Note: Descriptions are shown in the official language in which they were submitted.
~Q~O
PROCESS OF REMOVING AND CONCENTRATING
DESIRED MOLECULES FROM SOLUTIONS
FIELD OF THE INVENTION
This invention relates to a process for removing and
concentrating certain desired molecules, such as gases, amino
acids, anions, and others, from solutions wherein such
molecules may be admixed with other molecules which may be
present in much higher concentrations. More particularly, this
invention relates to a process for removing such molecules from
an admixture with others in solution by forming a complex of
the desired ions or molecules with a ration complexed to a
ligand molecules covalently banded to an inorganic matrix by
flowing such solutions through a packed column packed with such
ration-ligand-matrix and then breaking either the molecule-
bound ration or ration-bound ligand complex by flowing a
receiving liquid in much smaller volume than the volume of
solution passed through the column to remove and concentrate
the desired ions or malecules in solution in the receiving
liquid. The concentrated ions or molecules thus removed may be
analyzed and/or recovered by known methods. For the sake of
convenience the term "desired molecules" is used throughout the
specification to include both molecules and anions.
HACRGROUND OF THE INVENTION
Effective methods of recovery and/or separation of
particular molecules such as gases, anions, amino acids, and
others, from other molecules in water supplies, organic
2
solvents, waste solutions, and industrial solutions and streams
represent a real need in modern technology. These molecules
are often present at low concentrations in solutions containing
other molecules at much greater concentrations. Likewise there
is a need to concentrate these molecules so that an effective
analysis using known methods can be carried out. Hence, there
is a real need for a process to selectively recover and
concentrate these molecules.
It is known that many cations present as solutes in a
solvent such as water, existing either as the free cation or
complexed by a ligand solute, are capable of additional
complexation at binding sites initially held by H20 or other
weakly coordinated ligands or via ion pairing. These cations
or cation-ligand complexes are characterized by their ability
to selectivity form strong bonds with other strongly bonding
ligand(s) solutes When the H2O or other weakly coordinated
ligands are released. See, for example, Smith et al., CRITICAL
STABILITY CONSTANTS, 6 volumes, Plenum Press, New York, 1975,
1982, 1989., and Bard, et al., STANDARD POTENTIALS IN AQUEOUS
SOLUTION, Marcell Dekker, New York, 1985. However,
researchers have not previously been able to effectively
incorporate these cation-ligand complexes, which are capable of
further selective complexation, into separation systems where
the behavior of the cation-ligand complex in the separation
systems in comparison to that of the cation-ligand complex as a
solute remains unchanged. Nor have researchers developed a
~03~~~~
3
system wherein the cation-ligand complex will remain in the
separation system for use in repeated separations.
Many organic ligands have been attached to polymeric
supports such as polystyrene, but the properties of the
support bound ligands are substantially different compared to
the analogous unbound ligand as an aqueous solute. A review
article on this subject is found in Volume 19 of the series
"Critical Reports on Applied Chemistry", in Chapter 4 (pp. 167-
223) entitled CHELATING 30N EXCHANGERS by A. Warshawsky, Edited
by Streat et al., John Wiley and Sons, 11987. Attaching these
organic ligands to hydrophobic supports substantially changes
the properties of the ligand molecules.
Articles such as SILANE COMPOUNDS FOR SILYLATING SURFACES
by E. P. Pleuddemann, in "Silanes, Surfaces and Interfaces
Symposium, Snowmass, 1985", Ed. by D. E. Leyden, Gordon and
Breach Publishers, 1986, pp. 1-25 and SILANE COUPLING AGENTS by
E. P. Plueddemann, Plenum Press, 1982, pp. 1-235 list many
different types of organic materials which have been attached
to silane compounds and discusses some of their properties. E.
F. Plueddemann in METAL EXTRACTION FROM SOLUTION AND
IMMOBILIZED CHELATING AGENTS USED FOR THIS PROCESS, Canadian
Patent 1,196,618 issued November 12, 1985 and others have
reported in the patent literature other ligands which can be
immobilized on silica gel and used to complex metal cations
from aqueous solutions. However, the use of coordinating
molecules covalently bound to solid materials to complex metal
4
cations to the solid support and the subsequent use of
additional coordination sites of the metal cation to perform
specific separations with regard to gases, amino acids,
anions, and other molecules has not been previously reported.
