Solvent extraction process employing comminuting and dispersing surfactants

The present invention is directed to a process for treating an oily substrate, including a mixture comprising water and oily material or a mixture comprising water, solids and oily material as components, and wherein such treatment comprises contacting the oily substrate with a solvent for the oily material, and wherein the solvent for the oily material ranges in solubility in water from sparingly soluble to substantially water insoluble, in the presence of an added comminuting and dispersing surfactant, to produce by such contacting at least one phase differentiating interface, and to thereby render one or more of the components of the oily substrate separable.

FIELD OF THE INVENTION 
The present invention relates to a process for treating an oily substrate 
which can include for example, water, and an oily material such as organic 
hydrocarbons as components of the oily substrate and which can 
additionally contain solids, and dispersions and/or emulsions thereof, 
which process provides the ability to recover, recycle or dispose of any 
of the components present. More particularly, the present invention 
successfully treats oily substrates such as sludges containing oily 
materials, solids made up of particles having a tendency to agglomerate or 
agglutinate and water, and particularly such mixtures containing large 
amounts of water. This invention also successfully treats emulsions such 
as oil-in-water and water-in-oil emulsions which may or may not contain 
solid particulate matter. This invention particularly relates to treatment 
of oily materials such as sludges resulting from petroleum refining 
operations, sludges present in waste disposal pits, ponds or lagoons, 
sludges generated from deep oil and gas well injection streams and soils 
contaminated with oily materials, other emulsions comprising solids and 
water and oily materials and emulsions comprising only oily materials and 
water. 
BACKGROUND OF THE INVENTION 
Many industrial endeavors result in the creation of effluent or liquid 
waste which can be characterized as an oily substrate and which can 
require treatment for component recovery and potential reuse and/or 
disposal of waste components depending on environmental concerns. Many 
industrial processes economically depend upon recycle of component 
materials. Further, recent and proposed environmental laws and regulations 
increasingly place an environmental consciousness and stress upon 
producers of oily material waste, and regulations have changed causing 
disposal methods which had previously been acceptable to become 
unacceptable from an environmental viewpoint. 
Oily substrates as wastes generally involve mixtures of water and oily 
materials such as hydrocarbons including potentially hazardous components 
such as polychlorinated biphenyls, benzene, toluene and the like and can 
additionally contain solids. A common source of such oily substrates is 
due to oil and gas industry activities in exploration, production, 
refining and petrochemical production. Oily substrates are created at the 
well head in deep well injection systems in the form of residue from 
drilling mud and production water. Oily substrates are also created in 
refineries in many different forms from water collected in storm sewers at 
a refinery to streams from the refining process. Oily substrates are also 
created in the cleaning of transport trucks and rail cars which move crude 
petroleum and oil products. Moreover, oily substrates are created in the 
same manner in chemical plants which involve the processing of petroleum 
products and which involve the manufacture of chemicals and chemical 
products for distribution and sale. Nearly all of these oily substrates 
have common characteristics. For example, they routinely contain, as 
components, solids, usually in a small amount, and oily materials which 
contaminate both the solids and water. Oily substrates also typically 
exist in the form of emulsions comprising solids, oily materials and 
water, or oil-in-water or water-in-oil emulsions. Water is normally 
present and at times can make up a large part of the oily substrates. The 
presence in these oily substrates, particularly of large amounts of water, 
often emulsified with the oily material present, compounds the difficulty 
and expense with respect to separating these materials into components for 
either recycle use or environmentally acceptable disposal. 
Many attempts have been made to deal with this problem in order to be able 
to remove or separate the oily materials present, to recycle reusable 
components or, to dispose of environmentally detrimental materials and to 
limit the resultant liability of the generator or owner of the oily 
substrate as a waste and waste disposal site. 
Several varieties of treatment techniques are known involving various 
solvents and approaches to remove or separate the components in oily 
substrate type effluent or hazardous waste. For example, one such attempt 
at separating materials for disposal is described in John H. Moses, "Use 
of Liquified Gas Solvent Extraction in Hazardous Waste Site", presented at 
the AICAG 1988 Summer National Meeting in Denver, Colo., August 1988, 
wherein sludges containing oil, water and solids are treated under high 
pressures with propane in a gaseous treatment process. The pressurized 
extraction of the oil or hydrocarbon is followed by a separation of water 
and solids with the propane solvent being recovered by flashing it off as 
a vapor in a flash tank. The solvent is then recovered, repressurized and 
returned to the process. This gaseous solvent process thus is 
distinguished from liquid solvent treatments which require separation by 
distillation. However, while simple in concept, the above-described 
process as well as other conventional processes are yet to be successfully 
applied to the clean-up of sludges, as, often the solids in sludges and 
oily substrates comprising solids in general tend to agglomerate when 
conventional treatment procedures are attempted thus trapping oily 
materials within the solids mass preventing contact with the solvent used 
for oily material removal. 
Although attempts made in the art to clean such oily material wastes have 
been admirable, problems still remain in connection with the processing of 
such materials in an environmentally safe manner for reuse or disposal. 
Heretofore, waste effluent and sludges in particular with oily materials 
present and containing large quantities of water could not be economically 
treated and the components thereof separated and such oily substrates are 
usually disposed of via land disposal techniques. However, current 
environmental legislation and regulations ban use in the future of land 
disposal techniques. 
Also, oily substrates in the form of emulsions of oil-in-water and 
water-in-oil, for example formed during oil production operations or in 
petrochemical processing, also present heretofore unsolved treatment 
problems for recycle and waste disposals. 
If treatment can occur at locations where oily substrates are generated and 
some of the components thereof, such as solids and water, can be disposed 
of on site after processing, considerable savings can result compared to 
hauling the oily substrate as a waste to another location for disposal. 
SUMMARY OF THE INVENTION 
Accordingly, an object of this invention is to provide a treating process 
which will breakdown an oily substrate and allow phase separation to occur 
permitting solids therein to be removed from the oily materials present in 
an oily substrate. 
A further object of this invention is to provide a treating process which 
will break down an oily substrate comprising an oily material and water 
and allow phase separation to occur to permit recycle of desirable 
components therein and/or their removal. 
A further object of this invention is to provide a method whereby oily 
substrates often containing high water concentrations can be treated for 
separation of oily material and water, and which may additionally contain 
solids, in a manner which allows for environmentally safe disposal of or 
recycle of the components of the oily substrate. 
An even further object of this invention to provide a process whereby oily 
substrates can be treated economically to quickly effect separation of the 
components present in the oily substrates and, in instances where a high 
oily material content is present, to recover such from the oily substrates 
in volumes and of sufficient quality to allow refinery processing to occur 
on the oily material component recovered in order to produce a product 
which can be utilized commercially. 
A still further object of this invention to provide a treatment process 
whereby a treating solvent used in the treatment process can be easily 
recovered for reuse. 
Further objects of the present invention will be readily apparent to 
persons skilled in the art from the following discussion. 
The present invention provides a process for treating oily substrates 
comprising water and oily materials and which can further comprise solids, 
in widely varying amounts, and emulsions thereof. 
In one embodiment of this invention, there is provided a process for 
treating an oily substrate selected from the group consisting of a mixture 
(a) comprising water and oily material or (b) comprising water, solids and 
oily materials as components of said substrate, wherein the process 
comprises: 
(1) contacting the oily substrate with a solvent for the oily material, 
said solvent being sparingly soluble in water, in the presence of a 
comminuting surfactant to produce at least one phase differentiating 
interface and to thereby render one or more components of the oily 
substrate separable. 
In an additional embodiment of this invention, there is provided a process 
for treating an oily substrate selected from the group consisting of a 
mixture (a) comprising water and oily materials or (b) comprising water, 
solids, and oily materials, as components of the substrate, said process 
comprising: 
(1) contacting the oily substrate with a solvent for the oily material, 
said solvent being sparingly soluble in water, in the presence of a 
comminuting surfactant, to produce at least one phase differentiating 
interface and to thereby render one or more components of the oily 
substrate separable; and 
(2) separating at least one phase from other phases present. 
In a further embodiment of this invention, there is provided a process for 
treating an oily substrate selected from the group consisting of a mixture 
(a) comprising water and oily materials, and or (b) comprising water, 
solids and oily materials, as components of the substrate, said process 
comprising: 
(1) contacting the oily substrate with a solvent for the oily material, 
said solvent being sparingly soluble in water, in the presence of a 
comminuting surfactant, to produce at least one phase differentiating 
interface and to thereby render one or more components of the oily 
substrate separable; 
(2) separating at least one phase from other phases present to obtain a 
separated phase comprising the solvent; and 
(3) removing the solvent from said separated phase. 
Also, an embodiment of this invention provides a process for treating an 
oily substrate selected from the group consisting of a mixture (a) 
comprising water and oily materials or (b) comprising water, solids and 
oily material as components of the substrate, said process comprising: 
(1) contacting the oily substrate with a solvent for the oily material, 
said solvent being sparingly soluble in water, in the presence of a 
comminuting surfactant, to produce at least one phase differentiating 
interface and to thereby render one or more components of the oily 
substrate separable; 
(2) separating at least one phase from other phases present to obtain a 
separated phase comprising the solvent; 
(3) recovering the solvent from said separated phase; and, 
(4) recycling the recovered solvent to the contacting of step (1) as at 
least part of the solvent of contacting step (1). 
