5-
tricarboxamide was dissolved in 80 mL THF and cooled to 0 C. 42.0 mL of 2.0M
LiA1H4 in THF solution (84 mmol) was added dropwise to the solution. The
solution
was then refluxed for 6 hours.
[00379] The solution was then cooled to 0 C and the excess LiA1H4 was
quenched by adding 3.2 mL H20, 3.2 mL 15% NaOH, and 9.6 mL H20. The solution
was warmed to room temperature and stirred for 12 hours. The precipitate was
filtered off and washed with THF. The washings were combined with the original
solution and dried with MgSO4. The solvent was removed in vacuo to yield 1.285
g of
a yellow liquid resulting in a 54.4% yield of 1,1',1"-(cyclohexane-1,3,5-
triy1)tris(N,N,-
dimethylmethanmine). 1H NMR (400 MHz CDCI3) -6: 2.18 (s, 18H), 2.07 (d, J = 7
Hz, 8H), 1.89 (d, J = 12 Hz, 3H), 1.52, (m, J= 7 Hz, 3H), 0.48 (q, J = 12 Hz,
3H). M =
255.2678, Expected = 255.2674.
[00380] Other cyclic triamines, N,N,N',N',N",N"-1,3,5-
benzenetrimethanamine,
were synthesized in a similar fashion utilizing the appropriate starting
materials.
1,3,5-benzenetricarbonyl trichloride was purchased from Sigma Aldrich and used
as
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received. 1,3,5-cyclohexanetricarboxylic acid was purchased from TCI and used
as
received.
[00381] EXAMPLE 11: Controlling the zeta potential of suspended clay
particles in water
[00382] In a suspension of solid particles in a liquid, a zeta potential
near to
zero indicates that the particles have little effective surface charge and
therefore the
particles will not be repelled by each other. The particles will then
naturally stick to
each other, causing coagulation, increase in particle size, and either settle
to the
bottom of the container or float to the top of the liquid. Thus the suspension
will not
normally be stable if the zeta potential is near zero. Therefore having the
ability to
bring a zeta potential close to zero is useful for destabilizing suspensions
such as
clay-in-water suspensions. However, strategies such as addition of calcium
salts or
other salts are sometimes undesirable because, while these strategies do cause
the
destabilization of suspensions, the change in water chemistry is essentially
permanent; the water cannot be re-used for the original application because
the
presence of added salts interferes with the original application. Therefore
there is a
need for a method for destabilizing suspensions that is reversible.
[00383] Experimental methods:
[00384] Clay fines were weighed and placed into individual vials (0.025
g,
Ward's Natural Science Establishment). Kaolinite and montmorillonite were used
as
received, but illite clay was ground into a powder using a mortar and pestle.
Solutions containing additives were made with deionized water (18.2 MO/cm,
Millipore) and 10 mL was added to the clay fines. A suspension was created
using a
vortex mixer and subsequently dispensed into a folded capillary cell. The zeta
potential was measured using a Malvern Zetasizer instrument. The errors
reported
on the zeta potential values were the standard deviations of the zeta
potential peaks
measured.
[00385] Unless specified, all carbon dioxide treatments were conducted
with
the aqueous solutions prior to addition to the clay fines. For applicable
measurements, ultra pure carbon dioxide (Supercritical CO2 Chromatographic
Grade,
Paxair) was bubbled through the solutions using a syringe.
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Results:
IIlite
Additive Zeta Potential (mV)
0.8 molal BDMAPAP - 19.1 3.92
0.8 molal BDMAPAP + 1h CO2 -1.87
0.8 molal TMDAB - 26.0 3.92
0.8 molal TMDAB + 1h CO2 -4.56
1 mM TMDAB -39.5 6.32
1 mM TMDAB + 1.5 hour CO2 -4.69 4.23
mM TMDAB -48.2 7.44
10 mM TMDAB + 1.5 hour CO2 -3.12 7,16
Kaolin ite
Additive Zeta Potential (mV)
0.8 molal BDMAPAP -24.3 2.29
0.8 molal BDMAPAP + 1h CO2 -3.99
0.8 molal TMDAB - 17.4 3.92
0.8 molal TMDAB + lh CO2 2.29
1 mM TMDAB -39.6 6.68
1 mM TMDAB + 1.5 hour CO2 -5.03 4.46
10 mM TMDAB -50.7 13.1
10 mM TMDAB + 1.5 hour CO2 -3.35 8.49
Montmorillonite
Additive Zeta Potential (mV)
0.8 molal BDMAPAP -16.8 4.64
0.8 molal BDMAPAP + 1h CO2 -2.99
0.8 molal TMDAB -25.8 4.14
0.8 molal TMDAB + lh CO2 -5.52
1 mM TMDAB -40.2 6.87
1 mM TMDAB + 1.5 hour CO2 -3.20 4.61
10 mM TMDAB -23.6 5.68
10 mM TMDAB + 1.5 hour CO2 9.07 4.18
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[00386] For three of the clays tested, it was found that switchable water
additives TMDAB and BDMAPAP were effective additives for changing clay zeta
potentials. Upon addition of CO2, the absolute values of the clay zeta
potentials were
reduced. This effect was observed even at low concentrations of the switchable
water additive (1 mM).
[00387] The data above demonstrates the ability of switchable water to
affect
the zeta potential of clay suspensions, however, the CO2 treatments were
conducted
on the aqueous solutions of TMDAB before the clay fines were added (a method
referred to as "switching externally"). Another experiment was performed in
which
CO2 was bubbled through a 1 mM aqueous solution of TMDAB that already
contained clay fines (a method referred to as "switching in situ"). The
results with
kaolinite clay are summarized in the table below.
Kaolinite clay
Zeta Potential (my)
Switching externally Switching in situ
1 mM TMDAB -39.6 6.68 -38.9 . 8.69
1 mM 170DAB + 1 h CO2 -5.03 4.46 -0.31 4.15
1 mMTMDAE3 + 1 h CO2+ 1.5 n 1+42. -25.0 5.84 -32.5 6.38
at 70'C
[00388] It was observed that the magnitude of the zeta potential of the
clay
surfaces decreased regardless of whether the switching externally method or
the
switching in situ method was used. In addition, the zeta potential could be
restored
to its original value upon treatment with nitrogen gas at 70 C.
[00389] EXAMPLE 12: Reversible destabilization of a clay-in-water
suspension
[00390] Three variations of clay settling experiments were conducted with
1
mM TMDAB (ICI America, Batch FIB01) to elucidate the ability of this
switchable
ionic strength additive to affect stability of clay suspensions.
[00391] Experiment 1
[00392] As depicted in Figure 14A, Kaolinite clay fines (5 g) were added
to 100
mL of 1 mM TMDAB in deionized water. The mixture was stirred for 15 minutes at
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900 rpm prior to transferring into a 100 mL graduated cylinder, which was
subsequently sealed with a rubber septum. Settling of the clay fines was
monitored
as a function of time using a cathetometer.
[00393] CO2 was bubbled through 100 mL of 1 mM TMDAB using a dispersion
tube for 1 hour. Kaolinite fines (5 g) were added to the aqueous solution and
the
mixture was stirred for 15 minutes at 900 rpm prior to transferring into a 100
mL
graduated cylinder and sealing with a rubber septum. Settling of clay fines
was
monitored. CO2 was bubbled through 100 mL of 1 mM TMDAB using a dispersion
tube for 1 hour. The solution was heated to 70 C and N2 was bubbled through
for 1
hour. After cooling to room temperature, kaolinite fines (5 g) were added and
the
mixture was stirred 900 rpm for 15 minutes prior to transferring into a 100 mL
graduated cylinder and sealing with a rubber septum. Settling of clay fines
was
monitored.
[00394] Experiment 2
[00395] As depicted in Figure 14B, Kaolinite clay fines (5 g, Ward's
Natural
Science Establishment) were added to 100 mL of 1 mM TMDAB in deionized water.
The mixture was stirred for 15 minutes at 900 rpm prior to transferring into a
100 mL
graduated cylinder, which was subsequently sealed with a rubber septum.
Settling of
the clay fines was monitored as a function of time.
[00396] CO2 was bubbled through the suspension above. The mixture was
stirred for 15 minutes at 900 rpm prior to transferring into a 100 mL
graduated
cylinder, which was subsequently sealed with a rubber septum. Settling of the
clay
fines was monitored.
[00397] The clay fines above were resuspended in the solution and the
mixture was heated to 70 C. N2 was bubbled through for 1 hour. After cooling
to
room temperature, the mixture was stirred 900 rpm for 15 minutes prior to
transferring into a 100 mL graduated cylinder and sealing with a rubber
septum.
Settling of clay fines was monitored.
[00398] Experiment 3
[00399] As depicted in Figure 140, Kaolinite clay fines (5 g, Ward's
Natural
Science Establishment) were added to 100 mL of 1 mM TMDAB in deionized water.
The mixture was stirred for 15 minutes at 900 rpm prior to transferring into a
100 mL
graduated cylinder, which was subsequently sealed with a rubber septum.
Settling of
the clay fines was monitored as a function of time.
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[00400] The suspension above was filtered. CO2 was bubbled through the
filtrate for 1 hour. Kaolinite clay fines (4.5 g) were added and the mixture
was stirred
for 15 minutes at 900 rpm prior to transferring into a 100 mL graduated
cylinder,
which was subsequently sealed with a rubber septum. Settling of clay fines was
monitored.
[00401] Control Experiment
[00402] CO2 was bubbled through 100 mL of deionized water for 1 h.
Kaolinite
clay (5 g) was added and the mixture was stirred for 15 minutes at 900 rpm
prior to
transferring into a 100 mL graduated cylinder, which was subsequently sealed
with a
rubber septum. Settling of clay fines was monitored.
[00403] Results
[00404] Experiment 1 was conducted to examine the effect of the
switchable
water additive on the settling behavior of clay. The switching was conducted
in the
absence of clay to ensure that the switching occurred fully without any
impedance
from the clay. The results are plotted in Figures 15A-C.
[00405] A stable suspension was formed with kaolinite clay and 1 mM
TMDAB. However, kaolinite clay with 1 mM of CO2 treated TMDAB resulted in the
settling of clay with a clean supernatant and a clear sediment line. A stable
suspension was also formed with kaolinite clay and 1 mM of TMDAB treated for 1
hour with CO2 followed by 1 hour of N2 treatment. Photographs were taken after
each
1 hour treatment and are provided in Figure 15D.
[004061 Experiment 2 was conducted to examine if the switchable water
additives would still switch upon addition of CO2 in the presence of kaolinite
clay.
[00407] Kaolinite clay and 1 mM TMDAB were initially mixed to give a
stable
suspension. This suspension was treated with CO2, which resulted in the
settling of
the clay fines with a clean supernatant and a clear sediment line. As shown in
Figures 16A-B, the behavior observed was exactly as that observed for
Experiment
1. The settled clay was stirred to reform a suspension, which was treated with
N2,
after which the suspension was stable. Experiment 3 was conducted to determine
if
the switchable ionic strength additive adheres to the clay surface and would
therefore
be lost upon removal of the clay. The suspension created with the CO2 treated
filtrate settled much like the previous two experiments. A clear sediment line
was
observed, however, the liquid above the sediment line was turbid and still
contained
clay fines (See, Figures 17A and C). This behavior was also observed with
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deionized water treated with CO2 in the absence of any switchable water
additive
(See, Figures 17B and C).
[00408] EXAMPLE 13: The Removal of Water from an Organic Liquid
[00409] 2.710 g THF (3.76 x 10-2 mol) and 0.342 g H20 (1.90 x 102 mol)
were
mixed together in a graduated cylinder to create a single phase solution of
roughly
8:1 THF:H20 (w/w). 0.109 g (7.56 x 10-4 mol) of N,N,N'N'-tetramethy1-1,4-
diaminobutane (TMDAB) was added to the solution again generating a single
phase
solution. The THF:TMDAB ratio was approximately 25:1 (w/w). This solution
containing three components had a mol% composition as follows: 65.6 mol% THF,
33.1 mol% H20, and 1.3 mol% TMDAB.
[00410] A stir bar was added to the solution in the graduated cylinder
and the
cylinder was capped with a rubber septa. A long narrow gauge steel needle was
inserted through the septa and into the solution. A second needle was pushed
through the septa but not into the solution. CO2 was bubbled into the solution
through
the first steel needle at a flow rate of about 5 mL mind with stirring of -300
RPM for
30 minutes. At the end of the bubbling a clear, colourless aqueous phase at
the
bottom of the cylinder had creamed out of the original organic phase. The
organic
phase was separated from the aqueous phase by decantation.
[00411] 76.1 mg of the top organic phase was extracted and placed in an
NMR tube. The sample was diluted with deuterated acetonitrile and 32.3 mg of
ethyl
acetate was added to act as an internal standard. A 1 H NMR spectrum was
acquired. Using the integration of the NMR signals of the H20 and TMDAB
compared
to those of the known amount of ethyl acetate added, calculated masses of 4.58
mg
and 0.46 mg of H20 and TMDAB were acquired respectively. The remaining mass of
71.06 mg corresponds to the THF in the sample.
[00412] The "dried" organic THF phase had a mol% composition as follows:
79.3 mol% THF, 20.5 mol% H20 and 0.3 mol% TMDAB.
[00413] EXAMPLE 14: Use of a switchable additive to expel an organic
compound out of water and then the removal of much of the additive
from the aqueous phase
[00414] In some embodiments, the non-ionized form of the additive is
water-
immiscible. This makes it possible to create high ionic strength in the water,
while
CO2 is present, in order to achieve some purpose such as the expulsion of an
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organic compound from the aqueous phase and then, by removing the CO2, to
recover the majority of the additive from the water. Here we describe the
expulsion
of THF from a water/THF mixture and subsequent recovery of much of the
additive
from the water.
[00415] 1.50 g H20, 1.50 g THF, and 0.30g N,N,N'N'-tetraethyl-1,4-
diaminobutane (TEDAB) were mixed together in a graduated cylinder to generate
a
single phase solution. The solution had a total volume of 3.54 mL. A small
stir bar
was added to the solution and the cylinder was capped with a rubber septa. The
following procedure was run in triplicate with a new sample (of the same
contents
shown above) each time.
[00416] A long, narrow gauge needle was inserted through the septa into
the
solution. A second small needle was inserted into the septa but not into the
solution
itself. CO2 was bubbled through the solution a flow rate of about 5 ml/min for
45
minutes with stirring until a 2nd phase creams out on top of the aqueous
phase. The
CO2 bubbling was stopped and the needles withdrawn. The cylinder was immersed
in a hot water bath for several seconds to facilitate the separation of the
liquid
phases. Both phases were clear and yellow in colour. The top organic layer had
a
volume of 1.50 mL and the remaining aqueous layer had a volume of 2.04 mL.
[00417] The organic phase was decanted off giving a mass of 1.253 g
(density
= 0.84 g/mL). The aqueous phase had a mass of 1.94 g (density = 0.98 g/mL)
resulting in a loss of 0.12 g due to transferring of solutions or blow-off.
[00418] A 39.1 mg sample of the organic phase was placed in an NMR tube
with deuterated acetonitrile and 50.2 mg ethyl acetate to act as an internal
standard.
A 66.2 mg sample of the aqueous phase was placed in a 2'd NMR tube with
deuterated acetonitrile with 22.3 mg ethyl acetate to act as an internal
standard. A 1H
NMR spectra was acquired and knowing the corresponding amount of ethyl acetate
in each sample the resulting amounts of THF in the aqueous sample and additive
in
the organic sample can be calculated. Knowing the mass, volume, and density of
each layer, the total amount of THF or additive in a respective layer can be
calculated.
[00419] It was found that an average of 77.2 3.5% THF was removed from
the aqueous phase with 91.1 3.7 % of the TEDAB residing in the aqueous
phase.
[00420] 1.943 g (1.90 mL) of the aqueous phase was returned to the same
graduated cylinder. The needles and septa were put back into the cylinder and
the
cylinder was immersed in a 60 C water bath. N2 was introduced in the same
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as CO2 performed previously and the N2 was bubbled through the solution for 90
minutes causing a deep yellow organic phase to cream out of the aqueous phase.
[00421] The new organic phase had a volume of 0.17 mL leaving an aqueous
phase of 1.57 mL. The organic layer was decanted off giving a mass of 0.09 g
while
the remaining aqueous phase had a mass of 1.507 g (density = 0.96 g/mL). A
37.9
mg sample of the aqueous phase was taken up in an NMR tube with deuterated
acetonitrile and 41.5 mg ethyl acetate to act as an internal standard. A 1H
NMR
spectra was acquired and using the same procedure of comparing integrations as
performed above, it was found that 49.3 6.3 % of the TEDAB was removed from
the aqueous phase. It was also found that the overall 90.0 2.1 % of the
total THF
had been removed from the aqueous phase at the end of the procedure.
[00422] Using N,N'-diethyl-N,N'-dipropy1-1,4-diaminobutane instead of
N,N,N'N'-tetraethyl-1,4-diaminobutane (TEDAB) in the above procedure caused
the
expulsion of 68% of the THF from the aqueous phase after CO2 treatment. After
N2
treatment of the separated aqueous phase, 81% of the N,N'-diethyl-N,N'-
dipropyl-
1,4-diaminobutane was removed from the aqueous phase.
[00423] EXAMPLE 15: Determining the miscibility of several diamines and
triamines with water in the presence and absence of CO2
[00424] In some embodiments, the non-ionized form of the additive is
water-
immiscible while the charged form is water-miscible or water-soluble. The
following
experiments were performed in order to identify whether certain diamines and
triamines have this phase behavior.
[00425] A 5:1 w/w solution of water and the liquid additive (total volume
5 mL)
were mixed together in a glass vial at room temperature. Whether the mixture
formed one or two liquid phases was visually observed. Then CO2 was bubbled
through the mixture via a single narrow gauge steel needle at a flow rate of ¨
5 mL
min-lfor 90 min. Whether the mixture formed one or two phases was visually
observed. The results were as follows:
Additive Before addition of CO2 After addition of CO2
1,3,5-C61-13(CH2NMe2)3 miscible miscible
1,3,5-cycloC6Hg(CH2NMe2)3 immiscible miscible
Et2NCH2CH2CH2CH2NEt2 immiscible miscible
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Additive Before addition of CO2 After addition of CO2
PrEtNCH2CH2CH2CH2NPrEt immiscible miscible
Pr2NCH2CH2CH2CH2NPr2 immiscible immiscible
[00426] EXAMPLE 16: Preparation and use of a polyamine for expulsion of
acetonitrile from water
[00427] EXAMPLE 16A: Preparation of the polyamine:
I
rNH2 NHH2 formaldehyde NMe2
H formic acid
NH
2 reflux, 16h
-n
I'vle2N"NMe2
[00428] Polyethyleneimine samples of three different molecular weights
(M.W.
600, 99%; M.W. 1800, 99%; and M.W. 10,000, 99% ) were purchased from Alfa
Aesar. Formaldehyde (37% in H20) and formic acid were purchased from Sigma-
Aldrich. All reagents were used without further purification. Amberlite TM IRA-
400 (OH)
ion exchange resin was purchased from Supelco.
[00429] For the samples using polyethyleneimine M.W. 600 and 1800: A 250
mL round bottom flask was equipped with a 2 cm teflon stirring bar and placed
over a
magnetic stirring plate. 1.8 g (M.W. 600: 41.9 mmol, 1 eq, M.W. 1800: 41.9
mmol, 1
eq) of the polyethyleneimine were placed in the flask and 9.73 mL (120 mmol:
M.W.
600:40 eq and M.W. 1800 120 eq) formaldehyde solution and 4.53 mL (120 mmol:
M.W. 600: 40 eq and M.W. 1800 120 eq) formic acid were added. The flask was
equipped with a condenser and the reaction mixture was heated to 60 C for 16
hour
with an oil bath. After 16 hour the mixture was allowed to cool to room
temperature
and the solvents were removed under reduced pressure. Then, the crude product
was dissolved in 20 mL Et0H anhydrous and 4 g of Amberlite resin was added to
the
solution. The resulting mixture was stirred for 4 hour or for 16 hour at room
temperature before the resin was filtered of and the Et0H was removed under
reduced pressure. The methylated polymer was obtained as a dark yellow oil
(1.8 g
from the M.W. 600 sample and 1.7 g from the M.W. 1800 sample).
[00430] For the sample using polyethyleneimine M.W. 10,000: A 250 mL
round bottom flask was equipped with a 2 cm teflon stirring bar and placed
over a
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magnetic stirring plate. 1.8 g (41.9 mmol, 1 eq) of the polyethyleneimine were
placed
in the flask and 9,73 mL (120 mmol, 120 eq) formaldehyde solution and 4.53 mL
(120 mmol, 120 eq) formic acid were added. The flask was equipped with a
condenser and the reaction mixture was heated to 60 C for 16 hour with an oil
bath.
After 16 hour the mixture was allowed to cool to room temperature and the
solvents
were removed under reduced pressure. Then, the crude product was dissolved in
20
mL Et0H anhydrous and 4 g of Amberlite resin was added to the solution. The
resulting mixture was stirred for 16 hour at room temperature before the resin
was
filtered of and the Et0H was removed under reduced pressure. The resulting
crude
product was dissolved in 10 mL CH2Cl2 and 10 mL of a 2 M aqueous solution of
NaOH in water. The phases were separated and the aqueous layer was extracted
three times with 10 mL of CH2Cl2. The organic phases were dried over MgSO4 and
the CH2Cl2 was removed under reduced pressure to yield the methylated
polyethyleneimine as a yellow oil.
[00431] Methylated polyethyleneimine (M .W. 600 before methylation):
1H NMR (CDCI3, 400 MHz): 5 = 2.18-2.91 (m), no NH signal appear in the spectra
130 NMR (CDCI3, 100.7 MHz): 5 = 42.2 (q), 44.1 (q), 44.4(q), 50.5-56.0 (m, t)
[00432] Methylated polyethyleneimine (M .W. 1800 before methylation)
1H NMR (CDC13, 400 MHz): 5 = 2.16 (s, CH3), 2.23 (bs, CH3), 2.44-2.64 (m), no
NH
signal appear in the spectra
13C NMR (CDCI3, 100.7 MHz): 5 = 41.5(q), 44.0(q), 50.8-51.1 (m, t), 53.7(t),
55.0
(t)
[00433] Methylated polyethyleneimine (M.W. 1800 before methylation)
1H NMR (CDCI3, 400 MHz): 5 = 2.18 (s, CH3), 2.21 (s, CH3), 2.28-2.62 (m), no
NH
signal appear in the spectra.
13C NMR (CDCI3, 100.7 MHz): 5 = 42.9 (q), 43.0 (q), 45.9 (q), 46.0 (q), 52.8-
54.0 (m,
t), 55.8-56.9 (m, t), 57.2-57.8 (m, t)
[00434] EXAMPLE 16B; Use of the polyamine to expel acetonitrile from
water.
[00435] The methylated polyamines were investigated as additives for
switchable ionic strength solutions. To measure the extent of acetonitrile
being forced
out of an aqueous phase by an increase in ionic strength, and the amounts of
amine,
which remained in the aqueous phase, 1:1 w/w solutions of acetonitrile and
water
(1.5 g each) were prepared in graduated cylinders. 300 mg of the non-ionic
polyamine additive were added and the cylinders were capped with rubber septa.
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After 30 min of bubbling carbon dioxide through the liquid phase from a single
narrow
gauge steel needle at room temperature, a visible phase separation was
observed.
The volumes of each phase were recorded. Aliquots of the non-aqueous and
aqueous layers were taken and dissolved in D20 in NMR tubes. A known amount of
ethyl acetate or dimethylformamide (DMF) was added to each NMR tube as an
internal standard. 1H NMR spectra were acquired and through integration of the
ethyl
acetate or DMF standard, a concentration of acetonitrile or additive was
calculated
and scaled up to reflect the total volume of the aqueous or non-aqueous phase
giving
a percentage of the compound being forced out. The results are shown in the
following table.
polyethyleneimine Acetonitrile forced out
M.W. 600 56%
M.W. 1800 72%
M.W. 10000 77%
[00436] 99.9% of the polyamine was retained in the aqueous phase.
