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EXAFS and DFT Investigations of Uranyl-Arsenate Complexes in Aqueous Solution

Title data

Gezahegne, Wondemagegnehu A. ; Hennig, Christoph ; Tsushima, Satoru ; Planer-Friedrich, Britta ; Scheinost, Andreas C. ; Merkel, Broder J.:
EXAFS and DFT Investigations of Uranyl-Arsenate Complexes in Aqueous Solution.
In: Environmental Science & Technology. Vol. 46 (2012) Issue 4 . - pp. 2228-2233.
ISSN 0013-936X
DOI: https://doi.org/10.1021/es203284s

Abstract in another language

Uranium and arsenic often co-occur in nature, for example, in acid mine drainage waters. Interaction with arsenic is thus important to understand uranium mobility in aqueous solutions. For the present study, EXAFS spectroscopy was used to investigate the formation and identify the structure of aqueous uranyl arsenate species at pH 2. The nearest U−As distance of 3.39 Å, observed in shock-frozen liquid samples, was significantly shorter than that observed in solid uranyl arsenate minerals. The shorter bond length indicated that the solution contained a bidentate-coordinated species, in contrast to the monodentate coordination in solid uranyl arsenate minerals. The U−As coordination number of 1.6 implied that two uranyl arsenate species with U:As ratios of 1:1 and 1:2 formed in nearly equal proportions and that the hydrated uranyl ion was present only as a minor component. The two uranyl arsenate species could not be differentiated spectroscopically, since their U−As distances were equal. A comparison based on DFT modeling indicated for both the 1:1 and the 1:2 species, that the bidentate arsenates were bound to uranium with one of the binding oxygen atoms being protonated. Based on the present spectroscopic study, the two species that will have to be considered in acidic uranium−arsenic-rich solutions are thus UO2H2AsO4+, and UO2(H2AsO4)20.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER100430
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Professorship Environmental Geochemistry Group
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Professorship Environmental Geochemistry Group > Professorship Environmental Geochemistry - Univ.-Prof. Dr. Britta Planer-Friedrich
Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences
Research Institutions
Research Institutions > Research Centres
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 05 May 2015 12:10
Last Modified: 17 Mar 2016 10:27
URI: https://eref.uni-bayreuth.de/id/eprint/12750