In a still further embodiment of this invention, provided is a process for 
treating an oily substrate selected from the group consisting of a mixture 
(a) comprising water and oily material or (b) comprising water, solids and 
oily materials as components of the substrate said process comprising: 
(1) contacting the oily substrate with a solvent for the oily material, 
said solvent being sparingly soluble in water, in the presence of a 
comminuting surfactant, to provide at least one phase differentiating 
interface and to thereby render one or more components of the oily 
substrate separable; 
(2) separating at least one phase from other phases present to obtain a 
separated phase comprising the oily material and at least some of the 
solvent; 
(3) removing the solvent from said separated phase; and 
(4) recycling said oily material from said separated phase to the 
contacting of step (1) for further treatment. 
In yet a further embodiment of the present invention, a process is provided 
such as set forth in any of the above-described embodiments which 
comprises the step of contacting an oily substrate with a solvent for the 
oily material, said solvent being sparingly soluble in water, in the 
presence of a comminuting surfactant, and at a pH effective to produce at 
least one phase differentiating interface and to render one or more 
components of the oily substrate separable at a rate faster than in the 
absence of said pH. 
In yet still a further embodiment of the present invention a process is 
provided such as set forth above which comprises the step of contacting an 
oily substrate containing solid particulate matter with a solvent for the 
oily material, said solvent being sparingly soluble in water, in the 
presence of a comminuting surfactant, to produce at least one phase 
differentiating interface and flocculating the solids present to render 
one or more components of the oily substrate separable at a rate faster 
than in the absence of said flocculation. 
A still further embodiment of the present invention provides such a process 
as described in any of the aforesaid embodiments which comprises the step 
of contacting an oily substrate containing solids with a solvent for the 
oily material, said solvent being sparingly soluble in water, in the 
presence of a comminuting surfactant, and at a pH effective to produce at 
least one phase differentiating interface and flocculating the solids 
present to render one or more of the components of the oily substrate 
separable at rate faster than in the absence of said flocculation and at 
said pH. 
The present invention is particularly successful in removing oily materials 
such as hydrocarbons from oily substrates comprising oily material and 
large quantities of water and which may additionally contain solids, and 
emulsified versions thereof, which are notoriously difficult to handle and 
separate components for recycle and/or disposal, and which could not 
heretofore be economically treated. The rapid comminution of the oily 
substrate and phase differentiation interface formation followed by 
separation and settling of one or more phases, for example, separation of 
a solids phase from liquid phases present are particular advantages of the 
invention. The invention is more fully described in the following detailed 
discussion.

DETAILED DESCRIPTION OF THE INVENTION 
A difficult factor in the easy removal of oily organic materials from an 
oily substrate, which can additionally include solids, is the presence of 
water. If water were not present, the separation of the organic oily 
material could be accomplished by a simple solvent extraction or leaching 
treatment or washing of the solids with a solvent in which the organic 
oily materials were soluble. However, when water is present, the mixture 
is sometimes in the form of an emulsion presenting additional problems. 
An emulsion is a mixture of two or more immiscible liquids, one being 
present in the other in the form of droplets, and emulsions frequently 
contain solid particulate material as a third ingredient such as the oily 
substrates described above. Generally, in emulsions an oily substance may 
either be dispersed in water (oil-in-water emulsion) or water dispersed in 
the oily substance (water-in-oil or an inverse emulsion), where the first 
phase represents the dispersed phase and the second the continuous phase. 
In industrial effluent streams, for example waste effluent streams, wherein 
oily materials are designated for recycle or waste disposal, emulsions 
present particularly difficult treatment and separation problems, as the 
oily materials are trapped between emulsified droplets or particles making 
it very difficult to remove the substances by simple extraction processes. 
In order to extract such oily materials from emulsified mixtures, it is 
necessary to completely break these emulsions to facilitate the transfer 
of oily materials from the emulsion into a solvent for its removal. In 
oily substrates comprising organic oily material, water and solids, for 
example sludges, emulsions have made treatment processes thereof less 
effective and commonly present distinct separation problems which 
heretofore have prevented the use of solvent treatment for recycle or 
decontamination of oily substrates. 
First, if a hydrophilic solvent is used with a sludge containing oily 
material and solids particles which tend to agglomerate or agglutinate as 
an example of an oily substrate, the solvent may have no physical effect 
on the solid particles and the solid particles may be easily phase 
separable. However, the liquids phase present and which comprises the oily 
material, water and the hydrophilic solvent which is usually infinitely 
soluble in water, is a very difficult mixture to separate cleanly, 
especially economically, into its component parts. 
On the other hand, if a hydrophobic solvent alone is used, the solvent may 
cause the solids particles in the oily substrate to agglomerate or 
agglutinate in the presence of the water in the oily substrate. The 
agglomeration of the particles with a hydrophobic solvent due to the 
presence of water, prohibits contact of solvent with the solids present, 
effectively prohibiting any significant removal of oily material from the 
solids. 
The present invention overcomes the aforesaid problems and provides a 
process for treating oily substrates comprising organic oily material and 
water and such substrates additionally comprising solids, and such oily 
substrates in emulsified form. 
Some examples of oily substrates such as sludges which can be treated using 
the process of this invention include the following: 
Oil and petroleum Refinery Sludges as Oily Substrates 
Refinery sludges are often characterized by their source and can be 
generally described as follows: 
Once-Through Cooling Sludge: This type of sludge accumulates in the bottom 
of tanks and heat exchangers were water is used for once-through cooling. 
These wastes may contain various amounts of hydrocarbons. 
API Separator Sludge: This type of sludge includes solids which accumulate 
in the API Separator or other gravity-type separators during primary 
wastewater treatment. Refinery waste water streams for process water and 
contaminated storm water are usually connected to the API Separator. The 
quantity and quality of these sludges are dependent upon the crude oil 
characteristics, composition and quantity of process wastewater, spills 
and leaks, blowdown, refinery housekeeping, refinery size and age, and 
segregation of refinery oily drains. Oil content and solids levels can 
vary widely in such sludge, and can also include significant water 
content. 
Air Flotation Sludge: This type of sludge is generated when solids are 
removed following wastewater treatment in separators in processes called 
dissolved air flotation (DAF) or induced air flotation (IAF). 
Air flotation sludge is generated where air under pressure in circular or 
rectangular flocculation tanks brings the finely divided solids and oil 
droplets to the surface where they are skimmed off and disposed of. Many 
refineries use some type of chemical coagulant which is added to the 
flocculation tank. Factors which can affect the constituents of and 
quantities of this type of sludge are residence time, quantity and 
frequency of flocculating chemicals used; whether the float is recycled to 
oil recovery processes; and efficiency of API Separators used for primary 
oil/solids removal. 
The float resulting from this process is a mixture of oil-water-solids from 
DAF and IAF units. These types of units are used to reduce the amount of 
oil and solids going to the biotreatment operation. Some DAF units use 
alum to assist in flocculation of the solids. Certain DAF and almost all 
IAF units use polyelectrolytes to flocculate the oil and solids. As is 
well known the components of a typical DAF or IAF sludge can vary widely 
depending upon diverse processing conditions. 
Biological Solids: These types of solids comprise excess biological sludge 
that must be removed periodically from the treatment plant. The biosludge 
is usually dewatered prior to disposal, and dewatering may be preceded by 
digestion, usually aerobic. The constituents and quantity of this sludge 
depends on compositions and quality of wastewater treated, type of 
biological treatment, efficiency of prior treatment units, operating 
conditions and practices and type of dewatering or other treatment used 
prior to disposal. 
Storm Water Silt: This type of silt considered herein as a sludge is 
collected in storm water setting basins and is periodically removed and 
disposed of. The amount and nature of this silt or sludge is dependent on 
plant housekeeping, amount of rainfall, amount of paved areas in the 
refinery, and segregation of surface drainage from non-process area 
streams. 
Sump Sludge: This type of sludge comprises collections of silt, coke 
corrosion and oily material. 
Storage Tank Bottoms: This type of sludge involves solid settlement from 
incoming crude oil that accumulates at the bottom of storage tanks. The 
bottoms are generated when the tanks are cleaned. Constituents in the 
bottoms vary with the type of crude oil as well as the shipping and 
handling methods of production and transportation. Crude Sludge Bottoms 
usually contain a mixture of rust, iron, sand, water, and settlement along 
with oil and wax. Distilled and residual storage tank bottoms vary with 
the type of product stored. The constituents vary depending on the type of 
crude, recovered oil processing methods, in-tank mixing, type and quantity 
of chemical additives, plant and tank metallurgy, type of product 
treatment used, and type of process used in the producing products. 
Oily substrates as effluent steams and waste streams similar to those 
described above are also generated in oil fields during oil drilling and 
production. Crude is stored in tanks which must be cleaned and the 
resulting tank bottoms include a combination of crude oil, silt, metals 
and a large amount of water which collect in the tanks. 
