Note: Descriptions are shown in the official language in which they were submitted.
1~7~097
This ls a division of Canadian application No.
~96,228 filecl Noven~er 26, 1985 wl-ich relates to a method of removing
chlorine-based contaminants such as dioxin ~e.g. TCDD or
2,3,7,8-tetrachlorodibenzo-p-dioxin), PCB (po]ychlorinated
biphenyl), DDT and chlordane, from materials contaminated
with same, and which is particularly directed to the de-
contamination of dioxin contaminated soils.
The decontamination of numerous sites con-
taminated with dioxin in the United States and else-
where i.s presently on hold pending the development of
a suitable clean-up method. Dioxin is typically
found in the parts per million to parts per billion
range and is tightly bound to the soil. It is highly
hydrophobic, which accounts for its lack of mobility
in the soil, except where the soil itself is moved
such as in the case of rainwater runoff or erosion.
The toxicity and uncertainty about long term
ef~ects of exposure to dioxins have combined to make
work in them very difficult. The analysis for dioxins
is still at the frontiers of analytical chemistry, with
new techniqu~s still being developed.
Applicant has described in his Canadian Patent
No. 1,154,70~ of October 4, 1983 a method of separating
oil or bitumen from a surface of a substrate covered
with same, by first dissolving the oil or bitumen in a
solvent to form a solution thereo~. Water is then
intimately contacted with the surface of the substrate,
the 301vent and water being capable of forming together
in the preserlce of the oi:L or b;tumen an interfacial
membrane-like material whlCh has a water side and is
impermeab]e to the oil or bitumen. The intimate
-- 1 --
~ ~ ?
`' i
1~7~ 37
contacting of the water with the surface of the subs-
trate causes the membrane-like material to form at the
surface of the substrate while the water wets the sur-
face and spreads thereover, the water displaci.ng the
membrane-like material away from the surface as it is
being formed thereacross to thereby separate the
solution from the surface and cover the surface with a
layer of water. The mem~rane-like material acts as a
barrier to maintain the oil or bitumen in the solution
and to prevent passaga of same into the water layer.
The solvent is selected for its ability to
dissolve the oil or bitumen and to form a membrane-like
material in the presence of the oil or bitumen and water.
As example~ of suitable solvents, the halogenated
hydrocarbons can be mentioned. Among these, the
chlo-inated hydrocarbons such as methylene chloride,
chloroform, trichlorethylene and perchlorethylene and
the fluorinated hydrocarbons such as those available
under the trademark FREO~, particularly FREON TF
(trichlotrifluoroethane), have given excellent results.
A solvent which i9 not halogenated, p-xylene; has also
been found to give results similar to methylene chloride.
~owever, other hydrocarbon solvents such as m-xylene,
o-xylene, gasoline, kerosene, naphtha and ether, which
are conven-tionally used for extracting oil from bitu-
minous sands or other oil-bearing materials, do not
form the desired membrane-like material.
Applicant's earlier method is based on the
in situ formation of a membrane-like material which
involves the few molecular~layers of oil or bitumen
- 2 - ,'
.. . .
i`
~7~(~97
and sol.vent ad~cent to the surface of the substra-te, which
are incorporated i.nto the membrane-like material as it is
being formed, leaving the actual molecular surface exposed
to wetting by the water, wi-th no residual solvent or oil
on it. In other words, since the solven-t is selected to form
membrane-li.ke material, it will form the membrane-like mate-
rial using the oi.l or bitumen at the surface of the substrate
and the water whi.ch is i.ntroduced by the wetti.ng of the
surface, th~us entirely removing the oil or bitumen with the
solvent and leaving a water-wet surface.
It has been found, according to the invention of
the parent application, that an active component of the mem-
brane-like material can be extracted therefrom and that the
extracted membrane-1.i.ke material forming component can be
used to effectivel.y remove chl.or.i.ne-based contami.nants, from
materials contami.nated wi-th same.
The invention of the parent application thus pro-
vides a method of removing chlorine-based contaminants from
materials contaminated with same, allowing such contaminants
to be concentrated for easy disposal.
