MXPA99002789A - Anionic water-soluble polymer precipitation in salt solution - Google Patents

Abstract

This invention relates to aqueous compositions of precipitated anionic polymers in solutions of cationic organic salts and cosmotropic salts, as well as process for making and using the same.

Description

PRECIPITATION OF A SOLUBLE POLYMER IN WATER, ANIONIC, IN A SALT SOLUTION Field of the Invention This invention relates in general to aqueous compositions of certain salts which contain water-soluble, anionic, precipitated polymers, to methods for precipitating water-soluble, anionic polymers, in aqueous solutions containing certain salts, to methods for polymerizing the monomers in aqueous solutions containing certain salts to form water-soluble, anionic, precipitated polymers, optionally precipitated as polymer dispersions, and to methods for using the compositions of the water-soluble, anionic, precipitated polymers, in aqueous solutions of certain salts for various applications, for example papermaking, mining, wastewater treatment, and soil conditioning.

Background of the Invention Water-soluble anionic polymers, from Ref.029707 high molecular weight, are useful in various applications for example in the flocculation of suspended solids, recovery of minerals from mining operations, removal of water from coal waste, manufacturing of paper, the de-inking of pulps, improved oil recovery, waste water treatment, soil conditioning, etc. In many cases, the polyelectrolytes are supplied to the user in the form of substantially dry polymeric granules. The granules can be manufactured by the polymerization of water-soluble monomers, in water, to form a water-soluble polymer solution, followed by dehydration and milling to form polymeric water-soluble granules. Other means for isolating the polymer from the polymer solution is to precipitate the polymer by mixing the polymer solution with an organic solvent for example acetone or methanol, which is not a solvent for the polymer, then isolating the polymer by evaporation or filtration. However, in many cases, this method is inconvenient, expensive and dangerous because of the problem of handling large amounts of flammable organic solvent.

Water-soluble anionic polymers can also be supplied in the form of a water-in-oil emulsion or microemulsion, wherein the droplets of the polymer solution are isolated from one another by the continuous oily phase. The polymer emulsions can be used directly in the desired application, or by dilution in water in the presence of a "breaker" surfactant. Although this mode of delivery is convenient and can avoid the need for dehydration, the oil can be expensive and often flammable; In addition, the oil may also present a secondary contamination problem. Alternatively, the emulsion may be precipitated in an organic liquid which is a solvent for water and oil, but is not a solvent for the polymer, followed by isolation and drying to recover the substantially dry polymer. However, these precipitation methods can be disadvantageous for the same reasons mentioned above. Processes for preparing water-soluble polymers in the form of non-tacky, hard, swollen granules are described in U.S. Pat. No. 3,336,270. The water-soluble polymers were prepared by dissolving the acrylamide-type monomers in water-tertiary butanol mixtures and allowing the monomer to polymerize to give polymers that precipitate out of the water-tertiary butanol mixture. A first water-soluble polymer can also be dispersed in the presence of a second water-soluble polymer to form aqueous polymer dispersions, as taught in U.S. Pat. Nos. 4,380,600 and 5,403,883. Since the two polymers do not dissolve with each other, the first water-soluble polymer is said to form small globules which are dispersed in the solution of the second water-soluble polymer. Optionally, salt can be added to improve the ability to flow. The U.S. patent No. 3,891,607 described thermoreversible coacervates that were produced by copolymerizing from 30 to 50 mole percent of acrylic acid and from 70 to 30 mole percent of acrylamide in aqueous solution, lowering the pH to below 3.3 and adjusting the temperature below the transition temperature of the coacervate. The U.S. Patent No. 3,658,772 discloses a process for the copolymerization of acrylic acid in a solution containing 0.1 to 10 percent of the salt, by weight, based on total weight, to form a polymerized material in the form of a fluid suspension of solid, dispersed polymer particles. Hereinafter, all concentrations, unless stated otherwise, are expressed as percent by weight of the total weight. Significantly, the pH of the polymerization was in the range of 1 to 3.2, and it was reported that by increasing the pH to 4 and above, it led to gel polymerized, non-fluid materials, apparently because of the increased solubility of the form of the polymer. salt of acrylic acid at higher pH. In U.S. Pat. No. 3,493,500; the pH range was increased to a value as high as 4 including a water-soluble, cationic polymer, in the formulation, in an amount from about 0.03 to 0.2 parts, per parts by weight of the polymeric solids of acrylic acid. However, in no case fluid suspensions were obtained at pH values higher than 4. Japanese Patent Publication No. 14907/1971 describes a method for the copolymerization of acrylic acid and acrylamide in saline solutions to form a polymerized material able to flow. The copolymerization was carried out at a pH of 1 to 4 in the presence of 0.1-60% by weight of the inorganic salt. In several systems containing 90/10 acrylic acid and acrylamide and 50/50 acrylic acid and acrylamide, if the pH of the polymerization system was increased to 4 or more, polymerized gel materials which can not flow were produced. The homopolymer of acrylic acid could be manufactured as a "suspended compound" at a pH of 4 or slightly higher. The aqueous dispersions of the anionic polymers which are precipitated in the saline solutions at low pH are generally used by diluting the dispersion in water so that the concentration of the salt is greatly reduced. At low salt concentrations, the anionic polymers become more soluble and therefore dissolve. However, the rate of dissolution tends to be a function of pH, so that if the dispersions are diluted in acidic water, the polymer dissolves at a disadvantageously slow rate, often necessitating the addition of a base to raise the pH and increase the dissolution speed. Therefore, for practical reasons, it is desirable that the pH of the polymer dispersion be higher than 4 so that the pH adjustment of the dissolution water is unnecessary. The effect of the salts on the solubility of various substances in the aqueous solution is well described in the scientific literature, for example, Kim D. Collins and Michael. Washabaugh, Q. Rev. Biophys., Vol. 18 (4) pp.323-422, 1985. "Cosmotropic" salts tend to reduce the solubility of the substances in the aqueous solution. There are numerous means known to those skilled in the art to determine whether a particular salt is cosmotropic. Representative salts which contain anions such as sulfate, fluoride, phosphate, acetate, citrate, tartrate and acid phosphate are cosmotropic. Some salts are more cosmotropic than others, based on the principles of the well-known "Hofmeister series". The use of the salts to precipitate anionic polymers is also taught in EP 183 466 Bl. This invention provides a method for obtaining a dispersion of a water soluble polymer by dissolving a monomer in an aqueous salt solution and carrying out the polymerization while depositing the polymer as fine particles in the presence of a dispersant. The solution of the aqueous salt is required to dissolve the monomer and precipitate the polymer. As the dispersant, a polymeric electrolyte and / or a polymer soluble in an aqueous salt solution is / are effective (s). Where the deposited polymer is an anionic or cationic polymer electrolyte, the polymer electrolyte used as the dispersant is required to have charges of the same kind as the deposited polymer. Representative salts include sodium sulfate, ammonium sulfate, and other strongly cosmotropic salts. For polymers whose anionicity is derived from the presence of sulfonate groups for example polymers and copolymers of poly (2-acrylamido-2-rnethyl-propanesulfonate), here poly (AMMPS), the polymer is difficult to precipitate even at low pH and at elevated of the cosmotropic salt. The precipitation of anionic polymers by cationic organic salts, for example surfactants, is well known. A review by E. D. Goddard (Colloids and Surfaces, vol 19 pp 301-329, 1986) is incorporated herein by reference. The precipitation phenomenon is said to be controlled by the relative concentrations of the anionic polymer and the cationic organic salt, as well as by the size of the organic portion of the anionic organic salt and by the type of polymer. Precipitation of the anionic polymer tends to occur when the cationic organic charged oppositely binds to the polymer and neutralizes the charge. The prevailing point of view has been that the addition of salt weakens agglutination, making precipitation more difficult. For example, the effect of added sodium chloride is described on p. 313 of the review by ED Goddard, cited above, where the author states that "adding salt substantially reduces the affinity of the union as observed by a gradual increase in the concentration [of the surfactant] at which agglutination begins. .. " A similar point of view was advanced by Y. Li and P. Dubin, in "Structure and Flow in Surfactant Solutions, ACS Sy posium Series 578, American Chemical Society, 1994, on page 328 where the authors state:" for avoid precipitation in mixtures of strong polyelectrolytes with micelles [of surfactant] loaded oppositely, the strength or strength of the agglutination ... should be reduced. Practically, several ways or ways could be used to attenuate the strong electrostatic interaction between the polyelectrolytes and the oppositely charged surfactant, such as ... the addition of the salt. "Surprisingly, and contrary to the teachings cited above, it is now has found that the precipitation of many typical water-soluble anionic polymers by the cationic organic salts in the aqueous solution can be greatly improved by the addition of cosmotropic salts Significantly, these polymers remain precipitated even at a pH greater than 4. Therefore, according to the invention, the compositions comprised of water, at least one cationic organic salt, at least one cosmotropic salt, and at least one water-soluble, anionic, precipitated polymer are provided. In addition, processes for precipitating water-soluble anionic polymers in compositions comprising water and one or more cationic organic salts, and one or more cosmotropic salts are also embodied in the present invention. The compositions in which the precipitated anionic polymer is dispersed in the form of small droplets to produce a polymer dispersion are preferred. These polymer dispersions remain able to flow even at a pH greater than 4. These polymer dispersions can be stabilized by a dispersant, which can be a water soluble polymer, and the precipitated anionic polymer is preferably formed by the polymerization of the polymers. monomers in the salted solution, optionally in the presence of a dispersant.