On review of the types of industrial sludges set forth above, petroleum and 
drilling sludges in particular exemplify oily substrates can be treated by 
the process of this invention and comprise a mixture of water, oily 
material and solids in widely varying proportions. Often the water and 
oily material will be present in large amounts. However, the water content 
of such oily substrates is generally the predominant component. 
An oily substrate which can be treated with the process of this invention 
may have a water content of about 2% to about 95% by weight, but more 
typically has a water content from about 5% to about 90% by weight, and 
most typically about 40% to about 80% by weight of the oily substrate; and 
an oil content of from about 0.01 to about 90 weight % and more typically 
from about 0.02 to about 50 weight %, and most typically from about 5 to 
about 20% by weight. 
In one embodiment the treating process of this invention is effective to 
remove oily materials from the solids present in an oily substrate, for 
example a sludge, for recovery and safe disposal. In the case when the 
oily material is present in large quantities, the recovered oil or 
hydrocarbon may be passed into refining for further processing and 
recovery. The amount of the solids in an oily substrate which can be 
treated in accordance with this invention, such as, for example a sludge, 
is not critical and may vary widely from less than about 0.01 to greater 
than about 90 weight % and typically from about 5 to about 25 weight 
percent, such as in the case of API Separator sludge. 
These solids can include solids of a soil like nature and finely divided 
solids materials recovered from air flotation separation processes, 
whether dissolved (DAF) or induced (IAF) air flotation. The solids treated 
in this process can also include materials such as silt and coke, metal 
oxide corrosion from the tanks and piping involved and, in the case of 
drilling rigs, the solids from wading and drilling muds. Often the solids 
may include metal particles such as lead, nickel, barium, chromium, 
selenium, arsenic, mercury and the like, and salts thereof. 
Further examples of oily substrates which can be treated using the process 
of the present invention include effluent and waste streams from well 
injection streams, and effluent and waste streams associated with primary, 
secondary and tertiary oil recovery processes in general; pit, pond and 
lagoon disposal wastes; and soil solids containing organic and/or 
hazardous compounds. 
Oily materials which can be present in the oily substrates which can be 
subjected to the process of this invention can be crude oil directly from 
the well head; organic hydrocarbons typically produced in industrial 
processes such as in the drilling, refining and the petrochemical 
industry, and hazardous materials, for example, chlorinated organics such 
as polychlorinated biphenyls, benzene, toluene and halogenated derivatives 
of such compounds. In a preferred embodiment of the process of this 
invention refinery sludges containing various oily and/or hydrocarbon 
waste streams are successfully treated thereby. Sometimes the material 
being treated is one which has worked its way into a ground water sump or 
blowdown tank in a refinery. The source of the water which is present in 
the sludge can be, for example, rain water collected in a surface water 
sump or cooling water from heat exchangers or water used in scrubbers to 
remove pollutants from air steams and water employed in chemical 
processing in general. 
In many instances the water and the oily material in an oily substrate may 
be emulsified and present particular difficulty in ordinary cleanup 
systems. Thus, in another preferred embodiment the process of the present 
invention can be successfully employed to break emulsions and to separate 
and remove organic phases, for example organic recycle or hazardous waste 
streams, from aqueous emulsion mixtures which may also contain solids. The 
solvent for the oily materials employed in this invention to treat such 
oily substrates discussed above is a hydrophobic solvent which ranges in 
water solubility from being sparingly soluble in water to substantially 
water insoluble. The term "sparingly soluble" is used to characterize a 
solvent under normal ambient conditions having a degree of solubility 
which requires on the order of about 30 to 100 parts solvent needed to 
dissolve one part of a substance. This degree of solubility, however, may 
increase under elevated temperatures and pressure. The solvents used in 
the process of the present invention are primarily hydrophobic solvents 
which result in a distinct interface between organic and aqueous phases 
when mixed. 
Hydrophobic solvents which are preferred in the practice of the present 
invention are hydrocarbon solvents having a density which enhances the 
phase separation of mixtures of organic materials and water which may also 
contain solids. Generally solvents with low densities of from about 0.5 to 
about 0.9 are preferred with those having a density of from about 0.6 to 
about 0.8 being most preferred. Most hydrocarbons are excellent solvents 
for the oily material present, including such oily material as 
hydrocarbonaceous oils and halogenated organics such as PCBs, and will 
easily extract oily materials from the highly dispersed solid particles in 
the oily substrate being treated or from a broken emulsion of oily 
materials and water. 
In addition to good solvation power for the oily materials present, the 
solvent employed in the process of the present invention should have a 
boiling point lower than the boiling point of water, at atmospheric 
pressure, preferably a boiling point in the range of from about 0.degree. 
C. to about 100.degree. C. and most preferably from about 30.degree. C. to 
about 70.degree. C. to facilitate separation of the solvent from the oily 
materials, for example, separated from a sludge, for example, by 
distillation, for recycle. A specifically preferred group of hydrophobic 
solvents are the (C.sub.1 to C.sub.10) aliphatic, linear, branched or 
cyclic saturated hydrocarbons, particularly C.sub.5 to C.sub.10 
hydrocarbons such as pentane, hexane or heptane and the like. Specific 
solvents especially suitable for hydrocarbons such as PCBs as oily 
materials present are propane, butane, pentane, hexane, heptane, octane, 
nonane, cyclopentane, and cyclohexane. Other straight chain or branched 
chain aliphatic or aromatic solvents, such as benzene, toluene, and 
xylenes and the like may be used in the process of the present invention. 
Halogenated derivatives of the aforesaid solvents are also useful in this 
invention, such as, for example, methylene chloride, tri- and tetra 
chloroethylene. Hydrocarbons such as C.sub.1 to C.sub.4 alkanes such as 
methane, ethane, propane, butane, which are gases at normal temperatures 
and pressures but may be used under sufficient pressure to be in liquid 
form, are preferred in the practice of the present invention. 
The amount of solvent employed is not critical to the present invention and 
can vary widely, but is usually from about 0.3 to about 10 times the 
weight of the oily substrate being treated and preferably from about 0.5 
to about 5 times and, most preferably from about 1 to about 3 times the 
amount of the oily substrate being treated. As the solvent to oily 
substrate ratio is increased the time required for phase differentiating 
interface formation between organic and aqueous layers and phase 
separation is decreased and the treatment efficiency is increased. As 
solvents which are easily recovered are generally employed, savings in 
cycle time may justify solvent usage in liberal amounts. 
Not only is the selection of the solvent for the oily material present in 
the oily substrate being treated important, but in accordance with the 
present invention, a comminuting surfactant is also employed. A 
"comminuting" surfactant is one which, when included in the solvent, 
essentially neutralizes the agglomerating and the shielding effect of the 
water present, even when the water is present in large amounts in the oily 
substrate. While not desiring to be bound by theory, it appears the water 
shields the solids and oily materials from contact with the solvent used. 
The comminuting surfactant disperses the solid mass and bridges the water 
barrier to extract the oily materials into the solvent. The action of the 
comminuting surfactant in conjunction with a desired pH and added 
flocculent, as hereinafter explained in more detail, and the ratio of 
solvent to oily substrate enhances removal of oily materials from the 
solids present speeds and improves separation and improves solvent 
recovery. 
It is the solvent/comminuting surfactant combination which treats the oily 
substrate to produce phases including a comminuted mixture of a dispersed, 
flowable, and discrete solids, water and solvent and makes the separation 
of oily materials from the solids feasible. 
In contrast to comminuting surfactants, certain surfactants in combination 
with solvents, when contacting a solid, such as soil or sludge particles, 
may cause swelling, clumping, and thickening of the mixture and are 
referred to herein as swelling surfactants. The physical mixture becomes 
similar to a water and clay mixture and is characterized as agglomerated 
or agglutinated. The mixture expands, clumps, thickens and is sticky. 
Swelling is accompanied by absorption of the solvent into the 
solid/water/surfactant mixture, thereby preventing recovery of the 
solvent. 
In the case of emulsions, for example of an oily substrate or organic 
material contained therein with water e.g. (a typical oil-in-water 
emulsion), or such emulsions additionally containing solids, the 
comminuting surfactant in the presence of solvent facilitates breaking the 
emulsion and the subsequent phase separation between the aqueous phase and 
the solvent, and thus facilitates the transfer of organic compounds of 
interest, for example, organic contaminants, from the emulsified mixture 
into the solvent for separation and removal. 
The term "phase differentiating interface" is used herein to describe a 
discrete boundary between different phases. 
The appropriate selection of a comminuting surfactant can easily be made by 
shaking a sample of the oily substrate to be treated in a flask with the 
solvent and surfactant considered for use and observing the formation of a 
phase differentiating interface and comminution of the solids in the 
mixture if present and/or the breaking of an emulsified mixture. 