Researchers have had moderate success in using plain ion
exchange beds to complex cations and then using the bound
cations to effect separations. Articles such as DETERMINATION
OF THE TWO-PHASE EQUILIBRIUM CONSTANTS OF COPPER Cu(II)-
MODIFIED SILICA GELS USED IN LIQUID CHROMATOGRAPHY by Guyon et
al., Analytica Chimica Acta, 170 (1985) 311-317 describe such
efforts with hydrophilic supports such as silica gel. Suzuki
et al., in SEPARATION OF OLEFINIC COMPOUNDS, Japanese Kokai
Patent number 75 05, 302 (Cl.i6A0) published January 21, 1985
report an example of the use of metals bonded to an ion
exchange resin composed of hydrophobic supports such as
polystyrene to effect separations. However, there has been no
previous report of using bound coordination ligands covalently
attached to a solid support, such as silica gel, and containing
a complexed cation to effect separations. The use of the bound
coordinating ligand rather than an ion exchange bed allows for
both much greater stability and selectivity in maintaining the
cation on the resin as well as a much greater variety of
separations to be performed.
There is a particular need in modern society to (1)
measure the concentrations of molecules in low parts per
million (ppm) to low parts per billion (ppb) concentrations;
CA 02030596 2003-05-O1
69912-185
(2) to remove low levels of toxic molecules from solutions
such as potable and saline water; and (3) to recover
valuable molecules which are present in solution at low
concentrations. For example the allowable amount of ammonia
5 in saline water in order for fish to live is approximately
1-2 parts per million. Present methods for analysis of
these molecules at these levels are not accurate and/or are
very time consuming. Furthermore, removal of the molecules
is not selective, but is expensive and equipment intensive
using present methods. Other present needs in industry
which present utility opportunities for the use of solid
supported ligand bound rations include removal of toxic
anions such as Cr042-, preparation of ultrapure salts
(halide separations), preparation of ultrapure gases (02 and
other separations), separation of amino acids and amines and
others. Thus, development of means to utilize the molecule
complexing properties of complexes of rations with ligands
attached to an inorganic support, such as silica gel or
titanized silica gel, would be of the utmost importance for
the repeated separation and concentration of certain
molecules for analysis, and/or recovery purposes. The
process of the present invention accomplishes this feat.
SUMMARY OF THE INVENTION
In one aspect, the invention provides a method for
the removal and concentration of desired molecules from a
source solution which comprises bringing said source
solution having a first volume into contact with a solid
ration-ligand-matrix consisting of a ration complexed to a
ligand molecule covalently bonded to a matrix consisting of
an organic spacer bonded to a solid inorganic support
through a silicon atom said ration having an affinity for
the desired molecules to form a complex between said desired
CA 02030596 2003-05-O1
69912-185
5a
molecules and said ration portion of said solid cation-
ligand-matrix; removing said source solution from contact
with said ration-ligand-matrix complexed with desired
molecules; and contacting said solid ration-ligand-matrix
complexed with said desired molecules with a smaller volume
of a receiving solution in which said desired molecules are
soluble thereby breaking said complex and recovering the
desired molecules in concentrated form in said smaller
volume of said receiving solution.
The process of the present invention utilizes a
ration-ligand-matrix consisting of suitable rations
complexed to ligands which, in turn, are covalently bonded
through a spacer grouping and a silicon atom to an inorganic
support such as
~o~o=:
6
sand, silica gel, glass, glass fibers, alumina, nickel oxide,
zirconia or titania. The cation-ligand-matrix is represented
by Formula 1 as follows:
Matrix-L-M (Formula 1)
wherein M is a metal cation, L is a coordination ligand
consisting of an organic molecule known to chelate metal
cations, and Matrix is a member having the formula:
X
0
Y-Si-B-
i
1o z
wherein B is a spacer grouping having from 1 to 10 carbon
atoms and which is of a functional nature that it is
sufficiently hydrophilic to function in an aqueous environment
and will separate the ligand cation (-L-M) from the solid
support surface to maximize the interaction between L-M and the
desired molecules being separated; Si is silicon; and X, Y and
Z is each a member selected from the group consisting of C1,
Br, I, O-alkyl, alkyl, or O-solid hydrophilic inorganic support
wherein the solid hydrophilic support is a member selected from
the group consisting of silica, zirconia, titania, alumina,
nickel oxide or any other similar hydrophilic inorganic support
material, with the proviso that at least one of X, Y and Z must
be O-solid hydrophilic inorganic support. Alkyl or O-alkyl
means a 1-6 carbon member alkyl or alkoxy group which may be
substituted or unsubstituted, straight or branched chain. By
substituted is meant substituted by groups such as C1, Br, I,
~d ~~~)~~~
N02 and the like. When X, Y and Z are other than O-solid
hydrophilic support they are functionally classified as leaving
groups, i.e. groups attached to the silicon atom which, when
reacted with the O-solid hydrophilic support material, may
leave or be replaced by the 0-solid support. Hence, they are
functional groups left over after reacting a silicon containing
spacer group with the solid hydrophilic support and have no
direct function in the interaction between the cation-ligand-
matrix and the desired molecule. Typical silicon containing
spacer groups for reacting with a solid support material to
form the matrix of the formula:
X
Y-Si-B-
I
Z
include, diethyl(triethoxysilylpropyl)malonate; 3-mercapto-
propyltrimethoxysilane; 3-aminopropyltrimethoxysilane;
N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid;
p-(chloromethyl)phenyltrimethoxysilane; vinyltriethoxysilane;
3-bromopropyltriethoxysilane; 3-glycidoxypropyltrimethoxysilane
and the like.
