MXPA01000694A - Use of hydrophilic dispersion polymers for oily wastewater clarification - Google Patents

Abstract

A method for removing emulsified oil from industrial waste water streams utilizing dispersion copolymers is disclosed. Preferred dispersion copolymers are poly(dimethylaminoethylacrylate methyl chloride quaternary salt/acrylamide) and poly(diallyldimethyl ammonium chloride/acrylamide).

Description

USE OF HYDROFILIC DISPERSION POLYMERS FOR THE CLARIFICATION OF OILY WASTEWATER FIELD OF THE INVENTION A method is described for removing emulsified oil from water from industrial waste streams, using continuous dispersion copolymers. The copolymers of continuous dispersion in water are poly (quaternary salt of methyl dimethylaminoethylacrylate chloride / acrylamide) and poly (diallyldimethyl ammonium chloride / acrylamide).

BACKGROUND OF THE INVENTION In industry, oily wastewater is produced in various processes located in the steel and aluminum industries, in the chemical process industry (CPI), in the automotive industry, in the laundry industry and in the refinery industry. In these industries, highly refined oils, lubricants and fats make contact with water for various purposes, according to the particular industry. This results in a highly dispersed or severe oil-in-water emulsion in the waste water streams.

REF. DO NOT. 126596 For example, in the steel and aluminum industries, waste water from steel and aluminum laminates using hot rotating laminators containing lubricant and hydraulic pressure hydrocarbons. The waste water from cold rolling mills contains oils that lubricate the leaves and reduce corrosion. Specifically, on cold rotating rolls, oil-in-water emulsions are sprayed onto the metal during rolling to act as a cooler. Also, metallurgy plants generate water streams containing lubricating oils and cutting oils, grinding and deburring compounds, grinding and other special fluids. These oils are generally highly refined hydrocarbons.

"Waste oils come from two different sources: (1) Skimmers for water clarification equipment, that is, DAF separators, API and which generally consist of crude oil, and, (2) Process leaks, collected via traps and drains through the plant.This oil is sent "usually to a water treatment plant.

A type of waste oil is formed during the process of removing disperse oil from wastewater treatment plants. The oil (called "floating" or "frothing") is concentrated in clarification vessels such as dissolved air flotation units (DAFs), gas-induced flotation units (IGFs), corrugated plate interceptors (CPIs), and tanks containers. The oil floats on top of these units are removed by mechanical means and then stored. These waste oils can then be disposed of by incineration, shipped to oil recovery sites, or treated in-situ. These waste oils have a minimum of 50% to 95% oil, and contain emulsified water and solids, which are stabilized by chemicals used to remove the oil from the waste water.

Waste water from cotton and wool manufacturing plants contains oils and fats from cleaning, desizing and finishing operations. The final oils used in the manufacture of cotton and wool to reduce the friction and the hooking of the fibers in the rotating machines end up in the waste waters. Processes in other industries also generate oily wastewater, such as: paints, surface coatings, and adhesives; soaps and detergents; dyes and inks; and the skin industry. In each of these industries described above, the oils used in the processes eventually contaminate wastewater streams as highly dispersed oil-in-water emulsions.

The oil emulsified in wastewater is typically present in the range of several hundred to tens of thousands of ppm. It is critical to remove this oil from a waste stream before discharging it to an environmental point. The Environmental Protection Agency of thelym The United States has imposed strict restrictions on the limits of total oil and grease for water discharged into public drinking water supplies or open bodies of water. The removal of this oil is very critical to satisfy the established discharge limits for the total dissolved solids (TTS), the carbon oxygen demand (COD), the biological oxygen demand (BOD) and the total organic carbon in the local sewers and rivers. Not only has the EPA established strict limits on the discharge of oils and fats, these industries are affected by local city ordinances as well.

An emulsion is an intimate mixture of two liquid phases such as oil and water, in which the liquids are mutually insoluble and in which either phase can be dispersed in the other. An emulsion of waste oil, in which the oil is dispersed in the aqueous phase, can contain any of a variety of oils, in a wide range of concentrations. These oils are defined as the substances that can be extracted from water by hexane, carbon tetrachloride, chloroform, or fluorocarbons: In addition to oils, the typical contaminants of these emulsions can be solids, slime, metal particles, emulsifiers, cleaners , soaps, solvents, and other waste. The types of oils found in these emulsions will depend on the industry. They can be lubricants, cutting fluids, heavy hydrocarbons such as tars, grease, crude oil, and diesel oils, and also light hydrocarbons including gasoline, kerosene, and jet fuel. Their concentrations in wastewater can vary from only a few parts per millimeters to as much as 5 to 10% by volume.