Brief Description of the Invention The present invention is directed to compositions of the anionic polymers precipitated in solutions of cationic organic salts and cosmotropic salts, as well as to processes for manufacturing or using them. Compositions in which the polymer is dispersed in the form of small droplets are preferred, and methods for making these polymer dispersions which may include dispersing agents, are taught herein. A particularly preferred method is to form the polymer dispersed by the polymerization of the monomers in the solutions of the salts, optionally in the presence of one or more other water-soluble polymers which may act as dispersing agents. Since the polymer remains insoluble even at a pH greater than 4, dispersions of the flowable polymer are obtained which can easily be used without adjusting the pH. The methods of using the compositions of the present invention for applications such as flocculation of suspended solids, separations of solid-liquid, mining, papermaking, soil stabilization, etc., also take shape here . The embodiments of the present invention include compositions comprised of water, at least one water-soluble, anionic polymer, precipitate, an effective amount of at least one cosmotropic salt, and an effective amount of at least one cationic organic salt; Preferred embodiments include compositions comprised of water, at least one water-soluble, anionic, precipitated polymer, from 0.02 to 12%, by weight based on the total weight, of a tetraalkylammonium salt and from 0.1% to 30%, by weight based on the total weight of a sulfate salt, wherein the anionic, water soluble, precipitated polymer is comprised of recurring units containing sulfonic acid groups, the sulfonic acid salt, the carboxylic acid, or the salt of the carboxylic acid; as well as compositions in which the water-soluble, anionic polymer is precipitated as a dispersion, optionally in the presence of a second water-soluble polymer. Additional embodiments include processes comprising mixing, in any order, water, and at least one water-soluble, anionic polymer, an effective amount of 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 water-soluble, anionic, precipitated polymer; preferred embodiments include processes comprising mixing, in any order, water, at least one water-soluble, anionic polymer having recurring units containing a sulfonic acid group, a sulfonic acid salt group, a group of carboxylic acid, a group of the carboxylic acid salt, from 0.02 to 12%, by weight based on the total weight, of a tetralkylammonium salt, and from 0.1% to 30%, by weight based on the total weight, of a sulfate salt, to form an aqueous composition comprising at least one water-soluble, anionic, precipitated polymer; as well as the processes in which a second water-soluble polymer is mixed. Other embodiments include processes comprising polymerizing at least one anionic monomer in an aqueous solution comprised 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 polymer. water soluble, anionic, precipitated; preferred embodiments include processes comprising polymerizing the monomers containing a sulfonic acid group, a group of the sulfonic acid salt, a carboxylic acid group, or a carboxylic acid salt group, in an aqueous solution comprised of 0.02 to 12%, by weight based on the total weight, of a tetralkylammonium salt and from 0.1% to 30%, by weight based on the total weight, of a sulfate salt, to form an aqueous composition comprising minus one water-soluble polymer, anionic, precipitated; as well as processes in which the water-soluble, anionic polymer is precipitated as a dispersion, optionally in the presence of a second water-soluble polymer. The applications of the present invention include the processes of concentrating a dispersion of suspended solids, which comprise removing the water from a dispersion of suspended solids by adding to the dispersion an effective amount of an aqueous composition comprised of an effective amount of at least one cationic organic salt, an effective amount of at least one cosmotropic salt, and at least one water-soluble, anionic, precipitated polymer, and separating the resulting concentrated dispersion; Preferred embodiments include processes for concentrating a dispersion of suspended solids, which comprise removing the water from a dispersion of suspended paper solids or suspended mineral solids, by adding an effective amount of an aqueous composition comprised of a soluble polymer to the dispersion. in water, anionic, precipitated, from 0.02 to 12%, by weight based on the total weight, of a tetraalkylammonium salt and from 0.1% to 30%, by weight based on the total weight, of a sulfate salt, and separating the resulting concentrated dispersion, wherein the precipitated anionic water-soluble polymer is comprised of recurring units containing sulfonic acid groups, the sulfonic acid salt, the carboxylic acid and the carboxylic acid salt. In other preferred processes, the composition is a dispersion, optionally containing a second water-soluble polymer, and is first dissolved in water before it is added to the dispersion of the suspended solids. Additional applications include soil conditioning processes which comprise adding to the soil a soil conditioning amount of an aqueous composition comprised of an effective amount of at least one cationic organic salt, an effective amount of at least one cosmotropic salt, and at least one water soluble polymer, anionic, precipitated; Preferred applications include soil conditioning processes which comprise adding to the soil an effective amount of a soil conditioning solution made by diluting an aqueous composition comprised of a water-soluble, anionic, precipitated polymer, from 0.02 to 12% by weight based on the total weight, of a tetraalkylammonium salt and from 0.1% to 30%, by weight based on the total weight, of a sulfate salt, wherein the anionic, water soluble, precipitated polymer is comprised of recurring units containing carboxylic acid groups, the carboxylic acid salt, the sulfonic acid, or the sulfonic acid salt.

