Macro- and micro-scale studies on U(VI) immobilization in hardened cement paste
| Autor: | D. Kunz, Nathalie Macé, Rainer Dähn, Jan Tits, Erich Wieland |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
X-ray absorption spectroscopy
Materials science Absorption spectroscopy Precipitation (chemistry) Health Toxicology and Mutagenesis Public Health Environmental and Occupational Health Analytical chemistry chemistry.chemical_element Sorption Uranium Uranyl Pollution Synchrotron Analytical Chemistry law.invention chemistry.chemical_compound Nuclear Energy and Engineering chemistry law Radiology Nuclear Medicine and imaging Spectroscopy Wet chemistry |
| Popis: | Wet chemistry and synchrotron-based (micro-)spectroscopic investigations have been carried out to determine the uptake and speciation of U(VI) in hardened cement paste (HCP). The wet chemistry experiments included kinetic studies and the determination of the sorption isotherm. The latter measurements allowed conditions for linear sorption to be distinguished from those where precipitation occurred. Micro-X-ray fluorescence and X-ray absorption spectroscopy (μ-XRF/XAS) were used to determine the elemental distribution and the coordination environment of U(VI) in an intact HCP sample at the atomic level. The sample was prepared by in-diffusion of U(VI) into HCP over 9 months. Micro-XRF maps revealed a heterogeneous distribution of U(VI) in a ten micron thick layer on the surface of the HCP disk. Micro-XAS measurements on a U(VI) hot spot showed that the coordination environment of U(VI) is similar to that in U(VI) doped HCP and in C-S-H sorption samples. To the best of our knowledge this is the first synchrotron-based micro-spectroscopic study on the speciation of diffusing uranyl ions with micro-scale spatial resolution. |
| Databáze: | OpenAIRE |
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