Suitable surfactants for use in the process of the present invention are 
therefore those which effectively comminute the oily substrate, and cause 
a phase differentiating interface to be formed such that, for example, the 
solids and liquids phases are separable or, for example, an oil-in-water 
emulsion can be broken. Moreover, the preferred surfactants also have 
sufficient water solubility to enable removal of the oily materials from 
the solid particles present in the oily substrate into the solvent and/or 
to successfully break an emulsion. The surfactant therefore must have some 
water solubility or, may be, completely water soluble to provide a bridge 
or conduit between the solid particles or emulsified particles and the 
solvent whereby the oily material is extracted through the water barrier 
which surrounds the oily materials present in the oily substrate. While 
not desiring to be bound by theory, it is believed that the oily material 
adheres to the surface of solid particles or components in the oily 
substrate. The water present, therefore, acts to virtually encapsulate the 
oily material adhered to the solid particle surface comprising an 
emulsified particle or an emulsified droplet comprising oily material, and 
therefore, it is necessary to provide a bridge or conduit across this 
water barrier so that the treatment of the oily material adhering to the 
solid particles or in the form of emulsified droplets can take place. Such 
surfactant characteristics and the water solubility of the surfactant 
therefore result in an effective system for treatment of oily substrates. 
A surfactant by definition is a substance which alters the surface tension 
of water, and there are traditionally four types: nonionic, anionic, 
cationic and amphoteric. Surfactants in general are compounds which 
exhibit both hydrophilic and hydrophobic properties. All of the aforesaid 
types of surfactants are useful in the present invention. 
The comminuting surfactant is generally incorporated into the solvent for 
the treatment of an oily substrate but can be added directly in part or in 
whole to the oily substrate if desired. It is only necessary that the 
contacting of an oily substrate with the solvent be in the presence of the 
surfactant to achieve the advantages of this invention. 
Although the choice of comminuting surfactant and the amount employed will 
vary widely depending upon the composition of the oily substrate to be 
treated, and other variables such as the solvent employed, preferred 
comminuting surfactants for use herein are acidic in a 2 weight % water 
solution, and the pH of the surfactant solution will preferably range from 
about 1 to about 8. 
In general, suitable amounts of surfactant may range between about 0.05 and 
about 20 wt. % of the oily substrate being treated. More preferably the 
amount of surfactant is between about 0.1 and about 15 wt. %, and the most 
between about 0.5 and about 8 wt. % of the oily substrate being treated. 
Although incorporating the surfactant into the solvent is preferred in the 
process of the present invention, the surfactant can be added to the water 
phase or directly to the oily substrate as noted above. The amount of 
water will affect the ease with which the water barrier can be broken, and 
thus the surfactant and amount thereof added to the oily substrate will be 
influenced by the amount of water present in the oily substrate. 
Specific examples of some comminuting surfactants which may be used in the 
process of the present invention are set forth hereinbelow. Moreover, from 
the disclosure of specific examples from each type or class of these 
surfactants, and the examples which follow, it will be recognized by 
persons skilled in the art that only routine experimentation is necessary 
to arrive at other suitable comminuting surfactants which may be used to 
successfully treat particular oily substrates in accordance with the 
process of the present invention. 
Specific examples of comminuting nonionic surfactants useful herein are 
compounds which are formed by reacting alkylphenols, particularly octyl- 
or nonylphenols, with ethylene oxide. This class of nonionic surfactants 
are well known by the skilled artisan including their properties and the 
usefulness associated with particular amounts thereof depending upon their 
contemplated use. In general, the average number of ethylene oxide 
molecules per molecule of alkylphenol is between 1 and 6 molecules per 
molecule of octyl- or nonylphenol. The hydrophilic-lyophilic balance, HLB, 
increases as the number of ethylene oxide molecules increase. When the 
number of ethylene oxide molecules is between 1 and 4, the surfactant is 
immiscible in water, whereas if the average number of ethylene oxide 
molecules attached is between 4 and 6, the surfactant is dispersable in 
water, and with 8 or more ethylene oxide molecules, the surfactant is 
soluble in water. 
Preferred nonionic surfactants are those which are much more soluble in the 
solvent than the water. Suitable nonionic surfactants have an HLB between 
4 and 10. Particularly preferred nonionic surfactants have an HLB between 
7 and 10. These nonionic surfactants have been found to be most effective 
when used in amounts of about 0.5 wt. % to about 8 wt. % and preferably 
about 1.0 wt. % to about 6 wt. % based on the weight of the oily substrate 
being treated. Greater amounts can be used but the nature of the 
improvement is not necessarily enhanced further. 
Other nonionic surfactants may include ethylene oxide adducts of fatty 
acids, amides or other substances and their derivatives with ethylene 
oxide. 
Specific comminuting cationic surfactants are formed from quaternary 
ammonium chloride derivatives of polypropoxy tertiary amines. This class 
of cationic surfactants, the properties thereof and the usefulness thereof 
given a particular application and contemplated end result are also well 
known to the skilled artisan. Preferred cationic surfactants of this type 
for use herein are quaternary ammonium salts with a pH less than about 5.5 
and a molecular weight of at least about 1200 and preferably between 1600 
and 2500. 
and are of the general formula 
##STR1## 
where 
R is a C.sub.1 or C.sub.2 alkyl group, preferably a methyl group; 
R.sub.1 and R.sub.3 are each a C.sub.1 to C.sub.4 lower alkyl, preferably 
an ethyl group; 
R.sub.4 is a polyoxypropylene group having an average molecular weight of 
from about 400 to about 2000; and 
A is a halogen atom, preferably a chlorine atom. 
The molecular weight of these cationic surfactants depends on the R.sub.2 
group. The molecular weights of these compounds are generally between 600 
and 2500. In general, the water solubility of these compounds decreases as 
the molecular weight of the molecule increases. 
Other suitable cationic surfactants may include aliphatic (fatty) amines 
and their derivatives, homologues of aromatic amines having fatty acid 
constituents, fatty amides derived from disubstituted amines, quaternary 
ammonium compounds, amides derived from amino alcohols and their 
quaternary ammonium derivatives, quaternary ammonium bases derived from 
fatty amides of disubstituted diamines, basic compounds of sulfonium, 
phosphonium and antimonium, dimethylphenylbenzyl ammonium chloride, 
urethanes or basic salts of ethylene diamine, polyethylene diamines and 
their quaternary ammonium derivatives, polypropanol polyethanolamines and 
various cationic-active compounds. A preferred cationic surfactant for use 
in the present invention is EMCOL CC-42 by Witco Chemicals which is a 
quaternary ammonium salt. 
Effective anionic surfactants are those having a pH less than about 7, 
preferably less than about 5. The active ingredient in other comminuting 
anionic surfactants which may be used in the present invention can be 
sodium dioctylsulfosuccinate. 
Specific examples of suitable anionic surfactants include products obtained 
by direct sulfonation of fatty acids without previous treatment; products 
obtained by esterification of fatty acids with sulfonated monovalent 
alcohols; sulfonated derivatives of fatty acid esters of low molecular 
weight; sulfonated products of fatty amides; products obtained by 
condensation of fatty acid chlorides with amines; sulfonation products of 
fatty acid nitriles or aldehydes of ketones or other natural or synthetic 
alcohols; and products obtained by use of mineral esterification agents 
other than sulfuric acid and sulfonated aromatic compounds. 
A specific preferred example of an anionic comminuting surfactant is 
octylphenoxypolyethoxyethylphosphate (a phosphated ethylene oxide adduct 
of octylphenol), a material commercially available from Rohm and Hass 
Company under the trademark "TRITON QS-44". This anionic surfactant may be 
in a free acid form or as an alkali metal salt, preferably the sodium 
salt. 
While specific examples of suitable comminuting nonionic, cationic, and 
anionic surfactants are described above, surfactants which may be used in 
the present invention are not limited thereto. The foregoing illustrates 
that slightly water soluble, or soluble surface active agents or 
surfactants usually with a pH less than about 5.5 are preferred for use in 
the present invention. 
An important aspect of and a preferred embodiment of the process of this 
invention is the adjustment of the pH of the oily substrate to about pH 7 
or less. It has been found that in the practice of the present invention 
the pH of the oily substrate affects both the extraction efficiency and 
the phase separation characteristics, and thus the settling rate of solids 
in the mixture of oily substrate and solvent/surfactant, and also the time 
needed to break an emulsion. Acidic extraction mixtures are generally 
preferred. However, the optimum pH of an oily substrate to be treated can 
be determined by routine experimentation to produce satisfactory 
extraction results and settling characteristics, and/or emulsion breaking 
properties. The adjustment of the pH of the oily substrate, for example, 
by addition of an acid to the system can be conducted either prior to the 
introduction of the solvent/comminuting surfactant mixture or can be 
conducted after the solvent/surfactant has been initially contacted with 
the oily substrate. This aspect of the invention is described and 
illustrated in more detail below. 
Once the solvent and comminuting surfactant treating ingredients added to 
the oily substrate, the resultant mixture is agitated or mixed to provide 
intimate contact with the components of the oily substrate. Thus, through 
this treatment the oily materials are contacted with the solvent in the 
system. Suitable mixing takes place for a period from less than about 0.1 
minutes to in excess of about 10 minutes depending upon the nature and 
volume of the oily substrate being treated for a particular time. Of 
course, the lesser the amount of oily substrate being treated, the shorter 
the mixing time necessary for the complete contact and comminution of any 
agglutinated solids which are present in the oily substrate. In an 
emulsion, the oily material to water ratio may influence the mixing time 
necessary for breaking the emulsion, and the solvent extraction of oily 
material present. A preferred time for mixing is from about 1 to about 5 
minutes. 