In accordance with a first aspect of the invention
of the parent application, there is provided a method of
: separating a chlorine-base~ contam;nant from a surface of
a substrate covered with same, which comprises dissolving
the contaminant in a fi.rst solvent to form a solution thereof
and admixing a further sol.u-tion consisting of a membrane-
like material. forming component derived from mineral
-- 3
1.~720~7
crude oil, b~tumen or amphipathic lipids in a second
solvent selected from the group consisting of halo-
genated hydrocarbons and p-xylene, the second solvent
being miscible with the ~i.rst solvent and capable of
forming in the presence of water and the membrane-like
material forming component an interfacial memhrane-
like material which has a water side and is impermeable
to the contaminant. Water is then intimately contacted
with the surface of the substrate so as to cause the,
membrane-like material to form at the surface of the
substrate with the water side oriented toward the
surface while the water wets the surface and spreads
thereover, the membrane-like material incorporating
during its formation the contaminant and mixture of
solvents adjacent the surface, and the water displacing
the membrane-like material away from the surface as it
is being formed thereacross to thereby separate the
contaminant and mixture of solvents from the surface
and cover the surface with a layer of water. The
membrane-ll]ce material acts as a barrier to maintain
the contaminant in soluti.on with the mixture of solvents
and to prevent passage of same into the water layer.
According to a second aspect of the invention,
there is also provided a method of removing a chlorine-
based contaminant from a solution containing the con-
taminant dissolved in a first solventl which comprises
adding to the solution a further solution consisting
of a membrane-.l.i.ke material forming component derived
from mineral crude oil, bitumen or amphipathic lipids
in a second solvent selected from the group consisting
of halogenated hydrocarbons and p-x~lene, the second
solvent be.ing miscible with the first solvent and
', _ a _
,
. i
1;~7~U97
capable of forming in the presence of water and the
membrane-like material forming component an interfacial
membrane-like material. Water is then added and the
combined solutions and water are intimately mixed
so as to cause the membrane-like material to form,
and to generate sufricient array of the rlembrane-
like material so as to absorb the contaminant, thereby
removing same. The mixture of solvents, water and
membrane-like material with absorbed contaminant
are allowed to separate by relative densities and
the membrane-lilce material containing the contaminant
absorbed therein is thereafter isolated.
The first solvent is selected for its ability
to form a solution of the contaminant, whereas the
second solvent is selected for its ability to form the
desired membrane-like material in the presence of
water and the membrane-like material forming component.
The second solvent must of course also be miscible wlth
- the first solvent.
Examples of suitable solvents which may be `
used to dissolve the contaminant are hexane, toluene,
o-xylene, m-xylene, ether, gasoline, kerosene, fuel
oil and naphtha. On the other hand, as second solvent
that will form membrane-like material, use can be made
of methylene chloride, chloroform, trichlorethylene,
perchlorethylene, carbon tetrachloride, dichlorodi-
fluoromethane, trichlorofluoromethane, trichloro-
trifluoromethane and p-xylene.
1~7XV~7
It is also possible to use as first solvent
a sol~ent that will form membrane-like material, to
dissolve the contaminant. However, care must be taken
to avoid the simultaneous presence of water and any
membrane-like rnaterial forming component when such a
solvent is added since it will result in the formation
of membrane-like material in an undesirable condition
and thus hinder the method. This particular care is
applica~le only when the contaminant is removed from
a substrate or solid material, and does not apply in
the case where the contaminant is removed from a ~-
solution thereof. Moreover, it is apparent that when
using the second type of solvent to dissolve the
contaminant, the membrane-like material forming compo-
nent need not be in solution, but can be added as such
directly to the solution d'f contaminant.
The membrane-like material forming component
is preferably obtained by dissolving mineral crude oil,
bitumen or an amphipathic lipid such as cholesterol in
a solvent to form a solution thereof, the solvent being
of the second type mentioned above, that is, selected
from the group consisting of halogenated hydrocarbons
and p-xylene and capable o~ forming in the presence
of water and the oil, hitumen or amphipathic ]ipid an
interfacial membrane-like material. ~ater is then
admixed so as to cause the membrane-like material to
form and the solution, water and membrane-like mate-
rial are allowed to separate by relative densities.
