Microwave assisted synthesis and characterization of a novel bio-based flocculant from dextran and chitosan

Polysaccharide-modified flocculants as natural polymeric flocculants are receiving increased attention in the field of water treatment. In this study, a novel high-efficiency and ecofriendly flocculant was synthesized using dextran and chitosan. The flocculant-production method was based on a microwave-heating-initiated graft reaction. Results of Fourier transform infrared spectroscopy, nuclear magnetic resonance imaging, X-ray diffraction, elemental analysis, thermogravimetric analysis, and field-emission scanning electron microscopy confirmed that the grafting was successful. The influences of temperature, flocculant dosage, and pH on flocculation efficiency were investigated. Results indicated that 93.6% of the kaolin solid suspended particles were removed by the flocculant. Previous studies on the flocculation mechanism have shown that flocculation comprises adsorption bridging, charge neutralization, and sweeping flocculation. All these findings indicated the broad prospects of the improved dextran in treating industrial wastewater and developing novel high-performance flocculants. (C) 2019 Published by Elsevier B.V.