Note: Descriptions are shown in the official language in which they were submitted.
~07267
This invention relates to a novel material which is useful for
neutralizing the harmful effects of oil and like materials, particularly
floating on bodies of water.
BACKGROUND OF THE INVENTION
Hydrocarbons such as crude oil or various refinery products
cause contamination of oceanic or fresh waters when spilled thereon. Such
floating hydrocarbons constitute a nuisance and hazard from spills around
harbour facilities, leakage from tankers, or from damage to or sinking of
a vessel carrying crude oil. Incidents of this type can have disasterous
effects upon beaches and marine life.
Numerous methods have been proposed for removing spilled
hydrocarbons from the surface of a body of water. For example, it has been
proposed to apply various powdered minerals such as asbestos, dolomite,
magnetite, silicone treated floating agents such as perlite, wood chips,
paper, felt, straw, sawdust, expanded mica, peat fibres, hard and soft
clays and various foamed synthetic products such as polyisocyanates to
mention a few. In the case of heavy minerals they tend to absorb an -
appreciable amount of hydrocarbon and then sink. The oil however, may be
released and float to the surface again.
Those absorbent materials that float on the surface of the water
must be recovered with the oil in some fashion to effect removal from its
surface. A frequent flaw is that the oil tends to drain from the floating solid
and recoat the water surface. It has been suggested to add polymers such
as rubber latices with mineral fillers, to the floating body of the hydrocarbon,the rubber latex containing the hydrocarbon is subsequently coagulated by
addition of an acidic material to the latex after it is sprayed on the hydro-
carbon to coagulate the latex, particularly around the edge of the spill area.
It is then necessary to skim the coagulum from the surface of the water.
liO7267
Another approach is to produce a ine (35-45 mesh) powdery
mixture of a polymer (in which oil is g~nerally soluble) plus heavy mineral
filler. The fines are then carefully added on to the oily surface so they will
sink taking oil with them to the bottom. However, wherever it was added
in any appreciable thickness, the powdery mixture is so dense it would tend
to agglomerate into large blobs, the edges folding over on top of the heavy
matte to sink rapidly by-passing the oil. Silicone oils have been used to
coat light floating materials such as treated cellulosic material. ~il can
be recovered by collecting and squeezing the cellulosic material. However,
10 oil on this or other floating gleaning agents is not thoroughly fixed by solu-
tion in the floating agent and can float back out to recontaminate the water
surface. This occurs with perlite, wood chips, vermiculite and other
similar floating agents.
Among items of prior art which are of interest are the following.
U.S. Patent No. 3,591,494 of Crouch and Childers issued July 6, 1971,
discloses the use of a fine powder of portland cement and clay coated with
a polymer compatible with hydrocarbons. The material does not float on the
surface of the water. U.S. Patent No. 3,888,766 of De Young issued June 10,
1975 deals with a cellular material impregnated with a hydrophobic oleophilic
20 compounds, for use in absorbing oil from the surface of water. The matrix
is wood fibre or foamed plastic, and it will float, but would not be expected
tG sink when loaded with oil. Similarly, U.S. Patent No. 3,607,741 of
Sohnius issued September 21, 1971 involves a cellulosic material treated
with a surfactant and silicone oil, yielding a material which will not sink
when loaded with oil. British Patent Specification No. 1,340,333 of Harris
and Shorthouse published 12 December 1973 discloses the step o~ applying
to oil on a body of water a dispersion of a mineral filler in a latex of an oil
absorbing rubber. Again, that material would not be expected to float well
prior to its absorption of oil on the water, and accordingly problems are
30 encountered in ensuring that the material picks up oil before it sinks. Other
patents of some interest are U.S. Patent No. 3,562,153 of Fully, Lippe and
Fletcher issued February 9, 1971 and U.S. Patent No. 3,7~9,667 of
,
-- 2 --
0~7Z67
Lindstrom issued July 31, 1973. None of these items of prior art disclose
the invention set out in the present specification, nor do they render it
obvious .
