KR20000048720A - Anionic water-soluble polymer precipitation in salt solution - Google Patents

Abstract

PURPOSE: Anionic water-soluble polymer precipitation in salt solution is prepared. CONSTITUTION: Aqueous compositions of certain salts which contain precipitated anionic water-soluble polymers, methods for precipitating anionic watersoluble polymers in aqueous solutions containing certain salts, methods for polymerizing monomers in aqueous solutions containing certain salts to form precipitated anionic watersoluble polymers, optionally precipitated as polymer dispersions, and methods for using compositions of precipitated anionic water-soluble polymers in aqueous solutions of certain salts for various applications e.g. papermaking, mining, wastewater treatment, and soil conditioning.

Description

Anionic Water Soluble Polymer Precipitate in Salt Solution {ANIONIC WATER-SOLUBLE POLYMER PRECIPITATION IN SALT SOLUTION}

High molecular weight water soluble anionic polymers are useful in many applications, for example, flocculation of suspended solids, mineral recovery from mining operations, coal waste dewatering, papermaking, paper sludge deking, enhanced oil recovery, wastewater treatment, soil conditioning, etc. Do. In many cases, anionic polyelectrolytes are provided to the user in the form of substantially dry polymer granules. Granules can be prepared by polymerization of water soluble monomers in water to form a water soluble polymer solution followed by dehydration and polishing to form water soluble polymer granules.

Another means for separating the polymer from the polymer solution is to mix the polymer solution with an organic solvent that is non-solvent to the polymer, such as acetone or methanol, and then precipitate the polymer by separating the polymer by evaporation and filtration. . In many cases, however, this method is inconvenient, expensive and dangerous due to the problem of treating a large amount of flammable organic solvents.

Water soluble anionic polymers may also be provided in the form of water-in-oil emulsions or microemulsions in which polymer solution droplets are separated from each other by a continuous oil phase. Polymer emulsions can be used either directly in the desired application or by dilution with water in the presence of a “crusher” surfactant. Although the supply of these forms is convenient and the need for dehydration can be avoided, oils can be expensive and often flammable; Moreover, oil can also pose secondary pollution problems. In addition, the emulsion can be precipitated as an organic liquid that is a solvent for water and oil but non-solvent to the polymer, and then dried to recover the separated and substantially dry polymer. However, this precipitation method may be disadvantageous for the same reasons mentioned above.

Methods for preparing water-soluble polymers in the form of unexpanded, hard, non-viscous granules are described in US Pat. No. 3,336,270. Water-soluble polymers are prepared by dissolving acrylamide-type monomers in a tertiary butanol-water mixture and causing the monomers to polymerize to precipitate out of the tertiary butanol-water mixture.

The first water soluble polymer may also be dispersed in the presence of the second water soluble polymer to form an aqueous polymer dispersion as taught in US Pat. Nos. 4,380,600 and 5,403,883. Since the two polymers do not dissolve with each other, the first water soluble polymer forms microgranules dispersed in the second water soluble polymer solution. Optionally, salts can be used to improve the flow capacity.

U.S. Patent No. 3,891,607 describes thermoreversible coacervates produced by copolymerizing 30-50 mole% acrylic acid and 70-30 mole% acrylamide in an aqueous solution, lowering the pH below 3.3 and adjusting the temperature below the coacervate transition temperature.

U. S. Patent No. 3,658, 772 describes a process for copolymerizing acrylic acid in a salt solution containing 0.1 to 10% by weight, based on the total weight, to form polymerize in the form of a fluid suspension of dispersed solid-polymer particles. . Herein below, all concentrations are expressed as weight percent of total weight, unless stated otherwise. Importantly, the pH of the polymerization is in the range of 1 to 3.2, and increasing the pH above 4 results in non-fluid, gel polymerizate due to the increased solubility of the acrylic acid salt form at apparently higher pH. Reported. In US Pat. No. 3,493,500; The pH range is increased by 4 by including the cationic water soluble polymer in an amount of about 0.03 to 0.2 parts by weight of the acrylic acid polymer solids. However, in no case is a fluid suspension obtained at a pH of 4 or more.

Japanese Patent Application No. 14907/1971 describes a method for copolymerizing acrylic acid and acrylamide in a salt solution to form a flowable polymerizeate. The copolymerization is carried out in the presence of 0.1 to 60% by weight of inorganic salts at pH 1-4. In many systems containing 90/10 acrylic acid and acrylamide and 50/50 acrylic acid and acrylamide, when the pH of the polymerization system is increased to 4 or higher, non-flowable gel polymerize is produced. Homopolymers of acrylic acid can be prepared as "suspended compounds" at slightly above pH 4.

An aqueous dispersion of anionic polymer precipitated in a low pH salt solution is generally used by diluting the dispersion with water so that the salt concentration is greatly reduced. At low salt concentrations, the anionic polymers become more soluble and thus dissolve. However, the rate of dissolution is a function of pH so that when the dispersion is diluted with acidic water, the polymer dissolves at an unfavorably low rate and often requires the addition of a base to raise the pH and increase the rate of dissolution. . Therefore, for practical reasons, it is preferred that the pH of the polymer dispersion is at least 4 so that pH adjustment of the dilution water is not necessary.

The effects of salts on the solubility of various substances in aqueous solutions are described in the scientific literature [Kim D. Collins and Michael W. Washabaugh, Q. Rev. Biophys., Vol. 18 (4) pp. 323-422, 1985. "Cosmotropic" salts tend to reduce the solubility of materials in aqueous solutions. There are a number of means known to those skilled in the art to determine whether a particular salt is cosmotropic. Representative salts containing anions such as sulfate, fluoride, phosphate, acetate, citrate, tartrate and hydrogenphosphate are cosmotropic. Some salts are more cosmotropic than others based on the well known "Hofmeister series" law.

The use of salts to precipitate anionic polymers is also taught in EP 183 466 B1. The present invention provides a method of dispersing a monomer in an aqueous salt solution and carrying out a polymerization to obtain a dispersion of a water-soluble polymer and simultaneously deposit the polymer as fine particles in the presence of a dispersant. Salt aqueous solutions are required to dissolve the precipitates of the monomers and polymers. As the dispersant, polymers soluble in the polymer electrolyte and / or aqueous salt solution are effective. If the deposited polymer is an anionic or cationic polymer electrolyte, the polymer electrolyte used as the dispersion is required to have the same kind of charge as the deposited polymer. Representative salts include sodium sulfate, ammonium sulfate and other strong cosmotropic salts. In the present poly (AMMPS) which is a polymer and copolymer of anionicity derived from the presence of sulfonate groups, for example, poly (2-acrylamido-2-methyl-propanesulfonate), Difficult to precipitate even at pH and high levels of cosmotropic salts.

