Flocculative ability of uncharged and hydrolyzed graft and linear polyacrylamides

Uncharged and anionic copolymers Dextran-graft-Polyacrylamide (D-g-PAA) and linear PAA of similar molecular weight were tested as flocculants in model kaolin polydisperse suspensions (C = 3 g/dl) having high content of particles less than 2 μm in size (more than 60%) which are difficult to settle down. The flocculation process was characterized by suspension sedimentation rate and degree of supernatant clarification. Dependence of flocculation on the degree of branched copolymers compactness as well as the degree of hydrolysis of the amide groups in the polymers was investigated. The main regularities of selection of suitable branched flocculants based on D-g-PAA and optimal their concentration for effective flocculation process was obtained. It was shown that D-g-PAA in ionic form with the lower grafting efficiency and long PAA grafts ensured the highest degree of supernatant clarification and the highest rate of the suspension sedimentation.