Since the solution of oil, bitumen or amphipathic
- 6 -
. . .
1~7~097
lipid has a density greater than 1.0, there will be
formed a bottom layer of the solution, a top layer of
water and an intermediate layer between the bottom and
top layers, the intermediate layer comprising the
membrane-like materlal. As the membrane-like material
is more stable in water than in solvent, it is extended
into the top layer of water from which it can be easily
isolated, this can be done for instance by blowing air
into the solution and allowing the air bubbles to
rise up through the intermediate layer comprising the
membrane-like material, thereby extending the membrane-
like material into long tethers in the top layer of
water from which the tethers may be conveniently
gathered and removed by means of a wire brush. Upon
bringing the membrane-like material into air, it
dissociates due to the evaporation of its solvent
component, leaving water and a component derived from
the oil, bitumen or amphipathic lipid and which is
active to form or regenerate membrane-like material,
whenever recombined with water and the appropriate solvent.
Upon redissolving the extracted component
of the membrane~ e material into a solvent of the
type used for the formatlon of the membrane-like
material and admixing water, the process can be re-
peated so as to form new membrane-like material and
allow the extract to be recovered a second time to
produce a more pure active component which forms the
memhrane-like material under the correct conditions.
After several such extractions, the result is a white
semi-solid material.
~'7~0~'7
Accordingly, the invention of -the present divi.sional
application provi.des a method of preparing a membrane~ e
material formi.ng componen-t, which comprises dissolving m~neral
crude oil, bi.tnlmen or an amphi.patllic l.i.pi.d in a solvent to
form a soluti.on thereof, the solvent being selected from
the group consis-tin~ of halogenated hydrocarbons and p-xylene
and being capable of formin~ in the presence of water and
the oil, bitumen or amphipathic lipid and interfacial ;
membrane-like material, admixing water so as to cause the
membrane-like material to form, allowing the solution,
water and membrane-l.i.ke materi.al to separate by relative
densities and to form a bottom layer of ~olution, a top
layer of water and an intermediate layer between the bottom
and top layers, the intermediate layer comprising the
mémbrane-like materia], extending the membrane-like material
into the top layer oE water and thereafter isolating same
therefrom, whereby the membrane-like material upon being
brought into air dissociates and leaves a component derived
from the oil, bi.tumen or amphi.pathic lipid and acti.ve to
form membrane--lilce materi.al, when recombined with the solvent
and water.
In accordance wi~h another aspect of the present
invention, there is al.so provided a method of forming a
membrane-like material, which comprises the steps of:
a) dissolving a membrane-like material forming
component deri.ved from mineral crude oil, bitumen or am-
phipathic li.pids i.n a solvent to form a solution thereof,
the solvent being selected from the group consisting of
halogenated hydrocarbons and p-xylene and being capablé of
forming i.n the presence of wdter and the membrane-like
material form.i.ng eomponerlt an inl:erEacial membrane-l.ilce
material;
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1~'7~
b) ;nt;.mately mixing the solution formed in step
(a) with water so as to c~ause the membrane-like material
to formi and
. c) allowing the sol.uti.on, water and membrane-like
material to separate by relative densities and to form a
bottom layer o~ solution, a top layer of water and an
intermediate ].ayer between the bottom and the top layers,
the intermediate layer comprising the membrane-like material.
According to a ~urther aspec-t of the present invention,
there is provided a method of forming a membrane-like ma-
terial adjacent a surface of a substrate, which comprisesthe steps of:
. a) dissolving a membrane-like material forming
component derived from mineral crude oil, bitumen or amphi-
pathic lipids in a solvent to form a solution thereof, the
solvent being selected from the group consisting of halo-
genated hydrocarbons and p-xylene and being capable of
forming in the presence of water and the membrane-like
material forming component an interfacial membrane-like
material;
b) contacting the solution formed in step (a) with
the surface of the substrate to form thereon a layer of
solution;
c) intimately contacting water with the surface
of the substrate so as to cause the membrane-like material
to form at the sur:face of the substrate while the water
wets the surface and spreads thereover, whereby the membrane-
like material incorporates during its formation the solution
adjacent the surface and the water displaces the membrane-
like material away from the surface as it is being formed
3(' thereacross ~o thereby separate the solution from the surface
and cover the sl~rface wit-h a layer of water; and
.. ' ' ' ' .