The cation-ligand-matrix is characterised by high
selectivity for and removal of desired molecules or groups of
desired molecules such as gases, anions, amino acids and others
present at low concentrations from the source solution
containing a mixture of desired molecules with undesired
molecules one does not wish to remove from the solution. The
2(~3~~~~~
s
so-called undesired molecules may be present in much greater
concentrations than the desired molecules to be removed. The
separation is effected in a separation device such as a column
through which the source solution is flowed. The process of
selectively removing and concentrating the desired molecules)
is characterized by the ability to selectively and
quantitatively complex the desired molecules to the ration
portion of the ration-ligand-matrix system, from a large volume
of solution, even though the desired molecules may be present
at low concentrations. The desired molecules are subsequently
recovered from the separation column by flowing through it a
small volume of a receiving phase which contains a solubilized
reagent which need not be selective, but which will
quantitatively strip the molecules from the ration-ligand-
matrix. The analysis of the desired metal ions in the
concentrated solution is accomplished by known methods such as
atomic absorption spectroscopy. The recovery of the desired
metal ions from the receiving phase is easily accomplished by
well known procedures. The invention also includes a process
for the complexing of the rations to the bound ligand-matrix by
either flowing solutions containing the ration and any other
needed reagents through a column containing the bound ligand-
matrix or mixing the ration-containing solution and the bound
ligand-matrix material in a mixing vessel. The process for
producing the bound ligand-matrix will be mentioned but is not
a part of the present invention since such processes are
CA 02030596 2001-07-16
69912-185
9
disclosed and claimed in U.S. Patent No. 4,959,153 which issued
on September 25, 1990.
DETAILED DESCRIPTION OF THE INVENTION
As summarized above, the present invention is drawn
to the removal and concentration of certain desired molecules,
such as gases, amino acids, anions, and others, from source
solutions where the desired molecules may be admixed with other
molecules which may be present in much higher concentrations.
This is accomplished by forming a complex of the desired
molecules with a can on-ligand-matrix shown in Formula 1, by
flowing such source solutions through a packed column packed
with a can on-ligand-matrix to attract and bind the desired
molecules to the can on portion of such matrix and subsequently
breaking either the molecule-bound cation or cation-bound
ligand complex by flowing a receiving liquid in much smaller
volume than the volume of source solution passed through the
column to remove and concentrate the desired ions in the
receiving liquid solution. The desired molecules thus
quantitatively stripped
~~~~~k.~
l~
from the cation-ligand-matrix in concentrated form in the
receiving solution may then be analyzed and/or the concentrated
desired molecules may be recovered. The analysis and recovery
from the receiving liquid are accomplished by known methods.
The preparation of the cation-ligand-matrix is accomplished by
either flowing solutions containing the cation and any other
needed reagents through a column containing the matrix bound
ligand molecule or mixing the cation-containing solution and
the matrix bound ligand material in a mixing vessel.
In Formula 1 the coordinating ligand, L, can be any
ligand which has been found to complex the cation to be used
without using all of the coordination sites available to that
cation in the formation of complexes or which allows for ion
pairing interactions of the cation to be maintained.