- BRIEF STAT MENT OF THE ~N~ENTION
In accordance with our invention a mixture of roughly pea-sized
and smaller particles of a porous mixture are contacted with surface oil,
absorbing the latter in interstitial and porous areas coated with fine
particles of rubbery solvent. The oil then gradually dissolves in the poly-
mer and becomes strongly bound into the solid mixture.
The oil dissolves in the rubbery component forming a permanent
solid solution, displacing air from the void spaces increasing the density OI
the composite and sinking from the oil contaminated surface. The com- `
ponents of the mixture are chosen so they will avoid environmental contami-
nation.
The composition is effective in soaking up oil from either solid
or aqueous surfaces converting it to oil dissolved in a polymer spread out
on a porous support. This is a preponderantly irreversible process resulting
in a non-oily mixture which will eventually sink from view. Release of
hydrocarbon from the solid mixture is not a problem because of the very
20 high partition coefficient of oil in favour of the polymeric component fixed
on the solid support. The composite can incorporate special oil-eating
bacteria incorporated as one of the components to promote biodegradation
of the hydrocarbon content as it lies on the bottom. It is a further feature
of our invention that usually simple rinsing with water will remove evidence
of personal contact with the oil laden composite.
Thus in one aspect the present invention provides a granular
absorbent composition for absorbing oil, said composition being hydrophobic
and oleophilic, said composition being porous and being lighter than water
when dry, said composition being heavier than water when said pores are
30 loaded with liquid oil, said composition comprising a solid cellulosic
porous buoyant material whose intersticial voids are impregnated with a
hydrophobic agent and a rubbery polymeric solvent for oil, and a plurality
~.~
-- 3 --
1:10~6'7
of solid particles of a sinking agent, said solid particles being held
together and being adhered to the surface of the buoyant material by said
oil solvent.
In another aspect the present invention provides a method for
preparing a granular absorbent composition for oil and the like which
composition floats on an oi~-contaminated water surface and, upon absorbing
oil, sinks to the bottom of the water, comprislng: (a) mixing an emulsion
of a rubbery polymeric solvent for oil, a solid cellulosic porous buoyant
material and a hydrophobic agent; (b) adding to the mixture solid
particles formed of a porous sinking agent and a coagulant, and then
mixing together to form an intimate mixture of the above components;
(c) drying the intimate mixture thus obtained; and (d) comminuting the
dried mixture to particles of suitable size.
In a further aspect the present invention provides a method for
removing oil from a contaminated water surface, comprising the steps of:
(a) spreading on to the contaminated water surface a granular absorbent
composition for oil, said composition being hydrophobic and oleophilic,
said composition being porous and being lighter than water when dry,
said composition be:Lng heavier than water when said pores are loaded with
liquid oil, said composition comprising a solid cellulosic porous buoyant
material whose intersticial voids are impregnated with a hydrophobic agent
and a rubbery polymeric solvent for oil, and a plurality of solid particles
of a sinking agent, said solid particles being held together and being
adhered to the surface of the buoyant material by said oil solvent;
(b) adding further absorbent composition as the oil is absorbed and the
composition sinks, until no more oil is present on the water surface.
DETAILED DESCRIPTION OF THE INVENTION
Broadly speaking our invention is a composite of cellulose fibers,
cotton linters, or recycled paper coated with very fine particles of
polymer in which oil is soluble. This intimate mixture is easily obtained
by coagulation of a latex on the cellulose fines in the presence of a
¦ hydrophobic agent
~ 4 -
.. . . . _ .... .. . . . . . . .
110~267
such as aluminurn, zinc, calcium, or magncsium stearate, oleate, palmitate
or miYtures thereof with each other or with other fatty acids. These salts
are not water soluble so they will not adversely affect the aquatic environ-
ment. The mixture is then completed by adding a sinking agent and
binder such as Portland or Medusa cement, Plaster components,
plaster of Paris, any of which optionally may be extended with
fly ash, ground limestone, lime, quartz fines, clays and
other similar materials..
