Investigation of sorption/swelling characteristics of chemically crosslinked AAm/SMA hydrogels as biopotential sorbent

The aim of this study was to investigate the equilibrium swelling and sorption properties of chemically crosslinked copolymeric hydrogels as biopotential sorbent consisting of acrylamide (AAm) and sodium methacrylate (SMA). Highly swollen AAm/SMA hydrogels were prepared by free‐radical polymerization in aqueous solution of AAm with SMA as comonomer and three multifunctional crosslinkers such as 1,4‐butanediol dimethacrylate, ethylene glycol dimethacrylate, and trimethylolpropane triacrylate. Swelling experiments were performed in aqueous urea solutions and safranin T at 25°C, gravimetrically. The hydrogels showed enormous swelling in aqueous (urea/water or dye/water) medium and displayed swelling characteristics that were highly depended on the chemical composition of the hydrogels. Some parameters related swelling and diffusion behavior were investigated. The values of the equilibrium percentage swelling values of AAm/SMA hydrogels were between 585 and 19,900%. The numbers determining the type of diffusion (n) are between 0.54 and 0.99. Hence, the diffusion type was found to be non‐Fickian in character for the hydrogels. Chemically crosslinked AAm/SMA hydrogels were used in experiments on sorption of water‐soluble monovalent cationic dye such as safranin T (Basic red 2, ST). For sorption of cationic dye, ST into the hydrogels was studied by batch sorption technique at 25°C. The sorption capacity of AAm/SMA hydrogels was investigated. At the end of the experiments, 17.91–83.78 ST% adsorptions were determined.