A stable oil-in-water emulsion is a colloidal system of electrically charged oil droplets surrounded by an ionic environment. The stability of the emulsion is maintained by a combination of physical and chemical mechanisms.

Emulsions can be broken by chemical, electrolytic or physical methods. The breaking of an emulsion is also called resolution, since the objective is to separate the original mixture into its parts. Chemicals are commonly used for the treatment of oily wastewater, and are also used to enhance mechanical treatment. In breaking emulsions, the stability factors must be neutralized to allow the emulsified droplets to coalesce. The electrical charges accumulated on the emulsified droplets are neutralized to allow the emulsified droplets to coalesce. The electric charges accumulated on the emulsified droplets are neutralized by introducing a charge opposite to that of the droplets. The emulsion breaking chemicals provide this opposite charge, and are thus usually ionic in nature.

The treatment of the oily waste water is normally divided into two steps, that is, coagulation, which is the destruction of the emulsifying properties of the surface of the active agent or neutralization of the droplets loaded with oil, and the flocculation, which is the agglomeration of the neutralized droplets into larger and separable globules. The term oily wastewater refers to an oil-in-water emulsion, which contains oil, dispersed solids, and water.

Historically, dry pors, por solutions and reversible emulsion lactases have been used to treat wastewater. Each material has its own advantages and disadvantages.

Water-in-oil emulsions of water-soluble vinyl addition pors, known herein as latex pors, are used very frequently, although they have severe disadvantages. The first disadvantage is that the latex por must be inverted before use, which complicates the process of feeding the por into the system. Numerous problems associated with this feeding method have caused many users to avoid latex pors. Additionally, lataxas generally have a narrow range of treatment, which can result in overtreatment at high dosages. In addition, the latex polymers add even more oil to the stream to be treated, since the latex polymers typically include 20-30% by weight of a continuous hydrocarbon phase. Of course, the addition of more oil and surfractants to the system is undesirable when treating wastewater streams.

Although the polymers in solution do not require prior preparation, the characteristics of active polymer content and molecular weight of these polymers are inherently limited. These coagulants are often used to break down oil-in-water emulsions, but they are unable to flocculate the dispersed oil, thus requiring an adjunct chemical (a flocculant) to complete the process.

Water-soluble cationic polymers for the removal of emulsified oil from water produced in the oil field have been described in US Pat. No. 5,330,650. Dispersions of water-soluble cationic polymers for the removal of emulsified oil from the ethylene cooling water have been described in US Pat. No. 5,294,347. A method for the recycling of waste oil fluids with a dispersion of water soluble cationic polymers is described in US Patent No. 5,332,507. Additionally, dispersions of water-soluble polymers for purposes such as flocculation and / or dewatering of sludge or for the separation and treatment of industrial wastewater, which contain oils, have been described in U.S. Patent Nos. 4,929,655; 5,006,590; 5,708,071; 5,587,415; and JP 7-71678. However, such polymers are hydrophobic dispersions, since they are polymerized from at least 5% of monomers of general formula II.

In addition, hydrophilic dispersion polymers have been described for use in the pulp and paper industries to increase retention and drainage in EP 0 831 177 A2; for de-inking, in US Patent No. 5,750,034 and for the treatment of recycled broken coating in EP 0 821 099 Al. However, there is no indication that such polymers should also be demulsifiers.

Water-soluble cationic dispersion polymers having less than 5 mole percent of benzyl functionality, which can be used as demulsifiers are described in U.S. Patent Nos. 5,614,602; 5,696,194 and 5,707,533. However, the dispersion polymers described therein are hydrophobic, due to the incorporation of substituted acrylamides from 1 to about 50 mole percent N-alkyl acrylamide, N, N-dialkylacrylamide or mixtures thereof. In addition, attempts to make polymers without the incorporation of substituted acrylamide monomers failed, as described in Comparative Examples 1 and 2, column 8 of U.S. Patent No. 5,707,533. Therefore, these patents represent a distant teaching of hydrophilic dispersion polymers, of the type we have discovered.

