Preparation of Strong Cationic Chitosan-graft-Polyacrylamide Flocculants and Their Flocculating Properties

Abstract

Recently, more attentions have been paid to natural polymer-based flocculants in water treatment, since they are believed to be low-cost, nontoxic, and environmentally friendly materials. In this work, strong cationic chitosan-based graft copolymer flocculants (3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CTA) modified chitosan-graft-polyacrylamide, denoted as chitosan-CTA-g-PAM) have been prepared, and their flocculating properties were studied systematically, both at the laboratory scale and at the pilot scale. In laboratory scale, a kaolin suspension was employed as synthetic wastewater. The effects of dosage, temperature, and original turbidity of untreated wastewater were investigated, respectively. Moreover, in pilot scale, the raw water from the Zhenjiang part of the Yangtse River in China was used as wastewater. The influences of three external factors—dosage, sedimentation time, and mechanical mixing rate—on the flocculating performances have been studied by orthogonal testing, respectiv...