[00437] Argon was then bubbled through the solution while heating to 50 C
until the two phases recombined into a single phase (typically 30 min).
Bubbling CO2
through the mixture again for 30 min caused the liquid mixture to split into
two
phases and a subsequent bubbling of argon for 30 min caused the two phases to
merge again, which shows that the process was fully reversible.
[00438] EXAMPLE 17: Preparation and use of a tetraamine for expulsion of
THF from water
[00439] EXAMPLE 17A: Preparation of the tetraamine:
I
.- N ....õ.õ--,...õ. Nõ.....õ,---.,...õ----... ,..-....., ,...--...
N --- N --
I 1
[00440] Sperm me (97% purity) was purchased from Alfa Aesar, formaldehyde
(37% in H20), Zn powder from Sigma-Aldrich and acetic acid from Fisher
Scientific.
[00441] A 250 mL round bottom flask was equipped with a 2 cm teflon
stirring
bar and placed over a magnetic stirring plate. 2.02 g (10 mmol, 1.0 eq)
spermine
were placed in the flask and dissolved in 40 mL water. Afterwards, 9.72 mL
(120 mmol, 12.0 eq) formaldehyde solution and 13.7 mL (240 mmol, 24.0 eq)
acetic
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acid were added and the solution was allowed to stir at room temperature for
15 min.
Afterwards, 7.849 (120 mmol, 12.0 eq) Zn powder were added in small portions,
which resulted in gas formation. A cold water bath was used to maintain the
temperature in the flask under 40 C. After complete addition the reaction
mixture
was vigorously stirred for 16 hour at room temperature. 20 mL NH3-solution
were
added and the aqueous phase was extracted with ethyl acetate in a separation
funnel (3 x 25 mL).
[00442] The combined organic layers were dried over MgSO4, filtered
through
filter paper removed under reduced pressure. The crude product was purified by
high
vacuum distillation to yield 1.3 g (4.5 mmol, 42%) of a yellow oil which was
formally
called N1,N1'-(butane-1,4-diy1)bis(N1,N3,N3-trimethylpropane-1,3-diamine). As
used
herein, this compound is referred to as MeSpe (i.e. methylated spermine).
1H NMR (CDCI3, 400 MHz): 5 = 1.36-1.44 (m, 4H, CH2), 1.55-1.66 (m, 4H, CH2),
2.18 (s, 6H, 01-13), 2.19 (s, 12H, CH3), 2.21-2.27 (m, 4H, CH2), 2.28-2.35 (m,
8H,
CH2);
130 NMR (CDCI3, 100.7 MHz): 8 = 25.3 (t), 25.7 (t), 42.3 (q), 45.6 (q), 55.8
(t), 57.8
(t), 58.0 (t);
MS (El): m/z ( /0) = 287.32 (7), 286.31 (41) [M], 98.08 (28), 86.08 (44),
85.07 (100),
84.07 (41);
HRMS (El): calc. for [M]: 286.3097, found: 286.3091.
[00443] EXAMPLE 17B; Reversible solvent switching of tetraamine/water
system
[00444] The methylated spermine was investigated as an additive for
switchable ionic strength solutions. To measure the extent of THF being forced
out of
an aqueous phase by an increase in ionic strength, and the amounts of amine,
which
remained in the aqueous phase, 1:1 w/w solutions of THF and water were
prepared
in graduated cylinders. The appropriate mass of amine additive to result in a
0.80
molal solution was added and the cylinders were capped with rubber septa.
After 30
minutes of bubbling carbon dioxide through the liquid phase from a single
narrow
gauge steel needle, a visible phase separation was observed. The volumes of
each
phase were recorded. Aliquots of the non-aqueous and aqueous layers were taken
and dissolved in d3-acetonitrile in NMR tubes. A known amount of ethyl acetate
was
added to each NMR tube as an internal standard. 1H NMR spectra were acquired
and through integration of the ethyl acetate standard, a concentration of THF
or
additive was calculated and scaled up to reflect the total volume of the
aqueous or
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non-aqueous phase giving a percentage of the compound being forced out or
retained. Then argon was bubbled through the solution while heating to 50 C
until
the two phases recombined (15 to 60 min). The whole switching process (30 min
CO2, sample take, then another 30 min of Ar) was repeated. The results are
shown in
the following table.
Salting out-experiments using methylated spermine (MeSpe).
run THF forced out Additive retained in THF
1 84.3% 99.85%
2 85.5% 99.79%
[00445] EXAMPLE 17C: NMR measurement of the degree of protonation of
methylated spermine by carbonated water
[00446] The degree of protonation of the tetraamine (methylated spermine)
upon contact with a carbon dioxide trigger was investigated by 1H NMR.
[00447] In order to establish the chemical shifts of the protonated
bases, molar
equivalents of several strong acids, including HCl and HNO3, were added to
separate
solutions of the tetraamine dissolved in D20. 1H NMR spectra were acquired on
a
Bruker AV-400 NMR spectrometer at 400.3 MHz for three replicate solutions of
the
amine. An average value of each chemical shift for each protonated base was
calculated along with standard deviations. If the base when reacted with the
trigger
to ionic salt form showed chemical shifts within this error range, it was
considered to
be 100% protonated within experimental error. The 1FI NMR chemical shifts of
the
unprotonated amine were also measured.
[00448] The extent of protonation of the additive at room temperature at
0.1 M
(in D20) was monitored by 1H NMR. The amine was dissolved in D20 in an NMR
tube and sealed with a rubber septa. The spectrum was then acquired.
Subsequently, two narrow gauge steel needles were inserted and gas was gently
bubbled through one of them into the solution at approximately 4-5 bubbles per
second. The second needle served as a vent for the gaseous phase.
[00449] Firstly CO2 was bubbled through the solution for the required
length of
time and then the spectrum was re-acquired. This process was repeated. The %
protonation of the amine was determined from the observed chemical shifts by
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determining the amount of movement of the peaks from the normal position for
the
unprotonated amine towards the position expected for the fully protonated
amine.
[00450] The results show that the tetramine was protonated to a degree of
93%.
[00451] EXAMPLE 18: Osmotic Desalination System
[00452] Water desalination by reverse osmosis is energetically costly. An
alternative that has been proposed in the literature is forward osmosis
(Figure 18),
where water flows across a membrane from seawater into a concentrated ammonium
carbonate solution (the "draw solution"). Once the flow is complete, the draw
solution
is removed from the system and heated to eliminate the NH3 and CO2. The
principle
costs of the process are the energy input during the heating step and the
supply of
make-up ammonium carbonate. The limiting factors for the technology are,
according
to a 2006 review of the field (Cath, T. Y.; Childress, A. E.; Elimelech, M. J.
Membrane
ScL 2006, 281,70-87). a "lack of high-performance membranes and the necessity
for
an easily separable draw solution."
[00453] Described in this example is a new easily separable draw solution,
which takes advantage of the present method of reversibly converting a
switchable
water from low to high ionic strength. The osmotic pressure of a switchable
water
should dramatically rise as the conversion from low ionic strength to high
ionic
strength takes place. Although the osmotic pressures of the solution before
and after
CO2 have not been measured, literature data (Cath, T. Y.; Childress, A. E.;
Elimelech, M. J. Membrane ScL 2006, 281,70-87) show that the osmotic pressure
of
a 4 M solution of a neutral organic such as sucrose is much lower (about 130
atm)
than the osmotic pressure of a salt containing a dication such as MgCl2 (800
atm).
This reversible change in osmotic pressure can be used in a method for
desalination
of water as depicted in Figure 19.
[00454] The process depicted in Figure 19 employs a switchable water
solution in its ionic form as the draw solution. After forward osmosis, the
seawater is
removed and the CO2 is removed from the switchable water solution, dropping
the
osmotic pressure dramatically. Reverse osmosis produces fresh water from the
switchable water solution with little energy requirement because of the low
osmotic
pressure.
[00455] The key advantages of this process over conventional forward
osmosis are the expected lower energy requirement for the heating step (see
Table
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of expected energy requirements below) and the facile and complete recycling
of the
amine. The key advantage of the proposed process over conventional reverse
osmosis is the much lower pressure requirement during the reverse osmosis
step.
Process step Energy requirement for Energy requirement for
process with NH4CO3, proposed process, kJ/mol
kJ/mol
Deprotonation of NH4 + or 52.33 36.93
NR3H+
Removal of CO2 from 19.4 19.4
water
Removal of NH3 from 30.5 0
water
Reverse osmosis step 0 unknown
TOTAL 102.2 >56.3
3Mucci, A.; Domain, R.; Benoit, R. L. Can. J. Chem. 1980, 58, 953-958.
[00456] A modification of this process, shown in Figure 20, differs only
in the
last step, where the switchable water additive in the solution is switched
"off', or back
to its nonionic form, and then removed by a method other than reverse osmosis.
For
example, if the non-ionic form of the additive is insoluble or immiscible with
water,
then it can be removed by filtration or decantation, with any small amounts of
remaining additive in the water being removed by passing the water through
silica.
Results have shown successful use of such a separation process.
[00457] Sodium chloride was purchased from EMD Chemicals (Gibbstown,
NJ, USA) while bone dry grade carbon dioxide was purchased from Air Liquide
(Toronto, ON, Canada). The Seapack Emergency Desalinator bag was purchased
from Hydration Technology Innovations (Scottsdale, AZ, USA). Ultra pure water
(18
MO) was obtained using an Elga Lab Water PureLab Flex system (High Wycombe,
UK). Reverse Osmosis (RO) experiments were conducted using a Sterlitech HP4750
Stirred cell with two different Sterlitech ultra filtration membranes (TF UF
GM
membrane PN:YMGMSP3301 and Koch Flat sheet membrane HFK 131 PN:
YMHFK13118).
[00458] EXAMPLE 18A: Forward and reverse osmosis experiments with 1%
salt water using MW = 35k functionalized PMMA
[00459] A solution of 15 g of 3-(dinnethylamino)-1-propylamine
functionalized
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polymethyl methacrylate (MW=35,000) in 85 mL deionized water was added to the
inner membrane nutrient delivery spout (green capped) of the desalination bag.
Carbon dioxide was introduced to the same solution directly in the bag via a
glass
dispersion tube at a pressure of 10 psi. Bubbling was continued for 45
minutes. A
solution of 1 weight % sodium chloride in water (1050 mL) was added to the
sample
port (red capped) of the desalination bag typically used for introduction of
seawater.
The bag was left at room temperature for 6 hours and then the polymer solution
was
poured out via the green capped spout. The volume of solution was
approximately
145 mL and the solution was returned to the bag via the same spout. An
additional
15 g of solid polymer was added via the same spout along with an additional 15
mL
of water. The bag was agitated for approximately 10 minutes by hand and then
carbon dioxide was bubbled through polymer solution for 1 hour and rinsed with
an
additional 15 mL of water. The bag was left for 16 hours at room temperature
followed by measuring the volume of polymer solution which was found to be
approximately 370 mL. The solution was then heated to 75 C for 5 hours in a
glass
media jar until no evolution of gas bubbles was observed indicating solution
was
"switched off'.
[00460] The stirred cell was equipped with a membrane and 100 mL of the 3-
(dimethylam ino)-1-propylannine functionalized PMMA aqueous solution was
added.
The cell was closed and pressurized with argon. The table shows the use of two
different membranes and pressures and flux needed for each experiments.
Polymer solution Membrane Pressure Flux (ml/min)
PMMA 35,000 TF UF GM 67 bar 0.167
PMMA 35,000 HFK 131 40 bar 0.075
[00461] EXAMPLE 18B: Forward and reverse osmosis experiments with 1%
salt water using MW = 15k functionalized PMMA
[00462] A solution of 15 g of 3-(dimethylamino)-1-propylamine
functionalized
polynnethyl methacrylate (MW=15,000) in 100 mL deionized water was added to
the
inner membrane nutrient delivery spout (green capped) of the desalination bag.
A
solution of 1 weight % sodium chloride in water (1050 mL) was added to the
sample
port (red capped) of the desalination bag typically used for introduction of
seawater.
The bag was left at room temperature overnight without carbonating and then
the
polymer solution was poured out via the green capped spout. The volume of the
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solution was approximately 115 mL, which was unchanged since the polymer
solution was not "switched on" by carbon dioxide. The solution was returned to
the
bag via the same spout and carbonated directly by bubbling with carbon dioxide
using gas dispersion tube at 10 psi for 45 minutes. The bag was left for 16
hours at
room temperature followed by measuring the volume of polymer solution which
was
found to be approximately 250 mL. This solution was again carbonated directly
by
bubbling with carbon dioxide using a gas dispersion tube at 10psi for 5
minutes, and
100 mL of it was set aside for reverse osmosis experiment in "switched on"
form.
Remaining solution was heated to 70 C for 2 hours in a glass media jar until
no
evolution of gas bubbles was observed indicating solution was "switched off'.
[00463] Reverse Osmosis in Switched On Form
[00464] The stirred cell was equipped with a membrane and above 100 mL of
3-(dimethylamino)-1-propylamine functionalized PMMA aqueous solution was added
without previously removing the CO2. The cell was closed and pressurized with
argon. The table shows the use of two different membranes and pressures and
flux
needed for each experiment.
Polymer solution Membrane Pressure Flux (ml/min)
PMMA 15,000 ("ON") TF UF GM 40 bar 0.30
PMMA 15,000 ("ON") HFK 131 40 bar 0.20
[00465] Reverse Osmosis in Switched Off Form
[00466] The stirred cell was equipped with a membrane and 100 mL of 3-
(dimethylamino)-1-propylamine functionalized PMMA aqueous solution was added
in
the deactivated form. The cell was closed and pressurized with argon. The
table
shows the use of two different membranes and pressures and flux needed for
each
experiment.
Polymer solution Membrane Pressure Flux (ml/min)
PMMA 15,000 ("OFF") TF UF GM 40 bar 0.20
PMMA 15,000 ("OFF") HFK 131 40 bar 0.28
[00467] Forward Osmosis using DMCA as drawsolution
[00468] A draw solution of 127.0 mL (108.0 g, 0.85 mol)
dimethylcyclohexylamine in 127.0 mL deionized water was prepared. It was
carbonated by bubbling with carbon dioxide using a gas dispersion tube at 1
atm for
1.5 h until all of the amine disappeared and added to the inner membrane
nutrient
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delivery spout (green capped) of the desalination bag. A solution of 1 weight
%
sodium chloride in water (1.0 L) was added to the sample port (red capped) of
the
desalination bag typically used for introduction of seawater. After 5 h the
draw
solution was removed from the pack and the volume measured (900 mL), while the
volume of the NaCI feeding solution decreased to 350 mL. Due to the low
concentration of DMCA in water and incomplete conversion of the salt, it was
not
possible to force the DMCA out of the water.
[00469] EXAMPLE 19: Preparation and use of a diamidine for expulsion of
THF from water
[00470] EXAMPLE 19A: Preparation of the diamidine:
0
NH2 4. 60 C, 2 ho
91% N N
[00471] 1,4-Diaminobutane was purchased from Sigma-Aldrich and
dimethylacetamide dimethylacetale was purchased from TCI.
[00472] A 100 mL flask was equipped with a condenser and a 1 cm stirring
bar
and was then placed over a stirplate. 1.14 mL (1.0 g, 11.3 mmol, 1 eq.) of 1,4-
diaminobutane and 3.64 mL (3.31 g, 24.9 mmol, 2.2 eq.) of dimethylacetamide
dimethylacetale were the placed into the flask. The reaction mixture was then
stirred
with 600 rpm and heated to 60 C. After 2h the reaction mixture was allowed to
cool
to room temperature and the resulting methanol was removed under reduced
pressure to yield a yellow oil. This crude product was then purified by high
vacuum
distillation. The pure product was obtained as a light yellow oil (2.32 g,
10.2 mmol,
91%). The compound was called N',N"-(butane-1,4-diy1)bis(N,N-
dimethylacetimidamide) and in this application is referred to as "DIAC" (i.e.
diacetamidine)
N
1H NMR (CDCI3, 400 MHz): 5 = 1.45-1.53(m, 4H, CH2), 1.80(s, 3H, CCH3), 2.79(s,
6H, N(CH3)2), 3.09-3.19 (m, 4H, CH2);
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13C NMR (CD0I3, 100.7 MHz): 8 = 12.3 (q, CCH3), 30.2 (t, CH2), 37.9 (q, 2C,
N(CH3)2), 50.0 (t, CH2), 158.7 (s);
MS (El): miz (%) = 227.22 (3), 226.21 (21), 198.16 (7), 182.17 (7), 141.14
(14),
140.13 (21), 128.11 (10), 127.10(30), 114.11 (23), 113.11(28), 112.09 (52),
99.09
(27), 70.07 (45), 56.05 (100);
HRMS (El): calc. for [M]: 226.2157, found: 226.2161.
[00473] EXAMPLE 19B; Reversible solvent switching of diamidine/water
system
[00474] The diamidine was investigated as additive for switchable ionic
strength solutions. To measure the extent of THF being forced out of an
aqueous
phase by an increase in ionic strength, and the amounts of amine, which
remained in
the aqueous phase, 1:1 w/w solutions of THF and water were prepared in
graduated
cylinders. The appropriate mass of amine additive to result in a 0.80 molal
solution
was added and the cylinders were capped with rubber septa. After 30 minutes of
bubbling carbon dioxide through the liquid phase from a single narrow gauge
steel
needle, a visible phase separation was observed. The volumes of each phase
were
recorded. Aliquots of the non-aqueous and aqueous layers were taken and
dissolved
in dracetonitrile in NMR tubes. A known amount of ethyl acetate was added to
each
NMR tube as an internal standard. 1H NMR spectra were acquired and through
integration of the ethyl acetate standard, a concentration of THF or additive
was
calculated and scaled up to reflect the total volume of the aqueous or non-
aqueous
phase giving a percentage of the compound being forced out or retained. The
results
showed that the amount of THF forced out of the aqueous phase was 54.5% and
the
amount of additive retained in the aqueous phase was 99.5%
[00475] Then argon was bubbled through the solution while heating to 50
C
until the two phases recombined (15 to 60 min).
[00476] EXAMPLE 20: Precipitation of an Organic Solid using Switchable
Water
[00477] Ten millilitres of water was pipetted into a glass centrifuge
tube along
with 2.038 g TMDAB (-5:1 w/w solution). 68.2 mg of (+)-camphor (used as is
from
Sigma-Aldrich) was added to the solution. The solution was heated in a 70 C
water
bath to expedite the dissolution of the camphor. After complete dissolution of
the
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solid (camphor) and cooling to room temperature (23 C), the solid remained
dissolved in the aqueous solution.
[00478] The centrifuge tube was capped with a rubber septum. CO2 was
introduced into the solution via a single narrow gauge steel needle at a flow
rate of
about 5 mL min-1. A second needle was inserted into the tube, but not into the
solution, to act as a gas outlet. After 30 minutes of bubbling CO2 through the
solution
a white precipitate appeared throughout the aqueous solution.
[00479] The solution was centrifuged for 5 minutes, using a Fisher
Scientific
Centrific 228 centrifuge at a speed of 3300 RPM, such that all the white
solids
collected at the top of the aqueous solution. The white solids were collected
by
vacuum filtration and weighed on a Mettler-Toledo AG245 analytical balance. A
mass
of 24.0 mg was obtained, resulting in a 35.2 % recovery of the original
dissolved
solid.
[00480] EXAMPLE 21: Primary Amines as Switchable Additives
[00481] Primary amines were tested as switchable water additives. The
switching of the non-ionized form to the charged form (which is probably a
mixture of
bicarbonate and carbamate salts) proceeded well. The separation of an organic
liquid was observed. However, conversion of the ionic form back to the non-
ionized
form was unsuccessful. Primary amines are therefore only useful as additives
in
applications where a single switch to the ionic form, without conversion back
to the
non-ionized form, is sufficient. Thus, primary amine additives are not
reversibly
"switchable".
[00482] EXAMPLE 21A: Ethanolamine (5:5:1)
[00483] In a glass vial, 5.018 g H20, 1.006 g ethanolamine, and 4.998 g
THF
were mixed to generate a single phase, clear, colourless solution. A stir bar
was
added to the vial and the vial was capped with a rubber septa. CO2 was
introduced
into the solution via a single narrow gauge steel needle at a flow rate of
about 5 mL
min-1. A second needle was inserted through the septa, but not into the
solution, to
act as a gas outlet. CO2 was bubbled through the solution for 20 minutes until
two
liquid phases (aqueous and organic) were observed. It was found by 1H NMR
spectroscopy that ¨62 clo of the THF was forced out of the aqueous phase into
the
new organic phase.
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[00484] The two phase mixture was then placed in a 60 C water bath while
N2
was bubbled through the mixture in a fashion similar to the previous bubbling
of 002.
This was performed for 60 minutes. Although some THE boiled off, the two
phases
did not recombine. The temperature was increased to 75 C for 30 minutes which
appeared to boil off the remainder of the THF as the volume returned to that
of the
water and amine mixture. Some ethanolamine may have boiled off as well. At
this
point, a single liquid phase was observed, as the THE was boiled off, however,
the
phase was cloudy and it appeared to have a white precipitate (likely carbamate
salts).
[00485] The temperature of the water bath was then increased to 85 00 and
N2 bubbling was continued for 90 minutes, giving a total N2 treatment of 3
hours. No
additional physical changes were observed. The solution remained cloudy white
in
colour and some of the white precipitate had collected on the sides of the
vial.
[00486] EXAMPLE 21B: Ethylenediamine (18:18:1)
[00487] In a glass vial, 5.004 g H20, 0.283 g ethylenediamine, and 5.033
g
THF were mixed to generate a single phase, clear, colourless solution. A stir
bar was
added to the vial and the vial was capped with a rubber septa. CO2 was
introduced
into the solution via a single narrow gauge steel needle at a flow rate of
about 5 mL
min-1. A second needle was inserted through the septa, but not into the
solution, to
act as a gas outlet. CO2 was bubbled through the solution for 10 minutes until
two
liquid phases (aqueous and organic) were observed. It was found by 1H NMR that
-67 % of the THE was forced out of the aqueous phase into the new organic
phase.
[00488] The two phase mixture was then placed in a 60 C water bath while
N2
was bubbled through the mixture in a fashion similar to the previous bubbling
of CO2.
This was performed for 60 minutes where some THE evaporated, but the two
phases
did not recombine. The temperature of the water bath was then increased to 85
C
and N2 bubbling was continued for 120 minutes, giving a total N2 treatment of
3
hours. It appeared that all of the THE had evaporated as the volume had
returned to
that of the water and amine mixture. The solution was a single yellow liquid
phase at
this point, however a white precipitate (likely carbamate salts) caused the
solution to
appear cloudy.
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[00489] EXAMPLE 22: Salting out THF from Water using Secondary Amine
Switchable Additives
[00490] In general, from the observations using primary amines, secondary
amines were expected to be difficult to reverse, because both secondary and
primary
amines tend to form carbamate salts in addition to bicarbonate salts when
their
aqueous solutions are contacted with CO2. However the following secondary
amines
were found to be reversibly switchable. Without wishing to be bound by theory,
it is
possible that the reversibility results from a tendency to form more
bicarbonate than
carbamate salts.
[00491] The N-tert-butylethanolamine was purchased from TCI America and
N-tert-butymethylamine was purchased from Sigma-Aldrich. Both compounds were
used without further purification.
[00492] N-tert-Butylethanolamine and N-tert-butymethylamine were
investigated as additives for switchable ionic strength solutions. To measure
the
extent of THF being forced out of an aqueous phase by an increase in ionic
strength,
and to measure the amount of amine remaining in the aqueous phase, 1:1 w/w
solutions of THF and water (1.5 g each) were prepared in graduated cylinders.
The
appropriate mass of amine additive to result in a 1.60 molal solution was
added and
the cylinders were capped with rubber septa. After 30 minutes of bubbling
carbon
dioxide through the liquid phase from a single narrow gauge steel needle, a
visible
phase separation was observed. The volumes of each phase were recorded.