BRIEF DESCRIPTION OF THE INVENTION A method for the removal of emulsified oil from industrial streams of wastewater using copolymers of continuous dispersion in water is described. Preferred continuous water dispersion copolymers are poly (quaternary salt of methyl di-ethylaminoethylacrylate chloride / acrylamide) and poly (diallyldimethyl ammonium chloride / acrylamide).

DESCRIPTION OF THE INVENTION One aspect of this invention is a method of breaking an oil-in-water emulsion, which comprises the steps of: a) treating the emulsion with a de-emulsifying amount of a water-soluble dispersion polymer, said water-soluble dispersion polymer, formed under conditions of free radical formation in a medium containing water, monomers, stabilizing polymer and an aqueous solution of an anionic salt, wherein said water-soluble polymer is formed by polymerization of i. (meth) acrylamide; and ii. and at least one cationic monomer selected from the group consisting of: disubstituted diallyl-N, N-ammonium halides, wherein the substituents of said disubstituted ammonium halides are selected from the group consisting of: alkyl groups of C? -C20, aryl groups, alkylaryl groups and arylalkyl groups, and monomers of the general formula I wherein Ri is selected from the group consisting of the hydrogen and methyl groups, R 2 and R 3 are selected from the group consisting of Ci alkyl groups and C 2 alkyl; R4 is selected from the group consisting of the hydrogen, C1 alkyl and C2 alkyl groups; A is selected from the group consisting of an oxygen atom and NH; B is selected from the group consisting of C2 alkyl, C3 alkyl and C4 alkyl, and X ~ is an anionic counterion; b) separation of said emulsion in an oily phase and an aqueous phase; and c) recovery of said aqueous phase.

Another aspect of this invention is a method for breaking an oil-in-water emulsion, which comprises the steps of: a) treating the emulsion with a de-emulsifying amount of a water-soluble dispersion polymer, said polymer formed under conditions of formation of free radicals in a medium containing water, monomers, stabilizing polymer and an aqueous solution of an anionic salt, wherein said water-soluble polymer is formed from the polymerization of: i. (meth) acrylamide; ii. a cationic monomer selected from the group consisting of: disubstituted diallyl-N, N-amides, wherein the substituents of said disubstituted ammonium halides are selected from the group consisting of C? -C20 alkyl groups, aryl, alkylaryl groups and arylalkyl groups, and monomers of the general formula I wherein Ri is selected from the group consisting of hydrogen and methyl groups, R2 and R3 are selected from the group consisting of C1 alkyl groups and C2 alkyl; R4 is selected from the group consisting of the hydrogen, C1 alkyl and C2 alkyl groups; A is selected from the group consisting of an oxygen atom and NH; B is selected from the group consisting of the C2 alkyl groups, C3 alkyl and C4 alkyl, and X "is an anionic counterion, and iii less than 5% monomers according to general formula II wherein Rx is selected from the group consisting of, H and CH3, R2 and R3 are selected from the group consisting of Ci alkyl and C2 alkyl, A is selected from the group consisting of O and NH , B is selected from the group consisting of the C2 alkyl groups, C3 alkyl and C4 alkyl, and X ~ is an anionic counterion; b) separating said emulsion in an oily phase and an aqueous phase; and, c) recovering said aqueous phase.

The steps of separation and recovery can be carried out in any conventional manner generally known to those skilled in the art. Preferably, the hydrophilic dispersion polymer of the invention is a copolymer of cationic quaternary chloride monomers of methyl dimethylaminomethyl (meth) acrylate (DMAEA'MCQ) and (meth) acrylamide or diallyldimethylammonium chloride. It has been found that the polymers described above confer advantages for use in a process that generates oily waste water. Specifically, the hydrophilic dispersion polymers of the invention show improved activity with respect to the breakdown of the emulsion compared to the standard, commercially charged DMAEA methyl chloride quaternary latex of the same filler, and also when compared to polymers of continuous dispersion in water, soluble in water. The use of these flocculants gives a removal of particulate materials without the unwanted addition of oils and surfing agents contained in conventional latex polymers. Additionally, these flocculants do not require an inversion system and can be introduced to the process stream using simple feeding equipment. Latex is defined in this application, as a water-in-oil emulsion polymer.

LOS MONOM? ROS As used herein, the term "arylalkyl" means accompanied by benzyl groups and phenethyl groups.