Publications detailing such cation-molecule complexation either
with the cation not being complexed by another ligand or with
the ca n on complexed by a ligand not bound to a solid sugport
include Smith et al, CRITICAL STABILITY CONSTANTS, 6 vols.,
Plenum Press, New York, 1975, 1982, 1989 and Bard et al.,
STANDARD POTENTIALS IN AQUEOUS SOLUTION, New York, 1985.
Illustrations of typical ligand-cation combinations are given
in the examples which are contained below.
The ligands which can be most effectively used are
generally members selected from the group consisting of amino
acids, amines, pyridines, thiols, phenantrolines, hydroxamic
acids, oximes, amides, thioethers, and combinations thereof.
CA 02030596 2001-07-16
69912-185
11
The cations most effectively used are members selected
from the group consisting of Co3+, Cr3+, Hg2+~ Pd2+~ Pt2+~
Pd4+, Pt4+, Rh3+, Ir3+, Ru3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+,
Pb2+, Mn2+, Fe3+, Fe2+, Au3+, Au+, Ag+, Cu+, Mp22+~_T13+~ T1+.
Bi3+, CH3Hg+, A13+, Ga3+, Ce3+, 0022+ and La3+ and combinations
thereof.
However, the above ligands and cations are only exemplary
and any other ligands and cations which will function to
attach to a matrix and bind the desired molecules are
considered to be within the scope of the invention.
The process of selectively and quantitatively removing and
concentrating a desired molecule or group of desired molecules
present at low concentrations from a plurality of other
undesired molecules in a multiple molecule source solution in
which the undesired molecules may be present at much higher
concentrations comprises bringing the multiple molecule source
solution into contact with a cation-ligand-matrix shown in
Formula 1 which causes the desired molecules) to complex with
said cation-ligand-matrix and subsequently breaking either the
cation-molecule or cation-bound complex with a receiving
solution which takes the desired molecules) into solution in a
concentrated form from which they can be analyzed and/or
recovered by known means.
The cation may be attached to the ligand-matrix by either
flowing solutions containing the cation and other needed
reagents such as oxidation-reduction reagents) and/or
~~~~P) ~'~
12
complexing agents needed for solubility of the metal through a
column containing the ligand molecule bound to the matrix or
mixing the cation-containing solution and the ligand-matrix in
a mixing vessel.
The cation-ligand-matrix functions to attract the desired
molecules according to Formula 2:
Matrix-L-M + DM ----> Matrix-L-M:DM (Formula 2)
wherein L and M stand for ligand and cation as above defined
and wherein DM stands for the desired molecule being removed.
Once the desired molecules are bound to the cation, they
are subsequently separated by use of a smaller volume of a
receiving liquid according to one of Formula 3 or Formula 4:
(receiving)
Matrix-L-M:DM ----------------~ P9atrix-L-M + DM (Formula 3)
(liquid)
or
(receiving)
Matrix-L-M:DM ----------------aP Matrix-L + M:DM (Formula 4)
(liquid)
The preferred embodiment disclosed herein involves
carrying out the process by bringing a large volume of the
source multiple molecule solution into contact with a cation-
ligand-matrix of Formula 1 in a separation column through which
the mixture is first flowed to complex the desired molecule or
molecules (DM) with the cation-ligand-matrix as indicated by
Formula 2 above, followed by the flow through the column of a
smaller volume of a receiving liquid, such as dilute aqueous
hydrochloric or nitric acid, to break the complex by chemical
20~~Jr:~~='~
13
or thermal means, dissolve the desired molecules and carry them
out of the column in a concentrated form. The degree or
amount of concentration will obviously depend upon the
concentration of desired molecules in the source solution and
the volume of source solution to be treated. The specific
receiving liquid being utilized will also be a factor.
Generally speaking the concentration of desired molecules in
the receiving liquid will be from 50 to 1,000,000 times greater
than in the source solution. Other equivalent apparatus may be
used instead of a column, e.c~., a slurry which is filtered,
washed with a receiving liquid to break the complex and recover
the desire molecule(s). The desired molecules are then
analyzed by known methods, and/or recovered from the receiving
phase by known procedures.
More particularly, the process of the invention comprises
placing the cation-ligand-matrix of Formula 1 in a contacting
device such as a tall column. A relatively large volume of a
source solution containing a mixture of desired and undesired
molecules is passed through the column in contact with the
ration-ligand-matrix. The desired molecules complex with the
ration-ligand-matrix which still contains available
coordination sites with respect to the ration. The complexing
of the desired molecules with the solid ration-ligand-matrix
separates the desired molecules from the rest of the source
solution mixture which then flows out of the column. A small
volume of a receiving liquid is then passed through the column.