Precipitation of anionic polymers by cationic organic salts, for example surfactants, is well known. E. D. Goddard [Colloids and Surfaces, Vol. 19 pp 301-329, 1986, incorporated herein by reference. The precipitation phenomenon is reportedly controlled by the relative concentration of the anionic polymer and the cationic organic salt, the size of the organic portion of the anionic organic salt, and the polymer type. Anionic polymer precipitation appears to occur when the counter charged cationic organic salt binds to the polymer and neutralizes the charge. A strong view is that the addition of salts weakens the binding and makes precipitation more difficult.

For example, the effect of added sodium chloride is described in the review by ED Goddard, above, page 313, and the authors added, “Adding salts is… a steady increase in the concentration of [surfactant] at which binding is initiated. It substantially reduces the affinity of the binding as shown by ... ". A similar view is developed by Y. Li and P. Dubin in Structure and Flow in Surfactant Solutions, ACS Symposium Series 578, American Chemical Society, 1994, p.328, and the authors wrote "Strong polyelectrolytes and relatives." In order to avoid precipitation in a mixture of charged [surfactant] micelles, the bond strength ... should be reduced.In practice, several methods, such as the addition of salts, are strongly electrostatically charged between the polyelectrolyte and the relative charged surfactant. Can be used to reduce interaction. "

Surprisingly, in contrast to the above technique, it has now been found that the precipitation of a number of typical water soluble anionic polymers by cationic organic salts in aqueous solutions is greatly enhanced by the addition of cosmotropic salts. Importantly, these polymers remain precipitated even at pH of 4 or higher. Therefore, according to the present invention there is provided a composition consisting of water, at least one cationic organic salt, at least one cosmotropic salt and at least one precipitated anionic water soluble polymer. Furthermore, a method for precipitating a water soluble anionic polymer in a composition comprising water and at least one cationic organic salt and at least one cosmotropic salt is also embodied in the present invention. Preferred are compositions in which the precipitated anionic polymer is dispersed in the form of droplets to produce a polymer dispersion. These polymer dispersions are present in flowable conditions at pH of 4 or more. These polymer dispersions may be stabilized by dispersants, which may be water soluble polymers, and the precipitated anionic polymer is preferably formed by polymerization of monomers in a salt solution, optionally in the presence of a dispersant.

The present invention relates to compositions of precipitated anionic polymers in solutions of cationic organic salts and cosmotropic salts, and methods of making and using the same. Compositions in which the polymer is dispersed in the form of droplets are preferred, and methods of making this polymer dispersion, which may include a dispersant, are taught herein. Particularly preferred methods are the formation of dispersed polymers by polymerization of monomers in salt solutions in the presence of one or more other water soluble polymers which may optionally act as dispersants. Since the polymer remains insoluble even above pH 4, a flowable polymer dispersion is obtained that can be readily used without adjusting the pH. Also used herein are methods of using the compositions of the present invention for applications such as flocculation of suspended solids, solid-liquid isolates, mining, papermaking, soil stabilization, and the like.

Embodiments of the present invention include a composition consisting of water, at least one precipitated anionic water soluble polymer, an effective amount of at least one cosmotropic salt and an effective amount of at least one cationic organic salt; Preferred embodiments include water, at least one precipitated anionic water soluble polymer (consisting of repeating units containing sulfonic acid, sulfonic acid salts, carboxylic acids or carboxylic acid salt groups), 0.02-12% by weight of tetraalkylammonium salts, based on the total weight And from 0.1 to 30% by weight of the sulfate salt, based on the total weight; And compositions wherein the anionic water soluble polymer is precipitated, optionally as a dispersion, in the presence of a second water soluble polymer.

Further embodiments include an effective amount of water, at least one anionic water soluble polymer, at least one cosmotropic salt and an effective amount of at least one cationic organic salt to form an aqueous composition comprising at least one precipitated cationic water soluble polymer. A method comprising mixing in any order is included; In a preferred embodiment there is a repeat containing water, at least one anionic water soluble polymer (sulfonic acid group, sulfonic acid salt group, carboxylic acid group or carboxylic acid salt group) to form an aqueous composition comprising at least one precipitated anionic water soluble polymer. Unit), mixing in any order from 0.02 to 12 weight percent tetraalkylammonium salts based on total weight and 0.1 to 30 weight percent sulfate salts based on total weight; And a method of mixing the second water soluble polymer thereto.

In another embodiment, at least one anionic monomer is polymerized in an aqueous solution consisting of an effective amount of at least one cationic organic salt and an effective amount of at least one cosmotropic salt to form an aqueous composition comprising at least one precipitated anionic polymer. A method comprising a; Preferred embodiments include 0.02 to 12% by weight of tetraalkylammonium salts and 0.1 to 30% by weight of sulfate salts based on total weight to form an aqueous composition comprising at least one precipitated anionic water soluble polymer. A method comprising polymerizing a monomer containing a sulfonic acid group, a sulfonic acid salt group, a carboxylic acid group or a carboxylic acid salt group in an aqueous solution consisting of; And anionic water soluble polymers are optionally precipitated as dispersions in the presence of a second water soluble polymer.

Application of the present invention involves the dispersion of a suspended solid by adding to the dispersion an effective amount of at least one cationic organic salt, an effective amount of at least one cosmotropic salt and an effective amount of an aqueous composition consisting of at least one precipitated anionic water soluble polymer. A method of concentrating a dispersion of suspended solids comprising dewatering and separating the resulting concentrated dispersion; Preferred embodiments include precipitated anionic water soluble polymers (consisting of repeating units containing sulfonic acid, sulfonic acid salts, carboxylic acids or carboxylic acid salt groups), 0.02 to 12% by weight of tetraalkylammonium salts and total weight based on total weight. A dispersion of suspended solids comprising dewatering suspended paper solids or suspended mineral solids and separating the resulting concentrated dispersion by adding to the dispersion an effective amount of an aqueous solution consisting of 0.1 to 30% by weight of sulfate salts on the basis of It includes a method of concentrating. In other preferred methods, the composition is a dispersion optionally containing a second water soluble polymer and is first dissolved in water prior to addition to the dispersion of suspended solids.

Further applications include adding soil to the soil an effective amount of at least one cationic organic salt, an effective amount of at least one cosmotropic salt, and a soil-conditioned amount of an aqueous composition consisting of at least one precipitated anionic water soluble polymer. A method is included; Preferred applications include precipitated anionic water soluble polymers (consisting of repeating units containing carboxylic acids, carboxylic acid salts, sulfonic acid or sulfonic acid salts), 0.02 to 12% by weight of tetraalkylammonium salts based on total weight and total weight And a soil conditioning method comprising adding to the soil an effective amount of a soil-conditioning solution prepared by diluting an aqueous composition consisting of 0.1 to 30% by weight of sulfate salt.