Aliquots
of the non-aqueous and aqueous layers were taken and dissolved in d3-
acetonitrile in
NMR tubes. A known amount of ethyl acetate was added to each NMR tube as an
internal standard. 1H NMR spectra were acquired and through integration of the
ethyl
acetate standard, a concentration of THF or additive was calculated and scaled
up to
reflect the total volume of the aqueous or non-aqueous phase giving a
percentage of
the compound being forced out or retained. Then argon was bubbled through the
solution at 5 mL/min while heating to 50 C until the two phases recombined
(30 min
for N-tert-butylethanolamine). The recombining of the phases when N-tert-
butymethylamine was used as an additive was not successful at 30 min but was
achieved after 2 hours at a higher Ar flow rate of 15 mUmin. THF was added
afterwards to replace the amount of THF being evaporated during the procedure.
The
whole switching process (30 min CO2, sample take, then another Ar treatment)
was
repeated. The results are shown in the following table.
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Salting out-experiments using secondary amine additives.
Amine THF forced out Additive retained in H20
N-tert-butylethanolamine 68.7 0.4% 99.84 0.04%
N-tert-butymethylamine 67.6 0.8% 99.75 0.04%
[00493] EXAMPLE 23: Synthesis of Polymeric Switchable Water Additives
[00494] Polyethyleneimines ("PEls", MW= 600, 99%; 1,800, 99%; 10,000,
99%) were purchased from Alfa Aesar. lodoethane, 99%, lodopropane, 99%
lodobutane, 99% and K2CO3 were purchased from Sigma-Aldrich. NaOH was
purchased from Acros. Et0H was purchased from Greenfield Alcohols. Ethyl
acetate
and MgSO4 were purchased from Fisher. All reagents were used without further
purification. A 15% (w/v) NaOH solution was made by dissolving 15 g of NaOH in
100 mL deionized water.
[00495] General procedure I (GP I) for the alkylation of PEls: In a round
bottom flask, equipped with a magnetic stir-bar, iodoalkane was dissolved in
absolute
Et0H and stirred at 600 rpm. To this, a solution of PEI in Et0H and solid
K2CO3 were
added. The round bottom flask was then equipped with a reflux condenser and
the
reaction mixture was heated to reflux (80 C) for 3 days. After cooling to
room
temperature, the K2CO3 was filtered off and the Et0H was removed under reduced
pressure. The crude product was then dissolved in a mixture of Et0Ac and 15%
(w/v)
NaOH solution in water. The phases were separated and the organic layer was
washed twice with 15% (w/v) NaOH solution in water. The organic layer was then
dried with MgSO4 and removed under reduced pressure to yield yellow oils.
[00496] General procedure II (GP II) for the alkylation of PEls: In a
round
bottom flask, equipped with a magnetic stir-bar, iodoalkane was dissolved in
absolute
Et0H and stirred at 600 rpm. To this, a solution of PEI in Et0H and solid
K2CO3 were
added. The round bottom flask was then equipped with a reflux condenser and
the
reaction mixture was heated to reflux (80 C) for 3 days. After cooling to
room
temperature, another portion of K2CO3 was added and the mixture was refluxed
again
for 3 d. After cooling to r.t., the K2CO3 was filtered off and the Et0H was
removed
under reduced pressure. The crude product was then dissolved in a mixture of
Et0Ac
and 15% (w/v) NaOH solution in water. The phases were separated and the
organic
layer was washed twice with 15% (w/v) NaOH solution in water. The organic
layer
was then dried with MgSO4 and removed under reduced pressure to yield yellow
oils.
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[00497] 23.1.1 Synthesis of Ethylated Polyethyleneimines (EPEI)
[00498] 23.1.1.1 Ethylated Polyethyleneimine (EPEI) MW= 600
[00499] According to GP I, 3.1 mL (6.1 g, 39.0 mmol) iodoethane in 10 mL
Et0H was reacted with 1.8 g (41.9 mmol) polyethyleneimine (MW= 600) in 10 mL
Et0H in the presence of 8.3 g (60.0 mmol) K2003. Work-up with NaOH (3 x 10 mL)
and Et0Ac (10 mL) yielded 1.84 g (65%) of a light yellow oil.
1H NMR (CDCI3, 400 MHz): 6 = 0.969 (bt, 3H, CH3), 2.39-2.56 (m, 6H, CH2);
130 NMR (CDCI3, 100.7 MHz): 6 = 11.8 (CH3), 47.4 (CH2 ethyl), 48.6 (CH2
ethylene),
50.9-54.0 (CH2 ethylene);
NMR spectrum shows 9% quaternized nitrogens in the polymer.
IR (film) : 15 [cm-1] = 2967 (s), 2934 (m), 2808 (s), 1653 (w), 1457 (m), 1382
(w),
1292 (w), 1097 (w), 1062 (m).
[00500] 23.1.1.2 Ethylated Polyethyleneimine (EPEI) MW= 1,800
[00501] According to GP I, 3.1 mL (6.1 g, 39.0 mmol) iodoethane in 10 mL
Et0H was reacted with 1.8 g (41.9 mmol) polyethyleneimine (MW= 1,800) in 10 mL
Et0H in the presence of 8.3 g (60.0 mmol) K2003. Work-up with NaOH (3x 10 mL)
and Et0Ac (10 mL) yielded 2.38 g (84%) of a light brown oil.
1H NMR (CDCI3, 400 MHz): 6 = 0.91 (bt, 3H, CH3), 2.38-2.54 (m, 6H, CH2);
130 NMR (CDCI3, 100.7 MHz): 6 = 11.8 (CH3), 47.5 (CH2 ethyl), 50.8-54.1 (CH2
backbone);
IR (film): 15 [cm-1] = 2966 (s), 2933 (m), 2807 (s), 1456 (m), 1382 (w), 1292
(w), 1097
(w), 1061 (m).
[00502] 23.1.1.3 Ethylated Polyethyleneimine (EPEI) MW= 10,000
[00503] According to GP I, 3.1 mL (6.1 g, 39.0 mmol) iodoethane in 10 mL
Et0H was reacted with 1.8 g (41.9 mmol) polyethyleneimine (MW= 10,000) in 10
mL
Et0H in the presence of 8.3 g (60.0 mmol) K2003. Work-up with NaOH (3 x 10 mL)
and Et0Ac (10 mL) yielded 2.23 g (78%) of a light yellow oil.
1H NMR (CDCI3, 400 MHz): 6 = 0.98 (bt, 3H, CH3), 1.40 (bs, remaining free NH),
2.42-2.62 (m, 6H, CH2);
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NMR spectrum shows 7% quaternized nitrogens in the polymer.
130 NMR (CDCI3, 100.7 MHz): 6 = 11.7 (CH3), 47.4 (CH2 ethyl), 47.8-54.0 (CH2
backbone);
IR (film): /3' [cm-1] = 2973 (s), 2809 (s), 1643 (w), 1562 (w), 1471 (m), 1100
(w), 1055
(w).
[00504] 23.1.2 Synthesis of propylated polyethyleneimines (PPEI)
[00505] 23.1.2.1 Propylated Polyethyleneimine (PPEI) MW= 600
[00506] According to GP II, 4.7 mL (8.2 g, 48.0 mmol) iodopropane in 10 mL
Et0H was reacted with 1.8 g (41.9 mmol) polyethyleneimine (MW= 600) in 10 mL
Et0H in the presence of 21.6 g (156.0 mmol) K2CO3(over two equal additions).
Work-up with NaOH (3 x 10 mL) and Et0Ac (10 mL) yielded 2.54 g (71%) of a
yellow
oil.
1H NMR (CDCI3, 400 MHz): 6. = 0.84 (bt, 3H, CH3), 1,41 (bq, 2H, CH2, propyl),
2.30-
2.39 (m, 2H, CH2, propyl), 2.43-2.57 (m, 4H, 01-12, backbone);
NMR spectrum shows 6% quaternized nitrogens in the polymer.
130 NMR (CDCI3, 100.7 MHz): 6 = 11.4 (CH3), 20.4 (CH2, propyl), 52.2-53.9 (OH2
backbone) 56.9 (CH2, propyl);
IR (film): El [cm-1] = 2957 (s), 2933 (m), 2807 (s), 1458 (m), 1378 (w), 1261
(w), 1076
(w), 800 (m).
[00507] 23.1.2.2 Propylated Polyethyleneimine (PPEI) MW= 1,800
[00508] According to GP II, 4.7 mL (8.2 g, 48.0 mmol) iodopropane in 10 mL
Et0H was reacted with 1.8 g (41.9 mmol) polyethyleneimine (MW= 1,800) in 10 mL
Et0H in the presence of 21.6 g (156.0 mmol)K2003(over two equal additions).
Work-up with NaOH (3 x 10 mL) and Et0Ac (10 mL) yielded 2.3 g (65%) of a
yellow
oil.
1H NMR (CDCI3, 400 MHz): 6 = 0.83 (bt, 3H, CH3), 1.41 (bq, 2H, CH2, propyl),
1.76
(bs, remaining free NH), 2.35 (bq, 2H, CH2, propyl), 2.42-2.58 (m, 4H, CH2,
backbone);
NMR spectrum shows 12% quaternized nitrogens in the polymer.
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13C NMR (CDCI3, 100.7 MHz): 6 = 12.1 (CH3), 20.3 (CH2, propyl), 52.3-53.9 (CH2
backbone) 56.8 (CH2, propyl);
IR (film): 13' [CM-1] = 3421 (s), 2958 (s), 2872 (m), 2809 (s), 1653 (m), 2559
(m), 1464
(m), 1379 (w), 1076 (w), 800 (m).
[00509] 23.1.2.3 Propylated Polyethyleneimine (PPEI) MW= 10,000
[00510] According to GP II, 5.7 mL (10.0 g, 5870 mmol) iodopropane in 12
mL
Et0H was reacted with 1.8 g (41.9 mmol) polyethyleneimine (MW= 10,000) in 12
mL
Et0H in the presence of 26.2 g (190.0 mmol) K2CO3(over two equal additions).
Work-up with NaOH (3 x 12 mL) and Et0Ac (12 mL) yielded 4.2 g (99%) of a
yellow
oil.
1H NMR (CDCI3, 400 MHz): 6=0.82 (bt, 3H, CH3), 1.40 (bq, 2H, CH2, propyl),
1.76
(bs, remaining free NH), 2.34 (bq, 2H, CH2, propyl), 2.42-2.58 (m, 4H, CH2,
backbone);
NMR spectrum shows 15% quaternized nitrogens in the polymer.
13C NMR (CDCI3, 100.7 MHz): 6 = 11.8 (CH3), 20.4 (CH2, propyl), 52.2-53.9 (CH2
backbone) 56.8 (CH2, propyl);
IR (film): trY [cm-1] = 3439 (m), 2958 (s), 2933 (m), 2872 (s), 2808 (s), 1463
(m), 1379
(w), 1075(w).
[00511] 23.1.3 Synthesis of butylated polyethyleneimines (BPEI)
[00512] 23.1.3.1 Butylated polyethyleneimine (BPEI) MW= 600
[00513] According to GP II, 5.46 mL (8.83 g, 48.0 mmol) iodobutane in 10
mL
Et0H was reacted with 1.8 g (41.9 mmol) polyethyleneimine (MW= 600) in 10 mL
Et0H in the presence of 21.6 g (156.0 mmol) K2CO3(over two equal additions).
Work-up with NaOH (3 x 10 mL) and Et0Ac (10 mL) yielded 3.95 g (98%) of a
yellow
oil.
1H NMR (CDCI3, 400 MHz): 6 = 0.86 (bt, 3H, CH3), 1.19-1.30(m, 2H, CH2 butyl),
1.31-1.42 (m, 2H, CH2 butyl), 2.32-2.42 (m, 2H, CH2 butyl), 2.44- 2.54 (m, CH2
ethylene);
13C NMR (CDCI3, 100.7 MHz): 6 = 14.1 (CH3), 20.7 (CH2 butyl), 29.4 (CH2
butyl),
52.4-54.1 (CH2, ethylene) 54.5 (CH2 butyl), 54.8-55.1 (CH2 ethylene);
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IR (film): [cm-1] = 2956 (s), 2931 (s), 2861 (m), 2805 (s), 1458 (m), 1376
(w), 1083
(m).
[00514] 23.1.3.2 Butylated polyethyleneimine (BPEI) MW= 1,800
[00515] According to GP II, 5.46 mL (8.83 g, 48.0 mmol) iodobutane in 10
mL
Et0H was reacted with 1.8 g (41.9 mmol) polyethyleneimine (MW= 1,800) in 10 mL
Et0H in the presence of 21.6 g (156.0 mmol) K2003 (over two equal additions).
Work-up with NaOH (3 x 10 mL) and Et0Ac (10 mL) yielded 2.50 g (62%) of a
yellow
oil.
1H NMR (CDCI3, 400 MHz): 6 = 0.86 (bt, 3H, CH3), 1.24 (bq, 2H, CH2 butyl),
1.31-
1.44 (m, 2H, CH2 butyl), 1.64 (bs, remaining NH), 2.37 (q, 2H, CH2 butyl),
2.42-2.54
(m, CH2 ethylene), NMR spectrum shows 14% quaternized nitrogens in the
polymer;
13C NMR (CDCI3, 100.7 MHz): 6 = 14.1 (CH3), 20.7 (CH2 butyl), 29.4 (CH2
butyl),
52.1-53.8 (CH2, ethylene) 54.5 (CH2 butyl), 58.0-59.2 (CH2 ethylene);
IR (film): a [cm-1] = 3424, (s), 2957 (s), 2871 (m), 2810 (s), 1647 (s), 1558
(w), 1458
(m).
[00516] 23.1.3.3 Butylated polyethyleneimine (BPEI) MW= 10,000
[00517] According to GP II, 5.46 mL (8.83 g, 48.0 mmol) iodobutane in 10
mL
Et0H was reacted with 2.0 g (46.5 mmol) polyethyleneimine (MW= 10,000) in 10
mL
Et0H in the presence of 21.2 g (154.0 mmol) K2CO3(over two equal additions).
Work-up with NaOH (3 x 10 mL) and Et0Ac (10 mL) yielded 2.47 g (55%) of a
yellow
oil.
1H NMR (CDCI3, 400 MHz): 6 = 0.88 (bt, 3H, CH3), 1.27 (bq, 2H, CH2 butyl),
1.33-
1.44 (m, 2H, CH2 butyl), 2.32-2.43 (m, 2H, CH2 butyl), 2.44- 2.56 (m, CH2
ethylene);
NMR spectrum shows 3% quaternized nitrogens in the polymer.
130 NMR (CDCI3, 100.7 MHz): 6 = 14.1 (0H3), 20.7 (CH2 butyl), 29.5 (CH2
butyl),
52.0-53.5 (CH2, ethylene) 54.5 (CH2 butyl), 54.8-55.1 (CH2 ethylene);
IR (film): a [cm-1] = 2955 (s), 2930 (s), 2861 (m), 2805 (s), 1467 (m), 1378
(w), 1080
(m).
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[00518] 23.2 Polydiallylmethylamine (MW=5,000)
[00519] Polydiallylmethylamine hydrochloride MW= 5,000 (25% solids in
water) was purchased from Polysciences, Inc. NaOH was purchased from Acros
Organics. Dichloromethane and MgSO4 were purchased from Fisher. A 15% (w/v)
solution was made by dissolving 15 g of NaOH in 100 mL deionized water.
[00520] 4.0 g of Polydiallylmethylamine hydrochloride MW= 5000 (25%
solids
in water) was placed into a 50 mL round-bottom flask equipped with a 1 cm
magnetic
stir-bar. 10 mL of dichloromethane was added and the mixture was stirred at
600
rpm. Then 10 mL of 15% (w/v) NaOH solution was slowly added and the stirring
was
continued for 1 hour after complete addition. The mixture was then transferred
into a
100 mL separation funnel and the phases were separated. The organic layer was
then washed twice with 5 mL of a 15% (w/v) NaOH solution, dried over MgSO4 and
removed under reduced pressure. 0.5 g (69%) of the polydiallylmethylamine was
obtained as a yellow solid.
[00521] 23.3 Polymethyl methacrylate (PMMA) based materials
[00522] All reactions were conducted in air unless stated otherwise. NMR
spectra were recorded on a Varian 400-MR NMR spectrometer (Agilent,
Mississauga, Ontario, Canada). All NMR spectra are referenced against residual
protonated solvent.
[00523] All chemicals listed below were used as received. Polymethyl
methacrylate (MW = 15,000 and MW = 35,000) was purchased from Acros Organics
(Fisher Scientific, Ottawa, Ontario, Canada). Polymethyl methacrylate (MW =
120,000), and 3-dimethylamino-1-propylamine were purchased from Alfa Aesar
(VWR, Mississauga, Ontario, Canada).
[00524] All solvents were used as received. Methanol was purchased from
ACP Chemicals (Montreal, Quebec, Canada). lsopropanol was purchased from
Caledon Laboratories (Georgetown, Ontario, Canada). Tetrahydrofuran was
purchased from EMD Chemicals (Gibbstown, New Jersey, US).
[00525] 3-(dimethylamino)-1-propylamine functionalized PMMA
(IVIW=15,000):
[00526] Polymethyl methacrylate (1.47 g, 14.7 mmol) was weighed into a
100
mL 2 neck round bottom flask with a stir bar and evacuated on vacuum
line/refilled
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with nitrogen three times. A reflux condenser was also put under inert
atmosphere
using same procedure. 3-(dimethylamino)-1-propylamine (15 mL) was added via
syringe to the polymer and a reflux condenser was placed onto the flask. The
mixture was heated to 150 C for 3 days under nitrogen. After this time, the
reaction
mixture was a clear and colourless solution and was allowed to cool to room
temperature causing a white precipitate to form. The liquid was decanted and
the
remaining solid was washed with 2-25 mL portions of isopropanol. It was then
dried
at 80 C under high vacuum for 5 hours. The solid was then broken up with a
spatula
until more of a powder formed and then re-dried using the same conditions for
16
hours. 1.02 g of white powder was obtained and approximately 80% of the
methacrylate sites were functionalized, as determined by integration of the
appropriate resonances in the 1H NMR spectrum.
1H NMR (400 MHz, D20) 6. 3.64 (bs, 3H, OCH3), 2.86 (t, J = 8.0 Hz, 2H, NHCH2),
2.58 (t, J = 8.0 Hz, 2H, Me2NCH2), 2.35 (s, 6H, N(CH3)2), 2.0-1.6 (b, 2H,
backbone
CH2), 1.80 (m, 2H, CH2CH2CH2), 1.2-0.7 (b, 3H, CH3).
[00527] Large Scale Synthesis of 3-(dimethylamino)-1-propylamine
functionalized PMMA (MW=15,000):
[00528] Polymethyl methacrylate (40.0 g, 400 mmol) was weighed into a 1L
2
neck round bottom flask with a stir bar and fitted with a condenser and rubber
septum. The apparatus was evacuated on vacuum line/refilled with nitrogen
three
times. 3-(dimethylamino)-1-propylamine (350 mL) was poured into the flask
under a
flow of nitrogen. The mixture was heated to 150 C for 4.5 days under nitrogen.
After
stirring overnight the reaction mixture was observed to be white and cloudy
whereas
after the full reaction time it was more a clear and colourless solution and
was
allowed to cool to room temperature. The condenser was removed under a flow of
nitrogen and a distillation apparatus with condenser and receiving flask was
attached. The reaction flask was covered in aluminum foil and the amine
solvent
distilled off under nitrogen atmosphere at 155 C for 2 hours followed by 165 C
for 1
hour before being allowed to cool. The clear solid was then dried at 90 C
under high
vacuum for 2 hours causing it to swell. The swollen solid was then broken up
with a
spatula and drying continued for 3 hours. It was then broken up with a spatula
and
drying continued for 2 hours. Grinding yielded a powder which was dried for 16
hours
at 90 C under high vacuum. 49.9 g of light yellow powder was obtained and
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approximately 80% of the methacrylate sites were functionalized, as determined
by
integration of the appropriate resonances in the 1H NMR spectrum.
1H NMR (400 MHz, D20) 6. 3.65 (bs, 3H, OCH3), 2.89 (t, J = 8.0 Hz, 2H, NHCH2),
2.61 (t, J = 8.0 Hz, 2H, Me2NCH2), 2.38 (s, 6H, N(CH3)2), 2.0-1.6 (b, 2H,
backbone
CH2), 1.82 (m, 2H, CH2CH2CH2), 1.45-0.8 (b, 3H, CH3).
[00529] 23.3.1 3-(dimethylamino)-1-propylamine functionalized PMMA
(MW=35,000):
[00530] Polymethyl methacrylate (0.618 g, 6.17 mmol) was weighed into a
50
mL 2 neck round bottom flask with a stir bar and evacuated on vacuum
line/refilled
with nitrogen three times. A reflux condenser was also put under inert
atmosphere
using same procedure. 3-(dimethylamino)-1-propylamine (4 mL) was added via
syringe to the polymer and a reflux condenser was placed onto the flask. The
mixture was heated to 150 C for 16 hours under nitrogen. After this time, the
reaction mixture was a light yellow liquid with yellow precipitate. The liquid
was
decanted and the remaining light yellow solid was dried at 80 C under high
vacuum
for 2 hours. The solid was then broken up with a spatula until more of a
powder
formed and then re-dried using the same conditions for another 2 hours. This
step
was repeated once more after breaking up brittle chunks of the polymer using a
mortar and pestle to give a fine powder (in order to facilitate drying). 0.695
g of
yellow powder was obtained and approximately 50% of the methacrylate sites
were
functionalized, as determined by integration of the appropriate resonances in
the 1H
NMR spectrum.
1H NMR (400 MHz, D20) 6 3.64 (bs, 3H, OCH3), 2.82 (t, J = 8.0 Hz, 2H, NHCH2),
2.53 (b, 2H, Me2NCH2), 2.31 (s, 6H, N(CH3)2), 2.0-1.6 (b, 2H, backbone CH2),
1.76
(m, 2H, CH2CH2CH2), 1.3-0.7 (b, 3H, CH3).
[00531] Large Scale Synthesis of 3-(dimethylamino)-1-propylamine
functionalized PMMA (MW=35,000):
[00532] Polymethyl methacrylate (90.0 g, 899 mmol) was weighed into a 2L
3
neck round bottom flask with a stir bar and fitted with a condenser, gas inlet
and
rubber septum. The apparatus was evacuated on vacuum line/refilled with
nitrogen
three times. 3-(dimethylamino)-1-propylamine (1 L) was poured into the flask
under a
flow of nitrogen. The mixture was heated to 150 C for 5 days under nitrogen.
After
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reacting overnight the mixture was observed to be a white suspension with
stirring
hampered by the solid. It was allowed to cool to room temperature. The
condenser
was removed under a flow of nitrogen and a distillation apparatus with
condenser
and receiving flask was attached. The reaction flask was covered in aluminum
foil
and the amine solvent distilled off under nitrogen atmosphere at 155 C
followed by
160 C then 165 C for 6 hours before being allowed to cool. A1H NMR spectrum
was
recorded of the distillate showing resonances corresponding primarily to 3-
(dimethylamino)-1-propylamine along with methanol byproduct indicating
successful
reaction. 1H NMR (400 MHz, CDCI3) 6 3.28 (s, 3H, CH3OH), 2.63 (t, J = 8.0 Hz,
2H,
NHCH2), 2.20 (b, 2H, Me2NCH2), 2.11 (s, 6H, N(CH3)2), 1.50 (m, 2H, CH2CH2CH2).
[00533] A small amount of residual liquid was decanted from the flask and
the
light yellow crystalline solid was washed quickly with 100 mL of isopropanol.
It was
then dried at 80 C under high vacuum for 6 hours causing it to swell. The
swollen
solid was then broken up with a spatula and drying continued for 16 hours.
Solid
removed and ground yielding a light yellow powder which was added to a 1L 2
neck
round bottom flask and dried for 16 hours at 80 C under high vacuum. 101.8 g
of
light yellow powder was obtained and approximately 80% of the methacrylate
sites
were functionalized, as determined by integration of the appropriate
resonances in
the 1H NMR spectrum.
