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J Colloid Interface Sci. 2014 Feb 15;416:133-8. doi: 10.1016/j.jcis.2013.10.054. Epub 2013 Nov 8.

Probing the surface speciation of uranium (VI) on iron (hydr)oxides by in situ ATR FT-IR spectroscopy.

Author information

  • 1Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf e.V., Bautzner Landstr. 400, D-01328 Dresden, Germany. Electronic address: foersten@hzdr.de.
  • 2Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf e.V., Bautzner Landstr. 400, D-01328 Dresden, Germany.

Abstract

The surface speciation of uranium(VI) on maghemite (γ-Fe2O3) was elucidated at the spectroscopic level for the first time. By means of in situ ATR FT-IR measurements, the formation of uranium(VI) outer-sphere complexes was revealed under anoxic conditions and in ambient atmosphere at mildly acid conditions. This type of complexation was verified by the frequency of the ν3(UO2) mode observed for the surface species, the impact of the ionic strength of the background electrolyte on U(VI) sorption and by the high reversibility of the sorption process monitored by on line spectroscopy. The impact of carbonate ions from atmospherically derived CO2 on U(VI) sorption on maghemite was investigated. Although the surface speciation of the carbonate ions presumably change from a monodentate coordination on maghemite to a bidentate coordination in the ternary sorption system, the U(VI) speciation is not changed. A contrasting juxtaposition of comparable results obtained from maghemite and ferrihydrite reveals a basically different type of U(VI) complexation, namely outer and inner spheric coordination.

Copyright © 2013 Elsevier Inc. All rights reserved.

KEYWORDS:

ATR FT-IR spectroscopy; Carbonate; Ferrihydrite; Maghemite; Ternary surface complex; Uranyl

PMID:
24370412
[PubMed]
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