~o~o~~~~
14
The receiving liquid is capable of stripping the desired
molecules from the complex by breaking the complex and
dissolving the desired molecules that are released from the
solid ligand-matrix. The desired molecules are then carried
out of the column in concentrated form in the receiving
liquid. The desired molecules can then be analyzed by known
methods such as atomic absorption spectroscopy, and/or
recovered from the receiving liquid by known procedures.
Illustrative of classes of desired molecules which have
strong affinities for ligand bound cations with ion pairing
ability or additional coordination sites are solvated gases,
amino acids, anions, amines and neutral liquids and solutes
other than gases. There follows a listing of each of these
categories naming specific desired molecules (or anions) within
each grouping and the cations, which may be bound to a ligand,
to which the desired molecules have a strong affinity.
Desired Molecule Cations
Solvated Gases:
02 Fe2+ and Co2+
NH3 Cu2+, Ni2+, Pd2+, Hg2+, Co3+
S02 Ag+, Cu+, Cd2+, Hg2+
S03 Fe3+, pb2+
NO Fe2+
N2 Pd2+, Pt2+, Pt4+, Fe2+, M02+
CO Fe2+, Cu2+, Ni2+, Pd2+, Zn2+, Cd2+, Hg2+
C02 Zn2+
~G~~~~~;~
15
Ethene Cu2+,Ni2+,Fe2+~ Ag+~ Zn2+
Propene Cu2+,Ni2+,Fe2+, Ag+, Zn2+
Amino Acids:
Glycine Ni2+,Cu2+,Fed+, Pd2+,Hg2+
Alanine Ni2+,Cu2+,Fe3+, pd2+,Hg2+
Valine Ni2+,Cu2+,Fe3+, pd2+~Hg2+
Leucine Ni2+,Cu2+,Fe3+, Pd2+,Hg2+
Isoleucine Ni2+,Cu2+,Fe3+, Pd2+,Hg2+
Proline Ni2+,Cu2+,Fed+, Pd2+,Hg2+
Phenylalanine Ni2+,Cu2+,Fe3+, Pd2+,Hg2+, Zn2+
Aspartic Acid Ni2+,Cu2+,Fe3+, Pd2+,Hg2+, Zn2+,Co2+
Glutamic Acid Ni2+,Cu2+,Fe3+, Pd2+,Hg2+, Zn2+,Co2+
Tyrosine Ni2+,Cu2+,Fe3+, pd2+~Hg2+~ Zn2+~Co2+~ pb2+
Serine Ni2+,Cu2+,Fe3+, pd2+,Hg2+~ Zn2+,Co2+, Pb2+
Glutamine Ni2+,Cu2+,Fe3+, pd2+,Hg2+~ Zn2+
Arginine Ni2+,Cu2+,Fed+, Pd2+,Hg2+, Zn2+
Cysteine Ni2+,Cu2+,Fe3+, pd2+~Hg2+~ Zn2+
Methionine Ni2+,Cu2+,Fe3+, Pd2+,Hg2+, Zn2+,Fe3+
Histidine Ni2+,Cu2+,Co2+, pd2+~Fe2+, Zn2+,Cd2+
Nitrilotri-
acetic acid Ni2+ Cu2+ Fe3+
, ,
Anions:
C1- Pd2+,Ag+, Hg2+~ Cu+,
T13+
Br- Pd2+,Ag+, Hg2+~ Cu+, H3Hg+
T13+,
Bi3+,
C
I- Pd2+,Ag+, 1:~g2+,Cu+, H3Hg+, Cd2+
T13+,
Bid+,
C
502- Fe3+,Pb2+
S032- Cd2+,Hg2+~Ag+~ Cu+,
Ce3+,
CH3Hg+
16
Cr042- Hg2+~ Cu2+, T1+, Ag+
SCN Hg2+, Pd2+, Au+, Ag+
SeCN- Hg2+
N02- pd
2+
PO~ A13+, Pb2+, Ga3+, Cu2+, Ni2+
5203- Au3+
HS Ag'~'~Hg2+~ Cd2+
S2- CH3Hg +
Acetate 0022+ ~ Fe3+~ Hg2+~ T13+
Citrate La3+, pb2+
Amines, Neutral
Liquids and
Solutes Other
Than Gases:
Pyridine Cu2+, Ni2+, pat+~ Zn2+
Cyclo-
~pentadiene Cu2+, Ni2+, Fe2+, Zn2+, Ag+
Ethylene
diamine Cu2+, Ni2+, pd2a-~ Zn2+
Methyl amine Cu2+, Ni2+, pd2+~ Zn2+
Phenan-
throline Cu2+, Ni2+, Pd2+, Zn2+
The abov e listing of desired molecules and associated
preferred ions not comprehensive and is intended only
cat is to
show (1) the types f preferred molecules which may be
o bound to
ligand attached ons and (2) to further illustrate typical
cati
cations whichcan ligand bound and still attract and
be bind
the desired olecules in the manner described above.