1H NMR (400 MHz, D20) 6 3.64 (bs, 3H, CHO, 2.87 (t, J = 8.0 Hz, 2H, NHCH2),
2.59 (t, J = 8.0 Hz, 2H, Me2NCH2), 2.36 (s, 6H, N(CH3)2), 2.0-1.6 (b, 2H,
backbone
CH2), 1.82 (m, 2H, CH2CH2CH2), 1.5-0.8 (b, 3H, CH3).
[00534] 23.3.2 3-(dimethylamino)-1-propylamine functionalized PMMA
(MW=120,000):
[00535] Polymethyl methacrylate (1.706 g, 17.0 mmol) was weighed into a
100
mL two-neck round bottom flask with a stir bar and evacuated on vacuum
line/refilled
with nitrogen three times. A reflux condenser was also put under inert
atmosphere
using same procedure. 3-(dimethylamino)-1-propylamine (10 mL) was added via
syringe to the polymer and a reflux condenser was placed onto flask. The
mixture
was heated to 150 C for 16 hours under nitrogen. After this time, the reaction
mixture was a light yellow liquid with yellow precipitate. The liquid was
decanted and
the remaining light yellow solid was dried at 80 C under high vacuum for 2
hours.
The solid was then broken up with a spatula until more of a powder formed and
then
re-dried using the same conditions for another 2 hours. This step was repeated
once
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more after breaking up brittle chunks of polymer using a mortar and pestle to
give a
fine powder (in order to facilitate drying). 2.065 g of yellow powder was
obtained and
approximately 50% of the methacrylate sites were functionalized, as determined
by
integration of the appropriate resonances in the 1H NMR spectrum.
1H NMR (400 MHz, D20) 6 3.65 (bs, 3H, OCH3), 2.81 (b, 2H, NHCH2), 2.52 (m, 2H,
Me2NCH2), 2.31 (s, 6H, N(CH3)2), 2.0-1.6 (b, 2H, backbone CH2), 1.75 (m, 2H,
CH2CH2CH2), 1.3-0.7 (b, 3H, 01-13).
[00536] Large Scale Synthesis of 3-(dimethylamino)-1-propylamine
functionalized PMMA (MW=120,000):
[00537] Polymethyl methacrylate (47.14 g, 470.8 mmol) was weighed into a
1L
2 neck round bottom flask with a stir bar and fitted with a condenser and gas
inlet.
The apparatus was evacuated on vacuum line/refilled with nitrogen three times.
3-
(dimethylamino)-1-propylarn ine (350 mL) was poured into the flask under a
flow of
nitrogen. The mixture was heated to 150 C for 3.5 days under nitrogen. After
stirring
overnight the reaction mixture was observed to remain clear and colourless
with a
white opague gel precipitate. After full reaction time, the precipitate was a
more
compact, clear solid. It was allowed to cool to room temperature and the
liquid
decanted. The solid was then dried at 90 C under high vacuum for 2 hours
causing it
to swell. The swollen solid was then broken up with a spatula and drying
continued
for 3 hours before being further broken up. Drying continued overnight. Very
little of
the hard crystalline mass was removed because it was difficult to do so. In
order to
soften solid it was heated to 170 C under nitrogen before being put under
vacuum
causing the solid to inflate. It was then dried overnight at 100 C under full
vacuum.
Flask cooled, solid removed and ground yielding 48.9 grams of white powder and
approximately 80% of the methacrylate sites were functionalized, as determined
by
integration of the appropriate resonances in the 1H NMR spectrum.
1H NMR (400 MHz, D20) 63.64 (bs, 3H, OCH3), 2.85 (t, J = 8.0 Hz, 2H, NHCH2),
2.56 (t, J = 8.0 Hz, 2H, Me2NCH2), 2.34 (s, 6H, N(CH3)2), 1.95-1.55 (b, 2H,
backbone
CH2), 1.82 (m, 2H, CH2CH2CH2), 1.5-0.7 (b, 3H, CH3).
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[00538] 3-(dimethylamino)-1-propylamine functionalized PMMA
(MW=350,000):
[00539] Polymethyl methacrylate (1.47 g, 14.7 mmol) was weighed into a
100
mL two-neck round bottom flask with a stir bar and evacuated on vacuum
line/refilled
with nitrogen three times. A reflux condenser was also put under inert
atmosphere
using same procedure. 3-(dimethylamino)-1-propylamine (15 mL) was added via
syringe to the polymer and a reflux condenser was placed onto flask. The
mixture
was heated to 150 C for 5.5 days under nitrogen. After stirring overnight, the
reaction mixture was a clear, colourless liquid with clear, colourless
precipitate. The
liquid was decanted and the remaining white solid was washed with 2-25 mL
portions
of isopropanol before being dried at 100 C under high vacuum for 2 hours. The
solid
was then broken up with a spatula until more of a powder formed and then re-
dried
using the same conditions for another 2 hours. The solid was then ground into
more
of a powder and dried for 2 hours, before being further ground and dried for
16 hours.
0.888 g of white powder was obtained and approximately 80% of the methacrylate
sites were functionalized, as determined by integration of the appropriate
resonances
in the 1H NMR spectrum.
1H NMR (400 MHz, D20) 6 3.65 (bs, 3H, OCH3), 2.84 (b, 2H, NHCH2), 2.57 (b, 2H,
Me2NCH2), 2.35 (bs, 6H, N(CH3)2), 1.95-1.55 (b, 2H, backbone CH2), 1.79 (b,
2H,
CH2CH2CH2), 1.5-0.7 (b, 3H, CH3).
[00540] Neutral polyacrylic acid (PAA) based materials
[00541] All reactions were conducted in air unless stated otherwise. NMR
spectra were recorded on a Varian 400-MR NMR spectrometer (Agilent,
Mississauga, Ontario, Canada). All NMR spectra are referenced against residual
protonated solvent.
[00542] Polyacrylic acid samples (MW = 1,800 and 450,000) were purchased
from Sigma Aldrich Inc. (Oakville, Ontario, Canada). Polyacrylic acid (MW =
50,000)
was purchased from Polysciences Inc. (Warrington, Pennsylvania, USA) as a 25%
solution in water. This was dried under vacuum on a rotary evaporator, washed
with
hexanes and dried further under vacuum giving the polymer as a white solid. 3-
dinnethylam ino-1-propylamine was purchased from Alfa Reser (VWR, Mississauga,
Ontario, Canada).
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[00543] 23.4.1 3-(dimethylamino)-1-propylamine functionalized PAA
(MW=1,800):
[00544] Polyacrylic acid (1.000, 13.88 mmol) was weighed into a 25 mL 2
neck round bottom flask with a stir bar and fitted with a gas inlet and rubber
septum.
The apparatus was evacuated on vacuum line/refilled with nitrogen three times.
A
reflux condenser was also put under inert atmosphere using same procedure. 3-
(dimethylamino)-1-propylam ine (1.57 mL, 12.48 mmol) was added via syringe to
the
polymer and the reflux condenser was placed onto the flask. The mixture was
heated to 160 C for 2.5 days under nitrogen. After that time, the reaction
mixture
was a slightly cloudy colourless solution and was allowed to cool to 100 C
causing it
to become more cloudy and stirring difficult. The mixture was dried at 100 C
for 6
hours under full vacuum followed by removal of the solid which was ground with
a
mortar and pestle giving a sticky white solid. The solid was further dried at
80 C
under full vacuum for 16 hours. The flask was cooled and 1.04 grams of white
powder obtained.
1H NMR (400 MHz, D20) 63.18 (m, 2H, NHCH2), 2.41 (m, 2H, Me2NCH2), 2.24 (s,
6H, N(CI-13)2), 2.20-1.95 (b, 1H, backbone CH), 1.71 (m, 2H, CH2CH2CH2), 1.70-
1.20
(b, 2H, backbone CH2).
[00545] 23.4.2 3-(dimethylamino)-1-propylamine functionalized PAA
(MW=50,000):
[00546] Polyacrylic acid (1.00 g, 13.88 mmol) was weighed into a 50 mL 2
neck round bottom flask with a stir bar and fitted with a gas inlet and rubber
septum.
The apparatus was evacuated on vacuum line/refilled with nitrogen three times.
A
reflux condenser was also put under inert atmosphere using same procedure. 3-
(dimethylamino)-1-propylamine (1.57 mL, 12.48 mmol) was added via syringe to
the
polymer and the reflux condenser was placed onto the flask. The mixture was
heated to 160 C for 24 hours under nitrogen. After that time, the reaction
mixture
was a clear yellow solution with stirring stopped. The mixture was dried at
100 C
under full vacuum for 3 hours causing the solid to swell. This solid was
broken up
with a spatula and re-dried using the same conditions for another 2 hours. The
solid
chunks were broken up in a mortar and pestle giving a powder which was further
dried for 24 hours. The flask was cooled and 1.42 grams of light yellow powder
obtained.
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1F1 NMR (400 MHz, D20) 63.18 (m, NHCH2), 2.42 (m, Me2NCH2),
2.29 (s,
6H, N(CH3)2), 2.20-1.95 (b, 1H, backbone CH), 1/3 (m, 2H, CH2CH2CH2), 1.80-
1.25
(b, 2H, backbone CH2).
[00547] 23.4.3 3-(dimethylamino)-1-propylannine functionalized PAA
(MW=450,000):
[00548] Polyacrylic acid (1.00 g, 13.88 mmol) was weighed into a 50 mL 2
neck round bottom flask with a stir bar and fitted with a gas inlet and rubber
septum.
The apparatus was evacuated on vacuum line/refilled with nitrogen three times.
A
reflux condenser was also put under inert atmosphere using same procedure. 3-
(dimethylamino)-1-propylamine (1.57 mL, 12.48 mmol) was added via syringe to
the
polymer and the reflux condenser was placed onto the flask. The mixture was
heated to 160 C for 2.5 days under nitrogen. After that time, stirring had
stopped
and the reaction mixture remained a wet light yellow solid. The mixture was
dried at
100 C under full vacuum for 4 hours giving a very hard solid. Parts of this
solid were
broken up with a spatula and re-dried using the same conditions for another 16
hours. The solid chunks were ground up and further dried for 24 hours. The
flask
was cooled and 0.363 grams of light yellow powder obtained.
1H NMR (400 MHz, D20) 63.18 (m, 2H, NHCH2), 2.41 (m, 2H, Me2NCH2), 2.27 (s,
6H, N(CH3)2), 2.20-1.90 (b, 1H, backbone CH), 1.72 (m, 2H, CH2CH2CH2), 1.85-
1.25
(b, 211, backbone CH2).
[00549] Ionic polyacrylic acid (FAA) based materials
[00550] All reactions were conducted in air unless stated otherwise. NMR
spectra were recorded on a Varian 400-MR NMR spectrometer (Agilent,
Mississauga, Ontario, Canada). All NMR spectra are referenced against residual
protonated solvent. Centrifugation was conducted with a Sorvall Legend XT
laboratory centrifuge (Thermo Fisher Scientific, Ottawa, Ontario, Canada).
[00551] Polyacrylic acid samples (MW = 1,800 and 450,000) were purchased
from Sigma Aldrich Inc. (Oakville, Ontario, Canada). Polyacrylic acid (MW =
50,000)
was purchased from Polysciences Inc. (Warrington, Pennsylvania, USA) as a 25%
solution in water. This was dried under vacuum on a rotary evaporator, washed
with
hexanes and dried further under vacuum giving the polymer as a white solid. 3-
dimethylamino-1-propylamine was purchased from Alfa Aesar (VWR, Mississauga,
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Ontario, Canada). (2-iodo-5-methoxyphenyl)boronic acid was prepared according
to
the literature reference: Al-Zoubi, R.M.; Marion, 0.; Hall, D.G. Angew. Chem.
mt. Ed.
2008, 47, 2876.
[00552] All solvents were used as received. Methanol was purchased from
ACP Chemicals (Montreal, Quebec, Canada). lsopropanol was purchased from
Caledon Laboratories (Georgetown, Ontario, Canada). Tetrahydrofuran was
purchased from EMD Chemicals (Gibbstown, New Jersey, US).
[00553] Ionic polymers were synthesized through a simple acid-base
reaction
between the acidic polymer and the basic amine yielding a salt of the
polycarboxylate
with an ammonium counterion.
[00554] (Polyacrylic acid), 3-(dimethylamino)-1-propylammonium salt (MW =
1,800)
0
0 0
H3N
[00555] Polyacrylic acid (1.00 g, 13.88 mmol) was added to a 100 mL round-
bottomed flask. Methanol (20 mL) was added and stirred giving a clear,
colourless
solution. 3-(dimethylamino)-1-propylamine (1.75 mL, 13.91 mmol) was added
dropwise via syringe causing the immediate precipitation of a thick white
solid which
then disappeared after a few minutes. The solution was stirred overnight at 20
C
under air. The solvent was removed using a rotary evaporator giving a clear,
colourless oil which was re-dissolved in 3 mL methanol. This concentrated
solution
was added dropwise to 500 mL of rapidly stirred tetrahydrofuran giving a white
suspension which was stirred for 30 minutes before being allowed to settle.
Most of
the supernatant was decanted with the remaining 50 mL being transferred to a
Nalgene bottle and centrifuged at 2000 rpm for 60 minutes. Remainder of
supernatant decanted and solid dried under full vacuum at 20 C for 4 hours.
1.05
grams of fine white powder isolated.
1H NMR (400 MHz, 020) ô 3.08 (m, 4H, NHCH2 and Me2NCH2), 2.77 (s, 6H,
N(CH3)2), 2.30-1.95 (b, 1H, backbone CH), 2.08 (m, 2H, CH2CH2CH2), 1.90-1.20
(b,
2H, backbone CH2).
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[00556] (Polyacrylic acid), 3-(dimethylamino)-1-propylammonium salt
(MW=1,800):
[00557] Polyacrylic acid (1.51 g, 20.95 mmol) and (2-iodo-5-
methoxyphenyl)boronic acid (0.291 g, 1.05 mmol) were added to a 500 mL Schlenk
round-bottomed flask under nitrogen flush. Tetrahydofuran (125 mL) was added
and
stirred for 30 minutes gradually giving a colorless, clear solution. 3-
(dimethylamino)-
1-propylamine (5.27 mL, 41.88 mmol) was then added via syringe resulting in
the
immediate formation of a thick white slurry. The resultant suspension was
stirred for
2.5 days at 2000 under nitrogen. The cloudy, white mixture was filtered
through a
Buchner funnel and the collected white solid was washed with 2-50 mL portions
of
tetrahydrofuran. The filter paper and solid were placed in a dessicator and
dried
under full vacuum at 20 C for 6 hours. 2.20 grams of white solid were removed
from
the filter paper and crushed in a mortar and pestle giving a fine white powder
which
was judged to be suitably dry.
1H NMR (400 MHz, D20) 63.01 (t, J = 8.0 Hz, 2H, NHCH2), 2.91 (t, J = 8.0 Hz,
2H,
Me2NCH2), 2.62 (s, 6H, N(CH3)2), 2.20-1.95 (b, 1H, backbone CH), 1.99 (m, 2H,
CH2CH2CH2), 1.80-1.20 (b, 2H, backbone CH2).
[00558] (Polyacrylic acid), 3-(dimethylamino)-1-propylammonium salt
(MW=50,000):
[00559] Polyacrylic acid (1.51 g, 20.95 mmol) and (2-iodo-5-
methoxyphenyl)boronic acid (0.291 g, 1.05 mmol) were added to a 500 mL Schlenk
round-bottomed flask under nitrogen flush. Methanol (200 mL) was added and
stirred for 30 minutes gradually giving a colorless, clear solution. 3-
(dirnethylamino)-
1-propylamine (5.27 mL, 41.88 mmol) was then added via syringe resulting in
the
immediate formation of a white suspension. The white solid redissolved over
several
minutes giving a clear and colorless solution. The reaction mixture was
stirred
overnight at 20 C under nitrogen. The solution was decanted to a 500 mL round-
bottomed flask and concentrated under vacuum giving a clear, semi-viscous
liquid.
The liquid was added dropwise to 900 mL of rapidly stirred isopropanol
immediately
giving a fine white solid. The stirring was stopped after 30 minutes but
little solid
settled so supernatant was transferred to Nalgene bottles and centrifuged at
2000
rpm for 1 hour causing complete separation of supernatant and white gel. The
supernatant was decanted, the four Nalgene bottles placed inside a desiccator
and
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dried overnight at 20 C under high vacuum. The solid was then broken up using
a
mortar and pestle and dried at 80 C for several hours giving 1.62 g of white
powder.
1H NMR (400 MHz, D20) 53.19 (t, J = 8.0 Hz, 2H, NHCH2), 3.07 (t, J = 8.0 Hz,
2H,
Me2NCH2), 2.85 (s, 6H, N(CH3)2), 2.2-1.9 (b, 1H, backbone CH), 2.12 (m, 2H,
CH2CH2CH2), 1.75-1.25 (b, 2H, backbone CH2).
[00560] (Polyacrylic acid), 3-(dimethylamino)-1-propylammonium salt
(MW=450,000):
[00561] Polyacrylic acid (1.51 g, 20.95 mmol) and (2-iodo-5-
methoxyphenyl)boronic acid (0.291 g, 1.05 mmol) were added to a 500 mL Schlenk
round-bottomed flask under nitrogen flush. Methanol (200 mL) was added and
stirred for 30 minutes gradually giving a colorless, clear solution. 3-
(dimethylamino)-
1-propylamine (5.27 mL, 41.88 mmol) was then added via syringe resulting in
the
immediate formation of a white suspension. The white solid started to
amalgamate
after 1 minute into a lump which then proceeded to decrease in size over
several
minutes giving a clear and colorless solution. The reaction mixture was
stirred
overnight at 20 C under nitrogen. The slightly cloudy solution was decanted to
a 500
mL round-bottomed flask and concentrated under vacuum giving a clear, semi-
viscous liquid. The liquid was added dropwise to 900 mL of rapidly stirred
isopropanol immediately giving a white gel-like solid. Most of the supernatant
was
decanted while remaining suspension was transferred to Nalgene bottles and
centrifuged at 2000 rpm for 1 hour causing complete separation of supernatant
and
white gel. The supernatant was decanted, the two Nalgene bottles placed inside
a
desiccator and dried overnight at 20 C under high vacuum. The solid was then
broken up using a mortar and pestle and dried at 80 C for several hours giving
1.61 g
of white powder.
1H NMR (400 MHz, D20) 53.20 (m, 2H, NHCH2), 3.09 (m, 2H, Me2NCH2), 2.87 (s,
6H, N(CH3)2), 2.2-1.95 (b, 1H, backbone CH), 2.13 (m, 2H, CH2CH2CH2), 1.75-
1.25
(b, 2H, backbone CH2).
[00562] 23.5 Polymethyl methacrylate-co-styrene (PMMA/PS) based materials
[00563] All reactions were conducted in air unless stated otherwise. NMR
spectra were recorded on a Varian 400-MR NMR spectrometer (Agilent,
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Mississauga, Ontario, Canada). All NMR spectra are referenced against residual
protonated solvent.
[00564] Polystyrene-co-polymethyl methacrylate (1.4, 10, 20, and 31 nnol
%
styrene) were purchased from Polymer Source (Montreal, Quebec, Canada).
Polystyrene-co-polymethyl methacrylate (40 mol % styrene) was purchased from
Sigma Aldrich Inc. (Oakville, Ontario, Canada). 3-dimethylamino-1-propylamine
was
purchased from Alfa Aesar (VVVR, Mississauga, Ontario, Canada).
[00565] All solvents were used as received. Isopropanol was purchased
from
Caledon Laboratories (Georgetown, Ontario, Canada).
[00566] 23.5.1 3-(dimethylamino)-1-propylamine functionalized PMMA/PS (40
mol% styrene, MW=100,000-150,000):
[00567] Polystyrene-co-methyl methacrylate (2.938 g) was added to a 100
mL
2 neck round bottom flask and evacuated on vacuum line/refilled with nitrogen
three
times. Separately a reflux condenser was also put under an inert atmosphere
using
the same procedure. 3-(dimethylamino)-1-propylamine (20 mL) was added via
syringe and the reflux condenser was placed onto the flask. The mixture was
heated
to 150 C overnight under nitrogen. The resulting yellow solution was cooled to
only
80 C so that its viscosity didn't increase significantly; the solution was
decanted
slowly into 900 mL of rapidly stirred isopropanol giving a white-yellow
precipitate that
was filtered through a Buchner funnel. The polymer was dried at 80 C under
high
vacuum for several hours giving a solid chunk, which was broken up with a
mortar
and pestle giving a light yellow solid. This was dried overnight at 80 C under
high
vacuum. 2.85 grams of light yellow, water-insoluble powder was obtained.
1H NMR (400 MHz, CDCI3) 7.2-6.7 (b, 5H, aromatic CH), 3.52 (bs, 3H, OCH3),
2.80
(b, 2H, NHCH2), 2.39 (b, 2H, Me2NCH2), 2.23 (s, 6H, N(CH3)2), 2.1-1.4 (b,
backbone
CH2 and CH), 1.68 (b, 2H, CH2CH2CH2), 1.0-0.3 (b, backbone CH and CF13).
[00568] 23.5.2 3-(dimethylamino)-1-propylamine functionalized PIVIMA/PS
(31
nnol /0 styrene, MW=117,000-192,000):
[00569] Polystyrene-co-methyl methacrylate (1.13 g) was added to a 100 mL
2
neck round bottom flask and evacuated on vacuum line/refilled with nitrogen
three
times. Separately a reflux condenser was also put under an inert atmosphere
using
the same procedure. 3-(dimethylamino)-1-propylamine (15 mL) added via syringe
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and the reflux condenser was placed onto the flask. The mixture was heated to
150 C overnight under nitrogen. The resulting clear, colorless solution was
cooled to
20 C causing a white gel to precipitate. The supernatant was decanted and the
gel
was washed with two 50 mL portions of isopropanol before being dried at 80 C
for 2
hours under high vacuum. The solid then broken up and drying was continued for
another 2 hours under high vacuum. The solid was then broken up using a mortar
and pestle and drying was continued overnight at 80 C under high vacuum. 1.09
grams of white, water-insoluble powder was obtained.
1H NMR (400 MHz, CDCI3) 5 7.3-6.8 (b, 5H, aromatic CH), 3.55 (bs, 3H, OCH3),
2.83
(b, 2H, NHCH2), 2.42 (b, 2H, Me2NCH2), 2.26 (s, 6H, N(CH3)2), 2.0-1.5 (b,
backbone
CH2 and CH), 1.71 (b, 2H, CH2CH2CH2), 1.2-0.4 (b, backbone CH and CH3).
[00570] 23.5.3 3-(dimethylamino)-1-propylamine functionalized PMMA/PS (20
mol /0 styrene, MW=146,000-230,000):
[00571] Polystyrene-co-methyl methacrylate (1.075 g) was added to a 100 mL
2 neck round bottom flask and evacuated on vacuum line/refilled with nitrogen
three
times. Separately a reflux condenser was also put under an inert atmosphere
using
the same procedure. 3-(dimethylamino)-1-propylamine (15 mL) added via syringe
and the reflux condenser was placed onto the flask. The mixture was heated to
150 C overnight under nitrogen. The yellow solution was cooled to 80 C causing
a
yellow gel to precipitate. The supernatant was decanted and the yellow thick
gel was
washed with two 50 mL portions of isopropanol before being dried at 80 C for 2
hours under high vacuum. The solid was then broken up and drying continued for
another 2 hours under high vacuum. The solid was then broken up using a mortar
and pestle and drying was continued overnight at 80 C under high vacuum. 1.15
grams of light yellow, water-soluble powder was obtained.
1H NMR (400 MHz, D20) 6 7.5-6.8 (b, 5H, aromatic CH), 3.64 (bs, 3H, OCH3),
2.76
(b, 2H, NHCH2), 2.48 (b, 2H, Me2NCH2), 2.27 (s, 6H, N(CH3)2), 2.2-1.7 (b,
backbone
CH2 and CH), 1.72 (b, 2H, CH2CH2CH2), 1.4-0.5 (b, backbone CH and CH3).
