Chiang Mai Journal of Science

A series of semi-interpenetrating polymer network hydrogels (PAMABA) based on poly (vinyl alcohol) (PVA) and a copolymer of acrylamide (AM) and maleic acid (MA) were successfully synthesized. Unlike conventional mono-carboxylic acid-modified hydrogels, MA was selected as a functional monomer to provide abundant carboxyl groups for enhanced electrostatic interaction with cationic dye methylene blue (MB). However, due to the high steric hindrance of MA preventing self-polymerization, AM was introduced as a structural comonomer to facilitate network formation. The structure of PAMABA was characterized by infrared spectroscopy. Infrared spectroscopy confirmed the successful synthesis of the PAMABA products. The synergistic effect of AM and MA on the structure and adsorption properties was investigated by varying their molar ratio. Experimental results indicated that as the molar ratio of AM to MA decreased, the adsorption capacity and removal rate of MB by PAMABA initially increased and then decreased. The results indicate that the optimal performance was achieved at a molar ratio of AM to MA of 1.54:1, and the optimal adsorption capacity was 42.35 mg/g, and the removal rate was 98.52%. In regeneration experiments, the removal rates of MB reached 85.04% and 74.89% after two and three adsorption cycles, respectively. Kinetic studies revealed that the adsorption process followed the pseudo-second-order model.