Molecular- and Nano-Scale Structure and Reactivity of Biogenic Uranium (IV) Oxide

Schofield, E.J. et al. (2008) Molecular- and Nano-Scale Structure and Reactivity of Biogenic Uranium (IV) Oxide. In: Goldschmidt 2008, Vancouver, Canada, 13-18 July 2008, A838.

Abstract

Bioremediation has been proposed and extensively researched as an in situ immobilization strategy for uranium contamination in the subsurface with nanoparticulate uraninite (UO2) being the commonly reported product. Little detail is known about the structure and reactivity of this material, but based on comparison to its closest abiotic analog, UO2+x (0 < x < 0.25), we expect that it is complex and disordered. In addition, it has been predicted that the nanoparticulate form would induce strain and dramatically increase the solubility. In this study, the local-, intermediate and long-range atomic and nano-scale structure of biogenic UO2 (formed at varying pH using Shewanella oneidensis strain MR-1) was characterized using EXAFS, SR-based powder diffraction and TEM. The lattice parameter of the nanoparticulate phase is seen to be consistent with bulk UO2. There is no evidence for hyperstoichiometry or strain of the particles, the latter indicating that surface energy is relatively modest. In agreement with this structural analysis, the surface-area normalized dissolution rate of the biogenic UO2 was found to be comparable to that of coarser, synthetic UO2.00.

• Item Type: Conference Proceedings
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Veeramani, Dr Harish
• Authors: Schofield, E.J., Bargar, J.R., Ulrich, K.U., Mehta, A., Bernier-Latmani, R., Veeramani, H., Sharp, J.O., Conradson, S.D., Clark, D.L., Giammar, D.E., and Webb, S.,
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment

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