Application of Polyacrylamide in drinking water treatment research

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2016-02-27 08:19:32

Polyacrylamide is early in 1893 by moureu with acryloyl chloride and ammonia in low temperature was prepared. From 1954 first commercial production in the United States. Initially, acrylamide (AM) monomer is from acrylonitrile (an) - derived by Hydrate Catalyzed by sulfuric acid, by acrylamide homopolymerization of non ionic polyacrylamide (PAM) and subsequently developed by alkali hydrolysis of anionic polyacrylamide. The 70's with acrylamide production of the second generation of "catalytic hydration" and "the third generation of microbial engineering process technology have appeared. The series products have been developed by polyacrylamide. As in the 1970s, American Merck company and Halliburton company developed the first successful cationic polyacrylamide, dimethyl diallyl ammonium chloride (PDMDAAC) and dimethyl diallyl ammonium chloride and acrylamide copolymer P (DMDAAC / AM)]; more active in the 1990s foreign of amphoteric polyacrylamide research, development, products have been available.

Our country of poly (alkenyl amide research and production began in the 1960s, production process mainly uses the traditional aqueous solution polymerization, colloidal mining 8 -- 10%AM aqueous solution and in initiating agent under the action of direct polymerization, dry powder with 20 - polymerization concentration 30%AM aqueous solution, colloid aggregation after granulation, kneading, drying, crushing of polyacrylamide, ratio process is safe, simple, cost low. Inverse emulsion polymerization method -- am aqueous solution with surfactant of AM monomer decomposition in the oil phase formation of emulsion system, in initiating agent of emulsion polymerization to form stable high molecular weight instant Polyacrylamide Latex products, after azeotropic distillation dehydration can be powdered polypropylene products. The process for in the preparation of high molecular weight and narrow distribution of molecular weight of Polyacrylamide Latex or dry powder type products. And inverse suspension polymerization, polymerization of am in aqueous solution with small droplets suspended in the organic solution of system of molecular weight high, instant polyacrylamide beads. Radiation caused method -- calcined amide monomer in the R or ultraviolet ray triggered direct polymerization and a solid product, the process is simple, but the investment is larger, the obtained product molecular weight distribution is very wide. Most applications require some function of ion polyacrylamide. The properties of ionic properties can alter the solubility, viscosity, polyacrylamide solution. Manufacturing goods derivatives are the following reaction by polyacrylamide by copolymerization method or preparation. So far, have produced a non-ionic polyacrylamide, cationic polyacrylamide, amphoteric polyacrylamide with high molecular weight and its derivatives. The molecular weight from hundreds of thousands to more than ten million, according to supramolecular and molecular weight can be classified to below low molecular weight (100 million), molecular weight (100 million - 10 million), a high molecular weight (10 million ----1500 million) (15 million above). The goods mainly in the form of powder, colloid, emulsion powder; high quality, good use effect, easy to use emulsion dissolved, the cost is relatively high.

Polyacrylamide in production in a water supply company has been used for many years, to improve flocculation effect, saving alum consumption, removal of algae, decreasing mutagenicity, improve water quality, to cope with sudden water accidents have obvious effect.

1, improve the effect of flocculation, overcome the dry period of flocs floating, saving alum consumption and reduce the net cost of water. Low temperature and low turbidity, relative turbidity of water composition, organic matter accounted for a greater proportion, single dosage of aluminum sulfate and polymeric aluminum, the formation of floc structure loose, ethereal to precipitation. After adding polyacrylamide 0.025--0.05mg/L coagulation, due to their large adsorption surface area and excellent bridging ability, formed by the reaction of floc size increases, increasing the proportion of, settling speed, sedimentation tanks the ability to rapidly improve, turbidity is greatly reduced. Cast polypropylene acid coagulation after 5 minutes after the residual turbidity is below 20NTU, the same time than the residual turbidity water without adding coagulant in the low 20 - 30NTU. No coagulant water because of the serious pollution of raw water organic matter, floc frivolous. The final turbidity is unable to reduce the investment and will be placed 1 hour the residual turbidity also did not decrease significantly. Investment and polypropylene acyl and coagulation and improve the effect of flocculation, saving alum consumption about 25%, water production does not rise about 5 - 10% cost savings of about 24%.

2, improve water quality, color removal, removal of organic matter, algae removal, reduce mutagenicity. Due to the polyacrylamide coagulant effect. The effluent turbidity is obviously decreased, and content and turbidity in organic matter and algae have very close relationship, according to experts, when the turbidity reduced to 0.5 degrees, organic matter in water can remove 80%, so adding polyacrylamide gel can effectively to eliminate organic pollution and improve the quality of drinking water. The color removal rate increased by more than 10%, in addition to water organic matter decreased by more than 46%, the removal rate of algae increased by 16 - 26%. Sedimentation water mutagenicity decreased from positive to positive, that reduce the water turbidity, the removal of a part of the organic matter, so the water mutagenicity improved.