The polymer originally should be in latex form for ease
10 of widespread and fine dispersion. The preferred latices
are of any natural rubber or synthetic compositions which
dissol~re up to ten times their weight of oil and vary from
100% polybutadiene up to ca. 80% polybutadiene generally
the rest is simply polystyrene, together wit~ minor amounts
of other polymerizeable monomers. Polystyrene latex can
be used but is an inferior solvent component aue to
limited oil solubility in the polymer. Because oil solubilities are limited by
the presence of polyacrylonitrile, latices containing acrylonitrile are not
desirable. Polyisoprene components are useful but expensive. Polyvinyl
Z0 chloride polymers are satisfactory but may present possible environmental
problem~. For best results the composition of our invention is broadly
defined as follows. Wide variations are desired for different end uses.
- These ranges should not be considered limiting.
cellulose fiDes 2 - 30
polymer solvent 3 - ~0
hydrophobic agent 1 - 10
s inker and binder 10 - 9 0
coagulant 0- 10
If silicone oil is used as a hydrophobic agent it must be sprayed on after
30 the composite is dry, since otherwise it inhibits formation of air holes in
the composite.
7;~67
The presence of some large holes assures that the pieces will
float while oil is being absorbed.
The composition is a solid mixture of:
a) a polymer in which oil is soluble.
b) a porous support for the polymer or copolymer
to permit drying and crushing of the aggregate and sufficient
~eight to sink the mixture of oil and so1id after spreading
the composition on water.
c) preferably a bulking agent such as used paper
~ines to make it easier for the solid mixture to float for a
period of time after application on w~ter.
d) a hydrophobic agent that will delay wetting of.
the mixture by water but will not impede and preferablywillassist
in the wetting of the solid with oil.
e) a coagulant for residual emulsifier andtor
.. .
uncoagulated latex.
The most useful particle size ranges between ~ dusty powder
and pea-sized particles, say generally less than ~". I
. , . . I
Various procedure~ can be used in the incorporation of the
hydrophobic agent. The agent is formed in s;tu generally
by adding ammonium, sodium, or potassium salts of stearate
oleate or palmitate and other high molecular weight fatty
acids to the latex before coagulation. Then destabilizing
both with aluminum, calcium, magnesium, or zinc salts
; together with or just before adding the cementitious
component. The hydrophobic addition may be made by
adding the dry fatty acid salt before or after the
cementitious component. Silicone oil if used must be
added after the composite has been dried. This means
a second drying stage is necessary. Silicone oil is
, . _ . . _ .
~07Z67
relatively expensive and would only be used when necessary.
The solid composition is spread out on an oil contaminated water
surface. The oil is obsorbed in the porous solid by capillary action,
then permanently dissolves in the polymeric part of the composite. After
picking up and dissolving the oil the porous compite becomes relatively
heavy and sinks. The process apparently is unaffected by wave action, in
fact non-static conditions seem to help the process.
Since the process sequence is capillary action followed by solution
in a polymer, oil is removed from solid as well as aqueous surfaces by
the same composition of matter. Either the used material or an excess of
~ntreated material may be washed away by a stream of water.
The solid solvent can be brought into contact with hydrocarbon con-
taminant such as oil by a variety of methods. After thick layers of oil are
recovered as far as possible by conventional means such as pumping, then
the remaining oil is gleaned from the surface by adding the "solid solvent",
by flowing or blowing onto the hydrocarbon coated surface until the water
is free of contaminant. For larger spills or in emergency more than a
single vessel may be used to distribute the solid solvent or aerial spraying
can also be employed. Any conventional distributing or dispensing device
can be used with the oil-sinking composites of this invention. Mixing
action promotes contact of the solid solvent with the oil and normally wave
action is generally sufficient for this purpose. Micro-organisms, which
consume or degrade hydrocarbons, can be added to the dry composite
mixture before application of the composite to an oil spill. Examples of
micro-organisms that can be used are species of the genera Norcardia,
Pseudomonas and Bacillus. Together with naturally occurring micro-
organisms these strains will accelerate biodegradation of the sunken oil
component .
