Sorption of Eu(III) on Eibenstock granite studied by µTRLFS: A novel spatially-resolved luminescence-spectroscopic technique

Abstract

In this study a novel technique, micro-focus time-resolved laser-induced luminescence spectroscopy (µTRLFS) is presented to investigate heterogeneous systems like granite (mainly consisting of quartz, feldspar, and mica), regarding their sorption behavior. µTRLFS is a spatially-resolved upgrade of conventional TRLFS, which allows point-by-point analysis of single minerals by reducing the beam size of the analytic laser beam to below the size of mineral grains. This provides visualization of sorption capacity as well as speciation of a luminescent probe, here Eu 3+ . A thin-section of granitic rock from Eibenstock, Saxony, Germany was analyzed regarding its mineralogy with microprobe X-ray fluorescence (µXRF) and electron probe microanalysis (EPMA). Afterwards, it was reacted with 5.0 × 10 −5 mol/L Eu 3+ at pH 8.0 and uptake was quantified by autoradiography. Finally, the µTRLFS studies were conducted. The results clearly show that the materials interact differently with Eu 3+ , and often even on one mineral grain different speciations can be found. Alkali-feldspar shows very high uptake, with an inhomogeneous distribution, and intermediate sorption strength. On quartz uptake is almost 10-fold lower, while the complexation strength is higher than on feldspar. This may be indicative of adsorption only at surface defect sites, in accordance with low hydration of the observed species.

Influence of Muscovite (001) Surface Nanotopography on Radionuclide Adsorption Studied by Kinetic Monte Carlo Simulations

“…Another recent method is the spatially resolved time-resolved laser fluoresce spectroscopy (µTRLFS). This method was used to investigate the spatial distribution of adsorption complexes on a granite surface [35]. Combined with a measurement of surface nanotopography, a correlation between the two parameters might be possible leading to an improved mechanistic understanding.…”

Detection and Localization of Eu on Biosilica by Analytical Scanning Electron Microscopy

“…The recently developed μTRLFS addresses this issue. While it is a highly valuable tool for mineral studies in the context of permanent disposal sites, its laser excitation spot with a diameter of about 30 μm limits its use in the analysis of microalgae samples (Molodtsov et al, 2019).…”

Spatially resolved sorption of Cm(III) on crystalline rock: influence of surface roughness and mineralogy

“…As a representative for trivalent actinides, such as Am(III), Np(III), and Pu(III), which are expected to be present due to the reducing conditions encountered in a deep geological repository, we have chosen the actinide Cm(III). Cm(III) possesses excellent luminescence properties, which allows us to not only examine the sorption uptake but also the speciation of Cm(III) on the surface.We combined spatially resolved investigation techniques, such as vertical scanning interferometry, calibrated autoradiography, and Raman microscopy coupled to micro-focus time-resolved laser-induced luminescence spectroscopy (µTRLFS) (Molodtsov et al, 2019). Thus, we were able to correlate mineralogy, surface roughness, and grain boundary effects with radionuclide speciation, allowing us to identify important radionuclide retention processes and parameters (see Fig.…”

“…We combined spatially resolved investigation techniques, such as vertical scanning interferometry, calibrated autoradiography, and Raman microscopy coupled to micro-focus time-resolved laser-induced luminescence spectroscopy (µTRLFS) (Molodtsov et al, 2019). Thus, we were able to correlate mineralogy, surface roughness, and grain boundary effects with radionuclide speciation, allowing us to identify important radionuclide retention processes and parameters (see Fig.…”

“…Dazu kombinierten die Autoren räumlich aufgelöste Untersuchungstechniken wie die vertikale Scanning-Interferometrie, die kalibrierte Autoradiographie und die Raman-Mikroskopie in Kopplung mit µTRLFS (mikrofokussierte zeitaufgelöste laserinduzierte Lumineszenzspektroskopie; Molodtsov et al, 2019). Somit waren sie in der Lage, Mineralogie, Oberflächenrauheit und Korngrenzeneffekte mit der Radionuklidspeziation in Beziehung zu setzen, was die Identifizierung wichtiger Radionuklidretentionsprozesse und -parameter ermöglichte (Abb.…”