Polymeric flocculant based on cassava starch grafted polydiallyldimethylammonium chloride: Flocculation behavior and mechanism

•Flocculation performance of cassava grafted polyDADMAC was studied.•Turbidity and TSS removal increased with increasing grafting percentage.•The grafted polymer showed good removal in acidic and neutral region.•Zeta potential results pointed to the charge neutralization mechanism.•Flocs increased with increasing grafting percentage and molecular weight. In this work, flocculation properties of cassava starch grafted polydiallyldimethylammonium chloride (polyDADMAC) with different grafting percentages were investigated. Flocculation performance was evaluated in simulated kaolin suspension. The grafting percentages used were 1.76 %, 14.84 %, and 21.98 %. The effectiveness of the flocculation was measured based on the reduction of the turbidity and total suspended solids (TSSs), zeta potential measurements, particle size, and atomic force microscopy imaging. Grafted polymers improved the removal rate of turbidity and TSS compared with gelatinized starch, and the removal rate increased with increasing grafting percentage and dosage.