_ g _
. . .
~7~0~7
d) allowing the solution, water and substrate
to separate by relative densities and to form a bottom layer
of water on top of the substrate, a top layer of solution
and an intermediate layer between the bottom and top layers,
the intermediate layer consisting of a zone rich in membrane-
like material.
The membrane-like material has a water side and
an oily side, and is impermeable to oil, bitumen and chlo-
rine-based contaminants. It thus acts as a barrier to iso-
late such materials remote from the substrate from which
these came, and to prevent their return to the substrate.
The membrane-like material is so-called because
it consists of an agglomeration of molecules held together
by coulombic forces only. The membrane-like material forming
component used in the practice of the present invention
appears to be the fossilized remains of the lipidic membrane
of bacteria. Amphipathic lipids have one part of their
molecule as a hydrocarbon, which will dissolve only in a
non-polar solvent, whi]e the other part of the molecule is
polar and will dissolve only in a polar solvent such as
water. Two fossilized members of this class of amphipathic
lipids have been discovered in crude oil, bitumen and coal,
and they are cholestane and bacteriohopane, belng the
fossilized remains of cholesterol and bacteriohopanetetrol
respectively. The oily compounds found in crude oil and
bitumen consist almost entirely of the bacterial debris of
these two materials, plus the separated heads and tails
of phospholipids, appearirlg as steroids, and fragments
thereof. In the fossilizing process, the cholesterol and
bacteriohopanete~rol have lost -their hydrophilic portions
consisting of oxygen and hydro~en pairs, and gained other
materials instead, Ieaving the fossilized molecule hydrophobic
. . -- 1 0
1~7~ 7
instead of hydrophilic. In addition, these molecules
may have gained a coulombic bond with the oxygen sites
on silica, the major constituent of sand wlth which
oily compounds are usually ound to be associated.
The semi-solid extract derived from crude oil and used
in the practice of the invention is most likely a
mixture of these materials.
When starting from a contaminated substrate,
thè contacting of water with the surface of the sub-
strate, referred to in the method according to the
first aspect of the invention, can be effected by simple
mechanical agitation of the combined solutions, water
and substrate together. Where the substrate is in
granular form, such as sand grains, a mixer or attri-
tion mill can be used to provide grinding and tumbling
of the sand grains. The grinding action of the grains
rubbing against each other provides many opportunities
for the water to contact the surfaces of the grains
and immediately spread thereacross, and also for a
sand grain already covered with a layer of water to
transfer part of its water layer to a non-wet grain
while in contact with it. Thus, a wetting action is
initiated each time a wet grain contacts a non-wet one.
If, on the other hand, the contaminant is present in a
solution instead of being on a substrate, then shalcing,
preferably without the inclusion of air or other gases,
will result in the formation of the membrane-like
material into which the contaminant will be absorbed.
A particularly advantageous combination of
solvents for use in the met~hod according to the first
aspect of the invention is hexane and methylene chlo-
ride. Indeed, since hexane has a density less than
_ 11 _ ''
1;~7~(~97
1.0 and methylene chloride a density greater than 1.0,
one can adjust the ratio of these two solvents so that
when the hexane solution of contaminant and methylene
chlor~.de solution of membrane-like material forming
component are combi.ned, the combined solutions have
a density less than 1Ø Thus, when the combined
solutions, water and substrate are allowed to separate
by relative densities following agitation, there
will ~e formed a bottom layer of water on top of the
substrate, a top layer of hexane and methylene chloride
with the contaminant dissolved therein and an inter-
mediate layer between the bottom and top layers, the
intermediate layer consisting of a zone rich in the
membrane-like material. Moreover, where the substrate
is in granular form, traces of solvent dissolved in
water entrappecl i.n i.nterstitial spaces between gra-
nules of the substrate, as well as any membrane-like
material entrapped therein, can be removed in a final
wash of the substrate with water introduced from be3ow.
This will cause the entrapped membrane-like material
to be dislodged and to rise through the bottom layer
of water to col3.ect i.n the intermediate layer. Both
the .intermediate and top layers can thereafter be
isolated and subjected to distillation for solvent
recovery and disposal of the contaminant.
