Evaluation of the flocculation performance of carboxymethyl chitosan-graft-polyacrylamide, a novel amphoteric chemically bonded composite flocculant |
| |
Authors: | Yang Zhen Yuan Bo Huang Xin Zhou Junyu Cai Jun Yang Hu Li Aimin Cheng Rongshi |
| |
Affiliation: | a Key Laboratory for Mesoscopic Chemistry of MOE, Department of Polymer Science & Technology, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China b State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, PR China |
| |
Abstract: | In the present work, a novel amphoteric chemically bonded composite flocculant (carboxymethyl chitosan-graft-polyacrylamide, denoted as CMC-g-PAM) was successfully prepared and used to flocculate the kaolin suspension. The flocculation performance of CMC-g-PAM in acidic, neutral, and alkaline conditions was systematically evaluated by light scattering in combination with fractal theory, as well as by traditional turbidity and zeta potential measurements. Based on the experimental facts from in situ size and fractal dimension measurements, different flocculation mechanisms play key roles at various pH levels, resulting in substantially varied flocculation kinetic processes under three pH conditions. In acidic condition, patching was the main mechanism involved in the opposite zeta potential between CMC-g-PAM and the kaolin suspension. A flat configuration was favored when the polymeric flocculant was adsorbed onto the particle surface, leading to a slower initial floc growth rate but larger and denser flocs. Bridging was the dominant mechanism in neutral and alkaline conditions. A faster initial rate of bridging resulted in smaller and more open floc structures. A rearrangement process in neutral pH subsequently led to more compact flocs, whereas no restructuration of flocs occurred in alkaline conditions because of the electrostatic repulsion of the same negative charges on the flocculant and particles. |
| |
Keywords: | Amphoteric chemically bonded composite flocculant Flocculation kinetics Flocculation mechanism Fractal dimension Light scattering |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|