As it concerns, diallyl monomers, -N, disubstituted ammonium halide, the monomer substituents can be C? -C20 alkyl groups, aryl groups, alkylaryl groups or arylalkyl groups. In addition, each of the disubstituyentes can be a different group. For example, a projected halide is N-methyl-N-ethyl-N, N-diallyl ammonium chloride. Another example of a specific halide is DADMAC (diallyldimethyl ammonium chloride). Preferably, the amount of diallyl dimethyl ammonium chloride present in the copolymer is from about 5 mole percent to about 30 mole percent. Disubstituted diallyl-N, N-ammonium halides, especially diallylmethylammonium chloride, are well known and commercially available from a variety of sources. In addition to the chloride, the counterion can also be bromide, sulfate, phosphate, monohydrogen phosphate and nitrate among others. A method for the preparation of DADMAC is detailed in U.S. Patent No. 4,151,202, the description of which will be incorporated hereinafter as a reference in this specification.

Examples of the monomers represented by Formula I include salts such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, dimethylhydroxypropyl (meth) acrylate, and methylated and ethylated quaternary salts. A specific example of a quaternary (meth) acrylate is DMAEA'MCQ (quaternary salt of methyl dimethylaminoethyl acrylate chloride). Preferably, the amount of DMAEA.MCQ present in the copolymer is from about 0.1 mole percent to about 30 mole percent. Quaternary dialkylaminoalkyl (meth) acrylates, especially DMAEA.MCQ are commercially available from a variety of sources.

The term "quaternary salt" as used herein contemplates the use of any quaternizing agent, such as, for example, methyl chloride, methyl bromide, methyl iodide and dimethyl sulfate.

ANIONIC SALTS MULTIPURPOSE The polyvalent anionic salts to be incorporated into the aqueous solution according to the present invention are suitably a sulfate, a phosphate or a mixture thereof. Preferred salts include ammonium sulfate, sodium sulfate, magnesium sulfate, aluminum sulfate, hydrogen ammonium phosphate, sodium hydrogen phosphate and potassium hydrogen phosphate. In the present invention, these salts can each be used as an aqueous solution thereof having a concentration of 15% or above.

THE DISPERSANTS A dispersant polymer (also called a stabilizing polymer) is present in an aqueous solution of anionic salt in which the polymerization of the monomers above occurs. The dispersant polymer is a water soluble high molecular weight cationic polymer. The dispersing polymer is preferably soluble in the salt solution mentioned above. The dispersant polymer is preferably used in an amount of from 1 to 10% by weight based on the total weight of the monomers. The dispersant polymer is composed of cationic monomer units of a diallyl substituted ammonium halide or N, N-dialkyl-aminoethyl (meth) acrylates and their quaternary salts. Preferably, the residual% mole is acrylamide or methacrylamide. The molecular weight of the dispersant is preferably in the range of 10,000 to 10,000,000. Preferred dispersants are homopolymers of diallylmethyl ammonium chloride, quaternary salt of methyl dimethylaminoethylacrylate chloride and quaternary salt of methyl dimethylaminoethylmethacrylate chloride. According to one embodiment of the invention, a multifunctional alcohol such as glycerin or polyethylene glycol is co-existent in the polymerization system. The deposition of the fine particles is carried out rapidly in the presence of these alcohols.

THE DISPERSION POLYMERS Representative methods of methods for the synthesis of hydrophilic dispersion polymers are described in U.S. Patent No. 5,750,034, the disclosure of which is incorporated herein by reference. For polymerizations, a water-soluble radical forming agent may be employed, but water-soluble azo compounds, such as 2,2'-azobis (2-amidinopropane) hydrochloride and 2,2'-dihydrochloride, are preferably used. azobis (2- (2-imidazolin-2-yl) propane).

According to one embodiment of the invention, a seed polymer is added before the start of the polymerization of the above monomers, for the purpose of obtaining a fine dispersion, or, alternatively, it is formed in situ before the addition of more monomer . The seed polymer is a water-soluble cationic polymer insoluble in the aqueous solution of the polyvalent anionic salt. The seed polymer is preferably a polymer prepared from the above monomer mixture by the process described herein. However, the monomer composition of the seed polymer does not always need to be equal to that of the water-soluble cationic polymer formed during the polymerization. Nevertheless, similarly to the water-soluble polymer formed during polymerization, the seed polymer should contain at least 1 mole percent of cationic monomer units of quaternary salt of methyl dimethylaminoethyl acrylate chloride. According to one embodiment of the invention, the seed polymer used in a polymerization reaction is the water soluble polymer prepared in a previous reaction, which uses the same monomer mixture.