On the other hand, in the case where both
the first and second solvents have densities greater
than 1.0, it is preferable to wash the granular
substrate with a solvent having a density less than
1.0, such as hexane, so as to remove traces of solvent
in the water entrapped in interstitial spaces and, at
1~7~ 7
the same t;.me, gradual.ly lower the density of the ~.
solution of contaminant until it moves above the water
layer, the zone rich in membrane-like material collect-
ing at the bottom of it and above the water layer
which has been displaced downward. A final rinse
with water may be necessary to flush out slight traces
of hexane or other solvent used. Practically any
non-polar solvent can be used to wash the granular
~ubstrate because~ the granules of the substrate will
be covered with water constituting a hydration layer
which surrounds each granule and will reject such
sol~ents, effectively presenting the latter to contact
the surface of the substrate.
When carrying out the method according to a
second aspect of the invention, it is preferable to
use solvents having densities greater than 1.0 such
that when the separation takes place there are formed ~
a bottom layer consisting of the mixture of solvents,
a top layer of water and an intermediate layer between
the bottom and top layers, the intermediate layer
comprising the membrane-like material with absorbed
contaminant. ~his will enab.l.e the membrane-like
material t:o be convenien-tly removed through the l:op
layer of water in which it is more stable. For ins-
tance, air can be blown into the bottom layer of
solvents such that the air bubbles rise up through
the intermediate layer comprising the membrane-like
material with absorbed contaminant, thereby extending
the latter into long tethers in the top layer of water
from which the tethers may be gathered and removed by
means of a wire brush.
13
'
..
7~ 7
The method of the invention is of course not
limited to the removal of chlorine-based contaminants,
but may al,so be used for removing crude or ref,i,ned oils
or bitumen -~rom substrates covered with same, where
there is a deficiency of the so-called membrane-like
material Eorming component.
The inven-tion of -the paren-t application -thus ,,
provides, in a further aspect -thereof, a method of separating
oil or bit ~ n from a surface of a substrate covered with same, ,
which comprises dissolving the oil or bitumen in a first
solvent to f~rm a solul:ion ~hereof, separating the
solution from the substrate to provide a solution wet
sub~trate, and addin~ to the solution wet substrate
a further soJ.utlon consi.sting of a membrane-like ma-
terial forming component derived from mineral crude
oil, bitumen or amphipath,ic lipids in a second solvent
selected from the group consisting of halogenated
' hydrocarbons and p-xylene, the second solvent being
miscible with the first solvent and capable of forming
20 ~ in the presence of water and the membrane-like material
forming component an interfacial membrane-li1ce material
which has a water side and is impermeable to the oil
or bitumen. Water is then intimately contacted with
the surface of the substrate so as to cause the mem-
brane-like material to form at the surface of the
sub~trate with the water side oriented toward the
surface while the water wets the surface and spreads
thereover, the membrane-like material incorporating
during its formation the oil or bitument and mixture
of solvents adjacent the surface and the water dis-
placing the membrane-like material away from the
.
,' - 14 - ' ' ,
~;~7~0~7
surface as it is being formed thereacross to thereby
separate the oil or bitumen and mixture of solvents
from the surface and cover the surface with a layer
of water. The membrane-like material acts as a barrier
to maintain the oil or bitumen in solution with the
mixture of solvents and to prevent passage of same into
the water layer.
Further Eeatures and advantages of the inven-
tion will become more readily apparent from the
following description of experimental work and of the
application of the method to the decontamination of
dioxin contaminated soils as well as to the recovery
of oil or bitumen from tar sands.
A first experiment was conducted to investi-
gate the nature of the membrane-like material. A
solution of methylene chloride and bitumen was placed in
a beaker and water was admixed to form an interfacial
membrane-like material. Bubbles of air were introduced
from underneath so as to rise up through the membrahe-
like material and establish bubbles of air on tethers
of membrane-like material extending a few millimeters
in length. Additional bubbles were added below the
membrane-lilce material, which were then caused to move
to the bottom of a tether with a bubble above it. The
lower bubble was then observed to distend the tether,
and move up inside it to join the bubble at the top.