m
DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
Preparation of Ligand-Matrix Compounds
Ligands capable of complexing ca n ons without using all of
~~~(~ ~~~
I7
the coordination sites of the cations must be covalently bonded
to the inorganic support matrix. Although the formation of
ligand-matrix combinations is taught in the art, in order to
illustrate a complete embodiment of the invention, methods
which illustrate preparation of ligand-matrix compounds are
included.
Example 1
In this example 3-glycidoxypropyltrimethoxysilane (236 g,
1 mole) in 7 liters of toluene was added to 60 g (1 mole) of
IO the ligand ethylenediamine. The mixture was stirred at room
temperature for 24 hours before 2.5 Kg of 60-200 mesh silica
gel, as the solid support material, was added to the stirred
solution. The temperature was then increased to 55°-88° C and
heated for an additional 24 hours. The final product was
collected by filtration and dried yielding a matrix-ligand
complex. The matrix is formed by the reaction of the
trimethoxysilane end of the 3-glycidoxypropyltrimethoxysilane
spacer group with the silica gel support and the ethylene-
diamine ligand is covalently bonded to the 3-glycidoxypropyl
end of the spacer group.
Example 2
In this example 94 g (1 mole) of the coordinating ligand
ethanedithiol and sodium methoxide (catalytic amount) were
added to 7 liters of toluene containing 472 g (2 mole) of 3-
glycidoxypropyltrimethoxysilane as the spacer. The reaction
was warmed to 50°-70° C for 24 hours, 2.5 Kg of 60-200 mesh
18
silica gel was added and the solution stirred for an additional
24 hours. The product was collected by filtration and dried
before use. The matrix is essentially the same as that formed
in Example 1 with the ethylene dithioether, ethanedithiol,
attached as the ligand to the 2-glycidoxypropyl end of the
spacer group.
Example 3
This example is the same as Example 1 except that 150 g of
triethylene tetraamine was used in place of the ethylene-
diamine as the ligand.
Example 4
In this example the amino acid L-tyrosine was used as the
ligand and attached to silica geI through a spacer grouping by
the following procedure. In a three-necked 500 ml round bottom
flask equipped with a mechanical stirrer, 2.5g (13.8 mmol) of
L-tyrosine was combined with 27.6 mmol of sodium methoxide in
methanol. After the tyrosine had dissolved, 3.42g (13.8 mmol)
of 3-glycidoxypropyltrimethoxysilane was added as a spacer and
the mixture allowed to react overnight. After stirring
overnight, 34.5 g of 60-200 mesh silica gel was added along
with 250 ml of toluene and the mixture was heated to near
reflux overnight again. The product was collected by
filtration and washed followed by air-drying.
Preparation of Cation-Ligand-Matrix Compounds
The ligand bound to the matrix must now be made to
complex a cation with desired affinity for other molecule(s).
~~3~~~~
19
A listing of preferred,cations has been given previously. In
some cases this can be done simply by either mixing the bound
ligand-matrix material with a solution of just the ration or
passing this solution through a column containing the bound
ligahd-matrix material. However, in some cases other reagents
such as oxidation-reduction reagents and/or complexing agents
to maintain ration solubility must be added to the cation-
containing solution. Oxidation-reduction agents are required
when a particular oxidation state of a ration is not stable
until a complex with the bound ligand is formed. Gaseous
oxygen and hydrogen peroxide are typical reagents that are
used. In some cases, solubilized complexing agents must be
used to solu bilize rations. These complexing agents must form
sufficiently strong complexes with the ration for
solubilization to occur, but not form such a strong complex
that bound ligand-ration complexation is hindered. Typical of
common reagents used as complexing agents are ethylenediamine
tetraacetic acid (EDTA), ammonia, excess chloride ions, and the
like.
