Novel Polymeric Flocculants Based on Polyacrylamide Grafted Dextran in Kaolin Suspension

A study is done on ceric-ammonium-nitrate (CAN) initiated graft copolymerization of polyacrylamide (PAM) on to dextran (Dx) by solution polymerization technique. The average molecular weight of dextran is 7.0 x 10(-6) g/mole. By changing the concentrations of the initiator in the reaction feed, a series of graft copolymer (Dx-g-PAM1 to Dx-g-PAM4) with variation in the number and length of the grafted PAM chains are obtained. The flocculation characteristics of various polymers are investigated by the use of settling tests in 2 wt % using kaolin suspensions. Among the series of graft copolymers, the one with highest molecular weight shows superior performance. The flocculation characteristics of the best-performing graft copolymer (Dx-g-PAM3) are compared with those of various commercially available flocculants and PAM in the kaolin suspension. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 3539-3544, 2010