Detailed Description of the Preferred Modalities It has now surprisingly been found that the precipitation of the anionic polymers by the cationic organic salts is greatly improved by the addition of cosmotropic salts. For the purposes of this invention, a polymer is precipitated in a solution of the particular salt if the particular polymer does not dissolve to form a homogeneous, clear solution, when the particular polymer is stirred or mixed, for periods of up to about a week, in the solution of the salt at a particular temperature. A polymer is also considered to be precipitated when a solution of a polymer or polymers in the salt solution develops lumps or turbidity, when the temperature of the solution is changed. It is obvious from the foregoing that the solubility of a polymer or polymers in a particular salt solution can be temperature dependent, so that a polymer can be precipitated in a particular salt solution at low temperatures, but dissolves at higher temperatures. high, or vice versa. The polymer or polymers, the salt or the salts, and the water, can be mixed in any order, or the polymerization can be carried out in the presence of the salt or salts, or part of the salt or salts, to determine the solubility of the polymer in the salt solution. The polymer can be considered to be precipitated if all or only one part, for example 10% or more, of the polymer is precipitated. Those skilled in the art understand that the solubility of water-soluble, anionic polymers is often determined by measuring the cloud point of the polymer in the saline solution. The turbidity point of a particular polymer in a particular salt solution is defined, for the purposes of this invention, as the temperature at which a substantially clear solution of the polymer becomes cloudy when it is cooled. For example, a composition comprised of a water-soluble anionic polymer or a mixture thereof, water, and salts, can be heated to dissolve the polymer, forming a substantially clear solution. The solution is typically allowed to cool slowly, until the polymer begins to precipitate or separate into phases and the solution becomes turbid or lumpy. The temperature at which the solution begins to turn cloudy is the cloud point. The reproducibility of the turbidity points determined in this way is generally approximately + 3 ° C. The polymers which are less soluble have higher turbidity points, and the polymers which are more soluble have lower turbidity points. In some cases, the turbidity points are difficult to measure conveniently, because the polymers are so insoluble that they can not be solubilized by heating, even heating up to the boiling point of the salted solution. Similarly, some polymers are so soluble that they do not precipitate, even during cooling to the freezing point of the salted solution. Occasionally, a situation is encountered in which a polymer precipitates from the salt solution during heating, rather than during cooling. In these cases, the turbidity point of a particular polymer in a particular salty solution is defined, for the purposes of this invention, when the temperature at which a solution of the polymer begins to become cloudy when it is heated. Here later, all turbidity points were obtained during cooling, except when indicated otherwise. Alternatively, the polymerization of the monomers can be carried out in the presence of the exit (s). For example, the amounts of water, the monomers and the exit (s) can be mixed together and subjected to the polymerization conditions. The turbidity points can then be determined as above. The polymerization of the monomers in the presence of the salts may be preferable, particularly at a high concentration of the polymer or at a high molecular weight of the polymer, because of the difficulty of adequately mixing the polymer with the salt solution. These techniques may also be preferable when the cloud point is above 100 ° C. The cosmotropic salts useful in the present invention may be any cosmotropic salts including sulfates, phosphates, fluorides, citrates, acetates, tartrates, and acid phosphates. The counter ion has a small effect on the solubility of the polymer, and can be ammonium or any alkaline or alkaline earth metal such as lithium, sodium, potassium, magnesium, calcium, etc. The counterion can also be aluminum, or it can be a transition metal cation such as manganese or iron. However, it is preferred to use cosmotropic salts having monovalent cations because of the known tendency of the anionic polymers to form complexes with the divalent metal ions, for example Ca 2+. Ammonium sulfate and sodium sulfate are the preferred cosmotropic salts. The cationic organic salts with the general structure Rn-M + A ~, wherein R comprises the ester, alkyleneoxy, alkyl, or alkyl substituted with from about 1 to about 22 carbon atoms, or aryl or aryl substituted with from about 6 to about 22 carbon atoms, M is a cationic group such as ammonium, including monoalkyl, dialkyl, trialkyl and tetralkyl ammonium, and A is an anion for example chloride, bromide, iodide, methanesulfate, etc., are useful for the precipitation of the anionic polymers, particularly in the presence of cosmotropic salts. The group R can be linear or branched, and can be substituted with more than one cationic M group. The cationic M group can be substituted with more than one R group; for example n can vary from 1 to 4. The mixtures of the cationic organic salts with each other, are also useful, mixed with cosmotropic salts. The tetraalkylammonium halides having from 4 to 22 carbon atoms, the substituted tetralkylammonium halides having from 4 to 22 carbon atoms, the aryl trialkylammonium halides having from 9 to 22 carbon atoms, and the aryl trialkylammonium halides Substitutes having from 9 to 22 carbon atoms are preferred. More preferred are cetylpyridinium chloride (CPC), cetylmethylammonium chloride (CMAC), and benzyltriethylammonium chloride (BTEAC). The effective amounts of the cosmotropic salt and the cationic organic salt useful to cause precipitation or separation of the phases depends on the temperature, the inherent solubility of the polymer, the concentration of the polymer, the particular cationic organic salt used, the pH, and the particular cosmotropic salt used. The effective amount of the cationic organic salt also depends on the amount of the cosmotropic salt. When used without a cosmotropic salt, a larger amount of the cationic organic salt is generally required to carry it around a particular level of insolubility of the polymer than when a cosmotropic salt is present. The effective amounts of the cationic organic salt which will insolubilize a particular polymer are generally in the range of from about 0.01% to about 15%, preferably from about 0.02% to about 12%, more preferably from about 0.05% to about 10%, to the cationic organic salt and from about 0.1% to about 30%, preferably from about 1% to about 28%, more preferably from about 5% to about 25%, for the cosmotropic salt. Preferably, the salts are soluble in the solution, so that the upper limits with respect to the content of the salt are determined mainly by the ability of the solution to dissolve the salt. The effective amounts of the cationic organic salt and the cosmotropic salt that are useful for precipitating a particular polymer can be found by routine experimentation as described herein. The anionic polymers and copolymers can be precipitated over a wide pH range by the practice of the present invention. For example, as illustrated in Example A, a copolymer was prepared by copolyzing approximately 50 mole percent acrylamide and 50 mole% 2-acrylamido-2-methyl-propanesulfonic acid, followed by neutralization. The resulting polymer is diluted in deionized water to form a 0.2% solution, and the solubility of the polymer was determined in various saline solutions at a pH of 4.6, as illustrated in Examples B, C, D, and 1. In BTEAC at 0.2%, the polymer solution remained clear, but the polymer solution had a cloud point of 42 ° C in 28% ammonium sulfate. However, the same polymer had a cloud point > 105 ° C when both 0.2% BTEAC and 28% ammonium sulfate were present. The cloud point was increased because the combination of BTEAC and ammonium sulfate was more effective in precipitating