Sorption kinetics of copper, zinc, cadmium and nickel ions on synthesized silico-antimonate ion exchanger

Silico-antimonate as inorganic ion exchange material has been synthesized and characterized using different available tools (X-ray diffraction (XRD) pattern, X-ray fluorescence, infrared spectroscopy and differential thermal analysis). From the analysis data, the empirical formula of silico-antimonate was obtained to be H2SiSb4O13·10H2O. Sorption kinetics for Cu2+, Zn2+, Cd2+ and Ni2+ ions on silico-antimonate were studied and found to be follow the first order kinetics obeying the Freundlich isotherm over the entire range for the bulk concentration of the metal ions. Thermodynamic parameters (i.e. ΔG°, ΔS° and ΔH°) have also been calculated for the adsorption of Cu2+, Zn2+, Cd2+ and Ni2+ ions on silico-antimonate showing that the overall adsorption process is spontaneous and exothermic.