The foregoing description shows we have achieved the object of our
invention, i.e., combining quickly with the oil and removing it from the
surface and rendering the oil harmle~s to, and removing the hydrocarbon
'I
~)7Z67
- permanently from harmful contact with the sub-surface environment. Unlike
other sinking agents the oil retention is complete and there has been no
evidence of traces of oil being released later to repollute the surface.
There may be certain specific situations where the present invention
will not be the treatment of choice for the removal of an oil contaminant
from water. For example, if there is any reason why the presence of this
oil-filled material on the bottom of the water would be deleterious to certain
specific vegetable or animal life, then other means should be used for the
removal of the floating oil. Howe~er, in the great majority of cases no
10 harm will be done by causing the oil to sinlc to the bottom of the water on
this oil absorbent composition, where it can decompose gradually and
harmlessly without contaminating the environment. Obviously the farther
out from shore the treatment is effected the less likelihood there is of harm
accruing. The present invention is well adapted to prompt and complete
treatment of oil near the site of the spill, sinking it to the bottom in the
relatively deeper water away from shore wherever this is possible.
We have also found that the present oi~ absorbent composition is
useful for removing oil from solid surfaces. A.s an example the material
is useful for picking up spilled oil from ground or building floors. This
20 may hold certain advantages over prior art methods under certain circum-
stances. In such cases the oil soaked absorbent composition could be dis-
posed of by usual refuse disposal means or it could be burned. The material
is also a useful composition for absorbing oil from living animals and birds,
being harmless to the animals and being capable of picking up oil from their
surface .
The following examples will give some indication of the preparation
and use of the oil absorbent composition of the present invention. These
examples should be considered as illustrative only, and should not be
considered limiting. The invention iB capable of wide variations without
30 departing from the inventive concept, and the protection afforded by this
patent should be considered limited only by the claims appended hereto.
~7ZG7
Example 1:
40 9. of crude cellulose fibres were made from newspapers by
adding an excess of water and grinding it up in a high speed blender
for 10 seconds. The excess water was filtered off through a coarse
sieve an~ the wet residue squeezed to a non-flowing muddy consist-
ency (about 35~ water). 50 9. (dry weight basis) of 25% of type
776 latex, obtainable as a commercial product from Polysar Corp.,
Sarnia, Ontario, Canada was stirred in. Type 776 polymer typically
contains 25% polybutadiene, 70% polystyrene and about 5% of miscell- 1
aneous wetting or emulsifying agents like sodium stearate unsatur- I -
ated acids like itaconic acid and traces of antioxidants such as
hydroqu;none or substituted phenols. Then 5 9. of potassium
stearate as a 2% solution in water (to increase the hydrophobic
content of the mix) was stirred in, followed by 20 c. c. of AlCl3
(as a 20% solution in water) as rapidly as possible. After about
2 minutes the mixture was smooth but some of the latex had not
been completely destabilized since some white latex solution could
be observed around the top surface at the inside edge of the glass
container. 300 g. of Portland cement was then stirred in and latex
destabilization was then complete since water at the top edge of the
beaker was ciear. The mix was spread out on paper and dried
@103+3C for ~ hours at which time it was dry to touch. Some of the
dry cake was cooled and broken up into particles of approx;mately
pea size. when these particles were added to crude oil on the surface
of water @10C, it was noted that the solid mixture absorbed oil rap-
_ idly and the oil-rich particles settled in 5-10 minute~ to the bottom
of the vessel when given a slight Jar or some agitation.
