Synthesis and application of amphoteric starch graft polymer

An amphoteric starch-graft-polyacrylamide (S-g-PAM) was prepared by inverse emulsion polymerization, subsequent hydrolysis reaction and Mannich reaction. The copolymerization was carried out using ammonium persulfate and urea as redox initiator. The reaction conditions and application as flocculant were investigated. Experiments showed that in hydrolysis reaction, a stable emulsion of anionic S-g-PAM with high hydrolysis degree could be obtained in a shorter time when sodium carbonate and sodium hydroxide were used together as hydrolyzing agents. In Mannich reaction, after pre-formation of an aldehyde–amine adduct was added to the anionic emulsion product, the amination degree of amphoteric S-g-PAM could reach 43.6% and the highest solution viscosity was obtained. The application test showed that the results of treatment of several kinds of industrial waste water by amphoteric S-g-PAM were better than those treated with cationic polyacrylamide (PAM), hydrolytic PAM and amphoteric PAM.