From EXAFS of reference compounds to U(VI) speciation in contaminated environments

Autor: Anna Krot, Irina Vlasova, Alexander Trigub, Alexey Averin, Vasily Yapaskurt, Stepan Kalmykov
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Journal of Synchrotron Radiation, Vol 29, Iss 2, Pp 303-314 (2022)
Druh dokumentu: article
ISSN: 1600-5775
16005775
DOI: 10.1107/S1600577521013473
Popis: Understanding the speciation of technogenic uranium in natural systems is crucial for estimating U migration and bioavailability and for developing remediation strategies for contaminated territories. Reference EXAFS data of model laboratory-prepared uranium compounds (`standards') are necessary to analyze U-contaminated samples from nuclear legacy sites. To minimize errors associated with measurements on different synchrotrons, it is important not only to compare data obtained on environmentally contaminated samples with the literature but also with `standards' collected at the same beamline. Before recording the EXAFS spectra, all reference compounds were thoroughly characterized by Raman spectroscopy and powder X-ray diffraction. The U(VI) local molecular environments in the reference compounds, i.e. uranyl oxyhydroxides, phosphates, carbonates and uranates, were examined using XAFS. Based on the EXAFS fitting results obtained, including the nature of the bonding, interatomic distances and coordination numbers, parameters that are typical for a particular U compound were differentiated. Using data for `standards', U speciation in the sample of radioactively contaminated soil was determined to be a mixture of U oxyhydroxide and carbonate phases.
Databáze: Directory of Open Access Journals
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