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Molecules 2018, 23(8), 2005;

Cationic High Molecular Weight Lignin Polymer: A Flocculant for the Removal of Anionic Azo-Dyes from Simulated Wastewater

Key Laboratory of Paper Science and Technology of Ministry of Education, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China
Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada
Tianjin Key Laboratory of Pulp & Paper, Tianjin University of Science & Technology, Tianjin 300222, China
Authors to whom correspondence should be addressed.
Received: 31 July 2018 / Revised: 5 August 2018 / Accepted: 7 August 2018 / Published: 11 August 2018
(This article belongs to the Special Issue Lignin for Energy, Chemicals and Materials)
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The presence of dyes in wastewater effluents made from the textile industry is a major environmental problem due to their complex structure and poor biodegradability. In this study, a cationic lignin polymer was synthesized via the free radical polymerization of lignin with [2-(methacryloyloxy) ethyl] trimethyl ammonium chloride (METAC) and used to remove anionic azo-dyes (reactive black 5, RB5, and reactive orange 16, RO16) from simulated wastewater. The effects of pH, salt, and concentration of dyes, as well as the charge density and molecular weight of lignin-METAC polymer on dye removal were examined. Results demonstrated that lignin-METAC was an effective flocculant for the removal of dye via charge neutralization and bridging mechanisms. The dye removal efficiency of lignin-METAC polymer was independent of pH. The dosage of the lignin polymer required for reaching the maximum removal had a linear relationship with the dye concentration. The presence of inorganic salts including NaCl, NaNO3, and Na2SO4 had a marginal effect on the dye removal. Under the optimized conditions, greater than 98% of RB5 and 94% of RO16 were removed at lignin-METAC concentrations of 120 mg/L and 105 mg/L in the dye solutions, respectively. View Full-Text
Keywords: lignin-METAC; lignin modification; azo dye; flocculation; COD lignin-METAC; lignin modification; azo dye; flocculation; COD

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Wang, S.; Kong, F.; Fatehi, P.; Hou, Q. Cationic High Molecular Weight Lignin Polymer: A Flocculant for the Removal of Anionic Azo-Dyes from Simulated Wastewater. Molecules 2018, 23, 2005.

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