The experiment showed that the tether was a flattened
tube consisting of two sides face to face, and that
the inner material, never exposed to water, but only
to solvent, bitumen and air, remained separate and
distinct. Thus, the membrane-like material has a
- 15 _
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~ ~7XO~ ~
water side and an oily side, each defining a surface.
As long as the memhrane-like material remains in the
water, the material remains stable, but if it is
removed through the air interface, it dissociates by
loosing its solvent componen-t. If it is disturbed as
with fragments of membrane-like material settling
loose on the surface of the membrane, these fragments
eventually recombine with the membrane-like material.
A second experiment was performed to deter-
mine if the bitumen was responsible for the formation
of the membrane-like material, together with the
solvent and water, or if some specific component of
the bitumen was responsible and to determine whether or
not such a component was extractable. A quantity of
bitumen was extracted with methylene chloride from a
tar sand and left standing in a beaker for several
weeks without the addition of water. The solvent
gradually escaped and a skin formed on the surface of
the bitumen. This slcin layer was removed and saved'.
A ~ample of the bitumen material left after removal of
the skin was added to methylene chloride and a water
layer added on top. It was unexpectedly discovered
that no membrane-l;ke material could be formed. Only
an interfacial film was formed, and the membrane-like
material did not appear. Upon returning the skin layer
to the bitumen and solvent solution with added water,
the membrane-like material once again formed as before.
Thus, a specific ingredient of the bitumen was found to
be responsible for the formation of the membrane-like
material.
- 16 -
~72(~7
A third experiment was made to determine if
solvents, other than methylene chloride, and polar
liquids other than water would operate in the practice
of the invention. It was found that the following
solvents or random combinations thereof would produce
membrane-like material:
Methylene Chloride
Trichlorethylene
Chloroform
Perchlorethylene
Carbon tetrachloride
Trichlorofluoromethane
Dichlorodifluoromethane
FREON ~F
p-Xylene :
On the other hand, it was found that the
following solvents which are often disclosed in the
art as being suitable for the solvent extraction of
oil sand, tar sand, or oily compounds would not produce
20 ~ membrane-like material, but that these could be used
as diluents pr.ior to the formation of the mem~rana-like
material, thus reducing the amount of the membrane-like
material forming solvent from the above list that must
be used:
Gasoline
Kerosene
Fuel Oil
Naphtha
Ether
30 - m-Xylene
o-Xylene
.
- 17 - . ,~
.. i
'7
17exane
Toluene
The isomers of xylene were unexpectedly found
to be distributed hetween both the above lists.
It was also found that the following polar
liquids would produce membrane-like material:
Water
Ethyl alcohol
when used with the appropriate solvent and membrane-like
material forming component, but the following would not:
Ammon ia.
A fourth experiment was performed on a sample
of oil saturated sand from Bakersfield California, where
the clay fraction was later determined to be 40% by
weight. The sand and clay were contacted with methylene
chloride and agitated so'~as to bring the oil into
solution with the solvent. Water was added 910wly with
a wand so as to form membrane-like material throughout
the mass, and the excess water was allowed to collect
on top. The sand and clay were carefully extracted
from the bottom and were found to be water wet and oil
free. It was found on several repeats of the experi-
ment that an optimum concentration of solvent solution
existed at which the membrane-like material would form,
and then move through the mass of sand and clay as an
interfacial zone. Too much solvent and the material
was weak and would not separate cleanly from the sand,
and particularly from the clay. Too little solvent
and the interfacial zone would break up and form isola-
ted regions enclosing sand, clay and oil. At the correct
- ]8 - ,
.
1'~7~0~37
concentration of oil or bitumen, it has been found
that the separation is clean and complete. This opti-
mum concentration occurs when the concentration of oil
or bitumen is low so that the solvent is nearly clear
for this particular material. It was also found in
several repeats of the experiment that if the sand
mass was agitated the mass of sand increased in bulk
due to the formation of membrane-l~ke material forming
globules which were then coalesced by applying moderate
shearing forces to induce settling. If the introduction
of the water from underneath was done sufficiently slow~
ly, then such bulking could be avoided. Thus, it was
confirmed that the membrane-like material did form
with its water side towards the substrate. ITowever,
several failures of the experiment occured, indicating
the need for further experiments.
