Removal of cobalt ions from aqueous solution using chitosan grafted with maleic acid by gamma radiation

Chitosan was modified by gamma radiation-induced grafting with maleic acid and then used for the removal of cobalt ions from aqueous solutions. Chitosan-g-maleic acid was characterized by Fourier Transform infrared spectroscopy (FT-IR). The effect of the dose (1-5 kGy) and monomer concentration (0.3-1.3%, m/v) on the grafting ratio was examined. The adsorption kinetics and isotherms were also investigated. The results showed that the optimal dose for grafting was 2 kGy. When monomer concentration was within the range of 0.3-1.3% (m/v), the grafting ratio increased almost linearly. For the adsorption of cobalt ions by chitosan-g-maleic acid beads, the pseudo second-order kinetic model (R2 = 0.99) and Temkin isotherm model (R2 = 0.96) were able to fit the experimental data reasonably well. The equilibrium adsorption capacity of cobalt ions increased from 2.00 mg/g to 2.78 mg/g after chitosan modification.