One-pot production of a graft copolymer of cationic starch and cationic polyacrylamide applicable as flocculant for wastewater treatment

Abstract

A newly developed, high-performance, and environmentally friendly flocculant, i.e., a graft copolymer of cationic starch and cationic polyacrylamide (SC-CPAM), is synthesized via a single-step pathway in which the cationic agent is incorporated onto the starch backbone and into the polyacrylamide grafted branch simultaneously. One-pot preparation method is quick, reproducible, and easily scalable, which yields high-quality products with better flocculation performance than conventional cationic starch (SC) and starch-graft-polyacrylamide (S-PAM). The synthesized samples are characterized by physicochemical techniques, namely Fourier Transform Infrared Spectroscopy (FTIR), elemental analysis, H1 Nuclear Magnetic Resonance (H1NMR) Spectroscopy, Zeta Potential (ZP), and Dynamic light scattering (DLS). The application as a flocculant for wastewater treatment is investigated by flocculation of kaolinite suspension and analysis of turbidity (UV-Vis and NTU), ZP, and floc size in neutral pH. A high clarification of 97.8%, low turbidity of 1.97 NTU, and large floc size of 136 µm, obtained by SC-CPAM, are believed to result from dual flocculation mechanisms, i.e., polymer charge patch and particle bridging, enabled by the cationic high molecular weight branched bio-based flocculant for wastewater purification applications.