Swelling, diffusion, network parameters and adsorption properties of IPN hydrogel of chitosan and acrylic copolymer

Interpenetrating network (IPN) type hydrogels of a biopolymer and a synthetic polymer were prepared from chitosan and crosslink copolymer of acrylic acid, sodium acrylate and hydroxyethyl methacrylate. Acrylic acid, sodium acrylate, hydroxyethyl methacrylate and N′N′-methylenebisacrylamide (MBA) monomers were free radically copolymerized and crosslinked in aqueous solution of chitosan. Several IPN hydrogels were prepared by varying concentrations of initiator, crosslinker (MBA) and weight% of chitosan . These hydrogels were characterized by free acid content, pH at point of zero charge (PZC), FTIR, DTA–TGA, SEM and XRD. The swelling and diffusion characteristics, network parameters and adsorption of cationic methyl violet (MV) and anionic congo red (CR) dyes by these hydrogels were studied. The hydrogels showed high adsorption (9.5–119 mg/g for CR and 9.2–98 mg/g for MV) and removal% (98–73% for CR and 94–66% for MV) over the feed concentration of 10–140 mg/l dye in water. The isotherms and kinetics of dye adsorption by the hydrogels were also studied.