the polymer than any salt alone. The polymers useful in the practice of this invention may be any water-soluble anionic polymer, including polymers made by the polymerization and copolymerization of the anionic monomers, and polymers which become anionically charged after the polymerization has occurred. Polymers having recurring units which contain anionic groups such as carboxylic acids, salts of carboxylic acids, sulfonic acids, salts of sulphonic acids, and / or combinations thereof, are preferred. These polymers are typically made by polymerizing monomers which contain anionic groups such as the carboxylic acid, the salts of the carboxylic acid, the sulfonic acid, the salts of the sulfonic acid, and / or the combinations thereof. Polymers made by polymerizing acrylic acid and 2-acrylamido-2-methyl-propanesulfonic acid, and their salts, are more preferred. The mole% of the anionic recurring units in the polymer can vary from about 1 mol% to about 100 mol%, preferably from about 2 mol% to about 90 mol%, more preferably from about 5 mol% to about 70 mol%, more preferably from about 8 mol% to about 50 mol%, based on the total moles of the recurring units in the polymer. The anionic copolymers can also be prepared by copolymerizing the anionic monomers with other anionic comonomers, non-ionic comonomers, and / or cationic comonomers. The anionic monomers can include acrylic acid, methacrylic acid, vinyl sulfate, 2-acrylamido-2-methylpropanesulfonic acid, styrene sulfonic acid, their salts and the like. Polymers that become anionically charged after polymerization include polymers made by hydrolyzing cellulose, polymers made by hydrolyzing and / or hydroxamizing polyacrylamide, and polymers made from maleic anhydride. The present invention is particularly useful for precipitating polymers having 15 mol% or more units of AMMPS, based on the total moles of recurring units in the polymer, because these polymers are difficult to precipitate in aqueous solutions that do not They contain cationic organic salts. For example, the copolymers of acrylamide and AMMPS, wherein the mole% of AMMPS used to make the polymer is greater than 15%, are easily precipitated, according to the present invention, in a mixture of BETAC and (NH4) 2S0. Nonionic monomers may include substantially water soluble monomers such as acrylamide, methacrylamide, and N-isopropylacrylamide, or monomers which are poorly water soluble such as t-butylacrylamide, N, N-dialkylacrylamide, diacetone acrylamide, acrylate, ethyl, methyl methacrylate, methyl acrylate, styrene, butadiene, ethyl methacrylate, esters of alkyl (meth) acrylate, acrylonitrile, etc., and the like. The nonionic monomers may also include monomers which become charged at a low pH, such as the dialkylaminoalkyl (alk) acrylates, including dimethylaminoethylacrylate, diethylaminoethylacrylate, dimethylaminoethyl methacrylate, diethylaminoethylmethacrylate and the corresponding acrylamide derivatives such as methacrylamidopropyldimethylamine. Preferred nonionic monomers are acrylamide, t-butyl acrylamide, methacrylamide, methyl methacrylate, ethyl acrylate, acrylonitrile, and styrene. Cationic monomers include dialkylaminoalkyl (alk) acrylate salts such as the salts of dimethylaminoethylacrylate, dimethylaminoethylmethacrylate, diethylaminoethylacrylate, diethylaminoethyl methacrylate and salts of the corresponding acrylamide derivatives such as diallyldimethylammonium chloride, diallyldylammonium chloride, etc. In a mol basis, the polymer must contain few cationic recurring units so that the polymer, although it is ampholytic, retains a net negative charge. Preferably, the polymer contains less than 10 mol% of cationic recurring units, based on the total number of moles of recurring units in the polymer. Mixtures of one or more polymers can be precipitated by the practice of this invention. The polymers can be mixed together before, during or after they are mixed with part or all of the salt solution. The mixtures of the polymers can be separated from each other using a salty solution that tends to precipitate one or more polymers in the mixture, but it is a solvent for one or more of the other polymers in the mixture. Additional salts can be added before, during or after the precipitation process. A polymer or polymers can also be formed by the polymerization of the monomers in the presence of another polymer or polymers, which by themselves can be either precipitated or soluble in the salt solution. The polymerization of the monomers can be carried out in any manner known to those skilled in the art, including solution, volume increase or dilution, precipitation, dispersion, suspension, emulsion, microemulsion, etc. The polymerization of the monomers can be carried out in the presence of part or all of the salt solution. Initiation can be effected with a variety of thermal and redox free radical initiators, including peroxides, for example t-butyl peroxide; azo compounds, for example azoisobisbutyronitrile; inorganic compounds, such as potassium persulfate and redox couples, such as ammonium sulfate / ammonium persulphate and sodium bromate / sulfur dioxide. The addition of an initiator can be done at any time prior to the actual initiation per se. The polymerization can also be carried out by photochemical irradiation processes, such as ultraviolet radiation or by irradiation by ionization from a source of cobalt 60. The monomers can also all be present when the polymerization is initiated, or part of the monomers can be added in a final stage of the polymerization. The polymerization can be carried out in multiple stages. Additional materials such as pH adjusting agents, stabilizers, chelating agents, sequestering agents, etc. may also be added before, during or after polymerization. The molecular weights of the polymers which are precipitated or separated in phases by the practice of this invention are not particularly critical. The weighted average molecular weights of the polymers can vary 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 the polymer in the composition can vary from 0.01% to 90%, or occasionally even higher. It is generally preferred, for practical reasons such as the desire to keep production and shipping costs relatively low, that the level of polymer in the compositions is as high as possible. The compositions of the saline solutions, useful for precipitating the anionic polymers, can be prepared simply by dissolving the desired salts in water, preferably with stirring. The waters useful in the practice of this invention are not particularly critical and can be from any source of water, for example distilled water, tap water, recycled water, process water, well water, etc. However, care must be taken to avoid waters having high concentrations of divalent cations such as Ca 2+ which are known to form complexes with the anionic polymers. The precipitation of the anionic polymer in the salt solution can be carried out by mixing, in any order, the solution of the salt and the polymer solution or the polymer emulsion. Substantially dry polymeric granules of the water soluble polymer can be added to the solutions to form compositions comprising salts, water and the precipitated polymer. Alternatively, the water-soluble, anionic polymer can be formed by the polymerization of the monomers in the presence of the salts. The whole or part of the polymer can be precipitated. It is preferred to polymerize monomers in a salt solution to form a polymer dispersion. For the purposes of this invention, the precipitated polymer is a polymer dispersion if some or all of the precipitated polymer is in the form of small droplets that are dispersed in the aqueous salt solution. The precipitated polymer droplets may contain salt and water. Some or all of the polymer can be precipitated. The size of the droplet may be in the 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 more preferably from about 0.15 microns to about 15 microns. mieras As above, the monomer or monomers and the salt or salts may be added in stages during the polymerization or all may be present at the start. The initiation of the polymerization can be carried out in any way, as described hereinabove. The dispersed polymer droplets may tend to settle during rest.