The preparation of ration-ligand-matrix compounds are
illustrated in the following examples.
Example 5
In this example Pd2~ is the complexing ration which is
reacted with the ligand-matrix of Example 2. A solution of
0.001 M Pd(N03)2 in 1 M HN03 was passed through a column
containing the solid ligand-matrix material ethanedithia
20
(thioether) attached to silica gel through a spacer as
described in Example 2. The solid material turned from a white
to a light orange color and analysis (atomic absorption
spectroscopy) of the Pd-containing solution after separation
from the solid indicated that enough Pd had been removed to be
equivalent to loading 0.34 mmoles Pd/g solid material. This
matched within analytical error the amount of ethanedithia
ligand bound to the silica gel. Alternately, instead of using
a column, the solution and the solid ligand-matrix material
could have been mixed in a beaker.
Example 6
Tn this example Co3+ is the complexing cation which is
reacted with the ligand-matrix of Example 3. An aqueous
solution of 0.01 M CoCl2 containing 1-2$ H202 was passed
through a column containing (or mixed in a beaker) with the
solid ligand-matrix material made of tetraamine attached to
silica gel through a spacer as described in Example 3. The
solid material turned from an initial white color to a brown
color and then to a purple color. These colors are indicative
of the initial binding of Co2+ to a bound amine-containing
ligand followed by oxidation of the Co2+ to Co3+. An analysis
of the solution after separation from the solid by atomic
absorption spectroscopy showed that the amount of the Co
removed from the solution was equivalent to 0.40 mmoles Co/g
solid material. This also matched within analytical error the
amount of bound ligand on the solid material.
21
Example 7
The procedure of Example 6 was repeated using the
ethylenediamine ligand of Example 1 rather than the tetraamine
bound to silica gel through a spacer. Similar results were
obtained with the exception that the final color of the
material was reddish brown and the bound ligand and bound
cobalt capacities were found to be 0.33 mmoles/g.
Example 8
In this example Cu2+ is the complexing cation which is
reacted with the ligand-matrix of Example 4. The solid
material containing L-tyrosine ligand covalently bonded,
through a spacer, to silica gel as shown in Example 4 was
placed in a column and a solution of 0.001 M CuCl2 in 0.1 M
MgCl2 was passed through the column. The solid material turned
from a white to a dark blue color and analysis (atomic
absorption spectroscopy) of the Cu-containing solution after
separation from the solid indicated that enough Cu had been
removed to be equivalent to loading 0.18 mmoles Cu/g solid
material. This matched within analytical error the amount of
tyrosine ligand bound to the spacer-silica gel matrix.
Example 9
In this example Hg2+ is the complexing cation which is
reacted with the ligand-matrix of Example 4. The solid
material containing L-tyrosine covalently bonded, through a
spacer, to silica gel as shown in Example 4 was placed in a
column and a solution of 0.001 M Hg(N03)2 in 0.1 M Mg(N03)2 was
2~~fl~~
22
passed through the column. Analysis (atomic absorption
spectroscopy) of the Hg-containing solution after separation
from the solid indicated that enough Hg had been removed to be
equivalent to loading 0.18 mmoles Hg/g solid material. This
matched within analytical error the amount of tyrosine ligand
bound to the silica gel.
Removal of Desired Molecules With Cation-Ligand-Matrix
Compounds
The following Examples demonstrate how the cation-
ligand-matrix compounds may be used to concentrate and/or
remove desired ions. The cation-complexing bound ligand
containing inorganic matrix material of Formula 1 is placed in
a column. An aqueous solution containing the desired molecule
or molecules, in a mixture of other molecules which may be in a
much greater concentration, is passed through the column. The
flow rate fox the solution may be increased by applying
pressure with a pump on the top of the column or applying a
vacuum in the receiving vessel. After the solution has passed
through the column, a much smaller volume of a recovery
solution, i.e. an aqueous acid solution, which will protonate
some complexed molecules like ammonia thereby releasing the
ammonia from being complexed to the metal, is passed through
the column. This receiving solution contains only the desired
molecule in a concentrate form for subsequent analysis and/or
recovery. Suitable receiving solutions can be pH reagents,
i.e. acids or bases, or complexing agents that either complexes
~Q~Q
23
the desired molecule away from the bound cation-ligand-matrix
material as shown in Formula 3 or which complexes the metal
cation and desired molecules away from the solid supported
ligand as shown in Formula 4. Typical examples of suitable
receiving solutions are acids such as hydrochloric, nitric,
sulfuric, phosphoric and acetic acids; bases maintained at a pH
less than 11 such as ammonium hydroxide, sodium hydroxide;
EDTA, and NTA, thiourea, certain amino acids such as glycine,
other complexing agents such as pyridine, etc.
