Macroscopic and spectroscopic characterization of U(VI) sorption on biotite

Application of transition-edge sensors for micro-X-ray fluorescence measurements and micro-X-ray absorption near edge structure spectroscopy: a case study of uranium speciation in biotite obtained from a uranium mine

“…The results of XANES analysis with the SDD and TES indicated that the percentage of U(IV) species ranged between 21% and 42%, indicating that U was partially reduced in the biotite sample. The presence of reduced U(IV) species indicated that the soluble U(VI) species in the groundwater were reduced and accumulated as U(IV) species in the analysis spots A to D. In previous studies, uranyl ion adsorption on biotite was reported as adsorption without reduction 13,17,22 or with partial reduction into U(IV). 14 Our results supported that biotite retains some reduced U under the actual environmental conditions in the weathered granite in the Ningyo-toge area.…”

“…16 Conversely, Zhou et al reported considerably low redox reactivity of structural Fe( ii ) in biotite, and uranyl ions were adsorbed in the interlayer of biotite without reduction. 17 The mechanism of U accumulation in biotite in the environment, namely the presence or absence of a reduction reaction, remains unclear.…”

“…Zhou et al reported the sorption of U( vi ) on the biotite surface in batch experiments via X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). 17 However, XPS and XRD were not sufficiently sensitive for trace element analysis because of the interference of the main coexisting elements and crystal phases, respectively. Some researchers reported the speciation of U in the minerals using micro-Raman spectroscopy.…”