The present invention generally relates to aqueous compositions of certain salts containing precipitated anionic water soluble polymers, methods for precipitation of anionic water soluble polymers in aqueous solutions, and aqueous solutions containing certain salts to form precipitated anionic water soluble polymers, optionally precipitated as polymer dispersions. Processes for polymerizing monomers and methods for using the compositions of precipitated anionic water soluble polymers in aqueous solutions of specific salts for various applications, such as papermaking, mining, wastewater treatment and soil conditioning.

It has surprisingly been found that the precipitation of anionic polymers by cationic organic salts is greatly enhanced by the addition of cosmotropic salts. For the purposes of the present invention, when a particular polymer is stirred or stirred in a salt solution for a period of up to about 1 week at a certain temperature, it is precipitated in a particular salt solution when it is not dissolved to form a clear homogeneous solution. The polymer is also considered precipitated when the solution of polymer (s) in the salt solution becomes cloudy or turbid when the temperature of the solution changes. It is clear from the above that the solubility of the polymer (s) in a particular salt solution may be temperature dependent, so that the polymer precipitates in the particular salt solution at low temperatures, but vice versa. The polymer (s), salt (s) and water may be mixed in any order or the polymerization may be carried out in the presence of salt (s) or salt (s) moieties to determine the solubility of the polymer in the salt solution. The polymer may be considered to be precipitated if all or part of the polymer, ie at least 10%, is precipitated.

Those skilled in the art understand that anionic water soluble polymers are often measured by measuring cloud points of polymers in salt solutions. The cloud point of a particular polymer is defined for the purposes of the present invention as the temperature that is clouded as the substantially clear solution of the polymer is cooled. For example, a composition consisting of a water soluble anionic polymer or mixtures thereof, water and salts can be heated to dissolve the polymer and a substantially clear solution is formed. The solution is typically allowed to cool slowly until the polymer precipitates or the phases separate and the solution becomes cloudy or cloudy. The temperature at which the solution begins to cloud is the cloud point. The reproducibility of cloud points measured in this way is typically about ± 3 ° C. Less soluble polymers have higher cloud points, and more soluble polymers have lower cloud points. In some cases, cloud points are difficult to measure comfortably because the polymers are so insoluble that they cannot be dissolved by heating even upon heating to the boiling point of the salt solution. In addition, some polymers are so soluble that they do not precipitate upon cooling of the salt solution to the freezing point.

Often, a situation arises where the polymer precipitates out of the salt solution upon heating instead of cooling. In this case, the cloud point of a particular polymer in a particular salt solution is defined as the temperature at which for the purposes of the present invention it begins to cloud as the solution of the polymer is heated. Hereafter, all cloud points are those obtained at cooling, except as otherwise noted.

In addition, the polymerization of the monomers can be carried out in the presence of salt (s). For example, a predetermined amount of water, monomers and salt (s) can be mixed together and introduced under polymerization conditions. The cloud point can then be measured as above. Polymerizing monomers in the presence of salts may be particularly desirable at high polymer concentrations or high polymer molecular weights as it is difficult to properly mix the polymer and salt solution. This technique may also be desirable if the cloud point is at least 100 ° C.

Cosmotropic salts useful in the present invention may be other cosmotropic salts including sulfates, phosphates, fluorides, citrate, acetates, tartrates and hydrogenphosphates. Counterions have a minor effect on the solubility of the polymer and may be ammonium or other alkaline or alkaline earth metals such as lithium, sodium, potassium, magnesium, calcium and the like. The counterion may also be aluminum or may be a transition metal cation such as manganese or iron. However, it is preferable to use cosmotropic salts with monovalent cations due to the known tendency of anionic polymers to complex with divalent metal ions such as Ca ²⁺ . Ammonium sulfate and sodium sulfate are preferred cosmotropic salts.

R comprises esters, alkyleneoxy, alkyl or substituted alkyl having about 1 to about 22 carbons or aryl or substituted aryl having about 6 to about 22 carbons, M is monoalkyl, dialkyl, trialkyl and and cationic groups such as ammonium, including tetraalkyl ammonium, a is an anion, e.g., chloride, bromide, Yoda Id, methyl sulfate or the like general formula R _n ^- M ⁺ a ^- cationic organic salts, especially Cozmo tropic having Useful for precipitation of anionic polymers in the presence of an acid salt. R groups may be linear or branched and may be substituted with one or more cationic M groups. The cationic M group may be substituted with one or more R groups; For example, n can range from 1 to 4. Mixtures of cationic organic salts with one another are also useful in mixtures with cosmotropic salts. Tetraalkylammonium halides having 4 to 22 carbon atoms, substituted tetraalkylammonium halides having 4 to 22 carbon atoms, aryl trialkylammonium halides having 9 to 22 carbon atoms and substituted aryls having 9 to 22 carbon atoms Trialkylammonium halides are preferred. Most preferred are cetylpyridinium chloride (CPC), cetylmethylammonium chloride (CMAC) and benzyltriethylammonium chloride (BTEAC).

Effective amounts of cosmotropic salts and cationic organic salts useful for causing precipitation or phase separation depend on the temperature, the original solubility of the polymer, the concentration of the polymer, the specific cationic organic salt used, the pH and the specific cosmotropic salt used do. Effective amounts of cationic organic salts also depend on the amount of cosmotropic salts. When used without cosmotropic salts, higher amounts of cationic organic salts are generally required to cause a certain level of polymer insolubility than in the presence of cosmotropic salts. Effective amounts of cationic organic and cosmotropic salts that insolubilize certain polymers are generally from about 0.01% to about 15%, preferably from about 0.02% to about 12%, more preferably about 0.05% for cationic organic salts. To about 10%, and about 0.1% to about 30%, preferably about 0.1% to about 28%, more preferably about 5% to about 25% for cosmotropic salts. Preferably, the salt is soluble in the solution so that the upper limit of salt content is determined primarily by the ability of the solution to dissolve the salt. Effective amounts of cationic organic and cosmotropic salts useful for precipitating certain polymers can be found by routine experimentation as described herein.