The following examples of separations and recoveries of
molecules by the inorganic support-bound ligands containing
complexed metals which were made as described in Examples 10
through 14 are given as illustrations. These examples are -
illustrative only, and are not comprehensive of the many
separations of molecules that are possible using the materials
of Formula 1.
Example 10
In this example, 2 grams of the Co3+ cation complexed to
the tetraamine ligand which in turn is bound to a spacer-silica
gel matrix as shown in Example S was placed in a column 1.9 cm
in diameter and 2.3 cm in length. A 500 ml solution of about
10 ppm of NH3 in 0.1 aqueous MgCl2 was passed through the
column using a vacuum pump at 100 torr to increase the flow
rate. A 10 ml aqueous solution of 1 M HG1 was passed through
the column as the receiving liquid. An analysis of the
recovery solution by colorimetry showed that greater than 99~
2t~3~ ~,~
2~
of the NH3 molecules originally in the 500 ml solution was
present in the 10 ml recovery solution as NH~+ ions.
Example 11
The procedure of Example ZO was repeated with the
exception that 2 grams of the Co3+ cation complexed to
ethylenediamine ligand-containing which in turn is bound to a
spacer-silica gel matrix as shown in Example 7 was used.
Again, greater than 99~ of the NH3 in the original solution was
found in the recovery solution.
Example 12
In this example, 2 grams of the Pd2+ cation complexed to
the ethanedithia ligand which in turn is bound to a spacer-
silica gel matrix as shown in Example 5 was placed in a column
as described in Example 10. A 500 ml solution of about 0.001 M
I° and 0.001 M C1- was passed through the column using a vacuum
pump at 100 torr to increase the flow rate. After washing the
column with 50 ml of H20, a 10m1 aqueous receiving solution of
2 M NH40H, 1 M HN03 was passed through the column to remove
both the Pd2+ and the I°. An analysis of the recovery
solution by colorimetry showed that greater than 97~ of the
I- molecules originally in the 500 ml solution and a similar
percentage of the Pd2+ bound to the column were recovered in
the 10 ml recovery solution. The remaining Pd2+ and I- were
recovered within analytical standard deviation by flowing 10 ml
of 1 M NaCN through the column. No C1- could be detected in
either of the two recovery solutions. The Pd2+ was analyzed
~Q~~~~~3~~
using atomic absorption spectroscopy.
Example 13
The procedure of Example 11 was repeated with Br- used
instead of I-. Again, within experimental error, a
5 quantitative separation of C1-'and Br-a was obtained.
Example 14
In this example, 2 grams of the Hg2+ cation complexed to
the L-tyrosine ligand which in turn is bound to a spacer-silica
gel matrix as shown in Example 9 was placed in a column as
10 described in Example 10. A 500 ml solution of 0.001 M racemic
methionine and 0.001 M racemic glycine was passed through the
column using a vacuum pump at 100 torr to increase the flow
rate. After washing the column with 50 ml of H20, a 10 ml
aqueous receiving solution of 3 M HCl was passed through the
15 column to remove both the Hg2+ and the amino acids.
Chromatographic analysis of both the loading and recovery
solutions indicated that the amino acid purity of the glycine
in the recovery solution was greater than 99~. within
detection, and that all of the glycine bound was recovered
20 while all of the methionine passed through the column during
the loading stage without being bound.
From the foregoing, it will be appreciated that the
inorganic matrix-bound ligand-containing hydrocarbons with
complexed metal cations containing additional coordination
25 sites or ion pairing ability of Formula 1 of the present
invention provide a material useful for the separation and
26
concentration of the gases, anions, amino acids, and other
molecules from mixtures of those molecules with molecules. The
desired molecules can then be analyzed and/or recovered from
the concentrated recovery solution by standard techniques known
in the science of these materials.
Although the process of separating and concentrating
certain molecules in this invention has been described and
illustrated by reference to certain specific silica gel-bound
ligand-containing complexed cations of Formula 1, processes
using all analogs of these bound ligand-containing complexed
metal cations with additional coordinating sites are within the
scope of the processes of the invention as defined in the
following claims.
