Synthesis and Characterization of Cationic Polyelectrolytes to Address Changing Source Water Quality

Abstract

This research focuses on developing novel cationic flocculants (polyelectrolytes) for drinking water treatment. Cationic flocculants are currently used in many municipal water treatment processes, but are not able to effectively address changing source water quality challenges. These challenges include increased concentration of humic substances and more frequent algae bloom occurrences. Changes in source water quality generally require higher dosing of traditional coagulants and flocculants, which increases treatment cost and sludge production. Hence, this research investigates novel cationic flocculants to determine how comonomer selection and copolymer properties impact treatment performance.

Nine cationic copolymers were synthesized and characterized according to copolymer conversion, molecular weight distribution, zeta potential, and jar testing. Of the materials evaluated, the most promising cationic flocculant was the copolymer of methacrylamide (MAA) and (p-vinylbenzyl)trimethylammonium chloride (VBTMAC), which shows great UV-254 results among other alternative cationic flocculants. These results demonstrate that utilities can adapt to changing source water quality through material innovation, instead of (or alongside) costly process innovation.

Further optimization is still possible through future work, including manipulating the molar ratio of neutral monomer and cationic monomer, improving understanding of intermolecular interactions between target contaminants and promising cationic flocculants, and extending results to bio-derived polymer flocculants. Through an iterative design approach, novel cationic flocculants can be optimized for specific water treatment challenges.