Anionic polymers and copolymers can be precipitated over a wide range of pH by the practice of the present invention. For example, as described in Example A, the copolymer is prepared by copolymerizing about 50 mol% of acrylamide and 50 mol% of 2-acrylamido-2-methyl-propanesulfonic acid followed by neutralization. The resulting polymer is diluted with deionized water to form a 0.2% solution and the solubility of the polymer is measured in various salt solutions at pH 4.6 as described in Examples B, C, D and 1. At 0.2% BTEAC, the polymer solution is in a clear state but has a cloud point of 42 ° C. in 28% ammonium sulfate. However, when 0.2% BTEAG and 28% ammonium sulfate are present, the same polymer has a cloud point of 105 ° C. or higher. The cloud point is increased because the combination of BTEAC and ammonium sulfate is more effective at precipitating the polymer than the salt alone.

Polymers useful in the practice of the present invention may be water soluble anionic polymers prepared by the polymerization and copolymerization of anionic monomers and anionic charged polymers after polymerization takes place. Preference is given to polymers having repeating units containing anionic groups such as carboxylic acids, carboxylic acid salts, sulfonic acids, sulfonic acid salts and / or combinations thereof. These polymers are typically prepared by polymerizing monomers containing anionic groups such as carboxylic acids, carboxylic acid salts, sulfonic acids, sulfonic acid salts and / or combinations thereof. Most preferred are polymers prepared by polymerizing acrylic acid and 2-acrylamido-2-methyl-propanesulfonic acid. The molar percentage of anionic repeat units in the polymer is from about 1 mole% to about 100 mole%, preferably from about 2 mole% to about 90 mole%, more preferably from about 5 mole%, based on the total moles of recurring units in the polymer. About 70 mol%, most preferably about 8 mol% to about 50 mol%.

Anionic copolymers may also be prepared by copolymerizing anionic monomers with other anionic comonomers, nonionic comonomers and / or cationic comonomers. Anionic monomers may include acrylic acid, methacrylic acid, vinyl sulfate, 2-acrylamido-2-methylpropane sulfonic acid, styrene sulfonic acid, salts thereof, and the like. Anionic charged polymers after polymerization include polymers made by hydrolysis of cellulose, polymers made by hydrolyzing and / or hydroxamateizing polyacrylamide and polymers made from maleic anhydride.

The present invention is particularly useful for precipitating polymers having at least 15 mol% of AMMPS units, based on the total moles of repeat units in the polymer, since the polymers are unlikely to precipitate in aqueous salt solutions containing no cationic organic salts. . For example, copolymers of acrylamide with AMMPS having a mole% AMMPS of at least 15% used to prepare the polymer are readily precipitated according to the invention in a mixture of BTEAC and (NH ₄ ) ₂ SO ₄ .

Nonionic monomers include substantially water-soluble monomers such as acrylamide, methacrylamide and N-isopropylacrylamide or rarely water-soluble monomers such as t-butylacrylamide, N, N-dialkylacrylamide , Diacetone acrylamide, ethyl acrylate, methyl methacrylate, methyl acrylate, styrene, butadiene, ethyl methacrylate, alkyl (meth) acrylate esters, acrylonitrile and the like. Nonionic monomers also include monomers that are charged at low pH, such as dimethylaminoethylacrylate, diethylaminoethylacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate. (Alk) acrylates and corresponding acrylamide derivatives such as methacrylamidopropyldimethylamine can be included. Preferred nonionic monomers are acrylamide, t-butyl acrylamide, methacrylamide, methyl methacrylate, ethyl acrylate, acrylonitrile and styrene.

Cationic monomers include salts of dialkylaminoalkyl (alk) acrylates, such as dimethylaminoethylacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate and Salts of the corresponding acrylamide derivatives, such as methacrylamidopropyldimethylamine, and other cationic monomers such as diallyldimethylammonium chloride, diallyldiethylammonium chloride and the like. On a molar basis, the polymer is amphoteric but the polymer should contain less cationic repeat units than the anionic repeat units to maintain the net negative charge. Preferably, the polymer contains up to 10 mol% of cationic repeat units based on the total moles of repeat units in the polymer.

Mixtures of one or more polymers may be precipitated by the practice of the present invention. The polymer may be mixed together with some or all of the salt solution before, during or after mixing. Mixtures of polymers tend to precipitate one or more polymers into the mixture, but can be separated from each other by using salt solutions that are solvents for one or more other polymers in the mixture. Additional salts may be added before, during or after the precipitation process. The polymer (s) may also be formed by the polymerization of monomers in the presence of other polymer (s) which may themselves precipitate or dissolve in the salt solution.

The polymerization of the monomers can be carried out by methods known in the art, including solutions, bulks, precipitates, dispersions, suspensions, emulsions, microemulsions and the like. The polymerization of the monomers can be carried out in the presence of some or all of the salt solution. Peroxides such as t-butyl peroxide; Azo compounds such as azoisobisbutyronitrile; Initiation is carried out with various thermal and redox free radical initiators, including inorganic compounds such as potassium persulfate and redox couples such as ferrous ammonium sulfate / ammonium persulfate and sodium bromate / sulfur dioxide Can be. Initiator addition can be effected before actual initiation. The polymerization can also be carried out by a photochemical irradiation method, for example by ultraviolet irradiation or ionization irradiation from a cobalt 60 source. Both monomers may be present when the polymerization is initiated or some monomer may be added at a later stage of the polymerization. The polymerization can be carried out in a number of steps. Additional materials such as pH adjusters, stabilizers, chelating agents, promoters and the like can also be added before, during or after the polymerization.

The molecular weight of the polymer precipitated or phase separated by the practice of the present invention is not particularly critical. The weight average molecular weight of the polymer may range from about 1,000 to about 100,000,000, preferably from about 100,000 to about 75,000,000, more preferably from about 1,000,000 to about 60,000,000. The concentration of polymer in the composition may range from 0.01% to 90%, or often higher. For practical reasons as desired, it is generally desirable to keep the production and dropping costs relatively low and the polymer level in the composition as high as possible.

Compositions of salt solutions useful for precipitating anionic polymers may be prepared by simply dissolving the desired salt in water, preferably with stirring. The water useful in the practice of the present invention is not particularly critical and may be from water, such as distilled water, tap water, recycle water, process water, ground water and the like. However, care should be taken to avoid water with high concentrations of divalent cations, such as Ca ⁺² , which are known to complex with anionic polymers. Precipitation of the anionic polymer in the salt solution may be carried out by mixing the salt solution and the polymer solution or polymer emulsion in any order. Substantially dry polymer granules of the water soluble polymer may be added to the salt solution to form a composition comprising salt, water and precipitated polymer. Anionic water soluble polymers can also be formed by polymerization of monomers in the presence of salts. All or part of the polymer may precipitate.