When the identical sequence of the above experiment was repeated
except that 40 c.c. of 20g AlCl3 in water was added instead of 20 c.
c., complete destabilization of the latex occurred before the 300 g.
of Portland cement was stirred in. This mixture added to oil on water
at 10C permitted the oil-rich particles to settle to the bottom
in 3-5 minutes when the beaker was jarred slightly or some
agitation applied.
~ )7Z6~7
~ Example #2
A second sample of solid solvent was made by` adding
50g of type 776 latex, a commercial grade of latex
available from Polysar Corp. Ltd., and as in
example ~l it was added to 40g of paper fines, then
stirred in with 5g of potassium oleate as hydrophobic
agent (250cc of a 2~ solution~. After 2 minutes, when
the mixture was obviously smooth and homogeneous, 40cc
of 20% Al Cl3 solution was added and immediately there-
after while still stirring with a mechanical mixer
500g of Medusa cement as a binder and sinking agent.
When the mixture was obviously homogeneous after
4 - 5 minutes, mixing, it was spread out on an
absorbent base and dried at 103 + 3C for 4 - 5 hours,
at which time the "cake" was obviously dry to touch.
About lg of the "cake" was broken up into pea sized
pellets and these together with the small amount ¢10%)
of the dusty fraction co-produced were added to 20
drops ~O.Sg) of crude oil in the surface of water at
zo 8C. The oil was absorbed rapidly by the solid solvent.
After 15 minutes the oil soaked particles sank when a
slight agitation was applied to the container. By
- morning all oil soaked or partly oil soaked pellets
had sunk without further agitation.
When 500g of Portland cement was substituted for Medusa
cement in the same manner as above, the oil soaked
pellets left only a slight stain when rubbed firmly
between the fingers. The Medusa mixture was stain free
when the same test was applied to it.
3~
- - 10 -
6~
Example ~3
The same mixture as the Medusa cement Example in
~2 was made excepting that SOg rather than 40g of
paper fines were used. A solid solvent was produced
that soaked up oil rapidly and the oil saturated
sol~ent easily sank when slight motion was applied
after 10 - 15 minutes. After 1 week on the surface
of the water some white particles that had no chance
to pick up oil on the first occasion, attacked and
absorbed extra crude oil when it was added. Two
particles that were over half submerged after standing
1 week also picked up oil and sank.
Again, rubbing the o~l soaked particles between ones
fingers left no stain.
Example ~4
.
Repeating Example ~3 except that 500g of Plaster
of Paris rather than 500g of Medusa cement as a
sinking and binding agent produced a solid
solvent that was less friable and appreciably
harder to the touch than Example #3. It settled
- with very little agitation after absorbing oil
from the surface of 12C water in 5 minutes~
.
.
- 11 -
~0'~267
- Example ~5
This was a repeat of Example #4 except that 600g
rather than 500g of Plaster of Paris was used as a
binding and sinking agent. Surprisingly this
resulted in a mixture that did not sink as fast
from the surface as the lighter mix in example ~4.
It is believed that this is the result of less
continuity in the pores and/or interstitial areas
of t~e mixture, a fact confirmed by microscopic
examination, ie. a contInuous pore structure
permits air to be displaced as oil is abs~rbed.
Example #6
The procedure followed in Example ~4 was repeated
except that potassium salts of a typical impure
commercial mixture of fatty acids, rather than
potassium oleate was used. The fatty acid
composition was determined by gas chromatography
as follows:
Acid %
Stearic 27.4
Oleic 23.0
Palmitic 29.0
An 11 - 12 component mixture of miscellaneous small
amounts of acids such as myristic, ricinoleic,
and ClQ to C14 acids totalled 10.6%.
There was no evident difference in behaviour of this
~mixture and that produced i~ example ~4.