[00572] 23.5.4 PMMA/PS (10 mol% styrene, MW=10,600-15,900):
[00573] Polystyrene-co-methyl methacrylate (1.15 g, MW = 10,600-15,900)
was added to a 100 mL 2 neck round bottom flask and evacuated on vacuum
line/refilled with nitrogen three times. Separately a reflux condenser was
also put
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under an inert atmosphere using the same procedure. 3-(dimethylamino)-1-
propylamine (15 mL) was added via syringe and the reflux condenser was placed
onto the flask. The mixture was heated to 150 C overnight under nitrogen. The
resulting yellow solution was cooled to 80 C causing a yellow gel to
precipitate. The
supernatant was decanted and the yellow thick gel was washed with two 50 mL
portions of isopropanol before being dried at 80 C for 2 hours under high
vacuum.
The solid was then broken up and drying was continued for another 2 hours
under
high vacuum. The solid was then broken up using a mortar and pestle and drying
was continued overnight at 80 C under high vacuum. 1.07 grams of light yellow,
water-soluble powder was obtained.
1H NMR (400 MHz, D20) d 7.45-7.0 (b, 5H, aromatic CH), 3.65 (bs, 3H, OCH3),
2.85
(t, J = 8.0 Hz, 2H, NHCH2), 2.56 (b, 2H, Me2NCH2), 2.34 (s, 6H, N(CH3)2), 2.1-
1.6 (b,
backbone CH2 and CH), 1.79 (m, 2H, CH2CH2CH2), 1.6-0.6 (b, backbone CH and
CH3).
[00574] 23.5.5 PMMA/PS (1.4 mol% styrene, MW= 9,200-12,900):
[00575] Polystyrene-co-methyl methacrylate (1.09 g) was added to a 100 mL
2
neck round bottom flask and evacuated on vacuum line/refilled with nitrogen
three
times. Separately a reflux condenser was also put under an inert atmosphere
using
the same procedure. 3-(dimethylamino)-1-propylamine (15 mL) wa added via
syringe and the reflux condenser was placed onto the flask. The mixture heated
to
150 C overnight under nitrogen. The resulting yellow solution was cooled to
room
temperature causing a white gel to precipitate. The supernatant was decanted
and
the yellow thick gel was washed with three 50 mL portions of isopropanol
before
being dried at 80 C for 2 hours under high vacuum. The solid was then broken
up
and drying was continued for another 2 hours under high vacuum. The solid was
then broken up using a mortar and pestle and drying was continued overnight at
80 C under high vacuum. 0.469 grams of white, water-soluble powder was
obtained.
1H NMR (400 MHz, D20) 6. 7.4-7.0 (b, 5H, aromatic CH), 3.64 (bs, 3H, OCH3),
2.86
(t, J = 8.0 Hz, 2H, NHCH2), 2.57 (b, 2H, Me2NCH2), 2.35 (s, 6H, N(CH3)2), 2.2-
1.5 (b,
backbone CH2 and CH), 1.79 (m, 2H, CH2CH2CH2), 1.5-0.5 (b, backbone CH and
CH3).
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[00576] Polydiethylaminoethylmethacrylate (PDEAEMA) based materials
[00577] 2-(diethylamino)ethyl methacrylate was purchased from Sigma-
Aldrich, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] was purchased from Wako
Pure
Chemical Industries, Ltd. THF was purchased from Fisher Scientific. Size
exclusion
chromatography (SEC) was conducted using a Waters 2960 separation module with
Styragel packed columns HR 0.5, HR 1, HR 3, HR 4, and HR 5E (Waters Division
Millipore) coupled with a refractive index detector operating at 40 C.
[00578] Polydiethylaminoethylmethacrylate (PDEAEMA) MW = 55,000
[00579] 5.42 mL (5.0 g, 27.0 mmol) 2-(Diethylamino)ethyl methacrylate was
placed in a 100 mL 2-neck round-bottom flask equipped with a 1 cm stir bar, a
septum and condenser. 30 mL of THF and 0.050 g of 2,2'-azobis[2-(2-imidazolin-
2-
yl)propane] were added. The reaction mixture was degassed at room temperature
by
bubbling argon through the solution using a single gauge needle under stirring
with
600 rpm. After 1 h the needle was removed and the reaction mixture was heated
to
65 C for 5 h. After cooling to room temperature the solution was poured into
a
beaker equipped with a stir bar and 100 mL of cold water. The polymer
precipitated
over the 16 h under stirring to form a sticky gum-like solid that was
collected with a
spatula and dried in a dessicator for 24 h. The product was obtained as a
sticky gum
(2.7 g 54%)
1H NMR (400 MHz, CDCI3): 8 = 4.12-3.91 (m, 2H, OCH2), 2.74-2.66 (m, 2H,
CH2CH2N), 2.62-2.48 (m, 4H, CH3CH2N), 2.00-1.74(m, 2H, CH2 backbone), 1.14-
0.96 (m, 6H, CH3CH2N), 0.95-0.82 (CCH3);
13C NMR (100.7 MHz, CDCI3): 6 = 177.4, 63.1 (OCH2), 50.4 (CH2CH2N), 47.6
(CH3CH2N), 18.5 (CH2 backbone), 16.6 (CCH3), 12.0 (CH3CH2N);
GPC: (THF): Mn: 31000, Mw: 55,000, PDI: 1.78.
[00580] 23.6.2 Polydiethylaminoethylmethacrylate (PDEAEMA) MW = 69,000
[00581] 5.42 mL (5.0 g, 27.0 mmol) 2-(diethylamino)ethyl methacrylate was
placed in a 100 mL 2-neck round-bottom flask equipped with a 1 cm stir bar, a
septum and condenser. 15 mL of THF and 0.050 g of 2,2'-azobis[2-(2-imidazolin-
2-
yl)propane] were added. The reaction mixture was degassed at room temperature
by
bubbling argon through the solution using a single gauge needle under stirring
with
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600 rpm. After 1 h the needle was removed and the reaction mixture was heated
to
65 C for 5 h. After cooling to room temperature the solution was poured into
a
beaker equipped with a stir bar and 100 mL of cold water. The polymer
precipitated
over the 16 h under stirring to form a sticky gum-like solid that was
collected with a
spatula and dried in a dessicator for 24 h. The product was obtained as a
sticky gum
(2.0 g, 40%)
1H NMR (400 MHz, CDCI3): 8 = 4.12-3.91 (m, 2H, OCH2), 2.74-2.66 (m, 2H,
CH2CH2N), 2.62-2.48 (m, 4H, CH3CH2N), 2.00-1.74 (m, 2H, CH2 backbone), 1.14-
0.96 (m, 6H, CH3CH2N), 0.95-0.82 (CCH3);
1H NMR (100.7 MHz, 0D013): ö = 177.4, 63.1 (OCH2), 50.4 (CH2CH2N), 47.6
(CH3CH2N), 18.5 (CH2 backbone), 16.6 (CCH3), 12.0 (CH3CH2N);
GPC: (THF): Mn: 39000, Mw: 69,000, PDI: 1.76.
[00582] Switchable solubility of Polydiethylaminoethylmethacrylate
(PDEAEMA) MW = 69,000
[00583] 800 mg of polydiethylaminoethylmethacrylate (PDEAEMA) MW =
69000 was placed in a 100 mL round bottom flask equipped with a 1 cm stir bar.
60
mL of deionized water was added, CO2 was introduced by means of a glass
dispersion tube at 1 atm and the mixture was stirred at 900 rpm for 5 h at 50
C.
Then the dispersion tube was removed, the flask closed with a glass stopper
and the
mixture was stirred for another 16 h at 50 C. The solution was then filtered
off and
the undissolved polymer weighed. 200 mg of the polymer did not dissolve.
Therefore,
the polymer has a solubility of 600 mg in 60 mL of carbonated water.
[00584] The solution was then bubbled with argon under heating at 60 C.
After 10 min the solution turned turbid, and after 30 min, precipitate was
visible.
Bubbling with argon under heat was continued for another 30 min. Then the
polymer
was collected by filtration and the water evaporated. This left behind 5 mg of
a solid
that was analyzed by NMR. The NMR only showed traces of the polymer. The
solubility of the polymer in water is therefore <1%.
[00585] EXAMPLE 24: Viscosity Control with Switchable Water Additives
[00586] In order to study the use of switchable water additives in a
method
and system for viscosity control, a switchable additive or other molecule of
interest
was placed in a 50 mL round-bottom flask equipped with a 1 cm magnetic stir-
bar
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and placed on a stir-plate. Water was added and the mixture was agitated at
600 rpm
until the polymer was completely dissolved (1-24 h). The solution was then
transferred in to a Technical Glass Products, Inc. C. F. Opage viscometer with
either
a 100 or 200 capillary tube. The measurements were taken at room temperature
(i.e.,
from about 15¨ 30 C) and repeated twice. The solution was transferred back
into the
round bottom flask and CO2 was introduced to the mixture by bubbling for 30
minutes
at a flow rate of 80 ml/min. The carbonated solution was then put into the
viscometer
and the viscosity was measured three times. The viscosity in centistokes (cS)
was
calculated from the times the solution took to run through the viscometer.
[00587] 24.1 Switchable viscosity using 3-(dimethylamino)-1-propylamine
functionalized polymethylmethacrylate (MW= 120,000)
[00588] Using the general method described above, 207.3 mg of PMMA
(120,000) was dissolved in 20 mL H20 and stirred for 1 h. Measurements were
taken
on the 200 viscometer. The viscosity change was reversed by removing the CO2
through bubbling of Ar at 40 C for 30 min. Measurements were taken again,
leading
to similar results obtained for the first run with no CO2 present.
without CO2 with CO2
viscosity 8.3 cS 1.4 cS
[00589] 24.2 Switchable viscosity using 3-(dimethylamino)-1-propylamine
functionalized polymethylmethacrylate (MW= 35,000)
[00590] Using the general method described above, 100.6 mg of PMMA
(35,000) was dissolved in 10 mL H20 and stirred for 1 h. Measurements were
taken
on the 200 viscometer.
without CO2 with CO2
viscosity 1.7 cS 1.2 cS
[00591] 24.3 Switchable viscosity using ionic polyacrylic acid
(MW=450,000)
[00592] Using the general method described above, 54.9 mg of the ionic PAA
(450,000) was dissolved in 10 mL H20 and stirred for 1 h. Measurements were
taken
on the 200 viscometer.
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without CO2 with CO2
viscosity 10.5 cS 4.0 cS
[00593] 24.4 Switchable viscosity control experiment using polyacrylamide
(MW: 6,000,000)
[00594] Using the general method described above, 33.3 mg of
polyacrylamide (MW: 6,000,000) was dissolved in 10 mL H20 and stirred for 1 h.
Measurements were taken on the 200 viscometer.
without 002 with CO2
viscosity 6.9 cS 6.7 cS
[00595] These results demonstrate that the introduction of CO2 did not
change
the viscosity of a solution of a non-switchable water polymer, even when the
polymer
was a very high molecular weight polymer.
[00596] 24.5 Switchable viscosity control experiment using N,N-
dimethylcyclohexylamine
[00597] Using the general method described above, 104.6 mg of N,N-
dimethylcyclohexylam ine was dissolved in 10 mL H20 and stirred for 1 h.
Measurements were taken on the 100 viscometer.
without CO2 with CO2
viscosity 1.0 cS 1.0 cS
[00598] These results demonstrate that the introduction of CO2 does not
change the viscosity of a solution comprising a switchable water additive
having a
molecular weight that is too low to generate a substantial viscosity increase
over
water alone (which has a viscosity of about 1.0cS at 20 C), when the
switchable
water additive is in the non-ionized form.
[00599] 24.6 Switchable viscosity using 3-(dimethylamino)-1-propylamine
functionalized PMMA/PS (PS 10 mol%, MW=10,600-15,900)
[00600] Using the general method described above, 150 mg of 3-
(dimethylam ino)-1-propylamine functionalized PMMA/PS (PS 10 mol%) was
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dissolved in 7.5 mL H20 and stirred for 1 h. Measurements were taken on the
100
viscometer.
without CO2 with CO2
viscosity 1.4 cS 1.1 cS
[00601] In this study, the switchable additive 3-(dimethylamino)-1-
propylarnine
functionalized PMMA/PS (PS 10 mol /0) has a lower molecular weight than the
additives tested above. As a result, the difference in viscosity between water
alone
and water plus the switchable additive 3-(dimethylamino)-1-propylamine
functionalized PMMA/PS (PS 10 mol /0) is not as large as the difference
observed
using the polyamine switchable additives tested above. This study demonstrates
a
decrease in viscosity following the addition of CO2, despite the fact that the
presence
of the non-ionic form of the switchable additive causes only a modest increase
in
viscosity over water alone. However, even with low molecular weight polymers,
increasing the concentration of the polymer in a sample can also have a large
effect
on viscosity and, therefore, the relative change in viscosity when the
additive is
switched.
[00602] As demonstrated in this example, switchable water can be used
effectively in a system having switchable viscosity. Selection of the
appropriate
switchable additive will, in part, depend on the degree of viscosity change
required. If
a large viscosity change is required, the switchable additive should have a
relatively
large molecular weight while remaining sufficiently soluble in water when in
its non-
ionic form to generate a substantial increase in viscosity in comparison to
the
viscosity of water alone. In systems where only a small viscosity change is
desired,
then the switchable water additive should be selected to have a relatively low
molecular weight and be sufficiently soluble in water when in its non-ionic
form to
generate an increase in viscosity in comparison to the viscosity of water
alone.
[00603] EXAMPLE 25: Reversible Solvent Miscibility with Switchable Water
Additives
[00604] 25.1 Ceiling Salting Out Limits
[00605] NaCl, (NH4)2SO4, d3-MeCN, Me0D were all purchased from Sigma
Aldrich, Oakville. THF, ethyl acetate and acetonitrile were purchased from
Fisher
Scientific, Ottawa. Aliquots were taken using a Mettler-Toledo pipetor, all 1H
NMR
acquired on a 400 MHz Bruker instrument.
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[00606] Approximately 2 g of an organic solvent and approximately 2 g of
water were mixed in a graduated cylinder. Small amounts of either NaCI or
(NH4)2SO4 were added to the solution to induce a salting out of the organic.
Salt was
continually added until the salted out organic maintained a constant volume
above
the aqueous layer. The volumes of each phase were recorded. Additional salt
was
often added past the observation of a consistent volume and no additional
volume
change occurred.
[00607] A 50 fiL aliquot of the aqueous phase was extracted and placed in
an
NMR tube. The sample was diluted with a deuterated solvent. Approximately 20
mg
of ethyl acetate was added to the NMR tube to act as an internal standard. A
1H
NUR spectrum was acquired and the peaks integrated. Knowing the amount of
ethyl
acetate and its corresponding integrations, the amount of organic solvent in
the
aqueous aliquot was calculated and multiplied to reflect the total amount of
organic
solvent still in the aqueous layer. Subtracting this value from the total mass
of the
organic solvent used in the experiment provided a ceiling percentage of
organic
solvent that could be salted out with inorganic salts. This experiment was
carried out
in triplicate using both salts for THF and acetonitrile. The results are
presented in the
table below.
Solvent Salt % Organic Salted Out
THF NaCI 98 0.5 %
THF (NH4)2504 99 0.6 %
MeCN NaCI 93 1.0%
MeCN (NH4)2504 99 0.1 %
[00608] 25.2 Acetonitrile-Water Forcing Out
[00609] Polyamines were investigated as additives for switchable ionic
strength solutions useful in forcing out acetonitrile from an aqueous phase.
To
measure the extent of acetonitrile being forced out of an aqueous phase by an
increase in ionic strength, and the amounts of polyamine that remained in the
aqueous phase, 1:1 w/w solutions of acetonitrile and water were prepared in
graduated cylinders. Three hundred milligrams of the additive were added and
the
cylinders were capped with rubber septa. After 30 minutes of bubbling carbon
dioxide
through the liquid phase from a single narrow gauge steel needle, a visible
phase
separation was observed. The volumes of each phase were recorded. Aliquots of
the
non-aqueous and aqueous layers were taken and dissolved in D20 in NMR tubes. A
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known amount of dimethylformamide (DMF) was added to each NMR tube as an
internal standard. 1H NMR spectra were acquired and through integration of the
DMF
standard, a concentration of acetonitrile or additive was calculated and
scaled up to
reflect the total volume of the aqueous or non-aqueous phase, giving a
percentage of
the compound being forced out or retained.
Acetonitrile forced Polymer retained in
Polymer
out aqueous phase
EPEI (MW= 600) 60% 87%
EPEI (MW= 1,800) 56% 71%
EPEI (MW= 10,000) 55% 73%
3-(dimethylamino)-1-propylamine 99%
functionalized PMMA (MW= 66%
35,000)
3-(dimethylamino)-1-propylamine 99%
functionalized PMMA (MW= 65-75%
120,000)
Polydiallylmethylamine 72% 99%
Ionic PAA (MW=1,800) 76% 99%
[00610] Following phase separation and collection of samples from each
phase, argon was bubbled through the mixture while heating to 50 C until the
two
phases recombined (typically from 15 to 60 min). The switching process (i.e.,
30 min
of CO2 bubbling, sample collection, then 30 min of Ar bubbling) was
successfully
repeated, demonstrating that the reversible process can be cycled.
[00611] 25.3 THF-Water Forcing Out
[00612] Polyamines were investigated as additives for switchable ionic
strength solutions useful in forcing out THF from an aqueous phase. To measure
the
extent of THF being forced out of an aqueous phase by an increase in ionic
strength,
and the amounts of polyamine that remained in the aqueous phase, 1:1 w/w
solutions of THF and water were prepared in graduated cylinders. Three hundred
milligrams of the additive were added and the cylinders were capped with
rubber
septa. After 30 minutes of bubbling carbon dioxide through the liquid phase
from a
single narrow gauge steel needle, a visible phase separation was observed. The
volumes of each phase were recorded. Aliquots of the non-aqueous and aqueous
layers were taken and dissolved in acetonitrile-d3 in NMR tubes. A known
amount of
ethylacetate (Et0Ac) was added to each NMR tube as an internal standard. 1H
NMR
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spectra were acquired and through integration of the Et0Ac standard, a
concentration of THF or additive was calculated and scaled up to reflect the
total
volume of the aqueous or non-aqueous phase, giving a percentage of the
compound
being forced out or retained.
Polymer retained in
Polymer THF forced out
aqueous phase
EPEI (MW= 600) 76% 99%
Functionalized PMMA (MW= 99 /0
790/0
35,000)
[00613] Then argon was bubbled through the solution while heating to 50 C
until the two phases recombined (15 to 60 min). The switching process (i.e.,
30 min
of CO2 bubbling, sample collection, then 30 min of Ar bubbling) was
successfully
repeated, demonstrating that the reversible process can be cycled.
[00614] 25.4 Solvent Bridging with Switchable Water Additive
[00615] 25.4.1 Ethyl Acetate & Water: CO2-Induced Phase Separation:
[00616] 0.531 g H20 was mixed with 0.517 g ethyl acetate, generating a
biphasic solution. The addition of 0.319 g N,N,N,Ar-tetramethy1-1,4-
diaminobutane
(TMDAB) bridged the two solvents into a single phase, clear, colourless
solution
(5:3:5 w/w/w H20:amine:organic). A stream of CO2 was run over top of the
solution
for 5 minutes where an organic liquid phase began to cream out of the original
monophasic solution.
[00617] 25.4.2 n-Octanol & Water:
[00618] 0.515 g H20 was mixed with 0.315 g n-octanol, generating a
biphasic
solution. The addition of 0.498 g N,N,AP,N'-tetramethy1-1,4-diaminobutane
(TMDAB)
bridged the two solvents into a single phase, clear, colourless solution
(5:5:3 w/w/w
H20:amine:organic). A stream of CO2 was run over top of the solution for 5
minutes
where an organic liquid phase began to cream out of the original monophasic
solution.
[00619] The above results demonstrate the successful use of switchable
water
in a system and method for reversing organic solvent miscibility. In such a
system
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and method the switchable additive is selected such that it remains soluble in
water
when in its ionized form, but it is not necessary for the additive to be
soluble in water
when in the non-ionized form. In fact, in certain embodiments it may be
beneficial for
the additive to be insoluble or immiscible with water when it is in its non-
ionized form.
Additionally, in order to maximize the separation between the aqueous phase
and the
organic phase, the majority of additive should be retained in the aqueous
layer when
it is in its ionized form. That is, the ionized form of the additive should
exhibit little or
no solubility/miscibility with the organic solvent or little or no tendency to
partition into
the organic solvent from water.
[00620] EXAMPLE 26: Solvent Drying With Switchable Water Additives
[00621] THF was from Fisher Scientific, Ottawa. CO2 from Praxair,
Belleville.
Water content was determined on a Mettler-Toledo C20 coulometric Karl-Fischer
titrator using a Hydranal Coulomat AK solution from Sigma Aldrich, Oakville.
Samples were centrifuged on a Thermo Scientific IEC Medilite Centrifuge.
[00622] 26.1 Dehydration of THE using a polymer
[00623] In a glass vial containing a stirbar, 102.8 mg of 3-
(dimethylamino)-1-
propylamine-functionalized poly(methyl methacrylate-co-styrene) (40 mol%
styrene,
MW = 100,000-150,000) was dissolved a solution of 3.598 g THE (Fisher
Scientific)
and 0.398 g water (-9:1 THF:H20 w/w). The THE contained ¨1 wt% water as
determined by Karl-Fischer titration so the initial water content of the
solution was
approximately 109,000 ppm. The vial was capped with a rubber septum and a
single
narrow gauge steel needle was inserted through the septum into the solution. A
second needle was inserted into the septum, but not into the solution, to act
as a gas
outlet. CO2 was introduced into the solution through the first needle at a
flow rate of
¨10-20 mL min-1 for 60 minutes while stirring. Some small white precipitate
immediately formed and more formed during the course of CO2 treatment. After
60
minutes, the needles were withdrawn and the vial was sealed and left to sit
for
several hours.
[00624] The solids did not settle out after a few hours so the mixture
was
centrifuged at 3100 RPM for 5 minutes causing the precipitate to settle. The
liquid
was decanted off and the water content analyzed by Karl-Fischer titration. The
solution was found to have a water content of roughly 91,000 ppm, resulting in
¨17 %
of the water being removed via the polymer precipitate from CO2 treatment.
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[00625] 26.2 Dehydration of Isobutanol using a polymer at various
loadings
[00626] Isobutanol was from Sigma Aldrich, Oakville. CO2 from Praxair,
Belleville. Water content was determined on a Mettler-Toledo 020 coulometric
Karl-
Fischer titrator using a Hydranal Coulomat AK solution from Sigma Aldrich,
Oakville.
[00627] Solutions of 4.5 g isobutanol and 0.5 g H20 were made up in five
separate glass vials containing stirbars. Varied amounts of 3-(dimethylamino)-
1-
propylamine-functionalized polymethyl methacrylate (MW = 35,000) were
dissolved
into each solution. Vial 4 and 5 were blanks, with vial 4 containing the above
polymer
(with no later CO2 treatment) and vial 5 containing unfunctionalized
polymethyl
methacrylate. The majority of the unfunctionalized polymethyl methacrylate did
not
dissolve in this solution. The initial water content of each vial was roughly
100,000
ppm.
Vial Loading of Polymer
1 50.4 mg
2 102.5 mg
3 150.8 mg
4* 103.8 mg
5..
99.5 mg
* Functionalized polymer with no CO2 treatment,
** Unfunctionalized polymer with no CO2 treatment.
[00628] Vials 1-3 were capped with rubber septa and a single narrow gauge
steel needle was inserted through the septa into each solution. A second
needle was
inserted into the septa, but not into the solution, to act as a gas outlet.
CO2 was
introduced into each solution through the first needle at a flow rate of -10-
20 mL min"
1 for 30 minutes while stirring. Small white precipitate immediately formed
and more
formed during the course of CO2 treatment. After 30 minutes, the needles were
withdrawn and the vial was sealed and left to sit for 18 hours. Vials 4 and 5
were
capped under air and left to sit for 18 hours.
[00629] After 18 hours, the liquid was removed from each vial and
analyzed by
Karl-Fischer titration. The remaining polymer that precipitated or did not
dissolve
initially was dried in a 120 C oven overnight at 7 mm Hg pressure. The water
content of the solutions after treatment and polymer recovered after treatment
are
described below.