A fifth experiment was performed to check if
surfactants, used in the fourth experiment to clean
the laboratory glassware, were interfering with the'
separation and causin~ the failures referred to in the
fourth experiment. The~e surfactants are specifically
those used for oily compound separation from surfaces
by solubilization. The surfactants consist of an oil
qoluble part and a water soluble part, which may be
anionic, cationic, zwitterionic or non-ionic. These
parts are conventionally referred to as the heads,
usually water soluble, and the tails, usually oil
soluble. The fourth experiment was repeated with the
same tar sand and oil sand but with the addition of
the commercial surfactants commonly found in glassware
cleaning formulations, such as ammonium lauryl sul-
]9
phonate and sodium lauryl sulphonate. In all cases,
the experiment failed, and an emulsion was formed.
The following explanation was developed: The few
layers of oily compound and solvent mixed with them that
lie adjacent to the substrate form a convenient oil
layer that allows the oil soluble tails of the surfac-
tant to penetrate, leaving the water soluble surfac-
tant heads exposed. Since the oily compound, now
including the surfactant, is attached by coulombic
forces to -the substrate, and the surfactant is likewise
held, the membrane-like material, if it forms at all,
does so with its water side out and a water layer forms
outside the oily layer, at a location determined by the
surfactant heads thus effectively inhibiting the sepa-
ration of oily compound from the substrate by preventing
the water from reaching tlhe substrate. Thick oily `layers
have been observed on the sand substrate, with the con-
sequent loss of large amounts of solvent, when sur-
factants are present in even small amounts. Thus, ~the
ormation of the merr~rane-like material is inhibited by
at least one observable mechanism, namely when surfac-
tants are present. Upon repeating the fourth experiment,
but taking care to eliminate surfactants, the failures
referred to disappeared and the results becarne consistent
with clean separations being achieved with a wide range
of oily compound source material.
A sixth experiment was made to further define
the properties of the membrane-like material in liquids,
without the presence of a substrate. The conditions
of the first experiment were repeated but with
the separation of the membrane-like material
effected by bubbling air through the interfac1al zone
_ 2~ _ ,
., ' ,
1~7;~ 7
so as to ex-tend the membrane-like material into the
water layer, and then using a wire brush to capture the
material and deposit it into a vessel containing fresh
solvent. Repeating the extraction from the fresh sol-
vent several times resulted in a relatively concentra-
ted material. This material was then added to fresh
solvent, with a water layer added on top. The liquids
were then shaken together and a zone of membrane-like
material appeared at the top of the solvent layer and
at the bottom of the water layer. It was unexpectedly
discovered that all of the brown color, left over from
the extraction and concentration of the material had
been incorporated into the membrane-like material.
After some minutes, the brown materials, residues of
the original bitumen, diffused back into the solvent
until nearly the original,color was restored. This was
unexpected. The mixture was shaken again, and this time
the color was unexpectedly not taken up by the membrane-
like material, but rather remained in the solvent. ~,
20 I The formation of the membrane-like material thus invol-
ves a non-reversible step. Repeating the experiment
with oil soluble dyes placed in the solvent showed
the same effect, the dyes were first incorporated into
the membrane-like material, and later at least partially
released. ~ repeat of the experiment with dioxin showed
similar results, that is, there was an affinity between
the membrane-like material and dioxin, however, unlike
the dyes, the dioxin remained absorbed in the membrane-
like material.
~ seventh experiment was performed to determine
if the specific component derived from bitumen used in
the second experiment and found to be responsible for "
., ~
~7~(~97
the formation of the membrane-like material could be
sho~n to exist in bitumen and crude oil from sources
other than Athabasca. The extraction and test methods
developed in the previous experiment were used. It
was found by repeating the experiment that the membrane-
like material forming component was present in oil or
bitumen from the following sources: Athabasca,
Venezuela and Utah at ~ull strength relative to
Athabasca. It was also present at slightly reduced
strength in samples from New Mexico, Texas, Peru (South
America) and Columbia (South America). It was also
found in ]esser stren~th in samples from Bakersfiled
California. Additional samples of refined oil also
showed the effect but with one notable exception, a
re~ined oil from Pennsylvania did not show any membrane-
like material forming component.