It is preferable to polymerize the monomers in the salt solution to form the polymer dispersion. For the purposes of the present invention, when some or all of the precipitated polymer is in the form of droplets dispersed in an aqueous salt solution, the precipitated polymer is a polymer dispersion. Precipitated polymer droplets may contain salts and water. Some or all of the polymer may precipitate. The droplet size may range from about 0.05 microns to about 1 millimeter, preferably from about 0.08 microns to about 100 microns, more preferably from about 0.1 microns to about 25 microns, and most preferably from about 0.15 microns to about 15 microns. . As above, the monomer (s) and salt (s) can be added to the stage during the polymerization or both can be present at the start. Initiation of polymerization may be carried out in the same manner as described above.

Dispersed polymer droplets may tend to settle upon standing. Surprisingly, it has been found that certain water soluble polymers, referred to herein as dispersants, tend to assist droplet formation and also to stabilize droplets against sedimentation. Polymeric dispersants stabilize the polymer dispersion but do not allow anionic water-soluble polymers to be deposited. As above, the salt combination causes the anionic water soluble polymer to precipitate. Poly (AMMPS), polyacrylamide, and copolymers of acrylamide with predetermined amounts of cationic, nonionic and anionic monomers have been found to reduce the sedimentation rate of the polymer dispersion. Without dispersants, polymer droplets tend to settle over time and can be merged to form a layer separated from the aqueous phase. However, if the same polymerization is carried out in the presence of a water soluble polymer such as poly (AMMPS), polyacrylamide, or a copolymer of acrylamide with a predetermined amount of cationic, nonionic and anionic monomers, the sedimentation rate is Advantageously a reduced and predominant polymer dispersion is obtained.

Polymers useful as dispersants may include polyacrylamides and other nonionic polymers such as poly (methacrylamide), poly (vinyl alcohol), poly (ethylene oxide), and the like. Preferred dispersants are anionic polymers such as poly (acrylic acid), poly (AMMPS), copolymers of acrylic acid and acrylamide, and copolymers of AMMPS and acrylamide. Preferably, the dispersant is water soluble or mainly soluble in certain salt solutions. It is generally desirable to have greater solubility in certain salt solutions than the precipitated polymer droplets in which the dispersant is dispersed. Copolymers useful as dispersants have up to about 20 mole percent, preferably about 5 to about 15 mole percent, cationic comonomers, such as dialkylaminoalkyl (alk), based on the total moles of repeat units in the polymer. Acrylates, quaternary salts of diallyldialkylammonium halides, and the like. Other copolymers useful as dispersants include up to about 99 mole% of anionic comonomers, such as sodium 2-acrylamido-2-methylpropane sulfonic acid, based on the total moles of acrylamide and repeat units in the polymer. Copolymers, preferably from about 5 to about 95 mol% comonomer, most preferably from about 25 to about 75 mol% comonomer. Anionic monomers may include acrylic acid, styrene sulfonic acid, salts thereof, and the like. Nonionic comonomers include substantially water-soluble monomers such as methacrylamide or t-butylacrylamide, diacetone acrylamide, ethyl acrylate, methyl methacrylate, methyl acrylate, styrene, butadiene, ethyl methacrylate, acrylo Rarely water soluble monomers such as nitrile and the like can be included. Preferred nonionic monomers are acrylamide, t-butyl acrylamide, methacrylamide, methyl methacrylate, ethyl acrylate and styrene.

Dispersants are generally in an amount ranging from about 25% or less, preferably from about 1% to about 20%, more preferably from about 5% to about 15%, based on the total weight of the precipitated anionic polymer droplets to be dispersed. Used. Dispersants are not used in amounts that cause precipitation of the anionic polymer in the absence of cationic organic salts and cosmotropic salts. The weight average molecular weight of the dispersant polymer may range from about 1,000 to about 50,000,000, preferably from about 50,000 to about 10,000,000, more preferably from about 100,000 to about 5,000,000.

Anionic polymers can be precipitated over a wide range of pH by the practice of the present invention as illustrated in Examples 1, 2 and 3. The anionic polymer can be precipitated and the polymer dispersion can be prepared at a pH in the range of about 2 to about 12, preferably about 4 to about 10, more preferably about 5 to about 9. pH measurement methods are well known to those skilled in the art.

Routine experiments used to identify combinations of cationic organic salts, cosmotropic properties, temperature and pH, which will precipitate certain concentrations of specific anionic water soluble polymers can be performed in a number of ways. One method is by the above cloud point technology. For example, to measure cloud points of 1% poly (AMMPS), 0%, 5%, 10%, 15% or 20% ammonium sulfate and 0%, 0.02%, 0.04%, 0.06%, 0.08 Thirty samples of 1% aqueous poly (AMMPS) can be prepared containing both% or 0.1% cetylpyridinium chloride in combination at a particular pH. The cloud point of each solution is then measured by heating each sample to dissolve the polymer and then cooling until the solution becomes cloudy. Claudenis will indicate precipitation, and the temperature at which this occurs is the cloud point. This method can be repeated for any other polymer, polymer concentration, pH or salt. Typically, some samples remain transparent even below 0 ° C., while others remain cloudy when heated above 100 ° C. Although cloud point information cannot be obtained from these samples, one will know the phase behavior of a particular polymer for a particular salt system. If precipitation is observed upon heating and the polymer is dissolved upon cooling, the cloud point can be measured by cooling until the polymer is dissolved and then heating to precipitate the polymer. In this case, the cloud point will be the temperature at which Claudenis is observed upon heating.

Cloud points need not be measured to obtain solubility information. For example, a series of solutions containing varying amounts of cationic organic and cosmotropic salts can be prepared at a particular pH and then a polymer solution can be added to each salt solution. The polymer will be in the precipitated or dissolved state as measured by simple visual inspection, and the solubility behavior of the polymer can be correlated with each salt type and concentration.

A routine experimental method for identifying a combination of salt and temperature that will precipitate a particular anionic polymer is to polymerize the monomers in the salt solution and then measure the cloud points. For example, high concentrations of polymers are preferred for this technique, since concentrated solutions of at least 10% of the polymers may be difficult to manipulate, for example, to stir. This method is similar to the cloud point method in that it produces a series of salt solutions in which the monomer (s) are dissolved at the concentrations necessary to provide a polymer of the desired concentration. The solution can then be polymerized in a known manner, for example sparged with an inert gas, for example nitrogen, and then the polymerization is initiated by conventional free radical initiators to form a mixture of polymer and salt.