Preferably, the dispersion polymer is polymerized from acrylamide and a cationic monomer, which is quaternary salt of methyl dimethylaminoethyl acrylate chloride, and the molar ratio of acrylamide to quaternary salt of methyl dimethylaminoethyl acrylate chloride is from about from 95: 5 to around 50:50; or the cationic monomer may also be diallyldimethyl ammonium chloride and the molar ratio of acrylamide to diallyldimethylammonium chloride is from about 95: 5 to about 50:50. The hydrophilic dispersion polymer can have a cationic charge from about 1 mol% to about 30 mol%.

We have discovered that the hydrophobic character is less advantageous for an efficient de-efflux of oily wastewater. Therefore, the use of such monomers as N-mono- or di-substituted acrylamides in any amount, and quaternary salt of benzyl dimethylaminoethyl (meth) acrylate chloride in a ratio of more than 5 mol%, should result in a polymer having a degree of hydrophobic character, rendering it less suitable for the purposes described herein. In contrast, the dispersion polymers of the present invention do not have a hydrophobic character, since they do not contain monomers of the type defined above.

Additionally, conventional coagulants, conventional flocculants, alum, or a combination thereof can be used as adjuncts with dispersion polymers, although it can be emphasized that the dispersion polymers do not require any adjuncts for the optimization of their activity.

In addition, the range of intrinsic viscosities for the dispersion polymers of the invention can be from about 0.5 to about 15 dl / g. Depending on the conditions in the processes that are treated, the dosage may be in the range of about 1 ppm (0.0001%) to about 5000 ppm (0.5%), with the preferred dosage from about 0.5 to about 500 ppm . Exacerbated conditions may require a larger dose.

When the removal of the waste oil from the oil-in-water emulsions is effected by a chemical de-emulsifier, such as the copolymer prepared here below, the emulsion breaker is added to the suction side of the supply pump, or influent of the DAF unit. The effective amount will vary, depending on the application and types of oils present. The waste oil, as described herein, can encompass oils such as lubricants, fat and dispersed solids among others as described above. It does not seem to depend on the particular system, a maximum effective dose should be reached at a certain point. Above the dosage level, the polymers begin to overload the system, which causes a decrease in the clarity of the wastewater.

The following examples are presented to describe the preferred embodiments or utilities of the invention and in no way limit the invention unless stated otherwise in the appended claims.

EXAMPLE 1 The jar test was used to evaluate the hydrophilic dispersion polymers as demulsifiers in oily waste water (API influent) of a refinery. The demulsifier to be tested was added to 100 mL of the residual water obtained from refineries at the desired concentration and mixed using a Phipps and Bird agitator, for 2 minutes at 330 rpm and then mixed for 3 minutes at 30 rpm. The solution was then allowed to stand for 2 minutes. An aliquot supernatant was then collected and the turbidity of the water was measured using a Hach turbometer, ratio / xR. The results of the test are tabulated below in Tables I-IV. The turbidity units in all the tables are NTU. A low value indicates that a larger de-emulsification has occurred. For comparison purposes, the turbidity of untreated oily waste water was measured at 400 NTU. Polymer C, representative of the polymers of the present invention was compared to polymer A, a hydrophobic dispersion copolymer and polymer B, the same chemical as polymer C in the form of a latex.

The measurement of the replacement ratio found in Tables I-IV is an indication of the efficiency of the polymer, that is, how much dosage is required to obtain a certain level of performance. The replacement ratio of an experimental polymer is calculated with reference to a standard polymer. For example in Table III, A is the conventional hydrophobic dispersion polymer poly (quaternary salt of benzylated dimethylaminoethyl acrylate chloride / acrylamide) and C is the polymer of the present invention, a polymer of "poly-hydrophilic dispersion (quaternary salt of Methyl dimethylaminoethyl acrylate chloride / acrylamide) The selected level of performance is a turbidity of 46 NTU, which is the lowest turbidity achieved.The dosage of polymer A to achieve this turbidity is 10 ppm while that of C is 6 The replacement ratio is therefore 6/10 = 0.6, which should illustrate that polymer C provides unexpectedly superior results.