Surprisingly, it has been found that certain water-soluble polymers, referred to herein as dispersants, tend to assist droplet formation and also tend to stabilize the droplets against settling. The polymeric dispersant stabilizes the polymer dispersion, but does not cause the anionic, water-soluble polymer to be precipitated. As described above, the combination of the salt causes the anionic, water-soluble polymer to be precipitated. It has been found that polymers such as poly (AMMPS), polyacrylamide, and acrylamide copolymers with amounts of cationic, nonionic and anionic monomers, decrease the settlement rate of the polymer dispersions. Without the dispersant, the polymer droplets tend to dissolve over time and can melt to form a layer that is separated from the aqueous phase. However, when the same polymerization is carried out in the presence of water-soluble polymers, for example poly (AMMPS), polyacrylamide, or acrylamide copolymers with amounts of cationic, anionic or non-ionic monomers, the settling rate is reduced advantageously and higher polymer dispersions are obtained.

Polymers useful as dispersants may include polyacrylamide and other non-ionic polymers, for example poly (methacrylamide), poly (vinyl alcohol), poly (ethylene oxide), etc., and the like. Preferred dispersing agents are anionic polymers such as poly (acrylic acid), poly (AMMPS), copolymers of acrylic acid with acrylamide, and copolymers of AMMPS with acrylamide. Preferably, the dispersants are soluble or soluble mostly in the particular salty solution. It is generally preferable that the dispersant has a greater solubility in the solution of the particular salt than the precipitated polymer droplets which are being dispersed. Copolymers useful as dispersants can include copolymers of nonionic monomers eg acrylamide with up to about 20 mol%, preferably from about 5 to about 15 mol% of a cationic comonomer, for example the quaternary dialkylaminoalkyl (alk) acrylate salts , diallyldialkylammonium halide, etc., based on the total moles of the recurring units in the polymer. Other copolymers useful as dispersants include the acrylamide copolymers with up to about 99 mol% of an anionic comonomer such as sodium 2-acrylamide-2-methylpropanesulfonic acid, preferably from about 5 to about 95 mol% of the comonomer, more preferably from about 25 to about 75% mole of the comonomer, based on the total moles of the recurring units in the polymer. The anionic monomers can include acrylic acid, styrene sulfonic acid, their salts and the like. Nonionic comonomers may include substantially water soluble monomers such as methacrylamide, or monomers which are sparingly soluble in water such as t-butylacrylamide, diacetone acrylamide, ethyl acrylate, methyl methacrylate, methyl acrylate, styrene, butadiene, ethyl methacrylate, acrylonitrile, etc., and the like. Preferred nonionic monomers are acrylamide, t-butyl acrylamide, methacrylamide, methyl methacrylate, ethyl acrylate and styrene. The dispersants are generally used in amounts ranging up to about 25%, preferably from about 1% to about 20%, more preferably about 5% to about 15%, based on the total weight of the precipitated anionic polymer droplets that they are scattered. The dispersant is not used in amounts that cause precipitation of the anionic polymer in the absence of cationic organic salts and cosmotropic salts. The weighted average molecular weights of the dispersing polymers can vary 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. The 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 polymers can be precipitated, and the polymer dispersions can be prepared, at a pH which ranges from about 2 to about 12, preferably from about 4 to about 10, more preferably from about 5 to about 9. Methods for measuring pH are well known to those skilled in the art. Routine experimentation used to identify a combination of the cationic organic salt, the cosmotropic salt, the temperature and the pH that will precipitate a particular concentration of a water-soluble, anionic, particular polymer can be carried out in various ways. One way is by the turbidity point technique described above. For example, to determine the turbidity points of 1% poly (AMMPS) 30 samples of 1% aqueous poly (AMMPS) could be prepared, each containing either 0%, 5%, 10%, 15%, or 20% ammonium sulfate, and either 0%, 0.02%, 0.04%, 0.06%, 0.08% or 0.1% cetylpyridinium chloride, in all combinations, at a particular pH. The turbidity points of each solution could then be determined by heating each sample to dissolve the polymer, then cooling until the solution becomes turbid. Turbidity could indicate precipitation, and the temperature at which it occurred could be the cloud point. The process could be repeated for any other polymer, polymer concentration, pH, or salts. Typically, some of the samples may remain clear, even down to 0 ° C or below this value, while others may remain cloudy during heating, even at or above 100 ° C. Although the turbidity point information could not be obtained from these samples, one could know the behavior of the particular polymer phases for this particular salt system. In cases when precipitation is observed during heating, and the polymer dissolves during cooling, the cloud points could be determined by cooling the mixtures until the polymers dissolve, then heating to precipitate the polymer. In these cases, the turbidity points could be the temperatures at which the turbidity was observed during heating. Turbidity points do not need to be determined to obtain solubility information. For example, one could prepare a series of solutions containing various amounts of the cationic and cosmotropic organic salt, at a particular pH, and then add a polymer solution to each salted solution. The polymer could either be precipitated or remain soluble, as determined by simple visual inspection, and the solubility behavior of the polymer could be correlated with the type and concentration of each salt. Another routine experimental process to identify a combination of the salts and the temperature at which a particular anionic polymer will precipitate is to polymerize the monomers in the salt solution, then determine the cloud points. The technique is preferred at high concentrations of the polymer, because the concentrated solutions of the polymers, for example 10% or more, can be difficult to handle, for example stirring. The process is similar to the turbidity point process in that a series of salt solutions could be taken in which the monomer or monomers are dissolved at concentrations necessary to provide the desired concentration of the polymer. The solutions can then be polymerized in a known manner, for example dispersed with an inert gas such as nitrogen, then the polymerization is initiated by a conventional free radical initiator, to form a mixture of the polymers and the salts. The experimental routine process for identifying a combination of the salts and the temperature at which substantially dry water-soluble polymer powders or granules will not dissolve is similar to the process described above. A series of solutions of the salt could also be made as above, then adding the dry polymer to give a composition with the desired concentration of the polymer. The mixtures could then be stirred and heated to effect dissolution of the polymer. Then the information could be obtained, by direct observation, in that if the polymer dissolved or did not dissolve in any particular solution, and the information of the behavior of the phases dependent on the temperature could be obtained from those solutions that exhibited a cloud point as described above. The precipitated polymer can be recovered from the salt solution by any means known in the art, including filtration, centrifugation, evaporation, spray drying, combinations thereof, etc. The recovered polymer granules typically contain a water soluble, anionic polymer, residual salts, optionally a residual dispersant, and water. Preferably, the resulting polymer granules contain less than about 30% in water, more preferably from about 0.1% to about 20%, more preferably from about 1% to about 15%. Polymeric granules that flow freely, substantially dry, are preferred for handling purposes. Various pH adjusting agents, flow control agents, preservatives, agents for particle size control, etc., which are known to those skilled in the art, can be added, at any stage of the process, to give substantially dry granules containing the water soluble, anionic polymer. The compositions and processes of this invention provide water-soluble anionic polymers which are useful in various applications for example flocculation of suspended solids, recovery of minerals from mining operations, papermaking, improved oil recovery. , treatment of refinery waste, treatment of food waste, etc. Preferred applications are for removing water from dispersions of suspended minerals and dispersions of suspended paper or cellulosic solids, for deinking paper, and for removing water from biological sludge. To be effective in these applications, the compositions of the precipitated polymer can be added directly to the dispersion of the suspended solids to be treated, mixed, and the resulting concentrated dispersion separated by means known in the art such as a centrifugal machine, band presses, press filters, filters, etc. Preferably, the compositions are first diluted in water to form solutions 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 in a known manner with the dispersion of the suspended solids to be treated, and the resulting concentrated dispersion separated as above. It is known to those skilled in the art that the amount of the diluted polymer solution effective for a particular application can be found through routine experimentation. Polymer dispersions and substantially dry polymer granules are preferred because the size of the small droplet or granule of the polymer stimulates the polymer to dissolve more rapidly during dissolution. It is believed that the polymer dissolves, in spite of the presence of the salts which tend to precipitate it, because the concentration of the salt is reduced from the effective range to the interval that allows the polymer to dissolve, by dissolution. A particularly preferred application for the water-soluble anionic polymers of the present invention is the conditioning of the soil eg for the prevention of soil erosion. The process of irrigating a field may tend to cause the damaging loss of valuable top soil by erosion. The soil can be stabilized against erosion, particularly in situations where the soil is irrigated, by a process which comprises mixing (a) a soil conditioning amount of an aqueous composition comprised of one or more cationic organic salts, one or more cosmotropic salts, and a water soluble, anionic, precipitated polymer, or mixtures thereof, (b) water, and (c) soil. The addition of the polymer to the soil in a soil conditioning quantity tends to produce a greater cohesiveness between the soil particles, so that the soil is stabilized against erosion by wind, water, etc. Preferably, the composition is dissolved in water to form a conditioning solution, which can then be applied to the soil, preferably in addition to the water typically used to irrigate a field. The concentration of the polymer in the conditioning solution is generally from about 0.1 parts per million of the solution (ppm) to about 500 ppm, preferably from about 1 ppm to about 100 ppm, more preferably from about 5 ppm to about 50 ppm. The amounts for soil conditioning of the present invention can be determined by field tests or by laboratory tests. For example, to determine the amount of the precipitated anionic polymer composition useful for conditioning a particular soil, the composition could first be dissolved in water to form a conditioning solution. Next, various quantities of the conditioning solution could be agitated with various amounts of soil and water in a series of containers, then allowed to settle. The turbidity of each supernatant could then be evaluated visually or, preferably, by the use of a turbidimeter. The turbidity of the supernatant in each container is typically a good indicator of the efficiency of the polymer and the dose of the polymer for soil conditioning. For example, a high turbidity value, for example greater than 500 units of nephelometric turbidity (ntu), may indicate that the polymer or the polymer dose will probably not be particularly effective for the conditioning of this particular soil, while a low value of the turbidity, for example less than 25 ntu may indicate that the polymer and the polymer dose are likely to be effective for the conditioning of this particular soil. The information obtained from these laboratory tests is useful to determine the amounts of soil conditioning of the compositions of the present invention.Alternatively, and less likely, the polymer dispersions or the substantially dry polymer can be applied directly to the soil. In these cases, the polymer can form a conditioning solution when combined with water that is already present in the soil, or by the subsequent application of water to dissolve the polymer. In irrigation applications, soil conditioning amounts generally vary from about (0.0454 kg) 0.1 pounds to about 9.08 kg (20 pounds) of the polymer per 4.301 m2 (one acre) per year, preferably 0.454 kg (1 pound) to 4.54 kg (10 pounds) of the polymer per 4,301 m2 (1 acre) per year. Soil erosion can also take the form of large-scale ground movements such as landslides or avalanches, where the soil is typically not irrigated. For example, the destruction of vegetation on a hill, for example by fire, can leave the underlying soil unstable and make it prone to movement. In these applications, means other than irrigation, such as spraying, can be used to apply the conditioning solutions. Alternatively, the polymer dispersions or the dry polymer can be applied directly to the soil. In these cases, the polymer can form a conditioning solution when combined with water already present in the soil, or by the subsequent application of water to dissolve the polymer. The following examples are described for purposes of illustration only and are not to be construed as limits to the present invention.