Table I below illustrates the effect of acid selection and amounts added to 
a particular sludge (DAF) in hexane and is presented to illustrate how 
acid selection can be made. The results in Table I show that a strong 
inflection point is produced as the pH is reduced with the rate of change 
in settling time diminishing as higher amounts of acid are added so that 
the pH of the system becomes more acidic. Table I and FIG. 1 of the 
accompanying drawings both show a characteristic inflection point, or 
dramatic change in phase in settling rate, at some point during pH 
adjustment. This point may vary in terms of absolute pH value. The pH, or 
amount of acid or base added, if pH adjustment is needed, have a dramatic 
effect on the settling rate of the solids. The rate and degree of settling 
are an advantageous characteristic of the process of this invention. Also, 
Table I indicates a variety of different acids are equally effective in 
improving the settling rates. 
TABLE I 
______________________________________ 
SETTLING RATES OF DAF SLUDGE 
IN HEXANE WITH DIFFERENT ACIDS 
ACID 
% Acid H.sub.2 SO.sub.4 
HCL Nitric 
Phosphoric 
in Sludge (95.6%) (37%) (96%) (85%) 
______________________________________ 
0 51 51 51 51 
1 20 25 23 23 
2 13 13 9 14 
4 6 6 6 11 
5 4 5 5 10 
______________________________________ 
Note: The values in Table I above were obtained at a solvent to sludge 
volumetric ratio of 2:1. 1% of a comminuting surfactant EMCOL CC42 
(Witco), (described hereinafter) based on sludge weight was also added to 
the mixture. 
Suitable examples of inorganic acids which can be used for pH adjustment 
include those described in Table I, and can additionally include, for 
example, perchloric acid, hyphophosphorous acid, and the like. 
Organic acids can also be used for pH adjustment if desired or in addition 
to the use of inorganic acids as described above. Suitable organic acids 
include carboxylic and sulfonic acids such as acetic acid, propionic acid, 
and the like. 
Once the surfactant, solvent and acid ingredients are added to the oily 
substrate, the mixture is agitated or mixed to provide intimate contact 
with the components of the substrate and thus transfer of the oily 
materials into the liquids solvent phase. Once mixing is complete, phases 
are allowed to separate, and if present dispersed solids settle out. In 
the case of an emulsion, the emulsion must first be broken and phase 
separation allowed to occur to permit solvent extraction of oily materials 
in the resulting organic phase. A feature of the process of this invention 
and a great advantage thereof are that the phase separation/settling 
occurs very quickly when the comminuting surfactant is used with the 
sparingly soluble solvent, particularly at a pH of 7.0 or less, with the 
ratios of solvent to oily substrate as set forth herein. 
For an economical process, it is preferred to separate the solvent from the 
oily material after phase separation, and this can be accomplished by 
suitable conventional separation techniques. Distillation is one manner of 
separating the solvent from the oily material, but chemical methods may be 
also used. The separation of the solvent may also be accomplished by 
physical processes such as precipitation, membrane processes or ion 
exchange for reuse. 
Temperature can also be an important factor in improving the treatment 
efficiency of removing oily materials from the oily substrate. The effect 
of temperature in improving the treatment efficiency in the process of the 
present invention is two-fold. First, an increase in temperature increases 
the desorption rate of the oily materials adhered to solid particle 
surfaces thereby releasing the oily materials into the liquids phase. 
Second, an increase in temperature helps reduce the surface tension of 
water or the interfacial tension between the water present, for example, 
in sludge, and the solvent used in the process of the present invention. 
Both of these factors enhance the treatment efficiency to remove the oily 
materials from the oily substrate. Increased process temperature can also 
enhance the break-down of emulsions in accordance with the practice of the 
present invention. 
The operating temperature range is generally influenced by the boiling 
point of the solvent used for the treatment of the oily substrate, and 
typically effort is made not to exceed the boiling point of the solvent 
selected for use in the process of the present invention. However, in a 
more preferred embodiment higher treatment efficiencies are achieved by 
operating the contacting step of the process of this invention under 
elevated pressures. Increasing the pressure on a liquid generally 
increases its boiling point and thereby its usable range in the process of 
this invention. 
The process of the present invention is preferably operational at 
temperatures ranging from about 0.degree. to about 250.degree. C., more 
preferably from about 30.degree. to about 150.degree. C., and most 
preferably from about 50.degree. to about 100.degree. C. 
The process of this invention can be operated in a batch mode, a 
semi-continuous mode or a continuous mode. 
In the batch mode of operation, the solvent is contacted with the oily 
substrate in the presence of the comminuting surfactant, and preferably at 
a desired pH, for example, in a mixer/settler tank. The mixture is 
agitated for a specific time during which time the oily materials are 
transferred from the oily substrate into the liquids solvent phase. After 
equilibrium is reached, the agitation is stopped and as a result of the 
components used in the process of the present invention at least one phase 
differentiating interface is formed. This results in the mixture being 
separable based on the phases present, for example, into a solids phase 
and a liquids phase or in the case of an oil-in-water emulsion, an organic 
and an aqueous phase. 
The separation of the phases, for example, the solids phase from the 
liquids phase, can be accomplished by various conventional methods such as 
gravity settling, centrifugation, hydroclone settling, or a combination 
thereof. 
In some preferred embodiments where a mixture to be treated contains oily 
materials adsorbed or absorbed on solid particulate material, after 
dispersion and extraction of the oily material in accordance with the 
invention via a solvent/comminuting surfactant solids settling of 
particulate matter can be accelerated by the addition of a flocculant. 
Suitable flocculents for use in the practice of this invention can be 
inorganic or organic and include any material that enhances aggregation of 
treated solid particulate matter in this invention to form a floc and thus 
enhance settling of solids and phase separation. 
Some examples of inorganic materials useful as flocculants herein include 
water soluble aluminum salts, alum (aluminum sulfate hydrate), soluble 
inorganic iron salts and lime, and other conventional polyelectrolyte 
flocculants. 
Organic flocculants can be cationic, anionic or nonionic. Examples of 
cationic flocculants useful in this invention include poly(ethylenamide), 
poly(2-hydroxypropyl-1-N-methyl ammonium chloride), 
poly(2-hydroxypropyl-1,1-N-dimethylammonium chloride), 
poly[N-(dimethylaminomethyl)-acrylamide], poly(2-vinylimidazolinum 
bisulfate), poly(diallyldimethyl-ammonium chloride), 
poly(N,N-dimethylaminoethyl methacrylate), and 
poly[N-(dimethylaminoproply)-methacrylamide]. Examples of some anionic 
flocculents include poly (sodium or ammoniumacrylate), and poly(sodium 
styrene sulfonate). Examples of some nonionic flocculants include 
polyacrylamide, poly(ethylene oxide) and poly(vinylpyrrolidine). 
Natural and synthetic gums and various water soluble gums in general, such 
as, for example, quar gum, locust bean gum, gum carrageenan, gum arabic, 
gum ghatti, gum karaya, gum tragacanth, xanthan gum and the like are also 
useful as flocculants in the practice of this invention. 
After sufficient separation between the phases, for example, the solids 
phase and the liquids phase, or an organic phase and aqueous phase in an 
oil-in-water emulsion, is accomplished, the organic liquids phase 
containing the oily material is separated and is directed into a liquid 
separation device, such as, for example, a distillation column or any 
other separation mechanism, where a solvent can be recovered for recycle 
and reuse in the treatment process if desired. For higher treatment 
efficiency for the oily substrate, fresh solvent is added in the 
contacting step with partially cleaned oily substrate in the contacting 
step and the above procedure is repeated. The advantage of a batch 
operation is high efficiency of oily material removal in each contacting 
step conducted. 
The process of the present invention can also be conducted in a continuous 
mode in which solvent and oily substrate are contacted with each other 
continuously during which time oily materials are continuously transferred 
from, for example, a solids phase into a liquids phase. More specifically, 
the continuous mode can be practiced using a countercurrent extraction 
unit where the oily substrate being treated and the solvent travel 
continuously and countercurrently. As the oily substrate travels through 
the contacting unit, the amount of oily material present in the oily 
substrate is reduced and the amount of the oily materials present in the 
liquids-solvent containing phase increases. The advantage of continuous 
countercurrent operation is a significant reduction in the volume of 
solvent used and simplicity in operation. 
The amount of surfactant employed in the process of the present invention 
is also influenced by whether the process is conducted in a batchwise or 
continuous mode. 
In a batch mode of operation the surfactant can be added to the batch 
treatment tank in a first stage. If the surfactant is only soluble in the 
solvent to be used, the surfactant will be removed from the system with 
the liquids phase including the solvent where the liquids phase is 
separated from, for example, a solids phase, at the end of the contacting. 