Routine experimental methods for identifying combinations of temperatures and salts that do not dissolve certain substantially dry water soluble polymer powders or granules are similar to the above methods. A series of salt solutions are also prepared as above and then dry polymer is added to produce a composition having a polymer of the desired concentration. The mixture is then stirred and heated to effect dissolution of the polymer. Information can then be obtained by direct observation as to whether or not the polymer is dissolved in a particular solution; Temperature dependent phase behavioral information can be obtained from these solutions representing the cloud points above.

The precipitated polymer can be recovered from the salt solution by methods known in the art, filtration, centrifugation, evaporation, spray drying, combinations thereof, and the like. The recovered polymer granules typically contain an anionic water soluble polymer, remaining salts, optionally remaining residue dispersants and water. Preferably, the resulting polymer granules contain up to about 30%, more preferably from about 0.1% to about 20%, most preferably from about 1% to about 15% of water. Substantially dry free flowing polymer granules are preferred for handling purposes. Various pH regulators, flow regulators, preservatives, particle size regulators and the like, known to those skilled in the art, can be added at some stage of the process to produce substantially dry granules containing anionic water soluble polymer.

The compositions and methods of the present invention are useful in many applications, for example, flocculation of suspended solids, recovery of minerals from mining operations, papermaking, enhanced oil recovery, treatment of refined waste, treatment of food waste, and the like. Preference is given to applications for dewatering dispersions of suspended minerals and dispersions of suspended cellulose or paper solids, for deinking paper and for dewatering biological sludge. In order to be effective for these applications, the composition of the precipitated polymer is subjected to a dispersion of the suspended solids to be treated and mixed and the resulting concentrated separated by means known in the art such as centrifugation, belt presses, filter presses, filters and the like. It can be added directly to the dispersion. Preferably, the composition is first diluted with water to form a solution having an anionic polymer concentration of from about 0.01 to about 10%, preferably from about 0.05 to about 5%, more preferably from about 0.1 to about 3%. The diluted polymer solution can then be mixed with a dispersion of suspended solids to be treated by known methods and the resulting concentrated dispersion separated as above. It is known to those skilled in the art that dilute polymer solutions effective for a particular application can be found through routine experimentation.

Substantially dry polymer granules and polymer dispersions are preferred because they promote faster dissolution of polymers of small granule or droplet size upon polymer dilution. Despite the presence of salts that tend to precipitate the polymer, it is believed that the polymer dissolves since the salt concentration decreases from an effective range to a range that allows the polymer to dissolve by dilution.

Particularly preferred applications of the water soluble anionic polymers of the invention are, for example, soil conditioning for soil erosion prevention. Intestinal relations may tend to cause adverse loss of valuable topsoil by erosion. The soil mixes (a) one or more cationic organic salts, one or more cosmotropic salts and precipitated anionic water soluble polymers or mixtures thereof, in particular where the soil is concerned, (b) water and (c) soil It can be stabilized against erosion by a method comprising a. The addition of polymers to the soil in soil-conditioned amounts tends to produce greater cohesion between the particles of the soil such that the soil is stabilized against erosion by wind, water and the like. Preferably, the composition is then dissolved in water upon addition to water typically used to form an intestinal solution that can be applied to the soil, preferably to relate the intestines. The concentration of the polymer in the conditioned solution is generally from about 0.1 parts to about 500 parts, preferably from about 1 ppm to about 100 ppm, more preferably from 5 ppm to about 50 ppm per million parts of solution.

The soil-conditioned amount of the composition of the present invention can be determined by actual field trials or by laboratory tests. For example, to determine the amount of precipitated anionic polymer composition useful for conditioning certain soils, the composition may first be dissolved in water to form a conditioning solution. Various amounts of conditioned solution may then be stirred and allowed to settle with various amounts of soil and water in a series of containers. The turbidity of the supernatant in each vessel is then typically a good indicator of polymer potency and polymer capacity for soil conditioning. For example, high turbidity values above 500 Nefeltro turbidity units (nfu) may indicate that the polymer (s) dose will not be particularly effective for specific soil conditioning, whereas, for example, 25 nfu or less Low turbidity values may indicate that the polymer and polymer amount are effective for the conditioning of certain soils.

Also, less preferably, polymer dispersions or substantially dry polymers may be applied directly to the soil. In this case, the polymer may form a conditioned solution when combined with water already present in the soil, or by subsequent application of water to dissolve the polymer. In irradiation applications, the amount of soil-conditioning is generally in the range of about 0.1 to about 20 pounds polymer per year per acre, preferably 1 to 10 pounds per year per acre.

Soil erosion can also take the form of large-scale migration of soil, eg, slopes, to which soil is not typically associated. For example, the destruction of vegetation on hillsides by fire can leave the underlying soil unstable and mobile. In addition, polymer dispersions or dry polymers may be applied directly to the soil. In this case, the polymer will form a conditioning solution when combined with water already present in the soil, or by subsequent water application to dissolve the polymer.

The following examples are described for illustrative purposes only and should not be construed as limitations on the present invention.

Viscosity measurement

Standard viscosity (SV) is the viscosity of a 0.096% solution of water soluble polymer in 1 N sodium chloride at 25 ° C. Viscosity is measured by a Brookfield LVT Viscometer with a UL adapter of 60 rpm. The polymer solution to be measured is prepared by diluting the polymer dispersion or solution to a concentration of 0.2% by stirring with a suitable amount of deionized water for about 12 hours, followed by dilution with a suitable amount of deionized water and sodium chloride. The bulk viscosity (BV) of the polymer dispersion is the viscosity of the polymer measured at 30 rpm and 25 ° C. by a Brookfield LVT viscometer with spindle 4.

pH measurement

The pH measurement consists of a Jenco Electronis Microcomputer pH-Vision 6071R, Model 6000E, equipped with a 3-in-1 electrode, a conventional electrical pH meter. The pH meter is calibrated with buffer solutions commercially available at pH 4.00 and pH 7.01.

Example A

50/50 mole% poly (acrylamide / AMMPS) copolymer was added to 49.77 parts of 53.88% acrylamide solution, 78.97 parts of 99% 2-acrylamido-2-methyl-propanesulfonic acid, 5% sodium ethylenediaminetetraacetate (EDTA ) (Chelating agent) 3.02 parts, 30.3 parts of a 50% NaOH solution and 563.79 parts of deionized water are prepared by adding to a suitable vessel equipped with mechanical agitation. The solution is stirred at 30 ° C. and 1.05 parts of ammonium persulfate and 3.5 parts of 30% sodium meta-bisulfite solution are added. The solution is deoxidized by sparging with nitrogen and at the same time raising the temperature to about 50 ° C. After 10 hours of stirring at 50 ° C., the viscous polymer solution is allowed to cool to produce a 50/50 mol% poly (acrylamide / AMMPS) solution having a polymer content of about 15% by weight. A portion of the polymer solution is diluted with deionized water for solubility measurement to produce a 2% polymer solution.

