Surface complexation modeling of U(VI) adsorption on granite at ambient/elevated temperature: Experimental and XPS study - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Chemical Geology Année : 2016

Surface complexation modeling of U(VI) adsorption on granite at ambient/elevated temperature: Experimental and XPS study

Résumé

The Beishan granitic formation is being investigated as a potential host rock for a high-level radioactive waste repository in China. It is important to understand the retention processes, including influential parameters such as the metal ion concentration, pH, ionic strength (I) and temperature. The present study deals with U(VI) adsorption on Beishan granite using batch-type experiments in a CO2-free atmosphere. U(VI) adsorption on granite is shown to be insensitive to ionic strength. Temperature has a positive effect on U(VI) adsorption indicating that surface reactions are endothermic. Combining X-ray photoelectron spectroscopy (XPS) analysis and adsorption data at 25 °C, a Generalized Composite (GC) model with three surface complexes, triple bondSOUO2+, triple bondSO(UO2)2(OH)2+ and triple bondSO(UO2)3(OH)5, was constructed. The experimental data at 40 °C and 60 °C were fitted by the proposed model to obtain the equilibrium constants (K) of the surface reactions at these two temperatures. The enthalpy changes (ΔH) of the surface reactions were evaluated from the equilibrium constants obtained at three temperatures via the van't Hoff equation. Finally, blind modeling predictions were performed to test the robustness of the proposed model and ΔH. Satisfactory agreement with the literature data confirmed that this GC model with ΔH proving a useful tool to predict U(VI) adsorption on granite samples, especially on Beishan granite at ambient/high temperature.
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Dates et versions

hal-03891865 , version 1 (09-12-2022)

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Qiang Jin, Lin Su, Gilles F Montavon, Zongyuan Chen, Zhijun Guo, et al.. Surface complexation modeling of U(VI) adsorption on granite at ambient/elevated temperature: Experimental and XPS study. Chemical Geology, 2016, 433, pp.81-91. ⟨10.1016/j.chemgeo.2016.04.001⟩. ⟨hal-03891865⟩
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