MEASUREMENTS OF VISCOSITY The standard viscosity (SV) is the viscosity of a 0.096% solution of the water-soluble polymer in 1N sodium chloride at 25 ° C. The viscosity is measured by a Brookfield LVT viscometer with a UL adapter at 60 rpm. The polymer solution being measured is made by diluting a dispersion or polymer solution to a concentration of 0.2% by stirring with the appropriate amount of deionized water for about twelve hours, and then diluting with the appropriate amounts of deionized water and sodium chloride. The volumetric viscosity (BV) of a polymer dispersion is the viscosity of the polymer dispersion as measured by the Brookfield LTV viscometer with a # 4 spindle at 30 rpm and 25 ° C.

PH measurements The pH measurements were made with a conventional electronic pH meter, Jenco Electronics Microcomputer pH-Vision 6071R equipped with a 3-in-1 electrode, Model 6000E. The pH meter was calibrated with conventional buffer solutions at pH 4.00 and pH 7.01.

Example A A 50/50 mole poly (acrylamide / AMMPS) copolymer is prepared by adding 49.77 parts of 53.88% acrylamide solution, 78.97 parts of 99% 2-acrylamido-2-methyl-propanesulfonic acid, 3.02 parts of 5% sodium ethylenediaminetetraacetate (EDTA) (chelating agent), 30.3 parts of 50% NaOH solution, and 563.79 parts of deionized water, to a vessel equipped with mechanical stirring. The solution is stirred at 30 ° C, and 1.05 parts of ammonium persulfate and 3.5 parts of 30% sodium bis-bisulphite solution are added. The solution was deoxygenated by spraying with nitrogen while raising the temperature to about 50 ° C. After 10 hours of stirring at 50 ° C, the viscous polymer solution was allowed to cool to give a 50/50 mole poly (acrylamide / AMMPS) solution with a polymer content of about 15% by weight . Part of the polymer solution is diluted in deionized water to give a 2% polymer solution for the determination of solubility.

