Starch-derived flocculant with hyperbranched brush architecture for effectively flocculating organic dyes, heavy metals and antibiotics

Abstract

BackgroundIt is highly desired yet challenging for proper treatment of existing wastewaters containing broad-spectrum toxic contaminants of organic dyes, heavy metals and antibiotics. To tackle this problem, this work developed a novel starch-derived flocculant with hyperbranched brush architecture and evaluated its flocculation performance to removing combined pollutants of methylene blue (MB), tetracyline (TC) and Cu2+. MethodsA novel anion-grafted starch-based flocculant (AGSF) with hyperbranched brush structure was synthesized by grafting copolymerization of acrylamide and 2-acrylamido-2-methylpropane sulfonic acid to carboxylated corn starch. The as-prepared AGSF was characterized by a combination of Zeta potential, Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Its flocculation performance of AGSF to different cationic pollutants was investigated in terms of pH, initial pollutant concentration and flocculant dosage. Significant FindingsAGSF demonstrated an outstanding flocculation performance to cationic pollutants, such as organic dyes, heavy metals and antibiotics when compared to its counterparts, unmodified starch (ST) and anionic carboxymethyl starch (CMS). AGSF can achieve 98.6%, 95.7% and 99.2% of remove rates for MB, TC and Cu2+, respectively; while ST and CMS can only remove less than 50% of these pollutants at the optimized conditions. These results verify that the hyperbranched brush structure can make the polymer backbone of flocculants more extended and provide grafted branches with easier accessibility to the pollutants in water, thereby improving its flocculation performance. The current research offers great insight in the design of eco-friendly biosourced starch flocculants for effectively treating combined cationic pollutants of organic dyes, antibiotics and heavy metals.