More surfactant may needed to be added to the mixture in a second 
contacting, if such is conducted, to again disperse the oily substrate 
particles. The same is true for any subsequent contactings conducted is 
such are repeated. If a water soluble surfactant is used, upon separation 
of the liquids phase including the solvent used from the solids phase of 
the completion of the contacting, the surfactant will remain, for example, 
with the solids phase or an aqueous phase. Therefore, no additional 
surfactant or minimal additional surfactant may need be added to the 
mixture being contacted if subsequent contactings are conducted. Finally, 
if a surfactant which is mutually soluble in the solvent and water is used 
in the process of this invention, the amount of surfactant which is added 
in any subsequently conducted contacting in accordance with the present 
invention is a make up amount equivalent to the amount of surfactant which 
was soluble in the liquids phase during the previous contacting stage. 
In the continuous mode of operation, if a solvent soluble surfactant is 
used, routine experiments can be conducted to determine the continuous 
rate of surfactant removal and surfactant needs to be added continuously 
to the system to main a necessary amount of surfactant in the mixture 
during the contacting. However, if a water soluble surfactant is used, no 
further addition of surfactant may be necessary as surfactant will remain 
with the solids or aqueous phase and not be continuously removed in an 
organic liquids phase containing materials from the oily substrate and 
solvent. 
In another aspect of the present invention in treating oily substrates 
containing solids, due to the action of the treating solvent/comminuting 
surfactant mixture thereon in accordance with this invention at a desired 
pH, solid material behaves in a fluid-like manner such that liquid-liquid 
extraction apparatus can be surprisingly and advantageously employed 
herein to treat such solids. Further, because of the fluidized nature of 
solids-containing oily substrate, and its advantageous processing in 
liquid-liquid extraction apparatus, a high throughput can be obtained, and 
additionally simplicity in equipment design and reduction in equipment 
size can be achieved. 
The results in Table II shown below were obtained by physically 
characterizing a number of comminuting surfactants useful in the process 
of the present invention using well-known methods. To measure these 
properties, a 2 wt. % solution (unless otherwise specified) of the 
surfactant in water was prepared. The surfactant was classified as 
soluble, partially soluble, dispersible, partly dispersible, or insoluble. 
The cationic surfactants tested were all liquid-form quaternary ammonium 
chloride derivatives of polypropoxy tertiary amines having a formula as 
set forth in the description hereinabove as to cationic comminuting 
surfactants which can be used in this invention. Each are a light amber 
oily liquid having a specific gravity of about 1.01 and each surfactant 
differs in the length of the polyoxypropylene group so that they have 
different average molecular weights. Each is commercially available from 
Witco Chemical under the trademark "EMCOL". More specifically, exemplified 
is a quaternary ammonium chloride derivative having an approximate 
molecular weight of 600 and commercially available under the trademark 
"EMCOL CC-9"; such a derivative having an approximate molecular weight of 
1600 and commercially available under the trademark "EMCOL-CC-36"; and 
such a derivative having an approximate molecular weight of 2500 and which 
is biodegradable and is commercially available under the trademark "EMCOL 
CC-42". 
An example of an anionic surfactant found to be comminuting and suitable 
for use herein is octyl phenoxypolyethoxyethylphosphate anionic 
surfactant, which has an amber color and a viscosity of about 8000 
centipoise at 25.degree. C. It is commercially available from Rohm and 
Haas under the trademark "TRITON QS-44". Another surfactant found to be 
comminuting and useful herein is supplied as a 60% solution in a mixture 
of equal parts of isopropyl alcohol and water wherein the active 
ingredient is sodium dioctylsulfosuccinate, and is commercially available 
from Rohm and Haas under the trademark "TRITON GR-5M". 
Suitable nonionic surfactants evaluated are adducts of octylphenol or 
nonylphenol with ethylene oxide. These surfactants differ in the length of 
the polyoxyethylene chain. A product with 1 mole of ethylene oxide is 
commercially available from Rohm and Haas under the trademark "TRITON 
X-15". A product with 3 mols of ethylene oxide is commercially available 
as "TRITON X35", a product with 5 mols of ethylene oxide is commercially 
available as "TRITON X-45", and a product with 6 mols of ethylene oxide is 
commercially available as "TRITON N-60". 
Other examples of suitable nonionic comminuting surfactants are 
polyethoxylated nonylphenols with average ethylene oxide contents of 4-12 
moles per mole of nonylphenol and commercially available from Henkel 
Corporation. Further examples include a product with 4 mols of ethylene 
oxide and available under the trademark "HYONIC NP-40" and another with 6 
mols of ethylene oxide and available under the trademark "HYONIC NP-60". 
Two anionic sodium alkyl arylpolyether sulfonate surfactants commercially 
available from Rohm and Haas under the trademark "TRITON X-301" and 
"TRITON X-200" were found not comminuting surfactants in this example at 
the pH indicated. The characteristics of these surfactants are set forth 
in Table III below. As is shown below in Table III, a non-comminuting 
surfactant lacks ability to disperse the oily substrate in the 
solvent/surfactant system and thus does not facilitate extraction of oily 
material from an oily substrate into an extraction solvent. 
The treatment efficiency of the comminuting surfactants in the process of 
the present invention is defined with respect to two criteria: first, the 
amount of surfactant necessary to achieve a certain level of oily material 
removal; and second, the overall efficiency of the process defined as 
percent removal of oily material from the oily substrate. Column 6 in 
Tables II and III, respectively, rate the treatment efficiency of 
comminuting and non-comminuting surfactants which were studied in the 
process of the present invention. A rating of "excellent" means that the 
surfactant was useful in a very small quantity and the treatment 
efficiency was very high. A rating of "none" means that the surfactant had 
no comminuting capability. 
TABLE II 
______________________________________ 
PHYSICAL CHARACTERISTICS OF SURFACTANTS 
Sur- Surfactant Properties 
Trade factant Soluble Com- pH of 2% 
Extraction 
Name Type in water miting 
Solution 
Efficiency 
______________________________________ 
Emcol Cationic S Yes 6 F 
CC-9 
Emcol Cationic Pt. S Yes 4.5 G 
CC-36 
Emcol Cationic Pt. S Yes 4 VG 
CC-42 
Triton Anionic S Yes 2 E 
QS-44 
Triton Anionic S Yes 5 VG 
GR-5M 
Triton Nonionic D Yes 5 F 
X-15 
Triton Nonionic Pt. D Yes 4.5 G 
X-35 
Triton Nonionic D Yes 6 G 
X-45 
Triton Nonionic D Yes 6 P 
N-60 
Hyonic Nonionic I Yes 7* F 
NP-40 
Hyonic Nonionic D Yes 7* P 
NP-60 
NP-60 
______________________________________ 
*pH in 1% solution. 
S = Soluble; I = Insoluble; Pt. S = Partly Soluble; D = Dispersible; Pt. 
= Partly Dispersible; P = Poor, F = Fair, G = Good, VG = Very Good, E = 
Excellent 
TABLE III 
______________________________________ 
PHYSICAL CHARACTERISTICS OF SURFACTANTS 
Surfactant Properties 
Sur- Com- pH of 
Trade factant Solubility 
minuting 
2 wt % Treatment 
Name Type in Water Surfactant 
Solution 
Efficiency 
______________________________________ 
Triton 
Anionic S No 8** None 
X-301 
Triton 
Anionic S No 8** None 
X-200 
______________________________________ 
**pH in 5% solution. 
S = Soluble; I = Insoluble; Pt. S = Partly Soluble; D = Dispersible; Pt. 
= Partly Dispersible; P = Poor; F = Fair; G = Good; VG = Very Good; E = 
Excellent 
While other attempts to extract oily materials from oily substrates have 
met with difficulty because of lack of phase separation ability, it has 
now been discovered according to a preferred embodiment of the present 
invention that by adjusting the pH of an oily substrate to about 7 or 
less, preferably from about 2 to about 6, and most preferably from about 3 
to about 5, a significant reduction in the settling time for solids 
contained within an oily substrate can be obtained. 
The order of addition of the solvent/comminuting surfactant and acid, for 
example, to a contaminated sludge, is not limited and any addition order 
can be used. However, in some instances it has been found that 
pretreatment of an oily substrate by adding acid to adjust the pH thereof 
has desirably resulted in a water phase separation of the mixture whereby 
significant amounts of water could be removed prior to treatment. On the 
other hand, the solvent and comminuting surfactant may be first added to 
the oily substrate and the acid may be added last or the solvent and acid 
added together and the comminuting surfactant last added. The effect of 
reducing the pH of the oily substrate on the settling time is illustrated 
in FIG. 2 of an API sludge as an oily substrate. As shown in FIG. 2, the 
reduction of the settling time from a pH of 11 to a pH of 7 is 
approximately a ten fold reduction in settling time. The reduction in 
settling time for a pH of 4.5 as compared to a pH of 7 is another factor 
of approximately two. If the pH is reduced to a pH of about 2, an 
additional approximate reduction of a factor of about two is achieved. 
Thus, the pH is adjusted to a pH of preferably below 7 and especially 
preferably to a pH range of about 4 to 5.5. 
Examples which provide data for FIG. 1 are set forth hereinafter together 
with other examples illustrating the present invention in greater detail. 
