Adsorption Behavior of Sr2+ on Yangjiang Granite

Abstract

Studying the adsorption behavior of Yangjiang granite to Sr2+ is very meaningful for the safety assessment of the low- and medium-level nuclear waste repository in Yangjiang. In this study, experimental samples were obtained from the granite rock formations near the low- and medium-level nuclear waste repository in Yangjiang. The static adsorption experiment was performed study the adsorption behavior of Yangjiang surrounding rocks granite on Sr2+. And the effect of contact time, initial concentration, reaction temperature, pH, as well as cation and anion on the adsorption behavior of granite was studied in detail. The physical and chemical compositions of Yangjiang granite were investigated by X-ray diffraction spectra(XRD), X-ray fluorescence spectrometer(XRF), scanning electron microscopy-energy dispersive spectroscopy(SEM-EDS), Fourier transform infrared spectra(FTIR) and Zeta potential analyzer. The characterization studies show the granite surface becomes rough after adsorption. The results of static adsorption experiments indicate that adsorption equilibrium time is about 5 days. The Sr2+ adsorption decreases with the increase of Sr2+ concentration which conforms to the Langmuir isotherm adsorption model and belongs to single-layer adsorption. Under neutral and higher temperature conditions, the adsorption effect is better. The fitting thermodynamic equation suggests that adsorption is a spontaneous endothermic reaction. The ion in groundwater such as Ca2+, Mg2+, Fe3+, NO3- all can inhibit the adsorption of Sr2+ by Yangjiang granite, while CO32- can interfere with adsorption by forming polymers with Sr2+. The results of this study can provide a certain reference for the safety evaluation of the low- and medium-level nuclear waste repository in Yangjiang.

Keywords

• sr2+
• yangjiang granite
• low- and medium-level nuclear waste repository
• adsorption behavior