A novel carboxyl-rich chitosan-based polymer and its application for clay flocculation and cationic dye removal

作者:Liu, Bingzhi; Zheng, Huaili*; Wang, Yili; Chen, Xin; Zhao, Chuanliang; An, Yanyan; Tang, Xiaomin
来源:Science of the Total Environment, 2018, 640: 107-115.
DOI:10.1016/j.scitotenv.2018.05.309

摘要

Due to the complexity of contaminants, the effectiveness of traditional flocculants toward water purification is insufficient. To break the limitation, a novel polymer flocculant [chitosan grafted poly (acrylamide-itaconic acid), CS-g-P(AM-IA)] was synthesized via ultraviolet-initiated graft copolymerization reaction. Characterization results revealed that the graft copolymers were successfully synthesized and with rougher surface structure. The solubility of CS-g-P(AM-IA) and chitosan grafted polyacrylamide (CS-g-PAM) were greatly improved and they can dissolve in the wide pH range of 2.0-12.0. CaCl2 was used as a source of cation bridge to enhance the flocculation of kaolin particles, and its optimum dosage was 150 mg.L-1. At dosage of 30 mg.L-1 and pH of 5.0, the turbidity removal efficiency of CS-g-P(AM-IA) reached the maximum of 93.8%, whereas those of CS-g-PAM and CS were 96.7% and 76.9%, respectively. The patchwise adsorption of ionic groups embedded in the molecular chain on Ca2+-clay complexes took effect to generate flocs with larger particle size. Besides, the decolorization ability of cationic dyes by CS-g-P(AM-IA) was greatly enhanced due to the role of abundant carboxyl groups. In the crystal violet (CV) adsorption experiment, the maximum CV dye removal efficiency for CS-g-P(AM-IA) reached the maximum of 81.6% at dosage of 0.7 mg.mL(-1) and pH of 9.0, while those for CS-g-PAM and CS were 51.7% and 36.5%, respectively.