Equilibrium and kinetics studies on the absorption of Cu(II) from the aqueous phase using a β-cyclodextrin-based adsorbent

A novel β-cyclodextrin-based adsorbent (CDAA) for the removal of Cu2+ was prepared and characterized. The adsorption capacities of Cu2+ on CDAA were evaluated under various treatment conditions, including the solution pH, the dosage of the adsorbent, the initial Cu2+ concentration, and adsorption time. The results indicated that CDAA hydrogel exhibited typically three-dimensional cross-link network structure. There was a significant increase in the adsorption capacity (from 18.93 mg/g to 107.37 mg/g) when the solution pH increased from 2 to 5. The adsorption equilibrium data were fitted and analyzed with Langmuir, Freundlich, Temkin isotherm equations and four adsorption kinetic models. The results suggested that the Freundlich equation model was the best fit with experimental data (R2 = 0.995). The kinetic equations showed that the adsorption of Cu2+ on the adsorbent fit different equations for different concentrations of Cu2+. These results indicate that in the present study, Cu2+ adsorption onto the adsorbent occurred via ion exchange and chemical interaction mechanisms.