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Fabrication of amphoteric lignin and its hydrophilicity/oleophilicity at oil/water interface

Year: 2020

Journal: J. Colloid Interface Sci., Volume 561, MAR 1, page 231–243

Authors: Kazzaz, Armin Eraghi; Fatehi, Pedram

Organizations: NSERCNatural Sciences and Engineering Research Council of Canada (NSERC); Canada Research ChairsCanada Research ChairsCGIAR; Canada Foundation for InnovationsCanada Foundation for Innovation; northern Ontario Heritage Fund Corporation

Keywords: Amphoteric lignin; Colloid; COSY NMR; Adhesion force; Oil/water interface

Amphoteric polymers have tremendous applications in colloidal systems. Despite the enormous availability of lignin, the generation of amphoteric lignin polymer has yet to be discovered. In this work, amphoteric lignin was synthesized in an industrially attractive aqueous system via integrating the advantages of grafting quaternary ammonium groups onto lignin and polymerizing lignin with sulfonate containing monomers. The order of the reactions seemed to change the properties of the amphoteric lignin significantly, which was confirmed by H-1 and 2D H-1 COSY NMR analysis. In this research, the behavior of carbon chain length of the reagent containing the cationic group in inducing amphoteric lignin with superior properties was comprehensively discussed. The wettability and adhesion force analyses were performed to understand the impact of amphoteric lignin at the interface of a water/oil mixture. With the help of the contact angle and adhesion force measurements, the superior properties of the amphoteric lignin to those of only anionic or cationic modified lignin were determined. In water, the amphoteric and anionic lignin polymers strongly repelled oil droplets. In oil, both anionic and cationic lignin polymers showed poor water wettability, while the amphoteric lignin was wetted well by water. This paper discusses the fundamental mechanisms associated with the altered behavior of these lignin-based polymers at different interfaces. (C) 2019 Elsevier Inc. All rights reserved.