Swelling behaviour of starch-g-acrylic acid hydrogel and its potential application in removal of rhodamine b and alkali blue dyes

Abstract

Starch-g-acrylic acid hydrogel was prepared by free radical polymerization technique adopting potassium persulphate (KPS) as an initiator and N’N-methylenebisacrylamide (MBA) as a linking agent. The aim of the research is to inspect the potentials of starch-based hydrogel in remediating wastewater. Fourier Transform Infrared (FT-IR) spectroscopy was used to find the formation of hydrogel while Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM) were used for the characterization of the hydrogel. The FT-IR spectroscopy confirmed hydrogel formation. The DSC results showed that the generated hydrogel is thermally stable, and the SEM depicts a good porous site for dye adsorption. Batch adsorption for Rhodamine B (RDB) and Alkali blue (AB) dyes under the variation of contact time was 105 minutes for both dyes with percentage removal of 89.80 and 60.32%, adsorbent dose was 0.4 and 0.8 g with percentage removal of 86.42 and 57.95%, concentration was 50 and 30 ppm with percentage removal of 67.01 and 77.18% and pH was 8 for both dyes with percentage removal of 77.43 and 79.13% as the optimum. The results indicates that acrylic acid monomer was efficiently grafted on the starch, and the adsorption method correlated with Freundlich isotherm equation. It was concluded that the starch-based hydrogel is an appropriate adsorbent and can be explored for industrial wastewater treatment.