Web Release Date: January 22,
Mica Surfaces Stabilize Pentavalent Uranium
and
Pacific Northwest National Laboratory, Chemical Science Division, MSIN: K8-96, 902 Battelle Boulevard, Richland, Washington 99352, Shell Global Solutions International B.V., P.O. Box 38000, 1030 BN Amsterdam, The Netherlands, Department of Chemistry, George Washington University, Washington, D.C. 20052, and Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C. 20015
Received September 12, 2004
Abstract:
High-resolution X-ray photoelectron spectroscopy was used to
demonstrate that reduction of aqueous U6+ at ferrous mica surfaces
at 25 
C preserves U5+ as the dominant sorbed species over a
broad range of solution compositions. Polymerization of sorbed
U5+ with sorbed U6+ and U4+ is identified as a possible mechanism
for how mineral surfaces circumvent the rapid disproportionation
of aqueous U5+. The general nature of this mechanism suggests
that U5+ could play an important, but previously unidentified, role
in the low-temperature chemistry of uranium in reducing, heterogeneous aqueous systems.
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