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Final Water % Polymer
Vial A) Water Removed
Content Recovered
1 94,000 ppm 6 % 56 A
2 91,000 ppm 9% 44%
3 77,000 ppm 23 % 45 %
4* -100,000 ppm 0 % 0 %
5** -100,000 ppm 0 % 65 %
* Functionalized polymer with no CO2 treatment,
** Unfunctionalized polymer with no CO2 treatment.
[00630] 26.3 Dehydration of a mixed organic solvent with polymers
[00631] Toluene and xylenes were purchased from Fisher Scientific,
Ottawa.
Silica and methyl ethyl ketone were from Sigma Aldrich, Oakville. Ethanol was
from
Commerical Alcohols, Brampton and CO2 was from Praxair, Belleville. Water
content
was determined on a Mettler-Toledo C20 coulometric Karl-Fischer titrator using
a
Hydranal Coulomat AK solution from Sigma Aldrich, Oakville.
[00632] In a glass vial containing a stirbar, 49.2 mg of 3-
(dimethylamino)-1-
propylannine-functionalized poly (methyl methacrylate-co-styrene) (40 mol%
styrene,
MW = 100,000-150,000) was dissolved in 1.900 g 3:3:3:1 v/v methyl ethyl
ketone:toluene:xylenes:ethanol. The addition of 0.102 g water (to give a -19:1
organic:H20 w/w solution) caused some polymer to precipitate out of solution.
The
initial water content of the mixture was 51,000 ppm; however the actual amount
of
water dissolved into the organic solvent resulted in organic solution with a
water
content of -17,000 ppm. The vial was capped under air, stirred for 60 minutes
and
then left to sit for 24 hours.
[00633] In a 2nd glass vial container a stirbar, 50.1 mg of 3-
(dimethylamino)-1-
propylamine-functionalized poly(methyl methacrylate-co-styrene) (40 mol%
styrene,
MW = 100,000-150,000) was dissolved in 1.903 g 3:3:3:1 v/v methyl ethyl
ketone:toluene:xylenes:ethanol. The addition of 0.107 g water (to give a -19:1
organic:H20 w/w solution) caused some polymer to precipitate out of solution.
The
initial water content of the mixture was approximately 53,000 ppm; however the
actual amount of water dissolved into the organic solvent resulted in organic
solution
with a water content of -17,000 ppm. This vial was capped with a rubber
septum. A
single narrow gauge steel needle was inserted through the septum into the
solution.
A second needle was inserted into the septum, but not into the solution, to
act as a
gas outlet. CO2 was introduced into the solution through the first needle at a
flow rate
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of -10-20 mL min-1 for 60 minutes while stirring. After 60 minutes, the
needles were
withdrawn and the vial was sealed and left to sit for 24 hours.
[00634] After 24 hours, the liquid was decanted off from the polymer and
the
water content was analyzed by Karl-Fischer titration. The first solution, the
blank, was
found to have a water content of roughly 16,600 ppm, resulting in -2 % of the
water
being removed via the polymer. The solution from the 2nd vial had a water
content of
13,800 ppm, resulting in a -19 A removal of water by the polymer with CO2
treatment.
[00635] The polymer was dried for 18 hours in a 140 C oven and weighed to
determine the amount of polymer that did not precipitate during treatment and
is thus
lost. The blank was found to have lost 22 % of the original polymer mass and
the
CO2-treated solution lost 46 % of the original polymer.
[00636] 26.4 Dehydration of isobutanol with a polymer and recycling of
the
polymer
[00637] Isobutanol was purchased from Sigma Aldrich, Oakville and CO2 was
from Praxair, Belleville. Water content was determined on a Mettler-Toledo 020
coulometric Karl-Fischer titrator using a Hydranal Coulomat AK solution from
Sigma
Aldrich, Oakville.
[00638] In a glass vial container a stirbar, 28.0 mg of 3-(dimethylamino)-
1-
propylamine-functionalized poly(methyl methacrylate-co-styrene) (40 mol%
styrene,
MW = 100,000-150,000) was dissolved in 4.546 g isobutanol and 0.5099 H20. The
initial water content of the solution was 100,700 ppm. This vial was capped
with a
rubber septum. A single narrow gauge steel needle was inserted through the
septum
into the solution. A second needle was inserted into the septum, but not into
the
solution, to act as a gas outlet. CO2 was introduced into the solution through
the first
needle at a flow rate of -10-20 mL min-1 for 60 minutes while stirring at
which point
solids began to precipitate. After 60 minutes, the needles were withdrawn and
the
liquid was decanted off. The water content was analyzed by Karl-Fischer
titration and
found to be 92,000 ppm, a roughly 9% reduction in water content.
[00639] The precipitated polymer was dried for 18 hours in a 80 C oven.
The
solid was then weighed and it was found that approximately 50 % was lost
during the
1st
cycle. The remaining polymer was redissolved in 2.274 g of isobutanol and
0.265
g H20. The water content was 104,400 ppm. The mixture underwent a 002-
treatment
similar to the procedure outlined above. Once again the polymer precipitated
during
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CO2 treatment. The liquid was decanted off and the water content was found to
be
95,000 ppm, representing an approximately 9 c/o decrease in water content on
the 2nd
cycle.
[00640] 26.5 Dehydration of a mixed organic solvent with a polymer with
recycling of the polymer
[00641] Toluene and xylenes were purchased from Fisher Scientific,
Ottawa.
Silica and methyl ethyl ketone were purchased from Sigma Aldrich, Oakville.
Ethanol
was from Commerical Alcohols, Brampton and CO2 from Praxair, Belleville. Water
content was determined on a Mettler-Toledo C20 coulometric Karl-Fischer
titrator
using a Hydranal Coulomat AK solution from Sigma Aldrich, Oakville.
[00642] In a glass vial containing a stirbar, 25.8 mg of 3-
(dimethylamino)-1-
propylamine-functionalized poly(methyl methacrylate-co-styrene) (40 mol%
styrene,
MW = 100,000-150,000) was dissolved in 1.951 g 3:3:3:1 v/v methyl ethyl
ketone:toluene:xylenes:ethanol. The addition of 0.107 g water (to give a -19:1
organic: H20 w/w solution) caused some polymer to precipitate out of solution.
The
initial water content of the mixture was 50,100 ppm; however the actual amount
of
water dissolved into the organic solvent resulted in organic solution with a
water
content of -17,000 ppm. This vial was capped with a rubber septum. A single
narrow
gauge steel needle was inserted through the septum into the solution. A second
needle was inserted into the septum, but not into the solution, to act as a
gas outlet.
CO2 was introduced into the solution through the first needle at a flow rate
of -10-20
mL mind for 60 minutes while stirring where solids continued to precipitate.
After 60
minutes, the needles were withdrawn and the liquid was decanted off. The water
content was analyzed by Karl-Fischer titration and found to be 15,900 ppm, a
roughly
6 % reduction in water content.
[00643] The precipitated polymer was dried for 18 hours at 80 C. The
solid
was then weighed and it was found approximately 26 A was lost during the 1st
cycle.
The remaining polymer was redissolved in 1.900 g of 3:3:3:1 v/v methyl ethyl
ketone:toluene:xylenes:ethanol. The addition of 0.096 g water (to give a -19:1
Org:H20 w/w solution) caused some polymer to precipitate out of solution. The
water
content of the mixture was 48,100 ppm; however, the actual amount of water
dissolved into the organic solvent resulted in organic solution with a water
content of
-17,000 ppm. The mixture underwent a CO2-treatment similar to the procedure
outlined above. Once again, more polymer precipitated during CO2 treatment.
The
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liquid was decanted off and the water content was found to be 11,900 ppm,
representing a ¨30 % decrease in water content on the 2'd cycle.
[00644] EXAMPLE 27: Clay Settling With Switchable Water Additives
[00645] Montmorillonite (bentonite) from Panther Creek, Colorado, USA was
purchased from Ward's Natural Science. Kaolinite (China Clay) from Panther
Creek,
Colorado, USA was purchased from Ward's Natural Science.
[00646] In this study an equal amount of polyamine was placed into two
different 250 mL round bottom flasks equipped with a 2 cm Teflon stir-bar. 100
mL
deionized water was added and the solutions were stirred (600 rpm) until the
polymer
dissolved (10 min to 16 h). Then 1 g of Montmorillonite was added. Both
suspensions
were stirred at 600 rpm for 1 h, while CO2 was bubbled through one of the
solutions
using a gas dispersion tube. After that, both suspensions were transferred
into 100
mL graduated cylinders and the settling rate was monitored over time. After 16
hours
samples of both supernatants were taken and the turbidity was measured on a
Orbeco-Hellige TB200 turbidity meter. The range of the instrument is 0-1100
NTU.
[00647] 27.1 Butylated polyethyleneimine (BPEI), MW = 600
[00648] 27.1.1 Butylated polyethyleneimine (BPEI), MW= 600 low
concentration
[00649] Thirty-six milligrams of BPEI, MW= 600 were used in the method
set
out above. As shown in Figures 23A and 23B, the clay settles both with and
without
CO2 present, with a faster settling rate without 002 present. Importantly,
however, in
the presence of CO2 the supernatant was less turbid.
[00650] 27.1.2 Butylated polyethyleneimine (BPEI), MW = 600 high
concentration
[00651] Seventy-eight milligrams of BPEI, MW= 600 were used in the method
set out above. The presence of CO2 caused the clay to flocculate on top as a
voluminous layer (40%) leaving a clear phase behind (see Figure 24). Without
CO2
the clay settled slowly with a turbid supernatant after 16 hour settling time.
supernatant without CO2 lower clear layer with CO2
Turbidity (after 16 h) j 390 NTU 11 NTU
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[00652] Propylated polyethyleneimine (PPEI) MW = 600
[00653] Fifity-six milligrams of PPEI, MW = 600 were used in the method
set
out above. The clay settles both with and without CO2 present, with a faster
settling
rate with CO2 present. However, the clay becomes very voluminous and settles
only
to 59% of the starting value after 24 h. Supernatant is clearer in the
presence of
CO2.
supernatant without CO2 lower clear layer with CO2
Turbidity (after 2 h) 263 NTU 4 NTU
[00654] 27.2 3-(dimethylamino)-1-propylamine functionalized PMMA
(MW=120,000)
[00655] Forty six milligrams of 3-(dimethylamino)-1-propylamine
functionalized
PMMA (MW=120,000) was used in the method set out above. The settling was
slightly faster without CO2 present (see, Figure 25). During the settling
process, the
supernatant was less turbid in the presence of CO2. The turbidity measurement
was
taken after 2 hours.
supernatant without CO2 supernatant with CO2
Turbidity (after 2 h) 371 NTU 6 NTU
[00656] 27.3 3-(dimethylamino)-1-propylamine functionalized PMMA/PS (10
mol% styrene, MW=10,600-15,900)
[00657] Forty three milligrams of 3-(dimethylamino)-1-propylamine
functionalized PMMA/PS (10 mol% styrene, MW=10,600-15,900) was used in the
method set out above. Without CO2 bulk settling is impossible to observe due
to high
turbidity of supernatant. With CO2 settling is slow but produces very clear
supernatant. See Figures 26A and 26B.
supernatant without CO2 supernatant with CO2
Turbidity (after 16 h) 1100 NTU 10 NTU
[00658] 27.5 3-(dimethylamino)-1-propylamine functionalized PMMA
(MW=120,000)
[00659] Forty nine milligrams of 3-(dimethylamino)-1-propylamine
functionalized PMMA (MW=120,000) was used in the method set out above with the
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modification that 1 g kaolinite was used instead of montmorillonite.
Instantaneous
bulk settling was observed in the presence of CO2 leaving a slightly turbid
supernatant behind, which cleared out over 2 hours. See Figure 27. Without CO2
fast
bulk settling was observed, however, the supernatant was very turbid.
supernatant without CO2 supernatant with CO2
Turbidity (after 2 h) 1100 NTU 25 NTU
[00660] 3-(Dimethylamino)-1-propylamine functionalized PMMA
(MW=350,000)
[00661] Forty nine milligrams of 3-(dimethylamino)-1-propylamine
functionalized PMMA (MW=350,000) was used in the method set out above with the
modification of 2 g kaolinite being used instead of montmorillonite. Very fast
bulk
settling was observed both in the presence and absence of CO2. Supernatant
less
turbid with CO2.
supernatant without CO2 supernatant with CO2
Turbidity (after 2 h) 1100 NTU 28 NTU
[00662] Neutral 3-(dimethylamino)-1-propylamine functionalized PAA
(MW=50,000)
[00663] Fifty milligrams of neutral 3-(dimethylamino)-1-propylannine
functionalized PAA (MW=50,000) was used in the method set out above. Without
CO2 bulk settling is slower and supernatant more turbid than with CO2.
supernatant without CO2 supernatant with CO2
Turbidity (after 2 h) 62 NTU 1 NTU
[00664] Study using hydrochloric acid and 3-(dimethylamino)-1-propylamine
functionalized PMMA MW = 120,000
[00665] Fifty milligrams of 3-(dimethylamino)-1-propylamine functionalized
PMMA (MW= 120,000) was used in the method set out above. To one of the
suspensions, 45 pL of 4 M hydrochloric acid was added as opposed to acidifying
the
water by bubbling with carbon dioxide used previously. Both suspensions were
stirred for 30 min, then transferred to graduated cylinders and the settling
monitored
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over time. In the presence of hydrochloric acid, the settling was slightly
faster and the
supernatant slightly clearer than without the acid.
supernatant without acid supernatant with acid
Turbidity (after 2 h) 23 NTU 5 NTU
[00666] Study using sulfuric acid and 3-(dimethylamino)-1-propylamine
functionalized PMMA MW = 120,000
[00667] Fifty milligrams of 3-(dimethylamino)-1-propylamine
functionalized
PMMA (MW= 120,000) was used in the method set out above. To one of the
suspensions, 180 pL of 1 M sulfuric acid was added as opposed to acidifying
the
water by bubbling with carbon dioxide used previously. Both suspensions were
stirred for 30 min, then transferred to graduated cylinders and the settling
monitored
over time. In the presence of sulfuric acid, the settling was very fast (47%
of the
starting height after 2 h) and the supernatant slightly clearer than without
the acid.
Settling in the absence of sulfuric acid was slow (79% of the starting height
after 2h).
supernatant without acid supernatant with acid
Turbidity (after 2 h) 25 NTU 1 NTU
[00668] Study using formic acid and 3-(dimethylamino)-1-propylamine
functionalized PMMA MW = 120,000
[00669] Fifty milligrams of 3-(dimethylamino)-1-propylamine
functionalized
PMMA (MW= 120,000) was used in the method set out above. To one of the
suspensions, 1.8 mL of 0.1 M formic acid was added as opposed to acidifying
the
water by bubbling with carbon dioxide used previously. Both suspensions were
stirred for 30 min, then transferred to graduated cylinders and the settling
monitored
over time. In the presence of formic acid, the settling was very fast (33% of
the
starting height after 2 h) but the supernatant more turbid than without the
acid.
Settling in the absence of formic was slow (74% of the starting height after
2h).
supernatant without acid supernatant with acid
Turbidity (after 2 h) 24 NTU 116 NTU
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[00670] 27.6 Control experiment using polyacrylamide, MW= 6,000,000
[00671] Thirty-one milligrams of polyacrylamide, MW= 6,000,000 was used
in
the method set out above. Very fast settling rates were observed both in the
present
and absence of CO2 leaving very clear supernatants behind (see Figures 28A and
28B). In the presence of CO2 some clay particles were observed floating on top
and
in the supernatant.
supernatant without CO2 supernatant with CO2
Turbidity (after 16 h) 20 NTU 27 NTU
[00672] EXAMPLE 28: Osmotic Pressure Effects of Switchable Water
Additives
[00673] Formation of ionic species in the presence of switchable water
additives and suitable trigger(s) leads to an increase in osmotic pressure due
to an
increase in higher unit solute concentrations.
[00674] The switchable osmotic pressure measurements were conducted on a
Zimm-Meyerson osmometer using Sterlitech UTC-80LB toray flat sheet membranes.
A 0.1% (w/v) switchable polyamine solution in water was made by dissolving 20
mg
of the corresponding polyamine in 20 mL deionized H20. After the polyamine was
completely dissolved, 13 mL of the solution was transferred into the glass
cell of the
osmometer and the outer glass cell was filled with deionized water. The system
was
closed with a lid and allowed to reach equilibrium overnight. Measurements of
the
capillary tube and the control capillary were taken. The draw solution was
then taken
out of the cell and transferred into a graduated cylinder. Both the draw
solution and
the solution of the outer cell were carbonated by bubbling CO2 with a gas
dispersion
tube for 1 h. The draw solution was transferred back into the glass cell of
the
osmometer, the system was closed and held under an atmosphere of CO2. A
constant flow of CO2 was maintained using two gauche needles, one of them
connected to a CO2 source with a flow rate of 10 ml/min. The heights taken
were
height differences of the capillary tube connected to the cell and the control
capillary
tube. Based on these heights the hydrostatic pressure was calculated using the
equation:
n=phg
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where El is the hydrostatic pressure, p is the density of the solution, h is
the height of
the water column and g is the force of gravity. Hydrostatic pressure is taken
to be
proportional to osmotic pressure of the solution at equilibrium.
[00675] 28.1 Switchable osmotic pressure experiment using BPEI, MW=600
[00676] Twenty-eight milligrams of BPEI was suspended in 20 mL of
deionized
water. Height measurements were taken before and after CO2 treatment.
hydrostatic pressure hydrostatic
pressure increase
without CO2 pressure with CO2
BPEI, MW= 600 363 Pa 2433 Pa 6.7
[00677] 28.2 Switchable osmotic pressure experiment using BPEI, MW=
10,000
[00678] Twenty-seven milligrams of BPEI was suspended in 25 mL of
deionized water. Height measurements were taken before and after CO2
treatment.
hydrostatic pressure hydrostatic
pressure increase
without CO2 pressure with CO2
BPEI, MW= 10,000 88 Pa 618 Pa 7.0
[00679] 28.3 Switchable osmotic pressure experiment using ionic PAA
(MW=450,000):
[00680] Twenty-milligrams of ionic PAA (MW=450,000) with 3-
(dimethylamino)-1-propylammonium counterion were dissolved in 20 mL of
deionized
water. Height measurements were taken before and after CO2 treatment.
hydrostatic pressure hydrostatic
pressure increase
without CO2 pressure with CO2
Ionic PAA
000) 29 Pa 450 Pa 15.5
(MW= 450,
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[00681] 28.4 Switchable osmotic pressure experiment using 3-
(dimethylamino)-1-propylamine functionalized PMMA (MW=120,000):
[00682] Forty-six milligrams of 3-(dimethylamino)-1-propylamine
functionalized
PMMA (MW=120,000) were dissolved in 46 mL of deionized water. Height
measurements were taken before and after CO2 treatment.
hydrostatic pressure hydrostatic
without CO2 pressure with CO2 pressure increase
functionalized
PMMA 137 Pa 1923 Pa 14.0
(MW= 120,000)
[00683] 28.5 Switchable osmotic pressure experiment using 3-
(dimethylam ino)-1-propylamine functionalized PMMA (MW=35,000):
[00684] Sixteen milligrams of 3-(dimethylamino)-1-propylamine
functionalized
PMMA (MW=35,000) were dissolved in 48 mL of deionized water. Height
measurements were taken before and after CO2 treatment.
hydrostatic pressure hydrostatic
without CO2 pressure with CO2 pressure increase
functionalized
PMMA 412 Pa 1687 Pa 4.1
(MW= 35,000)
[00685] After treatment with CO2 and measurement of osmotic pressure, the
solution was taken out of the osmometer and heated to 50 C with nitrogen
sparging
for 6 hours. The hydrostatic pressure of the solution was then measured and
found to
be 638 Pa.
[00686] 28.6 Switchable osmotic pressure experiment using 3-
(dimethylamino)-1-propylamine functionalized PMMA/PS (1.4 mol% styrene,
MW:9,200-12,900)
[00687] 12 mg of 3-(dimethylamino)-1-propylamine functionalized PMMA/PS
(1.4 mol% styrene, MW:9,200-12,900) were dissolved in 38 mL1 of deionized
water.
Height measurements were taken before and after CO2 treatment.
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hydrostatic pressure hydrostatic
pressure increase
without CO2 pressure with CO2
functionalized
PMMA/PS 226 Pa 1403 Pa 6.0
(1.4mol% styrene)
[00688] 28.7 Switchable osmotic pressure experiment using 3-
(dimethylamino)-1-propylamine functionalized PMMA/PS (10 mol% styrene,
MW: 10,600-15 ,900)
[00689] 13 mg of 3-(dimethylamino)-1-propylamine functionalized PMMA/PS
(10 mol% styrene, MW:10,600-15,900) were dissolved in 40 mL of deionized
water.
Height measurements were taken before and after CO2 treatment.
hydrostatic pressure hydrostatic
pressure increase
without CO2 pressure with CO2
functionalized
PMMA/PS 118 Pa 1785 Pa 15.0
(10mol% styrene)
[00690] Switchable osmotic pressure experiment using neutral 3-
(dimethylamino)-1-propylamine functionalized PAA (MW=1,800)
[00691] Nine milligrams of 3-(dimethylamino)-1-propylamine functionalized
PAA (MW=1,800) were dissolved in 36 mL of deionized water. Height measurements
were taken before and after CO2 treatment.
hydrostatic pressure hydrostatic
without CO2 pressure with CO2 pressure increase
functionalized PAA
287 Pa 1579 Pa 5.5
(MW= 1,800)
[00692] Switchable osmotic pressure experiment using PDEAEMA (MW=
55,000)
[00693] Fifty-four milligrams of PDEAEMA were dissolved in 54 mL of
carbonated water. Height measurements were only taken of the carbonated
solution,
as the polymer was not soluble in non-carbonated water.
hydrostatic pressure hydrostatic
pressure increase
without CO2 pressure with CO2
PDEAEMA (MW =
55,000) Not soluble 1957 Pa
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[00694] 28.8 Switchable osmotic pressure control experiment using N,N-
dimethylcyclohexylamine:
[00695] Forty-eight milligrams of N,N-dimethylcyclohexylamine were
dissolved
in 21 mL of deionized water. Height measurements were taken before and after
CO2
treatment.
hydrostatic hydrostatic pressure
pressure with CO2 pressure with 002 increase
4N-
580 Pa 1550 Pa 2.7
dimethylcyclohexylamine
[00696] 28.9 Switchable osmotic pressure control experiment using
polyacrylamide (MW=6,000,000):
[00697] Twenty milligrams of polyacrylamide were dissolved in 20 mL of
deionized water. Height measurements were taken before and after CO2
treatment.
hydrostatic hydrostatic
pressure increase
pressure with 002 pressure with 002
polyacrylamide
98.1 Pa 176 Pa 1.8
(MW=6,000,000)
[00698] As demonstrated using polyacrylamide, only a very small change in
pressure can be achieved by the addition of CO2 in the absence of a switchable
additive. Further, the switchable tertiary amine tested in 28.8 was capable of
generating a lower change in osmotic pressure than the polyamines, but more
than
observed for polyacrylamide.
[00699] EXAMPLE 29: Homogenous Catalysis using Switchable Water
Additives
[00700] Homogeneous catalysts are often more active and selective than
heterogeneous catalysts but are far more difficult to separate from the
product. The
development of means to separate, recover, and recycle homogeneous catalysts
is
an important area of research for both industry and academia (Catalyst
Separation,
Recovery and Recycling: Chemistry and Process Design, D.J. Cole-Hamilton, R.
Tooze, Eds., Springer, Dordrecht, 2006; M.J. Muldoon, Dalton Trans., 2010, 39,
337). One approach, already industrialized in a few cases, is catalysis in a
biphasic
mixture of two solvents (B. Cornils, E.G. Kuntz, Aqueous-Phase Organometallic
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Catalysis 2nd ed., B. Cornils, W.G. Hermann, Eds., Wiley-VCH, Weinheim, 2004;
U.
Hintermair, W. Leitner, P.G. Jessop, Supercritical Solvents, W Leitner, P.G.