The examples which follow are offered for illustration are not to be 
considered a limitation of the scope of the present invention. Unless 
otherwise indicated herein, all parts, percents, ratios and the like are 
by weight. 
EXAMPLE 1 
An oily substrate, identified as Sludge I, which comprises approximately 
50% water, 25% oily material and 25% solids (percent by weight), was 
treated. The oily material comprised different types of hydrocarbons, such 
as aliphatic, unsaturated and aromatic hydrocarbons. 
In this treatment, 10 grams of Sludge I which contained about 5 grams of 
water, 2.5 grams of solid and 2.5 grams of oily material were placed in a 
bottle. To the sludge was added 0.1 gram or about 1% by weight thereof, of 
a cationic surfactant having an average molecular weight of 2500, 
commercially available from Witco Chemical under the trade name "EMCOL 
CC-42". In addition, 20 grams of hexane was added. The bottle was shaken 
and a very dark mixture resulted. After about 7 minutes, a phase 
differentiating interface formed and the phases separated. A liquids phase 
which contained most of the oily material had a very dark color. The 
liquid phase was decanted from the solids phase and this separation 
constituted one containing treatment stage. The liquids phase obtained was 
diluted with hexane and gas chromatographically (GC) analyzed. It was 
found that more than 80% of the oily materials was transferred into the 
hexane solvent liquids phase. 
To the resultant solids so treated in this first stage was added 20 grams 
of hexane. No surfactant was additionally added. The bottle was shaken for 
about 30 seconds and the mixture allowed to separate. Phase 
differentiating interface formation and phase separation was much quicker 
in this stage in that it took about two minutes for the phases to 
separate. After the phases had separated, the liquids phase with the 
solvent was then decanted off and this constituted a second treatment 
stage. The procedure of adding 20 grams of hexane to the solids phase was 
repeated 5 times and after shaking the bottle each time with the fresh 
hexane added, interface formation and phase separations occurred more 
quickly. After each treatment stage, a sample of the liquids solvent phase 
comprising the hexane was taken for gas chromatographic analysis. 
Reference is made to FIG. 3 which shows 4 chromatographs of samples 
removed in the first four treatment stages. The peaks are not totally 
representative of the concentration of each of the organic components 
since the samples from the first two treatment stages were diluted with 
hexane whereas the sample run in the last chromatograph was not diluted 
and represents the concentration of the hydrocarbons present as oily 
materials. 
EXAMPLE 2 
In the treatment, 10 grams of a sludge, identified as Sludge II, as an oily 
substrate was treated except that the surfactant used was an anionic 
surfactant commercially available from Rohm and Haas under the trademark 
"TRITON QS-44". As in Example 1, to the 10 grams of Sludge II were added 
about 0.1 grams (or 1% by weight) of the surfactant, the anionic 
surfactant "TRITON QS-44", and further 20 grams of hexane. The bottle was 
shaken vigorously and then allowed to stand for phase differentiating 
interface formation and phase separation. The first separation took 
approximately five minutes and this was considered the first treatment 
stage. The liquids phase was separated form the solids phase. To the 
solids phase obtained was added 20 grams of fresh hexane, the bottle was 
shaken, phase differentiating interface occurred and the mixture allowed 
to settle. This procedure was repeated for a total of four times or four 
treatment stages. The second stage of treatment required only two minutes 
for the phases to separate. Each time the settling time improved or 
shortened at each successive treatment stage. Again over 80% of the oily 
material was separated from the sludge in the first treatment stage and 
still further oily material was removed in the following treating stages; 
however, by the fourth stage no detectable quantity of oily material 
remained. 
The liquids phase was passed through a gas chromatographic column and the 
chromatographs obtained are shown in FIG. 4. The samples removed from the 
liquid of the first and second treatment stages were diluted with hexane 
but the third and fourth samples were samples of liquids phase itself. In 
the third treatment stage, a few peaks in the chromatograph were observed 
but none of these peaks represent hydrocarbons which are regulated by 
E.P.A. 
While the foregoing examples illustrate that the solids may be dispersed 
and materials comprising hydrocarbons can be successfully removed from the 
mixture, in each of the examples the time for the phase separation in the 
first treatment stage was five minutes or more. 
The source of Sludge I and Sludge II was the same. According to the present 
invention it was found that the settling time of the solids phase from the 
liquids phase could be substantially enhanced by adjusting the pH. When 
the solvent/surfactant mixture is a hexane/surfactant mixture and the pH 
is adjusted to a pH of 7 or less, the settling time of basic API 
separation sludges may be improved by a factor of 10. 
EXAMPLE 3 
The data in FIG. 1, which illustrates the present invention, was obtained 
in accordance with the following procedures. 
To five different and separate bottles was added 10 grams of sludge as an 
oily substrate. The sludge was composed of approximately 90 to 90% water, 
about 21/2 to 5% hydrocarbon oils as oily material and 21/2 to 5% solids 
(by weight). The pH of the sludge was measured and a pH of 11 was found. 
To four of the bottles was added concentrated sulfuric acid (98% by 
weight) in varying amounts such that the oily substrate was adjusted to a 
pH of 2.2, 4, 5, 7 and 9. No acid was added to one of the bottles which 
contained sludge with a pH of 11. To all five of the bottles containing 
these oily substrate samples was added 20 grams of hexane and 0.1 grams of 
surfactant. Each sample was shaken for complete mixing and contacting of 
the sludge with the solvent/surfactant and then each sample was allowed to 
settle. The time of settling was recorded using a stop watch. The time of 
settling of each of the samples was then plotted as shown in FIG. 1. 
As shown in FIG. 1, two distinct regions exist. A first region comprises a 
pH decrease from a pH of 7.0 to a pH of 2.2. In this region there is a 
increase in settling rate to a small extent as pH is decreased. However, 
in the second region comprising a pH of 7 or more, the settling time is 
greatly reduced as the pH is adjusted from a pH of 11 to a pH of 7. 
EXAMPLE 4 (Comparison) 
A sludge, identified as Sludge III - which comprised approximately 90 to 
95% water, 2.5 to 5.0% oily material and 2.5 to 5.0% solids (percent by 
weight) as an oily substrate. The oily material comprised different types 
of hydrocarbons, such as aliphatic, unsaturated and aromatic hydrocarbons. 
In this treatment, 5 grams of this sludge as an oily substrate were placed 
in a flask. The pH of the sludge was measured and the pH was 12. To the 
sludge was added 0.05 grams or about 1% by weight of sludge of a cationic 
surfactant, "EMCOL CC-42". In addition, 10 grams of hexane was added. The 
flask was shaken. About 15 to 20 seconds were required for phase 
differentiating interface formation and for the solids phase and the 
liquids phase to separate. A liquids phase which contained most of the 
hydrocarbons had a light amber color. The liquids phase was decanted from 
the solids phase and this separation constituted one treatment stage. The 
liquids phase separated was diluted with hexane and a gas chromatograph 
analysis was conducted. It was found that most of the oily material was 
transferred into the liquids phase containing the hexane solvent. 
To the solids phase from the first treatment stage was added 10 grams of 
hexane. No additional surfactant was added. The flask was shaken and the 
mixture allowed to separate. After phase differentiating interface 
formation and the liquids and solids phases had separated, the liquids 
phase with solvent containing the hydrocarbons was then decanted off and 
this constituted a second treatment stage. The procedure of adding 10 
grams of hexane to the solids phase was repeated 5 times. After each 
treatment stage, a sample of the liquids phase was taken for gas 
chromatographic analysis. FIG. 4 shows three chromatographs of samples, 
the first two representing the first and fifth treatment stages. The peaks 
are not totally representative of the concentration because of varying 
sample dilutions. However, it is clear from these results that the 
concentration of the hydrocarbons in these samples is much less than other 
corresponding samples. 
To the solids from the fifth treatment stage was added 10 grams of acetone. 
The third chromatograph in FIG. 4 shows the results of this acetone wash 
and indicates that certain hydrocarbons were not extracted or washed from 
the solids by the hexane solvent alone at a pH of 12. The peaks in the 
acetone wash indicate that hydrocarbon components were present at a level 
of from 20 ppm to about 100 to 150 ppm. 
EXAMPLE 5 
To demonstrate the effect of pH on treatment efficiency of Sludge III of 
Example 4, a sludge identified as Sludge IV was treated. 
