Characteristic study for the uranium and cesium sorption on bentonite by using XPS and XANES

X-ray photoelectron spectroscopy (XPS) and synchrotron X-ray techniques of absorption near edge structure (XANES) were used to probe the coordination numbers and chemical states of absorption atoms to characterize the retention processes of uranium and cesium transportation in bentonite. The results of XPS showed that minor Van der Waals force interaction near the surface of bentonite were found while cesium adsorbed onto bentonite. The result of XANES showed that the uranium valence state greater than 6, and the cesium valence state also find greater than 1. The uranium valence state of mixture of bentonite and UO2(NO3)2·6H2O solvent is greater than 6. It maybe due to the strong electron negativity of NO3−. From the results of added CsNO3 to bentonite also find the cesium valence state greater than 1. Checking the atom valence state may be able to identify nuclide migration mechanism, which is fundamental information to estimate nuclide migration to biosphere in natural environments.