Different behavior of uranium(VI) on two clay minerals: montmorillonite and kaolinite

This study investigated the feasibility of using montmorillonite and kaolinite to remediate uranium-contaminated groundwater. The results showed that the two minerals achieved U(VI) removal rates of 78.68% and 69.89%, respectively. The maximum saturation adsorption amounts were 3.78 x 10-5 mol g-1 and 3.85 x 10-5 mol g-1, respectively. The Langmuir model and pseudo-second-order kinetics can describe the adsorption process of kaolinite on U(VI). The adsorption process of montmorillonite on U(VI) was well-fitted by Freundlich, and pseudo-second-order models. Thermodynamic parameters indicated that the two minerals' adsorption of U(VI) was a heat-absorbing reaction. The results of SEM-EDS, FT-IR revealed that the adsorption of U(VI) by the two minerals was mostly an ion-exchange reaction, and various functional groups were involved in the adsorption process. XPS results showed valence changes accompanied by kaolinite adsorption of U(VI). Montmorillonite and kaolinite have some differences in the adsorption process of U(VI).