Studies on Swelling and Equilibrium Adsorption Isotherms of Basic Dye onto Poly (CMC/AAc) Hydrogels Prepared by Gamma Radiation and Their Thermodynamic Evaluations

In this study, ratios of carboxy methyl cellulose (CMC) and acrylic acid (AAc) monomer mixtures were irradiated at doses of 5, 10, 20, 30, 40 and 50 kGy of gamma radiation at dose rate 1.7 Gy/s. The FTIR spectra of the prepared hydrogels confirmed the copolymerization at 20 kGy. The swelling and diffusion in aqueous and basic dye solutions were studied. The hydrogel swelling demonstrated ph-dependence. Diffusions of water and basic dye within the hydrogel were found principally to be non-Fickian type and ph dependent. The equilibrium adsorption isotherm of basic dye via batch experiment revealed the typical Freundlish adsorption isotherm. The adsorption process showed also ph dependence within ph and concentration ranges of 310 and 50-500 ppm, respectively. Some thermodynamic parameters for CMC/ AAc hydrogel-basic dye system were evaluated. The values of adsorption enthalpy change (δH) and free energy change ((δG) of this system were calculated and found to be negative values, whereas entropy change ((δS) of adsorption was found to be positive. All of these thermodynamic parameters provide the validity of poly (CMC/AAc) hydrogels as adsorbent materials for dyes from wastewater