~iO7~7
Example ~7
The procedure followed in example #4 was repeated with
~he exception that Type 741 latex available commercially
from Polysar Corp. Ltd., Sarnia Canada was used in the
same way and at the same rubber solids concentration as
be~ore with Type 776 latex.
Type 741 latex typically contains 70 - 75% polybutadiene
and 30 - 25% polystyrene with sodium stearate as the
main emulsifier and typical water soluble initiators,
modifiers, and inhibitors to produce a general
purpose or tire rubber.
The final product while wet is slightly less smooth and
spreadable on an absorbent base for drying at 103C.
However, the oil absorption and sinking characteristics
are indistinguishable from Example ~4.
Since type 741 represents the highest polybutadiene/
lowest polystyrene co-polymer and type 776 represents
the lowest polybutadiene/highest polystyrene co-polymer
commercially available for butadiene/styrene co-polymers
it means that the whole range up to 80% polystyrene is
useful for making solid solvent compositions. This was
proved by successful use of 100% polybutadiene emulsion
and 60/40 and 40/60 polybutadiene/polystyr~ne co-polymers
in emulsion form in the formula used or the present example.
Polystyrene emulsion could be used but oil solubility
reduces rapidly by about 2 orders of magnitude as one
increased the polystyrene content frnm 80% to 100%.
- 13
-- ~iO72~;7
Example #8
60g of paper fines were prepared in the usual fashion
then 50g of commercial type 776 latex from Polysar
Corp. Ltd., Sarnia Canada plus Sg of potassium stearate
(as a 2% solution~ was mixed until thoroughly homo-
geneous as indicated by the smooth appearance of the
mixture. While stirring, 40cc of 20% Al C13 solution
were added, followed immediately by 500g of Plaster
of Paris until an obviously smooth and homogeneous
mixture was obtained. After drying in the usual
fashion it was tested by adding to oil on water at
11C. In 2 - 3 minutes the larger sized pieces had
picked up over 95% o~ the oil as determined by
extraction and sank to the bottom with very little
agitation. The fines from the grinding process
dissolved the fine droplets of oil that otherwise
would have remained on the surface of the water.
Example #9
60g of sawdust was used to replace the 60g o~
paper fines in example ~8. It was found that the
relatively low surface area of the sawdust ~compared
- to cellulose fines~ caused production of a relatively
dense cake which sank readily before it had a
chance to pick up surface oi1.
Exa~ #10
When Example ~8 was repeated substituting 500g of
plaster base coat ~Hardwall) in place of 500g o~
Plaster o Paris as a binding and sinking agent, it
had extrem~ly rapid oil scavenging properties with
both high and low concentrations of polybutadiene
latice~.
11~7Z6~
Example #11
When both examples #10 were repeated using 5~g of
paper fines instead of 60g and 7.5g of potassium
oleate instead of 5g potassium stearate, it was
noted that both finished mixes picked up oil more
selectively pressumably due to the 50% increase
in hydrophobic agent.
Example #12
When 50g of either type 776 or 741 latices or a
mixture thereof was homogenized as judged by an even
white color of mixtures with 50g of paper fines,
prepared in the usual manner, then lOg o dry
zinc stearate and 500g of hardwall were stirred
in until homogeneous to sight. It was found that ~-
the product was much more dense than when aluminum
stearate was made in situ, ie. adding Al C13 to
sodium or potassium fatty acid salts. In addition
air bubbles were noted bubbling up out of the solid
solvent while oil was being rapidly absorbed and the
solid sank in a few minutes without agitation.
EXample ~13
When 20g of dry zinc stearate was added instead of
lOg as noted in example ~12, the rate both of air
bubbling from the surface and the rate of sinking
increased.
:
.
110~72~7
Example #14
-
When 6g of dry aluminum stearate was added to the mixtures as
produced in Example #12 ie. Type 741, Type 776 and mixtures
thereof, excellent absorbents result. Air bubbles out of the porous
solid solvent and the solids sank in 3 minutes.
:: 10
- 16 _
