title: Flocculation of both anionic and cationic dyes in aqueous solutions by the amphoteric grafting flocculant carboxymethyl chitosan-graft-polyacrylamide.
abstract: In the current work, a series of amphoteric grafting chitosan-based flocculants (carboxymethyl chitosan-graft-polyacrylamide, denoted as CMC-g-PAM) was designed and prepared successfully. The flocculants were applied to eliminate various dyes from aqueous solutions. Among different graft copolymers, CMC-g-PAM11 with a PAM grafting ratio of 74% demonstrated the most efficient performance for removal of both the anionic dye (Methyl Orange, MO) and the cationic dye (Basic Bright Yellow, 7GL) under the corresponding favored conditions (80 mg/L of the flocculant at pH 4.0, and 160 mg/L at pH 11.0). In comparison with its precursors, chitosan and carboxymethyl chitosan, CMC-g-PAM11 showed higher removal efficiencies and wider flocculation windows. More importantly, the graft copolymer produced notably more compacted flocs based on image analysis in combination with fractal theory, which was of great significance in practical water treatment. Furthermore, the flocculation mechanism was discussed in detail. The grafted polyacrylamide chains were found to contribute much to the improved bridging and sweeping flocculation effects, but reduced charge neutralization flocculation for the effect of charge screening.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China. Electronic address: yanghu@nju.edu.cn.
authors.forename: Hu
authors.initials: H
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Ziwen
authors.initials: Z
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Tao
authors.initials: T
authors.lastname: Cai
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Haijiang
authors.initials: H
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Haibo
authors.initials: H
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Aimin
authors.initials: A
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Rongshi
authors.initials: R
authors.lastname: Cheng
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D001391:Azo Compounds / Q000737:chemistry*; D048271:Chitosan / Q000031:analogs & derivatives* / Q000737:chemistry; D004396:Coloring Agents / Q000737:chemistry*; D005427:Flocculation; D012996:Solutions; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D001391:Azo Compounds; D048271:Chitosan; D004396:Coloring Agents; D012996:Solutions; D014874:Water Pollutants, Chemical; C570828:carboxymethyl chitosan-graft-polyacrylamide; D000099166:Polyacrylamides; C100258:methyl orange