In this example, 5 grams of sludge as an oily substrate were placed in a 
flask. To the sludge was added 0.5 grams, or about 1% by weight, of a 
cationic surfactant, "EMCOL CC-42" and 10 grams of hexane. In addition, 
0.1 grams of sulfuric acid was added to adjust the pH. The pH of the 
sludge was measured and the pH was 4. The flask was shaken. About 15 to 20 
seconds were required for phase differentiating interface formation and 
the liquids phase and solids phase to separate. A liquids phase which 
contained most of the hydrocarbons had a light yellow color. The liquids 
phase was decanted from the solids phase and this separation constituted 
one treatment stage. The liquids phase was diluted with hexane and gas 
chromatographically analyzed. It was found that most of the oily material 
was transferred into the liquids phase containing the hexane solvent. To 
the solids phase from the first stage was added 10 grams of hexane. No 
additional surfactant was added. The flask was shaken and the mixture was 
allowed to separate. After the phase had separated, the liquids solvent 
phase containing the hydrocarbons was then decanted off and this 
constituted a second treatment stage. The procedure of adding 10 grams of 
hexane to the solids phase was repeated 5 times. After each stage of 
treatment, a sample of the liquids phase comprising the solvent was 
removed for gas chromatographic analysis. FIG. 5 shows three 
chromatographs of samples so obtained, the first two representing the 
first and fifth treatment stages. The peaks shown are not totally 
representative of the concentration, however, it is clear that the 
concentration of the hydrocarbons n these samples is much less than other 
corresponding samples. 
To the solids from the fifth stage was added 10 grams of acetone. The third 
chromatograph in FIG. 5 shows an analysis of this acetone wash. While it 
indicates that certain hydrocarbons remained, a comparison with the 
acetone wash as shown in FIG. 4 shows the most improvement achieved by the 
practice of the process of this invention is adjusting the pH to less than 
7. 
EXAMPLE 6 
A sludge, identified as Sludge V, which comprised approximately 90 to 95% 
water, 2.5 to 5.0% oily material and 2.5 to 5.0% solids (percent by 
weight) was centrifuged. The resulting filter cake was solid in appearance 
and produced an oily substrate sample comprising approximately 50% water, 
25% oily material and 25% solids. The oily material comprised a mixture of 
different types of volatile and semivolatile hydrocarbons, such as 
aliphatic, unsaturated and aromatic hydrocarbons. This sludge sample acted 
like a solid plastic amorphous material since when it was squeezed it did 
not crumble but remained a gooey mass. Samples, 10 grams each, were placed 
in vials with 20 grams of various solvents and water but did not easily 
break down. No breakdown occurred when a sample was shaken with hexane. 
In this example, 10 grams of such a filter cake sludge so obtained as 
described above after water removal were placed in a glass vial. To the 
sludge was added 0.1% grams, or about 1% by weight of a cationic 
surfactant, "EMCOL CC-42". In addition, 10 grams of hexane was added. The 
flask was shaken. About 15 to 20 seconds were required for phase 
differentiating interface formation and the solids phase and the liquids 
phase to separate. The liquids phase comprising the solvent, which 
contained most of the hydrocarbons were decanted from the solids phase and 
this separation constituted one treatment stage. The liquids phase was 
diluted with hexane and a sample was gas chromatographically analyzed. It 
was found that most of the oily material was transferred into the liquids 
phase containing the hexane solvent. 
To the solids phase from the first treatment stage was added 10 grams of 
hexane. No additional surfactant was added. The flask was shaken and the 
mixture allowed to separate. After the solids and liquids phases had 
separated, the liquids phase comprising the solvent containing the 
hydrocarbons was then decanted off and this constituted a second treatment 
stage. The procedure of adding 10 grams of hexane to the solids phase was 
repeated 5 times. After each treatment stage a sample of the liquids phase 
was removed for gas chromatographic analysis. FIG. 6 shows three 
chromatographs of samples so obtained, the first two representing the 
first and fifth treatment stages. The peaks are not totally representative 
of the concentration, however, it is clear that after the fifth treatment 
stage essentially no hydrocarbons were present. 
To the solids from the fifth stage was added 10 grams of acetone. The third 
chromatograph of FIG. 6 shows the characteristic of this acetone wash and 
indicates that essentially all hydrocarbons as oily materials were 
extracted or washed from the solids. The peaks indicate that total 
hydrocarbon components were present in amounts of about 20 ppm to about 
100 to 150 ppm. 
EXAMPLE 7 
A sludge identified as Sludge 4, which comprised approximately 90 to 95% 
water, 2.5 to 5.0% oily material and 2.5 to 5.0% solids (percent by 
weight) as an oily substrate was treated. The oily material comprised 
different types of hydrocarbons, such as aliphatic, unsaturated and 
aromatic hydrocarbons. 
Ten grams of the sludge as an oily substrate were placed in a flask. 
Sulfuric acid was added to the sludge and the pH adjusted until the pH was 
a pH of 7. To the sludge was added 0.1 grams or about 1% by weight of a 
cationic surfactant, "EMCOL CC-42". In addition, 10 grams of hexane was 
added. The flask was shaken. About 10 seconds were required for phase 
differentiating interface formation and the liquids and solids phases to 
separate. A liquids phase, comprising the solvent and containing most of 
the hydrocarbons, was decanted from the solid phase and this separation 
constituted one treatment stage. The liquid was diluted with hexane for 
gas chromatographic analysis. To the solids from the first treatment stage 
was added 20 grams of hexane. No additional surfactant was added. The 
flask was shaken and the mixture allowed to separate. After the solids and 
liquids phases had separated, the liquids phase comprising the solvent 
containing the hydrocarbons was then decanted off and this constituted a 
second treatment stage. The procedure of adding 20 grams of hexane to the 
solids phase was repeated 6 times. After each treatment stage a sample of 
the liquids phase was removed for gas chromatographic analysis. FIG. 7 
shows two chromatographs of samples, representing the first and last 
treatment stages. The peaks are not totally representative of the 
concentration, however, it is clear that the concentration of the 
hydrocarbons in the last treatment stage was below detectable limits. 
To understand more clearly the data that has been provided, reference is 
made to FIG. 8 which provides a calibration curve for the E.P.A. regulated 
compounds for materials tested and illustrated above. 
EXAMPLE 8 
This Example exemplifies the use of flocculants in the process of the 
present invention. 
To 5 g of a solids-containing oily substrate from a refinery pit was added 
enough sulfuric acid to reduce the pH of the oily substrate to below pH 6. 
The initial pH of the oily substrate was 8.5. To this sample was then 
added 0.1 g of EMCOL CC-42, a quaternary ammonium salt surfactant by Witco 
Chemical. 15 g of pentane was then added to the resulting mixture which 
was next aggitated for approximately 20 seconds. Once dispersion of solids 
in the solvent was achieved, the sample was allowed to phase separate. 
Complete phase separation took approximately 20 seconds. Next, 500 ppm of 
a flocculant of the trade name FILTER AID 9139 manufatured by Nalco 
Chemical was added to the mixture, which was then agitated and allowed to 
phase separate. The settling time was reduced to 6 seconds, indicating a 
significant improvement in settling characteristics. 
EXAMPLE 9 
This Example illustrates the present invention in treating emulsified 
solids-containing oily substrates. 
A sample of oily substrate containing approximately 50% water, 20% solids 
and 30% oil and emulsified to the point where phase separation would not 
occur using conventional emulsion breaking techniques such as emulsion 
breakers, was placed in a flask, to which was added 0.1 g EMCOL CC-42 
surfactant, and 20 g of hexane. The mixture was shaken for about 30 
seconds, and subsequently heated slightly to facilitate phase separation, 
which occurred in about 5 minutes. 
In a further aspect of the present invention, it has been surprisingly and 
unexpectedly found that processed and separated solids/water mixtures in 
accordance with this invention have physical properties which are 
significantly different from raw oily substrates containing solids, e.g. 
sludges, and can be filtered and dewatered in significantly less time than 
such raw oily substrates, thus, enhancing savings in processing costs. 
This aspect is more fully illustrated by the following example. 
EXAMPLE 10 
(Sludge Dewatering) 
This Example demonstrates the change in dewatering characteristics of a 
refinery oily waste which is treated with the extraction process of the 
invention. In test 1, 400 g of an API oily waste containing approximately 
4% oil, 5% solids and 91% water was filtered through No. 40 Whatman filter 
paper having a diameter of 15 inches. A vacuum of 23 inches Hg was applied 
during the filtering process. 
In test 2, 400 g of the API sludge was treated in accordance with the 
extraction process of the present invention employing hexane and 1% by 
weight Witco CC-42 surfactant, whereby substantially all the organic phase 
was removed. The sludge was then heated at 80.degree. C. to remove any 
residual solvent. The viscosity of the treated sludge decreased 
signifiantly as solvent was removed therefrom. The resulting treated 
sludge containing approximately 70% water was then filtered in the manner 
described above. 
In tests 1 and 2, the filtering times were 35 minutes and 1.5 minutes, 
respectively, and the filter cake from test 1 contained 70% water, and the 
filter cake from test 2 contained 45% water. The results are summarized 
below in Table IV. 
TABLE IV 
______________________________________ 
FILTRATION RATES FOR API SEATOR SOLIDS 
Test Initial Final 
Material % Water % Water Minutes 
______________________________________ 
1 Raw API Separator 
91% 70% 35 
Sludge 
2 Processed API 70% 45% 1.5 
Separator Solids 
______________________________________ 
These tests clearly demonstrate the advantageous aspect of the invention in 
signifiantly improving dewatering characteristics of solids-containing 
oily substrates. 
While the invention has been described in detail and with reference to 
specific examples thereof, it will be apparent to one skilled in the art 
that various changes and modifications can be made therein without 
departing from the spirit and scope thereof.