Evaluation of a novel dextran-based flocculant on treatment of dye wastewater: Effect of kaolin particles

• Published in: The Science of the total environment Vol. 640-641; pp. 243 - 254
• Main Authors: Zhao, Chuanliang, Zheng, Huaili, Sun, Yongjun, Zhang, Shixin, Liang, Jianjun, Liu, Yongzhi, An, Yanyan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.11.2018
• Subjects: Congo red; Dextran-based flocculant; Flocculation mechanism; Kaolin; Surface-active monomer; Ultrasound; Flocculation mechanism; Dextran-based flocculant; Congo red; Surface-active monomer; Ultrasound; Kaolin
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2018.05.286

Graft modified flocculants have recently received increasing attention in the field of water treatment as they have the combinative advantages of synthetic and natural polymeric flocculants. In this work, surface-active monomer benzyl(methacryloyloxyethyl)dimethylammonium chloride (BMDAC) was selected to graft on dextran (DX) with high molecular weight (10.3 × 106 g/mol) produced through enzyme-catalyzed process in order to remove dissolved dyes from wastewater. The flocculant (DAB) was fabricated by ultrasound initiated polymerization technique, and the structure characterization of FTIR, 1H/12C NMR, XRD and XPS spectrum confirmed the successful grafting. Then the Congo red (CR) removal efficiency by DAB was optimized based on the flocculation conditions, including wastewater initial pH, flocculant dosage and initial dye concentration. The effect of suspended solids on the removal of dyes was evaluated in kaolin-CR simulated wastewater. The results indicated that the optimal removal efficiency of CR was 68.1% and 88.2% in single CR and kaolin-CR flocculation system, respectively. The improvement of removal efficiency was attributed to the fact that partial CR molecules were adsorbed onto kaolin particles before flocculation, and were synergistically flocculated accompanied by kaolin particles. Finally, the flocculation mechanism was discussed by a detailed investigation of the zeta potentials, FTIR and XPS spectra of flocs, which can provide important reference for optimizing the flocculation conditions and designing novel high-performance flocculants. [Display omitted] •A dextran-based flocculant DAB was designed and prepared by ultrasound initiated polymerization technique.•Flocculation of dye wastewater was studied.•The high flocculation performance of DAB is due to structural advantages.•The existence of suspended solids markedly improved the removal of dyes.•Zeta potentials, FTIR and XPS spectra of flocs were measured for mechanism study.