The hydrolysis of dioxouranium(VI) investigated using EXAFS and O-17-NMR
2000 (English)In: Radiochimica Acta, ISSN 0033-8230, Vol. 88, no 7, 411-415 p.Article in journal (Refereed) Published
The structure of dioxouranium(VI) as a function of pH at different (CH3)(4)N-OH concentrations has been investigated with the aid of U L-III-edge EXAFS. Polynuclear hydroxo species were identified by an U-U interaction at 3.80(8) Angstrom at pH = 4.1. The precipitate formed at pH = 7 has a schoepite like structure. In solution at high pH [0.5 M (CH3)(4)N-OH], the EXAFS data are consistent with the formation of a monomeric four coordinated uranium(VI) hydroxide complex UO2(OH)(4)(2-) of octahedral geometry. The first shell contains two O atoms with a U=O distance of 1.83(o) Angstrom, and four O atoms were identified at a U-O distance of 2.26(5) Angstrom. In strong alkaline solutions [>1 M (CH3)(4)N)-OH],O-17-NMR spectra indicate the presence of two species, presumably UO2(OH)(4)(2-) and UO2(OH)(5)(3-), the latter in low concentration, which are in rapid equilibrium with one another at 268 K in aqueous solution.
Place, publisher, year, edition, pages
2000. Vol. 88, no 7, 411-415 p.
EXAFS, uranyl, hydrolysis, structure, O-17-NMR, aqueous-solution, uranyl-ion, exchange, schoepite, complexes, dynamics, u(vi)
IdentifiersURN: urn:nbn:se:kth:diva-20113ISI: 000089973900005OAI: oai:DiVA.org:kth-20113DiVA: diva2:338806
QC 201005252010-08-102010-08-10Bibliographically approved