Example B

About 12 parts of deionized water is added to a suitable vessel followed by about 1.5 parts of a 2% solution of BTEAC. About 1.5 parts of a 2% solution of 50/50 mol% poly (acrylamide / AMMPS) prepared in Example A are added with stirring to produce a clear solution. The pH is adjusted to about 4.6 by adding diluted hydrochloric acid. The solution is present in a clear state and demonstrates that 0.2% 50/50 poly (acrylamide / AMMPS) does not precipitate in a 0.2% solution of BTEAC.

Example C

About 9.26 parts of deionized water is added to a suitable container followed by about 4.24 parts of 99.1% ammonium sulfate and about 1.5 parts of about 2% BTEAC; The mixture is dissolved by stirring the salt. A clear solution with a pH of about 4.6 is produced, demonstrating that 0.2% BTEAC does not precipitate in the 28% ammonium sulfate solution.

Example D

About 9.26 parts of deionized water is added to a suitable vessel followed by about 4.24 parts of 99.1% ammonium sulfate; The mixture is dissolved by stirring the salt. About 1.5 parts of a 2% solution of 50/50 mol% poly (acrylamide / AMMPS) prepared in Example A are added with stirring to produce a cloudy mixture having a pH of about 4.6. The mixture is heated with stirring until it is clear and then allowed to cool slowly. The solution is cloudy at 42 ° C., demonstrating that 0.2% 50/50 mol% poly (acrylamide / AMMPS) has a cloud point of 42 ° C. in a 28% ammonium sulfate solution.

Example 1

About 7.76 parts of deionized water is added to a suitable vessel followed by about 4.24 parts of 99.1% ammonium sulfate; The mixture is dissolved by stirring the salt. About 1.5 parts of a 2% solution of 50/50 mol% poly (acrylamide / AMMPS) prepared in Example A are added with stirring to produce a cloudy mixture of pH 4.6. The mixture is heated with stirring to a temperature of about 105 ° C. or less without dissolving the precipitated polymer. The results demonstrate that 0.2% 50/50 poly (acrylamide / AMMPS) has cloud points above 105 ° C. in a solution of 28% ammonium sulfate and 0.2% BTEAC. The cloud point of the polymer is higher in the mixture of 28% ammonium sulfate and 0.2% BTEAC than in 28% ammonium sulfate alone (Example D) or 0.2% BTEAC alone (Example B).

Example E

About 12 parts of deionized water is added to a suitable vessel followed by about 1.5 parts of a 2% solution of BTEAC. About 1.5 parts of a 2% solution of 50/50 mol% poly (acrylamide / AMMPS) prepared in Example A are added with stirring to produce a clear solution. The pH is adjusted to about 8.5 by addition of NaOH solution. The solution is present in a clear state and demonstrates that 0.2% 50/50 poly (acrylamide / AMMPS) does not precipitate in a 0.2% solution of BTEAC at pH 8.5.

Example F

About 9.26 parts of deionized water is added to a suitable container followed by about 4.24 parts of 99.1% ammonium sulfate and about 1.5 parts of about 2% BTEAC; The mixture is stirred to dissolve the salt. The resulting clear solution is present in a clear state after adjusting the pH to about 8.5 by adding NaOH, demonstrating that 0.2% BTEAC does not precipitate in a 28% ammonium sulfate solution at pH 8.5.

Example G

About 9.26 parts of deionized water is added to a suitable vessel followed by about 4.24 parts of 99.1% ammonium sulfate; The mixture is dissolved by stirring the salt. About 1.5 parts of a 2% solution of 50/50 mol% poly (acrylamide / AMMPS) prepared in Example A are added with stirring to produce a cloudy mixture having a pH of about 4.6. The pH is adjusted to 8.5 by addition of NaOH solution. The mixture is heated with stirring until it is clear and then allowed to cool slowly. The solution was clouded at 33 ° C. and 0.2% 50/50 mol% poly (acrylamide / AMMPS) had a cloud point of 42 ° C. (Example D) in a solution of 33 ° C. versus pH 4.5 in a 28% ammonium sulfate solution at pH 8.5 Prove you are.

Example 2

About 7.76 parts of deionized water is added to a suitable vessel followed by about 4.24 parts of 99.1% ammonium sulfate; The mixture is dissolved by stirring the salt. About 1.5 parts of 2% BTEAC are added with stirring to produce a cloudy solution. About 1.5 parts of a 2% solution of 50/50 mol% poly (acrylamide / AMMPS) prepared in Example A are added with stirring to produce a cloudy mixture of pH 4.6. The pH is adjusted to 8.5 by addition of NaOH solution. The mixture is heated with stirring to a temperature of about 105 ° C. or less without dissolving the precipitated polymer. The results demonstrate that 0.2% 50/50 poly (acrylamide / AMMPS) even has cloud points above 105 ° C. in a solution of 28% ammonium sulfate and 0.2% BTEAC at about pH 8.5. The cloud point of the polymer is higher in the mixture of 28% ammonium sulfate and 0.2% BTEAC than in 28% ammonium sulfate alone (Example G) or 0.2% BTEAC alone (Example E).

Example H

About 12 parts of deionized water is added to a suitable vessel followed by about 1.5 parts of a 2% solution of BTEAC. About 1.5 parts of a 2% solution of 50/50 mol% poly (acrylamide / AMMPS) prepared in Example A are added with stirring to produce a clear solution. The pH is adjusted to about 6.4 by addition of NaOH solution. The solution is present in a clear state and demonstrates that 0.2% 50/50 poly (acrylamide / AMMPS) does not precipitate in a 0.2% solution of BTEAC at pH 6.4.

Example I

About 9.26 parts of deionized water is added to a suitable container followed by about 4.24 parts of 99.1% ammonium sulfate and about 1.5 parts of about 2% BTEAC; The mixture is stirred to dissolve the salt. The resulting clear solution is in a clear state after adjusting the pH to about 6.4 by adding NaOH, demonstrating that 0.2% BTEAC does not precipitate in a 28% ammonium sulfate solution at pH 6.4.

Example J

About 9.26 parts of deionized water is added to a suitable vessel followed by about 4.24 parts of 99.1% ammonium sulfate; The mixture is dissolved by stirring the salt. About 1.5 parts of a 2% solution of 50/50 mol% poly (acrylamide / AMMPS) prepared in Example A are added with stirring to produce a cloudy mixture having a pH of about 4.6. The pH is adjusted to 6.4 by addition of NaOH solution. The mixture is heated with stirring until it is clear and then allowed to cool slowly. The solution was clouded at 39 ° C. and 0.2% 50/50 mol% poly (acrylamide / AMMPS) was dissolved in a solution of 39 ° C. versus pH 4.5 in a 28% ammonium sulphate solution of pH 6.4 (Example D) and pH 8.5 Prove to have a cloud point of 33 ° C. (Example G) in a solution.

