Removal of hazardous pollutants using bifunctional hydrogel obtained from modified starch by grafting copolymerization

Abstract

The removal of industrial pollutants from wastewater is important to protect human health and the environment. For this reason, bifunctional hydrogel was synthesized by radiation-induced grafting copolymerization of 2-acrylamido-2-methylpropane-1-sulphonic acid (AMPS) and dimethylaminoethyl methacrylate (DMAEMA) onto starch and subsequent chemical modification of the prepared hydrogel by benzyl chloride. The physical and chemical properties of the hydrogel AMPS co DMAEMA modified with ion-exchange groups were investigated by FT-IR, DSC and SEM techniques. The modified copolymers were examined for the removal of basic dyes, cobalt ions, and phosphate anions from aqueous solution. The maximum adsorption capacities of dye, cobalt and phosphate ions were 600 mg/g, 350 mg/g, and 650 mg/g, respectively at the optimum conditions. The adsorption of dye, Co²⁺ ions, and phosphate anions onto the hydrogel obeyed both Langmuir and Freundlich models. The adsorption kinetics of dye was found to follow closely the pseudo-first-order kinetic model rather than the pseudo-second-order kinetic model. The kinetic study of Co²⁺ ions adsorption indicates that it obeys pseudo-second-order kinetic model rather than pseudo-first order one.

Keywords: Basic dyes; Bifunctional hydrogel; Heavy metal ions; Modified starch; Pollutants; Radiation-induced graft polymerization.