Table I shows a comparison of a hydrophilic dispersion polymer C, representative of the new polymers described herein, with a latex copolymer B of the same chemical as the hydrophilic dispersion polymer C and with a hydrophobic dispersion polymer A. C results in a larger reduction in turbidity at lower doses than the other polymers. Therefore, the hydrophilic dispersion polymers described herein represent a significant advancement in the demulsification technology since they can be effectively used at low dosages.

Table. I Turbidity as a Function of Polymer Dosage 1 = on the basis of equal assets 2 = polyhydrophobic dispersion copolymer (DMAEA.BCQ / AcAm), molar ratio 10/90, RSV = 15-20 dL / g measured at a concentration of 0.045% polymer in NaN030.25 M, available from Nalco Chemical Co. of Naperville, IL 3 = poly latex polymer (DMAEA.MCQ / AcAm) molar ratio 10/90, RSV = 13-21 dL / g measured at a polymer concentration of 0.045% in NaN03 1M, available from Nalco Chemical Co. of Naperville, IL 4 = hydrophilic dispersion copolymer poly (DMAEA.MCQ / AcA) molar ratio 10/90, RSV = 15-20 dL / g measured at 0.045% polymer concentration in NaN03 1M, available from Nalco Chemical Co, Naperville, IL 5 = replacement ratio Table II provides a comparison of the hydrophilic dispersion polymer C, representative of the polymers described here, with a polymer A in a wastewater stream different than the one that was demulsified to provide the results of Table I, which has the same RSV and molar elation of acrylamide, at lower dosages at more subtly increasing dosages than in Table I. This table also illustrates that hydrophilic dispersion polymers are superior to turbidity reduction for hydrophobic dispersion polymers, since they can be used less to achieve demulsification.

Table II Turbidity as a Function of Polymer Dosage 1 = on the basis of equal assets 2 = polyhydrophobic dispersion copolymer (DMAEA.BCQ / AcAm), molar ratio 10 / 9.0, RSV = 15-20 dL / g measured at a concentration of 0.045% polymer in NaN030.25 M, available from Nalco Chemical Co. from Naperville, IL 4 = polyhydrophilic dispersion copolymer (DMAEA.MCQ / AcAm) molar ratio 10/90, RSV = 15-20 dL / g measured at 0.045% polymer concentration in 1M NaN03, available from Nalco Chemical Co , from Naperville, IL 5 = replacement ratio Table III demonstrates the improvement in the efficiency of type C polymers over type A polymers in a third type of wastewater stream. The general trend of an improvement in efficiency is also evident there. Therefore, tables I-III show that in a variety of wastewater streams, the new type C polymers should be preferred for the "breaking" of the emulsions, since lower dosages should be required.

Table III Turbidity as a Function of Polymer Dosage 1 = on the basis of equal assets 2 = polyhydrophobic dispersion copolymer (DMAEA.BCQ / AcAm), molar ratio 10/90, RSV = 15-20 dL / g measured at a concentration of 0.045% polymer in 0.25 M NaN03, available from Nalco Chemical Co. From Naperville, IL 4 = poly hydrophilic dispersion copolymer (DMAEA.MCQ / AcAm) molar ratio 10/90, RSV = 15-20 dL / g measured at 0.045% polymer concentration in NaN03 1M, available from Nalco Chemical Co, Naperville, IL 5 = replacement ratio Table IV illustrates the results for another type of hydrophilic dispersion polymer D, poly (diallyldimethyl ammonium chloride / acrylamide), as compared to a latex polymer E, polymerized from the same monomeric components of the same molar ratios. D is more effective at dosages lower than E. Table IV Turbidity as a Function of Polymer Dosing 1 = on the basis of equal assets 5 = hydrophilic dispersion copolymer poly (DADMAC / AcAm), 50/50 molar ratio, RSV = 4-6 dL / g measured at 0.045% polymer concentration in 1M NaN03, available from Nalco Chemical Co. from Napeville, IL 6 = poly latex copolymer (DADMAC / AcAm), 50/50 mole ratio, RSV = 4-6 dL / g measured at 0.045% polymer concentration in NaN03, available from Nalco Chemical Co. De Naperville, IL Changes may be made in the composition, operation and arrangement of the method of the present invention described herein, without departing from the concept and scope of the invention as defined in the following claims: It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (8)

