Study on the retention of uranyl ions on modified clays with titanium oxide

Abstract

The experimental equilibrium adsorption data were tested for the Langmuir, Freundlich, Temkin and Redlich-Peterson equations. Results indicate the following order to fit the isotherms equations: Freundlich > Redlich-Peterson > Temkin > Langmuir. Influence parameters to the sorption process, such as initial concentration of uranium, contact time, solid/liquid ratio, were investigated using a batch mode technique. The results indicate that the adsorption of UO22+ ions from aqueous solution depends on the concentration of uranium in simulated wastewater, on contact time and on the ratio of sorbent/solution value. Some thermodynamic parameters (ΔHo, ΔSo and ΔGo) of the adsorption system were also determined. Thermodynamic values of ΔHo, ΔSo and ΔGo show spontaneous and endothermic nature of the sorption process of uranium ions from simulated wastewaters. The depletion of the uranium uptake at higher initial solution concentration (C>0.5 μg/mL) is probably attributed to the surface precipitation processes, which produce the blockage of micropores and disturb the ionic process evolution. The obtained results underline the possibility that Romanian modified clays can be used for the treatment of radioactive liquid waste containing UO22+ ions.