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

Structures of multinuclear U(vi) species on the hydroxylated α-SiO2(001) surface: insights from DFT calculations

“…7,10,30,33,34 In contrast, if multinuclear U( vi ) surface species are included, SCMs show better fitting performance to the experimental data. 20,30,35 The formation of multinuclear U( vi ) surface species at high U( vi ) concentrations and near-neutral pH values is supported by many spectroscopic investigations. For instance, Kowal-Fouchard et al 20 ascribed the species with a fluorescence lifetime of 400 μs to a multinuclear U( vi ) surface species ≡SiO(UO 2 ) 3 (OH) 5 on smectite below pH 5.0 in an air atmosphere (uranium concentration of 1 × 10 −4 mol L −1 ).…”

Uranium speciation in weathered granitic waste rock piles: an XAFS investigation

“…[9][10][11][12][13] Weathered granitic material generally produces phyllosilicates, Fe oxyhydroxides or uranyl phosphates that are efficient traps for U sequestration with sorption or neoformation processes. [14][15][16][17][18][19] The two major problems posed by these waste rocks lie in determining how oxidation related to weathering is affecting the piles based on the U valence of the minerals and, determining what the dominant speciation is. Geological timescales, however, are not necessarily sociological ones, and kinetic factors can cause the attainment of the new equilibrium to take a longer time than desired, during which intermediate species may be formed.…”

On the long-term migration of uranyl in bentonite barrier for high-level radioactive waste repositories: The effect of different host rocks

“…Voutilainen et al (2017) simulated transport of cesium in Grimsel granodiorite with micrometer-scale heterogeneities; they concluded that the heterogeneity of the mineral structure at the micrometer scale could significantly affect the diffusion and adsorption of cesium in Grimsel granodiorite at the centimeter scale. Jin et al (2016) conducted a surface complexation modeling of U(VI) adsorption, using a Generalized Composite model on granite at ambient/elevated temperature; model results showed that the exchange reaction is not important for U(VI) adsorption on granite.…”