1. A method for breaking an oil-in-water emulsion, which, characterized in that it comprises the steps of: a) treating the emulsion with a de-emulsifying amount of a water-soluble dispersion polymer, said dispersion polymer soluble in water; water, formed under conditions of formation of free radicals in a medium containing water, monomers, stabilizing polymer and an aqueous solution of an anionic salt, wherein said water-soluble polymer is formed by polymerization of i. (meth) acrylamide; and ii. and at least one cationic monomer selected from the group consisting of: dialkyl-N, N-disubstituted ammonium halides, wherein the substituents of said disubstituted ammonium halides are selected from the group consisting of: alkyl groups of C? -C20, aryl groups, alkylaryl groups and arylalkyl groups, and monomers of the general formula I wherein Ri is selected from the group consisting of the hydrogen and methyl groups, R 2 and R 3 are selected from the group consisting of the hydrogen, Ci alkyl and C 2 alkyl groups; R4 is selected from the group consisting of the hydrogen, C1 alkyl and C2 alkyl groups; A is selected from the group consisting of an oxygen atom and NH; B is selected from the group consisting of the groups C2 alkyl, C3 alkyl and C4 alkyl and X "is an anionic counterion, b) separation of said emulsion in an oily phase and an aqueous phase, and c) recovery of said phase watery

2. The method of claim 1, characterized in that said water soluble polymer is added to said oil in water emulsion in an amount from about 1 ppm to about 5000 ppm by weight of said emulsion.

3. The method of claim 1, characterized in that said monomers of general formula I are selected from the group consisting of methyl quaternary salt of dimethylaminoethylacrylate chloride and quaternary salt of methyl dimethylaminoethyl methacrylate chloride.

4. The method of claim 3, characterized in that said monomer is quaternary salt of methyl dimethylaminoethyl acrylate chloride, and the molar ratio of (meth) acrylamide to quaternary salt of methyl dimethylaminoethyl acrylate chloride is from about 95: 5 to about 50:50.

5. The method of claim 1, characterized in that said cationic monomer halide is diallyldimethyl ammonium chloride and the molar ratio of the (meth) acrylamide to dialkidimethyl ammonium chloride is from about 95: 5 to about 50:50.

6. A method for breaking an oil-in-water emulsion, characterized in that it comprises the steps of: a) treating the emulsion with a desulsifying amount of a water-soluble dispersion polymer, said water-soluble polymer, formed under conditions of formation of free radicals in a medium containing water, monomers, stabilizing polymer and an aqueous solution of an anionic salt, wherein said water soluble polymer is formed from the polymerization of: i. (meth) acrylamide; ii. a cationic monomer selected from the group consisting of: dialkyl-N, N-disubstituted ammonium halides, wherein the substituents of said disubstituted ammonium halides are selected from the group consisting of C? -C2o alkyl groups, aryl, alkylaryl groups, and arylalkyl groups, and monomers of the general formula I wherein R x is selected from the group consisting of hydrogen and methyl groups, R 2 and R 3 are selected from the group consisting of Ci alkyl groups and C 2 alkyl; R4 is selected from the group consisting of the groups hydrogen atom, Ci alkyl and C2 alkyl; A is selected from the group consisting of an oxygen atom and NH; B is selected from the group consisting of the C2 alkyl groups, C3 alkyl and C and X alkyl "is an anionic counterion, and iii less than 5% monomers according to general formula II wherein Ri is selected from the group consisting of, H and CH3, R2 and R3 are selected from the group consisting of Ci alkyl and C2 alkyl, A is selected from the group consisting of O and NH B is selected from the group consisting of the C2 alkyl groups, C3 alkyl and C alkyl, and X "is an anionic counterion, b) separating said emulsion into an oily phase and an aqueous phase; c) recovering said aqueous phase.

7. The method of claim 6, characterized in that said water soluble polymer is added to said oil in water emulsion in an amount from about 1 ppm to about 5000 ppm by weight of said emulsion.

8. The method of claim 6, characterized in that said monomers of general formula II are selected from the group consisting of quaternary salt of methyl dimethylaminoethyl acrylate chloride and quaternary salt of methyl dimethyl aminoethyl methacrylate.