Synthesis and flocculation characteristics of a novel biodegradable flocculating agent amylopectin-g-poly(acrylamide-co-N-methylacrylamide)

•Synthesis and characterization of a graft copolymer AP-g-poly(AM-co-NMA).•Biodegradation of the graft copolymer by enzyme hydrolysis.•Evaluation of flocculation performance of AP-g-poly(AM-co-NMA).

Amylopectin-g-poly(acrylamide-co-N-methylacrlymide) [AP-g-poly(AM-co-NMA)] was prepared in presence of potassium persulfate (K2S2O8) as the initiator by solution polymerization technique. The synthesised graft copolymer was characterized by various characterization techniques like FTIR, 1H NMR and 13C NMR spectroscopy, thermal analysis and SEM. Biodegradation of the graft copolymers was carried out by enzyme hydrolysis. Flocculation performance of the graft copolymer was evaluated in 1.0 wt% coal, 1.0 wt% silica, 1.0 wt% kaolin, 0.25 wt% iron ore and 1.0 wt% bentonite clay suspensions. The flocculation efficiency of the graft copolymer was also evaluated by the colour removal capacity from aqueous solution of a synthetic dye, malachite green. A comparative study of the flocculation performance AP-g-poly(AM-co-NMA) was also made with another laboratory synthesised graft copolymer namely amylopectin-g-polyacrylamide (AP-g-PAM) and some commercially available flocculants in the same suspensions and also in the malachite green solution. The results showed that the graft copolymer AP-g-poly(AM-co-NMA) showed better flocculation performance than that of AP-g-PAM as well as to some of the commercial flocculating agents.

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