An investigation of Re(VII) and Se(IV) adsorption by Tamusu clay: effect of time, pH, ionic strength, temperature and organic acids.

By the batch method, the effects of contact time, pH, ionic strength, initial concentration, temperature on the sorption of Re(VII) and Se(IV) were investigated. Our results illustrated that Re(VII) and Se(IV) sorption was well described by the pseudo-second-order kinetic model, as well as by Freundlich model. This suggests chemical reaction as a rate-controlling step on the surface with 0.51 and 2.24 mg/g maximum sorption capacity at pH 7.0. The pH has little effect on Re(VII) adsorption, While it significantly affects the Se(IV) sorption. The sorption capacity of Re(VII) and Se(IV) decreased with increasing NaCl concentration. And the adsorption processes of Re(VII) and Se(IV) were endothermic spontaneous processes. What's more, our results also show that the sorption of Re(VII) and Se(IV) in clay rock will not interfere with each other under various conditions. Additionally, the adsorption capacity of Se(IV) in clay is significantly increased under acidic conditions when organic acids in the solution, but not influenced under neutral and alkaline conditions. [ABSTRACT FROM AUTHOR]