Example 3

About 7.76 parts of deionized water is added to a suitable vessel followed by about 4.24 parts of 99.1% ammonium sulfate; The mixture is dissolved by stirring the salt. About 1.5 parts of 2% BTEAC are added with stirring to produce a cloudy solution. About 1.5 parts of a 2% solution of 50/50 mol% poly (acrylamide / AMMPS) prepared in Example A are added with stirring to produce a cloudy mixture of pH 4.6. The pH is adjusted to 6.4 by addition of NaOH solution. The mixture is heated with stirring to a temperature of about 105 ° C. or less without dissolving the precipitated polymer. The results demonstrate that 0.2% 50/50 poly (acrylamide / AMMPS) even has cloud points above 105 ° C. in a solution of 28% ammonium sulfate and 0.2% BTEAC at about pH 6.4. The cloud point of the polymer is higher in the mixture of 28% ammonium sulfate and 0.2% BTEAC than in 28% ammonium sulfate alone (Example J) or 0.2% BTEAC alone (Example H).

Example 4

A copolymer of 22.5 mol% acrylic acid and 77.5% acrylamide is prepared in the form of a polymer dispersion of pH 4.3 as follows: about 1.97 parts of 98% CPC, 48.41 parts of 53.88% acrylamide, 7.75 parts of 99% acrylic acid, 99% ammonium 60.38 parts of sulfate, 2.98 parts of 5% sodium ethylenediaminetetraacetate (EDTA) (chelating agent), 4.01 parts of 28% NH ₄ OH solution and 60.38 parts of deionized water are added to a suitable vessel equipped with mechanical agitation. The mixture is stirred to form a clear solution. About 0.51 part of ammonium persulfate is added followed by 73.6 parts of 15% poly (2-acrylamido-2-methyl-propanesulfonic acid) (commercial dispersion) to give a milky white pH of 3.2. About 3.04 parts of a 28% NH ₄ OH solution is added to raise the pH to 4.3. The mixture is deoxidized for 3 minutes by sparging with nitrogen and simultaneously raising the temperature to about 50 ° C. About 5 parts of 20% sodium metabisulfite solution are added over a 20 minute course. The reaction is stirred at 50 ° C. for about 5 hours and then allowed to cool. The resulting polymer dispersion has a viscosity of about 5100 centipoise and a pH of about 4.2. The standard viscosity of the polymer is about 4.2 centipoise, indicating high molecular weight.

Example K

In Example 4, except that a copolymer of 22.5 mol% acrylic acid and 77.5% acrylamide added 73.6 parts of deionized water instead of 73.6 parts of 15% poly (2-acrylamide-2-methyl-propanesulfonic acid) as a dispersant As prepared at pH 4.3. Instead of forming a low viscosity dispersion, the polymer precipitates in the form of a gelatinous white material that cannot be stirred.

Example 5

The conditioned solution is prepared by diluting the dispersion prepared as in Example 4 with deionized water such that the concentration of dissolved polymer in the resulting conditioned solution is 0.1%. About 3 parts of soil are added to a separate vessel containing 100 parts of deionized water, the mixture is stirred vigorously and 1.0 part of the conditioning solution is added. The resulting mixture is stirred for 15 minutes and then allowed to settle for 15 minutes. The turbidity of the supernatant is about 11 ± 5 nfu, as measured by a manual-keeping turbidimeter, and the composition appears to be useful for soil conditioning.

Example L

Example 5 is repeated except that deionized water is used instead of the conditioned solution. The turbidity of the supernatant is at least 1000 ntu.

Example M

Example 5 is repeated except that the conditioned solution contains a commercially available copolymer of acrylamide and acrylic acid known to be useful for soil conditioning instead of the polymer prepared as in Example 4. The turbidity of the supernatant is 8.1 ± 5 nfu.

The compositions and methods of the present invention are useful in many applications, for example, flocculation of suspended solids, recovery of minerals from mining operations, papermaking, enhanced oil recovery, treatment of refined waste, treatment of food waste, and the like.

Claims (10)

An effective amount of water, at least one anionic water soluble polymer, at least one cosmotropic salt and an effective amount of at least one cationic organic salt are in any order to form an aqueous composition comprising at least one precipitated anionic water soluble polymer. A method comprising mixing. Polymerizing at least one anionic monomer in an aqueous solution consisting of an effective amount of at least one cationic organic salt and an effective amount of at least one cosmotropic salt to form an aqueous composition comprising at least one precipitated anionic water soluble polymer. How to. The dispersion of the suspended solid is dehydrated by adding to the dispersion an effective amount of at least one cationic organic salt, an effective amount of at least one cosmotropic salt and an effective amount of an aqueous composition consisting of at least one precipitated anionic water soluble polymer, A method of concentrating a dispersion of suspended solids comprising isolating the concentrated dispersion. Adding to the soil an effective amount of at least one cationic organic salt, an effective amount of at least one cosmotropic salt and a soil-conditioned amount of an aqueous composition consisting of at least one precipitated anionic water soluble polymer. 5. The tetraalkylammonium halide having 4 to 22 carbon atoms, substituted tetraalkylammonium halide having 4 to 22 carbon atoms, 9 to 22 carbons according to claim 1. Aryl trialkylammonium halides having atoms and substituted aryl trialkylammonium halides having 9 to 22 carbon atoms. The method of claim 1, wherein some or all of the precipitated anionic water soluble polymer is precipitated as a polymer dispersion. A composition consisting of water, at least one precipitated anionic water soluble polymer, an effective amount of at least one cosmotropic salt and an effective amount of at least one cationic organic salt. 8. The method of claim 7, wherein the cationic organic salt is tetraalkylammonium halide having 4 to 22 carbon atoms, substituted tetraalkylammonium halide having 4 to 22 carbon atoms, aryl trialkylammonium having 9 to 22 carbon atoms A composition selected from the group consisting of halides and substituted aryl trialkylammonium halides having 9 to 22 carbon atoms. The composition of claim 7 or 8, wherein some or all of the precipitated anionic water soluble polymer is precipitated as a polymer dispersion. 10. The composition according to any one of claims 7 to 9, wherein the precipitated anionic water soluble polymer contains repeating units having an anionic group selected from the group consisting of carboxylic acid, carboxylic acid salt, sulfonic acid and sulfonic acid salt.