An eight experiment was performed to determine
the best method to be used to recover oil or bitumen
from tar sand, together with the solvents used to '
recover it. First, a membrane-like material forming
component was obtained as in the second experiment.
Then, a sample of oil wet tar sand from Utah was ex-
tracted with lcerosene as a solvent and most of the bitu-
ment was removed. Next, the membrane-like material
forming component in a solution of methylene chloride
was added and mixed thoroughly through the sand mass.
Water was added slowly from the bottom so as to cause
the membrane-like material to form adjacent the sand.
Finally, the sand was washed several times with water
and upon examination was found to be free of oil and
solvents. An instrumentation examination of the water
., .
- 22 -
~ 7~ 09~
wet sand showed 19.9 parts per million of methylene
chloride remaining, an extremely low value.
A ninth experiment was performed to determine
if materials other than those extracted from crude oil
or bitumen could be used to form membrane-like material.
A quantity of cholesterol was added to methylene
chloride and water was added on top. Upon shaking
the mixture, the membrane-like material was found to
ha~e formed. It was thinner and weaker than that
obtained from crude oil, but the extended structure was
the same.
A tenth experiment was performed with a view
to removing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)
from a sandy 90il substrate contaminated with same.
Unlike the earlier experiments, the amount of contami-
nant present was extremely small, of the order of 100
parts per billion. The maximum concentration of TCDD
on any of the samples run in the experiment was 10 parts
per million. These concentration levels contrast
sharply with bitumen or oil samples previously run
which have equivalent concentrations of 130,000 parts
per million ~r 13%. The soil was first dried using
- heat and then 8.0 grams of the dry soil were placed
in a separatory funnel, 15 ml of methylene chloride
were added and the mixture was shaken. A solution
of 250 ml of hexane and 50 ml of methylene chloride
with membrane-like material forming component added,
was made-up and tested for its activity to form
membrane-like material of the desired strength. A
few millil;ters of the mixture was added to water in
a flask and the mixture shaken. When the membrane-
- 23 - ,~
~ 7~
like material formed in a sufficient amount to pro-
duce at the interface between the water and methylene
chloride a visible membrane strong enough to hold
air bubbles 5 to 10 mm above the average membrane sur-
face, the mixture was considered to be of sufficient
strength. The ratio of hexane to methylene chloride
was selected to produce a density of less than 1~0
when 30 ml of the solution was added to the mixture
of soil and methylene chloride in the separatory
funnel. The 30 ml of solution containing methylene
chloride, hexane and membrane-like forming component
were added to the separatory funnel, and the mixture
shaken. ~bout 50 ml of water were added and the mix-
ture was shaken again. The separatory funnel was
set aside for the contents to settle, and several
layers formed. The solvent layer was on top, a zone
rich in membrane-like material waq at the bottom of
the solvent layer, adjacent to the water layer under-
neath, and finally the soil was at the bottom. A `
sample of each of the layers was taken and analysed
by the U.S. Environmental Protection Agency approved
GC/MS/MS method for dioxin. Each sample was spiked
with 10 ng of isotopically labelled C3 -2,3,7,8-TCDD
and 50 ng of C123-2,3,7,8-TCDD. The test results
showed that the original TCDD and the isotopically
labelled TCDD compounds could be reliably recovered
from all of the samples, except the membrane-likq
material. No recovery was possible o~ either the
original or the isotopically labelled TCDD from the
membrane~ e material. Using mass balance calcu-
lations, it was estimated that 53.7% of the original
,, ~
- 2~ -
.. , :
i~7~(397
TCDD plus 100% of the two isotopically labelled
TCDD compounds were absorbed in the membrane-like
material. In another run, 42.9% of the original TCDD
plus both isotopically labelled TCDD compounds were
absorbed in the membrane-like material. The strong
absorbtion of the dioxin by the membrane-like mate-
rial was confirmed. The reduction in the TCDD con-
centration in the soil was from 79 parts per billion
to 7.5 parts per billion.
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