Use of superswelling acrylamide/maleic acid hydrogels for monovalent cationic dye adsorption

Abstract

Acrylamide/maleic acid (AAm/MA) superswelling hydrogels prepared by irradiation with gamma radiation were used in experiments on swelling, diffusion, and adsorption of some water-soluble monovalent cationic dyes such as basic red 5 (BR-5), basic violet 3 (BV-3), and brilliant cresyl blue (BCB). The AAm/MA hydrogel containing 60 mg MA and irradiated at 5.20 kGy was used for swelling and diffusion studies in water and aqueous solutions of the monovalent cationic dyes. For this superswelling hydrogel the swelling studies indicated that swelling increased in the following order: BR-5 > water > BV-3 greater than or equal to BCB. The diffusion of water and the dyes within the hydrogels was found to have a non-Fickian character. The uptake of the cationic dyes to the AAm/MA superswelling hydrogels was studied by the batch adsorption technique at 25 degreesC, The uptake of dyes within the hydrogel increased in the following order: BR-5 > BV-3 > BCB. In the experiments of the adsorption equilibrium, S-type adsorption in Giles' classification system was found. The binding ratio of the hydrogel/dye systems was gradually increased with the increase of the MA content in the AAm/MA hydrogel and the irradiation dose. (C) 2001 John Wiley & Sons, Inc.