Removal of metal ions from aqueous solution with β-cyclodextrin-based hydrogels

In this study, a hydrogel SiO2-g-GMA/β-CD-Ac was synthesized by the free-radical cross-linking polymerization of SiO2-g-GMA/β-CD-Ac, it was then used for the adsorption of metal ions from aqueous solutions. The structure and properties of SiO2-g-GMA/β-CD-Ac were characterized by FT-IR and SEM. SEM image shows that SiO2-g-GMA/β-CD-Ac composite particles presented spherical morphology. Strongly depended on the pH of the solution, the maximum adsorption capacity for Cu2+, Pb2+, Cd2+ and Ni2+ were found to be 110.0, 51.02, 15.20, 11.69 mg/g as the pH was 5.5, respectively. Kinetic studies showed that the adsorption process obeys pseudo-second-order rate mechanism and the intra particle diffusion was not the only rate-limiting step. The equilibrium data were fitted well with the Langmuir isotherm model (R 2 > 0.99), where adsorption was an exothermic and spontaneous process.