Example B Approximately 12 parts of the deionized water are added to a suitable container, followed by approximately 1.5 parts of a 2% solution of BTEAC. Approximately 1.5 parts of a 2% solution of a 50/50 mole poly (acrylamide / AMMPS) prepared as in Example A are added with stirring to give a clear solution. The pH was adjusted to approximately 4.6 by adding the dilute hydrochloric acid. The solution remained clear, demonstrating that 0.2% poly (acrylamide / AMMPS) 50/50 was not precipitated in a 0.2% solution of BTEAC.

Example C Approximately 9.26 parts of deionized water are added to a suitable vessel, followed by approximately 4.24 parts of 99.1% ammonium sulfate and approximately 1.5 parts of 2% BTEAC; The mixture is stirred to dissolve the salt. A clear solution with a pH of about 4.6 was obtained, demonstrating that the 0.2% BTEAC was not precipitated in a 28% ammonium sulfate solution.

Example D Approximately 9.26 parts of the deionized water were added to a suitable vessel, followed by approximately 4.24 parts of 99.1% ammonium sulfate; The mixture is stirred to dissolve the salt.

Approximately 1.5 parts of a 2% solution of a 50/50 mole poly (acrylamide / AMMPS) prepared as in Example A are added with stirring to give a cloudy mixture with a pH of about 4. 6. The mixture is heated with stirring until it becomes clear, then it is allowed to cool slowly. The solution became turbid at 42 ° C, demonstrating that 0.2% poly (acrylamide / AMMPS) 50/50 had a cloud point of 42 ° C in an ammonium sulfate solution at 20 ° C. 28% Example 1 Approximately 7.76 parts of deionized water were added to a suitable vessel, followed by approximately 4.24 parts of 99.1% ammonium sulfate; the mixture was stirred to dissolve the salt. Approximately 1.5 parts of BTEAC are added to 2% with stirring to give a clear solution. Approximately 1.5 parts of a 2% solution of a 50/50 mole poly (acrylamide / AMMPS), prepared as in Example A is added with stirring to give a cloudy mixture with a pH of about 4.6. The mixture was heated with stirring to a temperature of about 105 ° C with the precipitated polymer solution. This result shows that the poly (acrylamide / AMMPS) 50/50 at 0.2% had a turbidity point higher than 105 ° C in a solution of 28% ammonium sulfate and 0.2% BTEAC. The cloud point of the polymer was higher in a 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 Approximately 12 parts of the deionized water are added to an appropriate container, followed by approximately 1.5 parts of a 2% solution of BTEAC. Approximately 1.5 parts of a 2% solution of a 50/50 mole poly (acrylamide / AMMPS) solution, prepared as in Example A was added with stirring to give a clear solution. The pH was adjusted to approximately 8.5 by adding a NaOH solution. The solution remained clear, demonstrating that 0.2% 50/50 poly (acrylamide / AMMPS) was not precipitated in a 0.2% solution of BETAC at pH 8.5.

Example F Approximately 9.26 parts of deionized water are added to a suitable vessel, followed by approximately 4.24 parts of 99.1% ammonium sulfate and approximately 1.5 parts of 2% BTEAC; The mixture is stirred to dissolve the salt. The resulting clear solution remained clear after adjusting the pH to approximately 8.5 by adding a solution of NaOH, demonstrating that 0.2% BTEAC was not precipitated in a 28% solution of ammonium sulfate at a pH of 8.5.

Example 6 Approximately 9.26 parts of the deionized water are added to a suitable vessel, followed by approximately 4.24 parts of 99.1% ammonium sulfate; The mixture is stirred to dissolve the salt. Approximately 1.5 parts of a 2% solution of a 50/50 mole poly (acrylamide / AMMPS), prepared as in Example A, was added with stirring to give a cloudy mixture with a pH of about 4.6. The pH was adjusted to 8.5 by adding a solution of NaOH. The mixture is heated with agitation until it became clear, then allowed to cool gradually. The solution became turbid at 33 ° C, demonstrating that 0.2% poly (acrylamide / AMMPS) 50/50 had a cloud point of 33 ° C in a solution of 28% ammonium sulfate at pH 8.5, against 42 ° C to pH 4.5 (Example D).

Example 2 Approximately 7.76 parts of the deionized water were added to a suitable vessel, followed by approximately 4.24 parts of 99.1% ammonium sulfate; The mixture is stirred to dissolve the salt. Approximately 1.5 parts of 2% BTEAC were added with agitation to give a clear solution. Approximately 1.5 parts of a 2% solution of a 50/50 mole poly (acrylamide / AMMPS), prepared as in Example A, were added with stirring to give a cloudy mixture with a pH of about 4.6. The pH was adjusted to 8.5 by adding the NaOH solution. The mixture was heated with stirring to a temperature of about 105 ° C without dissolving the precipitated polymer. This result demonstrates that the 0.2% poly (acrylamide / AMMPS) 50/50 had a turbidity point greater than 105 ° C in a solution of 28% ammonium sulfate and 0.2% BTEAC, still at a pH of about 8.5 . The cloud point of the polymer was higher in a 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 Approximately 12 parts of deionized water were added to a suitable container, followed by approximately 1.5 parts of a 2% solution of BTEAC. Approximately 1.5 parts of a 2% solution of a 50/50 mole poly (acrylamide / AMMPS) solution, prepared as in Example A was added with stirring to give a clear solution. The pH was adjusted to approximately 6.4 by adding the NaOH solution. The solution remained clear, demonstrating that 0.2% 50/50 poly (acrylamide / AMMPS) was not precipitated in a 0.2% solution of BTEAC at pH 6.4.

Example I Approximately 9.26 parts of deionized water are added to a suitable vessel, followed by approximately 4.24 parts of 99.1% ammonium sulfate and approximately 1.5 parts of 2% BTEAC; The mixture is stirred to dissolve the salt. The resulting clear solution remained clear after adjusting the pH to about 6.4 by adding the NaOH solution, showing that the 0.2% BTEAC was not precipitated in a 28% solution of ammonium sulfate at pH 6.4.

Example J Approximately 9.26 parts of deionized water were added to a suitable vessel, followed by approximately 4.24 parts of 99.1% ammonium sulfate, the mixture is stirred to dissolve the salt. Approximately 1.5 parts of a 2% solution of a 50/50 mole poly (acrylamide / AMMPS), prepared as in Example A, was added with stirring to give a cloudy mixture with a pH of about 4.6. The pH is adjusted to 6.4 by adding the NaOH solution. The mixture is heated with stirring until it becomes clear, then it is allowed to cool gradually. The solution became turbid at 39 ° C, demonstrating that a 0.2% poly (acrylamide / AMMPS) 50/50 had a cloud point of 39 ° C in a solution of 28% ammonium sulfate at pH 6.4, against 42 ° C to pH 4.5 (Example D) and 33 ° C to pH 8.5 (Example G).

