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Nanoscale mechanism of UO2 formation through uranium reduction by magnetite.

  • Pan Z Environmental Microbiology Laboratory, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland.
  • Bártová B Environmental Microbiology Laboratory, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland.
  • LaGrange T Laboratory for Ultrafast Microscopy and Electron Scattering, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland.
  • Butorin SM Molecular and Condensed Matter Physics, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20, Uppsala, Sweden.
  • Hyatt NC University of Sheffield, S10 2TN, Sheffield, UK.
  • Stennett MC University of Sheffield, S10 2TN, Sheffield, UK.
  • Kvashnina KO The Rossendorf Beamline at ESRF - The European Synchrotron, CS40220, 38043, Grenoble, Cedex 9, France.
  • Bernier-Latmani R Environmental Microbiology Laboratory, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland. rizlan.bernier-latmani@epfl.ch.
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  • 2020-08-12
Published in:
  • Nature communications. - 2020
General Biochemistry, Genetics and Molecular Biology
General Physics and Astronomy
General Chemistry
English Uranium (U) is a ubiquitous element in the Earth's crust at ~2 ppm. In anoxic environments, soluble hexavalent uranium (U(VI)) is reduced and immobilized. The underlying reduction mechanism is unknown but likely of critical importance to explain the geochemical behavior of U. Here, we tackle the mechanism of reduction of U(VI) by the mixed-valence iron oxide, magnetite. Through high-end spectroscopic and microscopic tools, we demonstrate that the reduction proceeds first through surface-associated U(VI) to form pentavalent U, U(V). U(V) persists on the surface of magnetite and is further reduced to tetravalent UO2 as nanocrystals (~1-2 nm) with random orientations inside nanowires. Through nanoparticle re-orientation and coalescence, the nanowires collapse into ordered UO2 nanoclusters. This work provides evidence for a transient U nanowire structure that may have implications for uranium isotope fractionation as well as for the molecular-scale understanding of nuclear waste temporal evolution and the reductive remediation of uranium contamination.
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  • English
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gold
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https://sonar.ch/global/documents/16236
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