Abstract: With chitosan and methacryloyloxyethyl trimethyl ammonium chloride (DMC) as raw materials, cerium ammonium nitrate as the initiator and Span-20 as the emulsifier, chitosan-DMC graft copolymer was synthesized through inverse emulsion polymerization. The effects of reaction conditions on graft degree were investigated through orthogonal experiments and the optimum conditions were determined as follows: reaction time 5 h, initiator concentration 16 mmol/L, mass ratio of chitosan to monomer 1:6, volume ratio of oil to water 1:1. Under the optimum conditions the average graft degree reached 110 %. The graft copolymer was used as flocculant for treating kaolin suspension. The results showed that the flocculation ability of the chitosan graft copolymer was better than chitosan and polyacrylamide (PAM). The best flocculation effect occurred at pH=6.0 and flocculant dosage 2.0 mg/L.

Key words: chitosan, DMC, graft copolymerization, flocculation