Radiation synthesis and characterization of starch-based hydrogels for removal of acid dye

Abstract

A series of hydrogels based on starch, acrylic acid (AAc) and 2-hydroxyethyl methacrylate (HEMA), namely AAc/starch and AAc/HEMA/starch hydrogels were synthesized by gamma radiation and used to adsorb acid fast red dye from aqueous solution. Alkali treatment of AAc/starch hydrogels to improve their ionic character was evaluated. The structure and surface morphology of prepared hydrogels were confirmed by Fourier transfer infrared spectra and SEM, respectively. The results indicated that the diffusion of water into the hydrogels pertains a non-Fickian character. The swelling equilibrium for AAc/starch and NaAc/starch hydrogels was obtained after 10 h whereas for AAc/HEMA/starch hydrogels after 5 h. The effects of the medium pH, initial dye concentration and temperature on the adsorption were studied. The adsorption capacity increases with increasing dye concentration and decreasing medium pH. The increase of temperature leads to higher adsorption capacity for AAc/starch and NaAc/starch hydrogels but lower adsorption capacity for AAc/HEMA/starch hydrogels. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.