Novel polymeric flocculants based on polyacrylamide grafted dextran in kaolin suspension

Abstract

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 × 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.