Jessop,
Eds., WileyNCH Weinheim, 2010). Such reactions involve the dissolution of a
catalyst into one of the solvents and the dissolution of the reagents into the
other
solvent. The small partitioning of the reagent into the solvent containing the
catalyst
allows the reaction to proceed. Aqueous/organic biphasic systems are of great
interest and are currently in use for the industrial hydroformylation of low
carbon
number-containing alkenes (B. Cornils, E.G. Kuntz, Aqueous-Phase
Organometallic
Catalysis 2nd ed., B. Cornils, W.G. Hermann, Eds., Wiley-VCH, Weinheim,
2004.).These systems often utilize transition metals ligated by sulfonated
phosphines
to increase the water solubility of the metal, causing the catalyst to reside
in the
aqueous phase. After the reaction is completed, the product (organic) phase is
decanted and the aqueous catalyst-containing phase is used again.
[00701] Aqueous/organic biphasic catalysis of this type has both
advantages
and disadvantages. An advantage of this method is, of course, the easy
separation
of catalyst from product. A key disadvantage is the slow rate of reaction that
results
from the catalyst and the reactants being in two different phases, especially
when the
reactant (such as 1-octene or styrene) has very poor solubility in water. One
solution
to this problem is to design a trigger to make the aqueous and organic phases
merge
into one phase during the catalysis and then to separate into two phases again
after
the reaction is complete. This can be accomplished using high pressure CO2 as
a
trigger (THF and water are miscible when high pressure CO2 is absent and form
two
liquid phases when high pressure CO2 is present) (J. Lu, M.L. Lazzaroni, J.P.
Hallet,
A.S. Bommarius, C.L. Liotta, C.A. Eckert, Ind. Eng. Chem. Res., 2004, 43,
1586).
The present example provides a method for achieving the same result using only
1
atm of CO2.
[00702] A switch of miscibility for organic solvents in water can provide
an
organic/aqueous mixture of solvents that is monophasic during homogeneous
catalysis and then switched to biphasic by the introduction of CO2 after the
catalysis
is complete. The process involves homogeneous catalysis (such as
hydroformylation
of an alkene) in a water/organic solvent monophasic mixture that also contains
a
small amount of a soluble amine (Figure 29). After the catalysis is complete,
CO2 is
added reacting with the amine, causing a rise in the ionic strength of the
solution and
thereby triggering the salting out of both the organic solvent and the product
from the
aqueous phase. If a suitably hydrophilic catalyst is selected, the catalyst
remains in
the aqueous phase isolated from the products or reaction. After decantation of
the
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product phase, the removal of CO2 from the water regenerates a low ionic
strength
aqueous phase that can accept fresh reagents and THE and the reaction can be
repeated.
[00703] The hydroformylation of styrene is an attractive model system
because its aldehyde products have potential use in pharmaceutical and fine
chemical production and its water solubility is low (CRC Handbook of Chemistry
and
Physics, 79" ed. D. R. Lide, Ed., CRC Press, Boca Raton, 1998), which make a
traditional aqueous/organic biphasic reaction inefficient. Our other examples
of
switchable water showed that THF could easily be forced out of aqueous
solution
with the application of CO2. Our initial studies into hydroformylation of
styrene found
that this weakly coordinating organic solvent may hinder the hydroformylation
reaction. We therefore searched for other water-miscible organic solvents that
could
solubilize styrene and could also be salted out by a switchable water additive
in the
presence of CO2, and found that tert-butanol is one appropriate organic
solvent
choice.
[00704] Styrene Hydroformylation in the Presence of Switchable Water
Additive:
[00705] To a 10 nnL 3:2 t-BuOH:H20 (v/v) mixture, 0.5 g N,N-
dimethylethanolamine (DMEA) was added as the amine additive to create a 1.4
molal
solution (relative to water). Styrene (0.15 mL), [Rh(COD)C1]2, and TPPTS were
added (Rh = 0.5 mol% relative to styrene, P/Rh = 7, COD = cyclooctadiene,
TPPTS
= tris(3-sulfophenyl)phosphine trisodium salt hydrate). This generated a
single phase
pale yellow solution (Figure 30, top left). The solution was transferred to a
pressure
vessel, heated to 100 C, pressurized to 5 bar with synthesis gas (1:1 CO:H2),
and
allowed to react for 3 h. After the reaction, CO2 was bubbled through the
solution,
generating a biphasic system with the catalyst residing in a dark red-brown
aqueous
phase and the product residing in the clear, colorless t-BuOH phase. The
organic
phase was removed and analyzed. The aqueous phase was heated to 65 C and N2
was bubbled through it in order to remove the CO2 and lower the ionic strength
of the
solution. This process changed the aqueous phase to a golden yellow colour. A
fresh
supply of t-BuOH, styrene, water (to account for some evaporation) and TPPTS
(3
Rh equivalents for each cycle, which brought the final P/Rh ratio to 13) was
added.
The catalysis and separation process was performed for three cycles, giving
consistently high conversion, good aldehyde selectivity and good
regioselectivity
towards the branched isomer (see Entry 1 in the table below). By-products were
identified as the hydrogenated product, ethylbenzene, and acetophenone; the
last of
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these forms through a completely different mechanism to the hydroformylation
when
advantageous molecular oxygen is present (rhodium can catalyze the oxidation
reaction of terminal alkenes with molecular oxygen to give methyl ketones,
see: (a)
H. Mimoun, M. P. Machirant, I.S. de Roch, J. Am, Chem. Soc., 1977, 100, 5437.
(b)
0. Bortolini, F. di Furia, G. Modena, R. Seraglia, J. Mol. Cat., 1984, 22,
313. (c) G.A.
Olah, A. Molnar, Hydrocarbon Chemistry 2nd ed.; John Wiley and Sons, Hoboken,
2003.).
[00706] It was found that the addition of more TPPTS through each cycle
was
necessary to maintain good conversions and selectivities. Without additional
TPPTS
added before each addition of fresh reactant, the aqueous phase progressively
darkened through the cycles and black precipitate formed. Conversions then
decreased sharply through the cycles (see Entry 2 in the table below). Without
wishing to be bound by theory, the likely cause of these observations is
oxidation of
TPPTS, deactivating the catalyst. Even under stringent oxygen-free conditions
(see
Entry 3 in the table below), the addition of additional TPPTS was necessary as
conversions eventually decreased upon recycling, although the aldehyde
selectivity
was improved compared to Entry 1 below where the recycling processes were
carried out in air.
Cycle 1 Cycle 2 Cycle 3
Additive % Conversion I % B/L % Conversion / A, B/L %
Conversion / % B/L
Aldehyde Selectivity Aldehyde Selectivity Aldehyde Selectivity
DMEA b 98.9 / 96.1 8.0 99.4 / 89.3 6.8 97.2 / 97.0
6.5
DMEA c 98.5 / 91.1 8.8 87.9 / 87.7 6.3 40.7 / 88.5 --
5.3
DMEA d 95.3 / 98.9 8.8 96.3 199.0 6.5 73.7/ 98.1
5.7
TMDAB c'e 85.2 / 87.7 7.7 43.8 / 87.3 5.4 8.9 / 85.2
4.6
a Conditions: Reaction mixture was comprising 6 mL tert-butanol, 4 mL H20, 1.4
molal of an amine additive, 0.25 mol% catalyst, and 7:1 P:Rh. Reaction was run
at
100 C at 5 bar syn gas (1:1 CO:H2) for 3 hours. Yields were determined by GC
with
the assistance of previously-prepared calibration curves.
b Average of two runs, 3 equivalents of TPPTS in regard to Rh added during
each
cycle for a final ratio of 13:1 P:Rh.
No phosphine added during recycling.
d Solvents degassed and kept under N2, 002 or CO/H2 at all times, no phosphine
added during recycling.
o 0.8 molal additive added.
[00707] The retention of the DMEA in the aqueous phase upon protonation
by
CO2 was not complete and loss of DMEA to the product phase in each cycle may
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account for the changing volumes of aqueous phase in successive cycles (Figure
30,
right side images). To minimize loss of the amine to the organic phase, it may
be
preferable to use polyamines as additives; they generally have better
retention in the
aqueous phase and can generate solutions of greater ionic strength at lower
loadings. However, a polyamine that does not interfere with the reaction
should be
selected. The conversions observed during hydroformylation of styrene when
N,N,W,Af-tetramethy1-1,4-diaminobutane (TMDAB) was used (see Entry 4 above),
while effective, were lower than observed using DMEA. Without wishing to be
bound
by theory, this may be the a result of the bidentate nature of the TMDAB,
which may
be competing with TPPTS for positions on the metal, ultimately deactivating
the
catalyst. The use of better chelating water-soluble phosphines may improve
conversions using the polyamine switchable water additives without the
resulting loss
of catalytic activity.
[00708] The leaching of rhodium metal into the organic product phase was
observed by ICP-MS (see the table below). Minimal leaching was observed
through
the first cycle; however upon the second and third cycles, the amount of
rhodium lost
to the product phase did increase. Despite the increases in rhodium leaching
as
recycling of the aqueous phase proceeded, the greatest amount of total loss in
a
single recycling step was never more than roughly 10% of the original amount
of
rhodium initially used.
[00709] The table below shows the concentration of rhodium found in the
organic phase, containing products, after separation by switchable water as
determined by ICP-MS. Samples were acquired from organic phases noted in Entry
1
of the table above.
Rhodium Concentrations in the Organic Phasesa
Cycle 1 Cycle 2 Cycle 3
1.07 0.04 mg L-1 3.63 0.04 10.12 0.25 mg-I L
mg L-1
a Average of two runs.
[00710] This example demonstrates the successful use of switchable water
additives to allow homogeneous catalysis to take place in a monophasic solvent
mixture and yet allow the subsequent catalyst/product separation to take place
in a
biphasic solvent mixture. This method does not suffer from the traditional
mass
transfer issues that accompany biphasic reactions because the system is
nnonophasic during the catalysis. This method can also tolerate alkenes of
lower
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water solubility than traditional biphasic aqueous/organic catalysis. The
hydroformylation reactions performed in switchable water are run at low syn
gas
pressures, on short timescales, and with facile separation of catalyst from
product
because of CO2 induced phase separation. Recycling of the catalyst solution
was
performed with ease by removing CO2 from the solution by sparging with an
inert gas
or air and/or moderate heating. The Rh/TPPTS catalyst maintained good
conversion,
product selectivity, and regioselectivity after recycling. This method for
solving the
inherent rate limitations of conventional biphasic catalysis does not require
high
pressure CO2 or expensive fluorous or ionic liquid solvents.
[00711] EXAMPLE 30: Solubility of Switchable Water Additives
[00712] 30.1 Switchable solubility of butylated polyethyleneimine
(MW=600)
[00713] In a 100 mL round bottom flask equipped with a 1 cm stir-bar, 293
mg
of butylated polyethyleneimine (MW=600) was suspended in 50 mL deionized water
and stirred for 30 min at room temperature. The solid was allowed to settle
for 72 h,
then 5 mL of the supernatant was removed and filtered. From the filtered
solution,
three samples of 1 mL each were placed into round bottom flasks. The water was
evaporated and the samples weighed. An average of all three sample weights was
taken.
[00714] The rest of the solution was treated with CO2 for 1 hour by
bubbling
with a single gauge needle (flow rate: 80 ml/min). The mixture turned almost
completely clear but some BPEI was still insoluble, hence saturated. Twenty
millilitres of the solution was filtered off and three samples of 5 mL each
were placed
into round bottom flasks. The water was evaporated and the samples weighed. An
average of all three samples was taken. An overview of the results is given
below.
sample 1 sample 2 sample 3 average
solubility without
0.33 mg/mL 0.33 mg/mL 0.33 mg/mL 0.33 mg/mL
CO2
solubility with CO2 7.2 mg/mL 7.8 mg/mL 8.4 mg/mL 7.8 mg/mL
[00715] Replacing CO2 with argon lead to the formation of a white
suspension.
Another addition of CO2 dissolved the polymer again. This process was repeated
3
times.
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[00716] 30.2 Switchable solubility of propylated polyethyleneimine
(MW=600)
[00717] In a 100 mL round bottom flask equipped with a 1 cm stir-bar, 293
mg
of propylated polyethyleneimine (MW=600) was suspended in 50 mL deionized
water
and stirred for 30 min at room temperature. The solid was allowed to settle
for 72 h,
then 10 mL of the supernatant was removed and filtered. From the filtered
sample,
three samples of 3 mL each were placed into round bottom flasks. The water was
evaporated and the samples weighed. An average of all three samples was taken.
[00718] The rest of the solution was treated with CO2 for 1 hour by
bubbling
with a single gauge needle (flow rate: 80 ml/min). The mixture turned
completely
clear, hence it wass below saturation point. 10 mL of the solution was
filtered off and
three samples of 3 mL each were placed into round bottom flasks. The water was
evaporated and the samples weighed. An average of all three samples was taken.
An overview of the results is given below.
sample 1 sample 2 sample 3 average
solubility without
3.3 mg/mL 3.3 mg/mL 3.6 mg/mL 3.5 mg/mL
CO2
solubility with CO2 72.0 mg/mL 72.0 mg/mL 73.0 mg/mL 72.3
mg/mL
[00719] As all of the polymer dissolved in the presence of CO2, the
actual
solubility was higher than 72.3 mg/mL.
[00720] Replacing CO2 with argon lead to formation of a white suspension.
Another addition of CO2 dissolved the polymer again. This process was repeated
3
times.
[00721] EXAMPLE 31: Switchable Water Additive Conductivity Measurements
[00722] Solution conductivity measurements were recorded on a Thermo
Scientific Orion 5-Star Plus conductivity meter (Fisher Scientific, Ottawa,
Ontario,
Canada). Ultra pure water (18 ma) was obtained using an Elga Lab Water PureLab
Flex system (High Wycombe, UK). Tetra-n-butylammonium bromide was purchased
from Sigma Aldrich Inc. (Oakville, Ontario, Canada). 3-dimethylamino-1-
propylamine
was purchased from Alfa Aesar (VWR, Mississauga, Ontario, Canada).
[00723] The solution conductivities of the materials given below were
measured. The mass of each material indicated was weighed into a 150 mL beaker
charged with a stir bar along with 100 mL of ultra pure water. The solutions
were
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stirred until visibly dissolved and their conductivity measured. In the case
of both
MW=450,000 functionalized and ionic polyacrylic acid samples and the
MW=350,000
polymethyl methacrylate sample, gel particles formed, indicating partial
solubility. All
solutions were left to stir overnight to test reproducibility. Solution
conductivities were
re-recorded giving little change in values. CO2 was bubbled at 10 psi through
a fine
glass frit tube (to make bubble size as small as possible for greater surface
area and
therefore faster carbonation) with each solution for 30 minutes. In the case
of TBAB
and functionalized PMMA, significant amounts of bubbling were observed.
Solution
conductivities were re-recorded.
Material Mass (g) Initial C (pS/cm) C after 30 mins
CO2 (pS/cm)
Ultrapure H20 N/A 1.31 41.2
H2N(CH2)3NMe2 0.255 398 3360
[aBu4N]Br 0.806 1892 1781
PAA(1,800) 0.180 235 238
Ionic PAA (MW=1,800) 0.196 398 1107 (1240)a
Ionic PAA 0.196 145 750
(MW=450,000)
Neutral Functionalized 0.200 251 818
PAA (MW=1,800)
Neutral Functionalized 0.200 58 334
PAA (MW=50,000)
Neutral Functionalized 0.200 2.07 42.4
PAA (MW=450,000)a
Functionalized PMMA 0.112 201 1086
(MW=35,000)
Functionalized PMMA 0.080b 102 494
(MW=120,000)
Functionalized PMMA 0.112 186 410
(MW=350,000)
a An aliquot of this solution after this measurement was sealed in a high
pressure reactor, pressurized to 130 psi, and stirred for 16 hours at room
temperature before solution conductivity measurement was re-measured.
This measurement was performed to verify that the procedure described
above (30 min, 10 psi CO2 bubbling) was sufficient to fully switch additive.
b Measurement performed in 80 mL deionized water.
This polymer sample was observed to have very low solubility in water.
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[00724] EXAMPLE 32: Kaolinite Clay Settling using Switchable Water
[00725] Kaolinite clay fines constitute about half of the solid content
in oil
sands tailing (Ramachandra Rao, S., 1980, "Flocculation and dewatering of
Alberta
oil sands tailings." mt. J. Miner. Process., 7 (3), 245-253). Kaolinite, a
hydrous
aluminum silicate of composition A1203.2Si02.2H20 (Giese, R., & van Oss, C.,
2002,
Colloid and Surface Properties of Clays and Related Minerals (Vol. 105), A.
Hubbard,
Ed. United States of America: Marcel Dekker, Inc.; and Velde, B., 1995, Origin
and
Mineralogy of Clays. United States of America: Springer-Verlag New York,
Inc.),
occurs in roughly hexagonal platelets with a length-to-thickness ratio of 10:1
(Michaels, A. a., 1962, "Settling Rates and Sediment Volumes of Flocculated
Kaolin
Suspensions." Ind. Eng. Chem. Fundamen., 1(1), 24-33). Due to the amphoteric
property of kaolinite, the faces of the particles possess a permanent negative
charge,
while the charge on the edge surface is pH-dependent. Under acidic conditions
(pH
lower than 6) (Michaels, 1962. supra), the aluminum exposed at the edges
acquires
hydrogen ions from water and assumes a positive charge. The edge and face
surfaces then mutually attract, leading to edge-face (E-F) flocculation, and
giving
form to "card-house" flocs. Under alkaline conditions the edges become neutral
or
even positively charged, thus disrupting the E-F interactions, providing that
electrolyte concentration is low. Increase in electrolyte concentrations, and
thus
increase in ionic strength of the solution, reduces electrostatic interactions
(attractive
or repulsive) due to compressed electrical double layer or ion shielding of
surface
charges. As a result, flocculation primarily occurs between basal surfaces ¨
or face-
face (F-F) ¨forming "card-pack" flocs. The ionic strength effect is
independent of
solution pH. (Schofield, R.,1954, "Flocculation of kaolinite due to the
attraction of
oppositely charged crystal faces" Discussions Faraday Soc., 18, 135-145;
Michaels,
1962, supra; and Nasser & James, 2006, "Settling and sediment bed behaviour of
kaolinite in aqueous media." Separation and Purification Technology, 51(1), 10-
17).
[00726] In this example, the use of a switchable water additive as the
flocculating agent is demonstrated. The use of a switchable water additive can
enhance water recyclability in oil sands operations by drastically reducing
the energy
and material demanded by conventional tailing dewatering methods.
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[00727] Experimental & Materials
[00728] Kaolinite Suspension Settling and Supernatant Turbidity
[00729] Two separate samples of kaolinite were purchased from Ward's
Natural Science and were used as received. Deionized water with a resistivity
of 18.2
MD.cm (Synergy UV, Millipore) was used throughout this study. CO2
(Supercritical
Chromatographic Grade, 99.998%, Praxair) was used as received. 100 mL
graduated cylinders (Kimble Kimax, single metric scale, 20025H 50) were used
for all
settling tests. TMDAB was purchased from TCI. Consistency in cylinder
dimensions
is particularly important, as it has been reported that container height can
influence
settling rate (Michaels, 1962, supra).
[00730] The kaolinite suspension was prepared by adding clay fines to 100
mL
of aqueous TMDAB. The effects of changing clay loadings (2.5%, 5%, and 7% w/v)
and TMDAB concentrations (blank, 0.01, 0.1, 1, 10 mM) on settling behaviour
were
investigated. The mixture was stirred with a magnetic stirrer for 15 minutes
at 900
rpm prior to transfer to a graduated cylinder. Both "on" (CO2-treated) and
"off forms
of TMDAB were investigated for their effect on settling. For the "on"
experiments,
CO2 was bubbled through the mixture in the graduated cylinder using a 20-gauge
needle for 1 hour at 100-150 mL/min. The cylinder was then immediately sealed
with
a rubber septum and bulk settling was monitored over 2 hours with a
cathetometer
(Eberbach). Supernatant from each of the settling experiments was sampled and
its
turbidity was measured using a turbidity meter (TB200, Orbeco-Hellige).
[00731] Settling tests to investigate the effect of pH and ionic strength
[00732] The pH of the following 5% (w/v) kaolinite suspensions were
measured: CO2 blank and 1 mM TMDAB and 10 mM TMDAB after CO2-treatment.
To investigate the effect of pH on suspension settling behaviour, 5% (w/v)
kaolinite
suspensions were prepared, and the pH of each suspension was adjusted with HCI
and NaOH to match the pH of corresponding treatment conditions. To investigate
the
effect of ionic strength on suspension settling behaviour, pH was again
corrected to
match the pH of corresponding treatment conditions, and ionic strength was
adjusted
with NaCI or ammonium sulphate, assuming all basic sites on the diamine were
protonated.
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[00733] Particle Size and Zeta Potential Measurements
[00734] Particle size and zeta potential were measured using Zetasizer
Nano
ZS (Malvern). 25 mg of clay fines (kaolinite and montmorillonite) were added
to 10
mL of deionized water. A suspension was created using a vortex. All CO2
treatments
were conducted for 1 hour. The pH was adjusted with HCI and NaOH.
[00735] Results & Discussion
[00736] The effect of TMDAB on kaolinite suspension behaviour
[00737] Kaolinite and montmorillonite clays fines naturally form a stable
aqueous colloidal suspension. The presence of TMDAB in suspension in the "off'
form did not have any observable effect on particle flocculation and settling
and
maintained a stable suspension. However, upon introduction of CO2 to turn on
TMDAB, settling was observed in a concentration-dependent manner, as presented
in Figure 31. The settling profiles are plotted as the percent column height
of the
interfacial plane between the slurry and the supernatant as a function of
time.
Increasing TMDAB concentration lead to slower settling rates. The upper limit
of
settling rate was characterized by a 002-treated suspension with no TMDAB. At
0.1
mM and 0.01 mM TMDAB (not shown) the settling profiles were not different from
that of the 002-treated suspension without additive. CO2 alone can facilitate
bulk
settling in a clay colloid. In fact, it is already an industrial practice of
Canadian Natural
Resources Limited to inject CO2 into tailing ponds to accelerate the settling
of tailing
fines. CO2 forms carbonic acid in water and thereby lowers the pH. Low pH
promotes
clay particle flocculation and the subsequent settling.
[00738] While settling rate was the most rapid in a 002-treated
suspension
without TMDAB, it resulted in the most turbid supernatant; as the
concentration of
TMDAB increased, the turbidity of the supernatant decreased (Figure 32).
However,
at high concentrations (100 mM), the presence of oxidized amine became
significant
and imparted a yellowish tinge in the supernatant. Thus, an important design
consideration is a compromise between desirable settling rate and acceptable
water
turbidity. 1 mM TMDAB was required to reduce the supernatant turbidity by a
significant amount. A photographic time-profile of the settling of a kaolinite
suspension treated with 10 mM TMDAB and CO2 is presented in Figure 33. The
clarity in the supernatant and the sharp sediment line suggest that flocs were
formed
with comparable size and density (Michaels, 1962, supra). Figure 34
illustrates the
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supernatant turbidity at different treatment conditions and colouration at 100
mM
TMDAB.
[00739] Zeta potential is a simple method to predict colloidal system
stability
(Delgado, A., Gonzalez-Caballero, F., R. Hunter, L. K., & Lyklema, J. (2005).
Measurement and Interpretation of Electrokinetic Phenomena. Pure App!. Chem.,
77
(10), 1753-1805). At large absolute zeta potential values, the particles are
highly
charged and repel one another. This prevents the particles from flocculating,
and
thus results in a stable suspension. Flocculation begins to take place at a
critical
value around -30 mV. (Everett, D. (1988). Basic Principles of Colloid Science.
London, England: Royal Soceity of Chemistry) The closer zeta potential is to
zero,
the more it indicates weakened repulsive forces, which allows the particles to
flocculate under attractive van der Waals forces. Figure 35 shows the zeta
potentials
of clay particles under different treatment conditions. A kaolinite colloid
without
treatment or with the "off' form of TMDAB generally exhibited zeta potential
values in
the stable range. This was consistent with the suspension settling
experiments, as no
settling was observed under these two conditions. The zeta potential of a CO2-
treated suspension with no additives indicated some flocculation and
destabilization
of the system; however, only to a minimal extent. This was also consistent
with the
settling test: while settling did occur, the supernatant was turbid. The "on"
form of 1
mM TMDAB was able to significantly lower the zeta potential of the suspension
components. This was once again reflected in the settling of clay and a much
clearer
supernatant.