Example 3 Approximately 7.76 parts of deionized water are added to a suitable vessel, followed by approximately 4.24 parts of 99.1% ammonium sulfate; The mixture is stirred to dissolve the salt. Approximately 1.5 parts of 2% BTEAC are added with agitation to give a clear solution. Approximately 1.5 parts of a 2% solution of a 50/50 mole poly (acrylamide / AMMPS), prepared as in Example A, is added with stirring to give a cloudy mixture with a pH of about 4.6. The pH was adjusted to 6.4 by adding the NaOH solution. The mixture is heated with stirring to a temperature of about 105 ° C without dissolving the precipitated polymer. This result shows that 0.2% poly (acrylamide / AMMPS) 50/50 had a turbidity point greater than 105 ° C in a solution of 28% ammonium sulfate and 0.2% BTEAC, even at a pH of about 6.4 . The cloud point of the polymer was higher in a 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 acrylic acid at 22.5% mol and 77.5% acrylamide was prepared in the form of a polymer dispersion at a pH of 4.3 as follows: Approximately 1.97 parts of 98% CPC, 48.41 parts of 53.88% acrylamide, 7.75. parts of 99% acrylic acid, 60.38 parts of 99% ammonium sulfate, 2.98 parts of 5% sodium ethylenediaminetetraacetate (EDTA) (chelating agent), 4.01 parts of 28% NHOH solution, and 60.38 parts of water deionized were added to a suitable vessel equipped with mechanical agitation.

The mixture is stirred to form a clear solution. Approximately 0.51 parts of ammonium persulfate were added, followed by 73.6 parts of 15% poly (2-acrylamido-2-methyl-propanesulfonic acid) (a commercially available dispersant) to give a milky white mixture with a pH of 3.2. Approximately 3.04 parts of the 28% NH4OH solution are added to raise the pH to 4.3. The mixture is deoxygenated by nitrogen sparging for thirty minutes, while the temperature was raised to about 50 ° C. Approximately 5 parts of the 20% sodium metabisulfite solution are added over the course of 20 minutes. The reaction is stirred at 50 ° C for about 5 hours, then allowed to cool. The resulting polymer dispersion had a volumetric viscosity of about 5100 centipoise and a pH of about 4.2. The standard viscosity of the polymer was about 4.2 centipoise, indicating the high molecular weight.

Example K a copolymer of 22.5% by mol of acrylic acid and 77.5% acrylamide is prepared at a pH of 4.3 as in Example 4, except that 76.3 parts of the deionized water were added to the mixture in place of the dispersant, 73.6 parts of the poly ( 15% 2-acrylamido-2-methyl-propanesulfonic acid). Instead of forming a low viscosity dispersion, the polymer precipitated in the form of a gelatinous white mass that could not be stirred.

Example 5 A conditioning solution was prepared by diluting a dispersion prepared as in Example 4 with deionized water so that the concentration of the polymer dissolved in the resulting conditioning solution was 0.1%. Approximately 3 parts of the soil were added to a separate vessel containing 100 parts of deionized water, the mixture is stirred vigorously, and 1.0 parts of the conditioning solution are added. The resulting mixture is stirred for 15 minutes, then allowed to settle for 15 minutes. The turbidity of the supernatant was approximately 11 + 5 ntu, as measured with a hand held turbidity meter, indicating that this composition is likely to be useful for soil conditioning.

Example L Example 5 was repeated, except that the deionized water was used in place of the conditioning solution. The turbidity of the supernatant was greater than 1000 ntu.

Example M Example 5 was repeated, except that the conditioning solution contained a commercially available copolymer of acrylamide and acrylic acid, which is known to be useful for soil conditioning, instead of a polymer prepared as in Example 4. turbidity of the supernatant was 8.1 + 5 ntu.

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 (10)

1. A process, characterized in that it comprises mixing, in any order, water, at least one water-soluble, anionic polymer, from 0.1% to 30% of at least one cosmotropic salt, and from 0.01% to 15% of at least one organic salt cationic, to form an aqueous composition comprising at least one water-soluble, anionic, precipitated polymer.

2. A process, characterized in that it comprises polymerizing at least one anionic monomer in an aqueous solution comprised from 0.01% to 15% of at least one cationic organic salt and from 0.1% to 30% of at least one cosmotropic salt, to form an aqueous composition which it comprises at least one water-soluble polymer, anionic, precipitated, and the cationic organic salt.

3. A process for concentrating a dispersion of the suspended solids, characterized in that it comprises removing the water to a dispersion of suspended solids by adding to the dispersion an effective amount of an aqueous composition comprised from 0.01% to 15% of at least one cationic organic salt, 0.1% to 30% of at least one cosmotropic salt, and at least one water-soluble, anionic, precipitated polymer, and separating the resulting concentrated dispersion.

4. A soil conditioning process, characterized in that it comprises adding to the soil a soil conditioning amount of an aqueous composition comprised from 0.01% to 15% of at least one cationic organic salt, 0.1% to 30% of at least one cosmotropic salt, and at least one water-soluble polymer, anionic, precipitated.

5. A process according to claims 1, 2, 3, or 4, characterized in that the cationic organic salt is selected from the group consisting of tetraalkylammonium halides having from 4 to 22 carbon atoms, substituted tetraalkylammonium halides having from 4 up to 22 carbon atoms, aryl trialkylammonium halides having from 9 to 22 carbon atoms, and substituted aryl trialkylammonium halides having from 9 to 22 carbon atoms.

6. A process according to claims 1, 2, 3, 4, or 5, characterized in that some or all of the precipitated anionic water-soluble polymer is precipitated as a polymer dispersion.

7. A composition, characterized in that it is comprised of water, at least one water-soluble, anionic, precipitated polymer, 0.1% to 30% of at least one cosmotropic salt, and from 0.01% to 15% of at least one cationic organic salt.

8. A composition according to claim 7, characterized in that the cationic organic salt is selected from the group consisting of tetraalkylammonium halides having from 4 to 22 carbon atoms, substituted tetraalkylammonium halides having from 4 to 22 carbon atoms, halides of aryl trialkylammonium having from 9 to 22 carbon atoms, and substituted aryl trialkylammonium halides having from 9 to 22 carbon atoms.

9. A composition according to claims 7 or 8, characterized in that some or all of the precipitated anionic water-soluble polymer is precipitated as a polymer dispersion.

10. A composition according to claims 7, 8, or 9, characterized in that the anionic, water soluble, precipitated polymer contains recurring units having anionic groups selected from the group consisting of carboxylic acid, sulfonic acid, and sulfonic acid salt .