Flocculation characteristics of grafted and ungrafted starch, amylose, and amylopectin

Graft copolymers of starch, amylose, and amylopectin with polyacrylamide have been synthesized using a ceric-ion-initiated solution polymerization technique. In the case of amylopectin-g-polyacrylamide (Ap-g-PAM), four graft copolymers have been synthesized with variation in the number and length of grafted polyacrylamide chains. The flocculation behavior has been studied in a 0.25% kaolin suspension. It has been found that among the three graft copolymers of the starch family, Ap-g-PAM is the best flocculating agent compared to starch-g-polyacrylamide (St-g-PAM) and amylose-g-polyacrylamide (Am-g-PAM). Among the series of Ap-g-PAM, the one with fewer but longer polyacrylamide chains has been found to be the most effective flocculant.