[00740] Aggregate size can serve as an indication of flocculation. While
aggregate size is not a fundamental property of a flocculated suspension, it
is a
dynamic property of the effective collisions that contribute to aggregation
(Michaels,
1962, supra). Figure 36 illustrates that particle size measurements exhibited
a similar
trend to zeta potential measurements under the same set of treatment
conditions. No
notable increase in particle size was evident in the presence of the "off'
form of
TMDAB or even under CO2 treatment. However, the particle size in the TMDAB-0O2
treated suspension was approximately double that of the suspension particles
under
no treatment. Particle size is only a crude indication of flocculation, since
naturally
occurring clay particles exhibit a wide range of sizes, as indicated by the
PDI of these
samples.
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[00741] The effect of clay loading on kaolinite suspension settling
behaviour
[00742] Kaolinite clay loading level can influence the suspension
settling
characteristics. Settling rate decreased as clay loading increased, as shown
in
Figure 37. This was consistent with the findings reported by Michaels and
Bolger
(Michaels, 1962, supra). The supernatant turbidity was also sensitive to clay
loading
in 002-treated suspensions: turbidity increased significantly with increasing
clay
loading (Figure 38). However, this loading-dependent effect on turbidity was
not
observed in suspensions treated with 1 mM TMDAB and CO2. TMDAB exerted a
much stronger effect on clay behavior in suspension, which overcame the
influence
of clay loading level.
[00743] The effect of pH and ionic strength on kaolinite suspension
behaviour
[00744] To investigate whether the TMDAB-induced effect on kaolinite
suspension was predominately driven by solution pH effect or ionic strength
effect,
settling tests were conducted with suspensions adjusted to have pH and/or
ionic
strength that corresponded to 002-treated TMDAB suspensions. All pH and ionic
strength suspension settling tests were conducted with kaolinite sample 2 (see
below).
[00745] The pH of kaolinite suspensions under different treatment
conditions
was measured and shown in Table A. Kaolinite clay particles were shown to have
acidic properties in an aqueous environment. Three suspensions were each
adjusted
to have the same pH as a suspension that was CO2 treated (1), 1mM TMDAB-002
treated (2), or 10 mM TMDAB-002 treated (3). Settling was observed in 1 and 2
but
not 3. The bulk settling for 1 and 2 exhibited comparable profiles. The
supernatant
turbidity of 2, however, was significantly higher than that of 1 (Table 2).
Low pH was
favourable for kaolinite flocculation. An increase in solution pH became
increasingly
unfavourable until settling was no longer observed. Michaels and Schofield had
reported that under pH 6 kaolinite particles could attract electrostatically
and form
"card-house" flocs. This electrostatic attraction is lost with increasing pH.
(Michaels,
1962, supra; and Schofield, R., 1954, "Flocculation of kaolinite due to the
attraction of
oppositely charged crystal faces." Discussions Faraday Soc. , 18, 135-145.).
While
pH exerted an effect on suspension behavior, in particular supernatant
turbidity, bulk-
settling rate was independent of solution pH.
[00746] Zeta potentials of 1, 2, and 3 all measured below the critical
value,
with 3 being significantly higher.
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Table A
pH Sample 1 Sample 2
No treatment 5.35 4.90
CO2 4.25
1 mM TMDAB 7.13
1 mM TMDAB + CO2 -- 4.75
mM TMDAB 10.41
10mM TMDAB +CO2 -- 5.95
Table B
Study pH Corresponding Supernatant turbidity
treatment (NTU)
1 4.25 CO2 Blank 64
2 4.75 1 mM TMDAB + CO2 520
3 5.95 10 mM TMDAB + CO2 NO SETTLING
[00747] TMDAB in its "off' form acted as a base and elevated suspension pH
in a concentration-dependent manner, as illustrated in Table A. Since it has
been
shown that settling does not occur at high pH, it is reasonable that no
settling was
observed in suspensions treated with the "off' form of TMDAB.
[00748] A discrepancy in supernatant turbidity was observed between the 2
samples of kaolinite in suspensions treated with CO2 in Figure 32. The
supernatant
turbidity that resulted from sample 2 was significantly lower than that which
resulted
from sample 1 under the same treatment condition. Without wishing to be bound
by
theory, the discrepancy could be explained by the pH effect and differences in
particle size. Sample 2 was more acidic than sample 1 in an aqueous
environment
(Table A); thus, a suspension created with sample 2 treated with CO2 was at a
lower
pH than a suspension similarly created with sample 1. The difference in pH was
likely
enough to result in the observed differences in supernatant turbidity.
Furthermore,
Figure 36 indicates that sample 2 particle sizes were on average larger than
sample
1 particles. Larger particle sizes lead to more pronounced Van der Weals
attractions
and larger influence by gravitational pull; thus, a suspension of larger
particles settles
more uniformly and rapidly.
[00749] While pH was found to influence the ability of clay particles to
settle,
the pH effect failed to explain why an increase in TMDAB concentration lead to
a
decrease in both settling rate and turbidity. Ionic strength, another known
factor in
suspension settling, was investigated as a potential mechanism through which
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TMDAB works. For a given amine additive (denoted B) with n basic sites, the
fate of
the aqueous amine in the presence of CO2 is illustrated by Equation (1):
B + nH20 + nCO2 BHnn+ + nHCO3- (1)
[00750] Assuming all basic sites are protonated, the ionic strength,
then,
switches from zero to 1/2m(n2+n), as illustrated by Equation (2):
I = 1/2 m(+n)2 + 1/2 mn(-1)2 =1/2 m(n2+n) (2)
where m is the molality of the additive.
[00751] TMDAB has two basic sites. Upon CO2-treatment, ionic strength of
aqueous TMDAB thus switches from zero to 3m. For each of the CO2 treated 1mM
TMDAB and 10 mM TMDAB solutions, a suspension was created with identical pH
and ionic strength as its TMDAB-treated counterpart. pH was adjusted with HCI
and
NaOH. Ionic strength was adjusted with NaCI to reproduce the ionic strength
imparted by 1 mM and 10 mM TMDAB (4 and 5 respectively) or ammonium sulphate
(hereafter AS) for the same set TMDAB treatments (6 and 7). Both 4 and 6
resulted
in comparable settling profiles as a suspension treated with 1 mM TMDAB and
CO2
(Figure 39). While corrected pH alone (3) was inadequate in promoting
settling, 5 and
7 were able to bring about similar settling profiles to a suspension treated
with 10 mM
TMDAB and CO2 (Figure 40). It is likely that settling rates can be influenced
by both
pH and ionic strength. Higher concentrations of TMDAB impart both increased pH
and ionic strength; high pH impedes settling while high ionic strength does
the
opposite. This could explain the observed decrease in settling rate that
accompanied
the increase in TMDAB concentration.
[00752] The supernatant turbidity measurements from pH and ionic strength
settling tests further show that ionic strength is an important factor in
reducing
turbidity, as illustrated in Figure 41.
[00753] Zeta potential measurements indicated that neither pH nor ionic
strength gave an adequate explanation of the behaviour brought about by CO2-
treated aqueous TMDAB on a microscopic level in terms of electrical double
layer
activities. Although the addition of electrolyte successfully decreased zeta
potentials
in comparison to the absence of electrolyte, increasing the concentrations of
electrolyte (at corresponding pH) did not produce the same trend as increasing
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TMDAB concentration (Figure 41). However, an increase in particle size was
observed at higher concentrations of electrolyte, which is consistent with the
trend in
particle size with increasing TMDAB concentration (Figure 42). pH alone was
unable
to produce the particle size trend imparted by TMDAB.
Particle size
Corresponding
pH
Treatment z-avg (d.nm) PDI
4.90 No treatment
4.25 CO2 980 0.202
4.75 1 mM TMDAB + CO2 939 0.305
5.95 10 mM TMDAB + CO2 858 0.011
Particle size
H Corresponding
p
I (mM) Treatment z-avg (d.nm) PDI
4.75 3 1 mM TMDAB + CO2 1092 0.247
5.95 30 10 mM TMDAB + CO2 1556 0.195
[00754] Thus, it appears that while pH and ionic strength are both
important
factors that affect clay suspension behavior, and ionic strength is likely the
predominant mode of action through which TMDAB operates.
[00755] EXAMPLE 33: Effect of Switchable Additives on Colloidal
Interactions
Found in Oil Sands and Measured by Chemical Force Spectrometry
[00756] In this study, adhesion forces between bitumen and mineral
surfaces
were modeled and studied by chemical force spectrometry (CFS), particularly to
demonstrate how switchable additives can be used to control these
interactions,
which are crucial to the bitumen liberation phase of the oil sands extraction
process.
Two organic functional groups commonly found in bitumen were selected to
represent the bitumen: an aromatic phenyl group and a carboxylic acid group.
Self
assembled monolayers (SAM) terminated with these functional groups were formed
on gold coated AFM tips for CFS experiments. The mineral substrates
investigated
include mica and silica, which are components of real oil sands systems
(Takamura,
K. Can. J. Chem. Eng. 1982, 60, 538. Gupta, V.; Miller, J. D. J. Coll. Inter.
ScL
2010, 344, 362-371). While clays such as kaolinite and montmorillonite are,
like
mica, sheet-like aluminosilicates and are found in oil sands, these minerals
proved to
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be unusable in the chemical force experiments, due to extensive swelling in
aqueous
solution. Tip/sample interactions were analyzed as a function of pH, in the
presence
of divalent cations (e.g. Ca2+, as used during the industrial process), and in
the
presence of switchable additives. As described above, CO2 switchable chemistry
is
mediated by changes in solution pH due to the dissolution of CO2 and the
formation
of carbonic acid. Thus, further measurements to determine the effects of
solution pH
on the interactions between SAM and mineral substrate, in the absence of
switchable
surfactant, were carried out. The literature related to oil sands chemistry
indicates
that divalent cations decrease bitumen recovery through the promotion of
adhesion
between the bitumen and sand moieties. The divalent cation both collapses the
electrical double layer and shields the two negatively charged surfaces to
increase
adhesion (1Ier, R. K. Chemistry of Silica-Solubility, Polymerization, Colloid
and
Surface Properties and Biochemistry; John Wiley & Sons, Hoboken U.S.A., 1979;
and Maslova, M. V.; Gerasimova, L. G.; Forsling, W. Colloid J. 2004, 66, 322).
Calcium sulfate, a common additive to oil sands tailings, was used in the CFS
studies
to demonstrate how our model systems serve in mimicking real oil sands
systems.
[00757] Experimental
[00758] Synthetic Methods
[00759] The synthesis of 12-phenyldodecanethiol was accomplished using
previously published literature methods (Lee, S.; Puck, A.; Graupe, M.;
Colorado Jr.,
R.; Shon, Y. S.; Lee, T. R.; Perry, S.S. Langmuir 2001, /7, 7364; Speziale, J.
Org.
Syn. Coll. 1963, 4, 396; and Frank, R.; Smith, P. J. Am. Chem. Soc. 1946, 68,
2103). The 1H-NMR, 13C-NMR and mass spectra (high res, Ell matched those
reported in the literature (Lee, S. 2001, supra). NMR and MS spectra showed
that
the product was a mixture of the thiol and the corresponding disulfide (3:1
ratio by
1H-NMR) due to partial oxidation during the synthesis. However, it has been
demonstrated in the literature (Nuzzo, R.; Allara, D. J. Am. Chem. Soc. 1983,
105,
4481; and Bain, C.; Bieyuck, H.; Whitesides, G. Langmuir 1989, 5, 723) that
disulfides also self assemble onto gold surfaces through scission of the
sulfur-sulfur
bond. Therefore, this material can still be used to create the desired self-
assembled
monolayers on gold.
[00760] N'-alkyl-N,N-dimethylacetamidines C4 and C8 were also synthesized
by previously published literature methods (Liu, Y.; P.G. Jessop, M.
Cunningham, C.
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Eckert, C. Liotta. Science 2006, 313, 958). 12-Mercaptododecanoic acid was
purchased from Sigma Aldrich and used as received.
[00761] Silicon (111) wafers were purchased from Virginia Semiconductors
Inc. These substrates were cleaned and oxidized with piranha solution (3:1
concentrated H2SO4: 35 wt% H202 in 1-120) for 1 hour prior to being thoroughly
rinsed
with deionized water and dried under a stream of N2(g).
[00762] Muscovite mica (V-4 grade, SPI) was freshly cleaved prior to use.
Double sided tape was adhered to the surface and subsequently pulled off to
reveal
a new basal surface for AFM force measurements.
[00763] Instrumentation
[00764] AFM force-distance curves were obtained using a PicoSPM
instrument (Molecular Imaging, Tempe, AZ) and a Nanoscope IIE controller
(Digital
Instruments, Santa Barbara, CA). All experiments were conducted at 25 C.
[00765] Gold-coated silicon nitride AFM tips (CSC-38, MikroMasch USA;
spring contant k=0.08 N/m; tip radius < 10 nm, as per manufacturer's
specifications)
were functionalized for adhesion force measurements by submerging the tips in
a
1x10-3M solution of 12-phenyldodecanethiol ("phenyl tip") or 12-
mercaptododecanoic
acid ("acid tip") in isopropanol for 24 h. Force measurements were conducted
under
aqueous conditions in solutions prepared using deionized water (18.2 MC),
Millipore).
The adhesive force between the tip and the sample was determined from
measuring
the well depth of over 1000 force distance curves under each experimental
condition.
The adhesion force was measured approximately 200 times at different surface
sites.
At least 5 surface sites were tested for each experimental condition, but
typically 15-
20 sites were studied. At least 2 different tips were used in these
measurements.
The large number of measurements was conducted to obtain a more representative
value of adhesion between the tip and the sample. The reported values are an
average of all the measured adhesive forces and the errors are the calculated
95%
confidence intervals.
[00766] The chemical force titration experiments were conducted using
freshly
prepared unbuffered aqueous solutions of pH ranging from 3 to 11. To modify
the
pH, addition of 1.0 M NaOH solution was used to achieve alkaline conditions
and
similarly a 1.0 M HCI solution was added to achieve acidic conditions.
Unbuffered
pH solutions were used to prevent unwanted interactions between the surface
and
the ionic species associated with the buffer. The pH values were checked
before and
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after the experiment and the solutions were changed frequently to minimize
changes
in pH due to the dissolution of atmospheric 002. Experiments were carried out
under
low ionic strength conditions and the only ions introduced into the system
were from
the use of HCI and NaOH for pH adjustment.
[00767] For experiments involving CO2 saturated solutions, the solutions
were
pretreated with CO2 prior to acquiring the force curves. Ultra pure CO2
(Supercritical
CO2 Chromatographic Grade, Praxair) was bubbled through the solutions using a
syringe for 30 min. For these force measurements, the AFM was outfitted with
an
environmental cell that was filled with CO2 to maintain a CO2 atmosphere
around the
aqueous solutions during the experiment.
[00768] Results and Discussion
[00769] When switchable additives are activated or deactivated through
the
addition or removal of CO2 from the system, the solution pH is varied.
Chemical force
titration profiles (plots of tip/sample adhesion as a function of pH) were
measured for
AFM tips functionalized using both phenyl- and carboxylate-terminated SAM's
with
mica and silica substrates. These experiments were an important control case
to
monitor the background effect of any solution pH changes. The chemical force
titration profiles for the silica substrate and the acid and phenyl terminated
AFM tips
are shown in Figure 43A. Note that the forces measured between silica
substrate and
the acid tip were scaled by a factor of 10 relative to the remaining data in
Figure 43A.
[00770] The maximum adhesion force of 0.18 0.04 nN was measured at pH
4 in the chemical force titration profile between the acid tip and the silica
substrate.
The adhesion force dropped off rapidly at higher and lower pH values, which is
similar to force titration profiles previously observed in systems where the
tip and
sample interactions are dominated by hydrogen bonding forces (van der Vegte,
E.
W.; Hadziioannou, G. J. Phys. Chem. B 1997, 101, 9563; and van der Vegte,
E.W.;
Hadziioannou, G. Langmuir 1997, 13, 4357). The surface pKa of the acid-
terminated
SAM has been previously observed to be at approximately 4 ¨ 5, consistent with
the
4.9 pKa of long-chain alkanoic acids in water. Assuming that the silica
substrate is
negatively charged over much of the pH range studied, a large number of ionic
H-
bonds may form at or below the surface pK, of the tip, leading to the strong
interactions observed in this pH range. At pH values above the pKa, the
adhesion
force diminished sharply with increasing pH, as would be expected because the
tip is
becoming increasingly negatively charged and it is interacting with a
negatively
charged substrate. Interestingly, the adhesion force increased again slightly
at pH
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11. This was a reproducible trend, seen in independent experiments. A possible
explanation may be the increase in Na concentration from the increase in NaOH
required to achieve this high pH. Both the silica substrate and the acid tip
are
expected to be negatively charged at pH 11 and the presence of Na + cations
may
serve to screen the two negatively charged surfaces. A maximum adhesion force
of
1.7 0.4 nN for the phenyl-terminated AFM tip and the silica substrate was
observed
at pH 7. The chemical force titration profile shows that the adhesion force
decreased
gradually at higher and lower pH values. This result is consistent with
hydrophobic
forces dominating the tip-sample interaction.
[00771] The chemical force titration profiles for the mica substrate and
the
acid- and phenyl-terminated AFM tips are shown in Figure 43B. As with the
silica
substrate, a maximum adhesion force (1.6 0.2 nN) between the acid tip and
the
mica substrate was observed at a pH of 4. This trend may also be attributed to
hydrogen bonding interactions between the substrate and tip with a similar
mechanism as outlined above. Adhesion forces between phenyl-terminated tip and
mica substrate were weak through the entire pH range (Figure 43B). Again,
hydrophobic interactions appear to be a main contributing factor in the tip-
sample
interaction.
[00772] In subsequent CFS experiments, the cationic switchable surfactant,
08 (Figure 44), was compared with 04, an amidine with a four carbon chain tail
(Figure 45). Unlike C8, C4 is not a surfactant molecule in the presence of CO2
due
to its short alkyl chain length. However, both C4 and C8 can be protonated in
aqueous solutions saturated with CO2 to yield a positively charged amidinium
head
group. Thus, comparison of C4 and 08 determines to what extent changes in
adhesion force may be attributed to the surfactant properties or simply due to
the
presence of the protonatable amidine functionality and consequent increase in
ionic
strength following protonation.
[00773] The results from the CFS experiments in the presence of 04 are
presented below.
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Additive Adhesion Force (nN)
Carboxylic Acid-terminated tip Phenyl-terminated tip
Silica Mica Silica Mica
1 mM C4 0 0.01 0.01 0 0.01 0.01
(pH 11 0.2)
1 mM C4 + CO2 0.18 0.04 1.58 0.18 0.07 0.02 0.74 0.35
(pH 5 0.2)
1 mM C8 0.39 0.20 0.23 0.28 0.97 0.33 1.97
0.19
(pH 11 0.2)
1 mM C8 + CO2 1.53 0.19 1.94 0.23 1.05 0.38 0.41 0.20
(pH 5 0.2)
pH 11 0.2 0.10 0.04 0 0.64 0.09 0
NaOH Modified
pH 5 0.2 0.08 0.05 0.31 0.30 0.36 0.26 0.35
0.46
HCI Modified
[00774] A consistent trend was observed for all four tip/sample pairs. In
the
absence of CO2, there was no interaction measured between the tip and the
surface.
Upon saturation of the aqueous solution with CO2, the adhesion force increased
dramatically.
[00775] Because the pH of solution changes due to addition of CO2, the
table
also shows the adhesion forces observed in the absence of the switchable
amidine,
but at the same pH (using HCI or NaOH). For three of the four tip/sample
pairs, the
increase in adhesion force that was observed in the presence of C4 was greater
than
when the solution pH was modified by HCI or NaOH, and in one pair
(carboxylate/mica) the increase was dramatically greater. The observed
modifications in adhesion force cannot be attributed to pH changes alone.
[00776] The table also shows a similar set of data using C8, the active
surfactant species. The addition of CO2 to the C8 solution caused a dramatic
rise in
the attractive force for the carboxylate-terminated tip, but not for the
phenyl-
terminated tip. Again, the changes induced were greater than what may be
attributed
to changes in pH alone. Unlike the C4 case, the presence of C8 lead to
significant
adhesion forces for all four tip-sample pairs regardless of the presence or
absence of
002.
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[00777] The results from the CFS experiments suggest a mechanism by which
amidines such as C4 and C8 can reversibly control adhesion between the various
components of an oil sand. They also show that such amidines may be
potentially
useful as additives for the reversible manipulation of the water chemistry in
oil sands
extraction. In aqueous solutions containing these additives without CO2, the
adhesion forces between the organic functionalized tips and the mineral
surfaces
were minimal. This suggests that this additive may be useful for decreasing
adhesion between bitumen and mineral surfaces, thus facilitating bitumen
liberation
and flotation during the separation stage of oil sands processing.
[00778] Gold-coated AFM tips functionalized with 12-mercaptododecanoic
acid or 12-phenyldodecanethiol were used as models of bitumen surfaces for a
study
of adhesive interactions between these model bitumen surfaces and mica or
silica.
The parameters investigated included variations in pH, changes in calcium
sulfate
concentration, addition of amidine additives C4 and C8, and the presence or
absence
of CO2. In the chemical force spectrometry experiments involving C4, the
adhesion
forces between the organic functionalized AFM probes and the mineral
substrates
were low in the absence of CO2, but an increase in adhesive interaction was
observed when in the presence of CO2. The same trend was observed with
experiments involving C8, but only when the acid tip was used. The lack of a
CO2-
triggered increase for the phenyl tip may be due to the hydrophobic tail of C8
being
attracted towards the phenyl tip.
[00779] Of the two switchable additives studied, C4 was most consistent
in
switching on and off the adhesion interactions between all of the organic and
mineral
pairs, while C8 only showed that effect with the carboxylic acid tip. This
suggests
that C4 can be useful for facilitating bitumen and mineral separation in the
extraction
phase of the industrial process.
[00780] EXAMPLE 34: Titanium Oxide Settling With Switchable Water
Additives
[00781] This titaniun oxide settling study was used as a model for waste
water
treatment to remove unwanted particulates using a switchable additive.
[00782] The titanium(IV) oxide (nanopowder, -21 nm particle size, 9.5%
trace metals basis) used was purchased from Sigma-Aldrich.
[00783] In this study 0.050 g of 3-(dimethylamino)-1-propylamine
functionalized PMMA (MW=120,000) was placed into two different 250 mL round
bottom flasks equipped with a 2 cm Teflon stir-bar. 100 mL deionized water was
172
added and the solutions were stirred (600 rpm) until the polymer dissolved (10
min to
16 h). Then 1 g of titanium(IV) oxide was added. Both suspensions were stirred
at
600 rpm for 1 h, while CO2 was bubbled through one of the solutions using a
gas
dispersion tube. After that, both suspensions were transferred into 100 mL
graduated
cylinders and the settling rate was monitored overtime. In the presence of CO2
very
quick bulk settling was observed in the presence of CO2, leaving a turbid
supernatant
behind that cleared up within 2 h. Without CO2 present no settling was
observed,
resulting in a stable suspension. The supernatant in the presence of CO2 was
only
slightly turbid, whereas without CO2 the supernatant consisted of a stable
suspension
that was not transparent at all. These results support the use of the
switchable
additive in a waste water treatment process
[00784] All publications, patents and patent applications mentioned in
this
Specification are indicative of the level of skill of those skilled in the art
to which this
invention pertains.
[00785] It will be understood by those skilled in the art that this
description is
made with reference to the preferred embodiments and that it is possible to
make
other embodiments employing the principles of the invention which fall within
its spirit
and scope as defined by the claims appended hereto. All such modifications as
would be obvious to one skilled in the art are intended to be included within
the
scope of the following claims.
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