Removal o f Congo red by copoly (DMAEMA-AMPS) hydrogels for water treatment

Abstract

Ten copolymer gels were prepared from dimethylaminomethacrylate and 2-acrylamido-methylpropane-1-sulfonic acid with crosslinking agent methylene-bisacrylamide by redox polymerization. Hydrogels were characterized by studying their swelling ratios, the surface morphology by SEM, and studying the porosity and specific surface area by BET technique. The hydrogel copolymers were used to remove Congo red dye from aqueous solutions. It was found that there are two copolymers (C20 and E20) gave the best results for removing this dye from aqueous solutions at pH 7. The adsorption behavior was in agreement with Freundlich's model for C20, while E20 matched with Langmuir's model. It was also found that adsorption of Congo red dye on the two copolymeric hydrogels followed a pseudo-second-order kinetics. The results of the activation energy showed that the adsorption of the dye with the hydrogel C20 is chemisorption in nature, while it is physisorption with the hydrogel E20. Finally, desorption studies carried out in 0.1 M of NaOH and hydrochloric acid, distilled water, and 95% ethanol indicated that the best eluent for dye recovery was NaOH.