In this work, we have studied the reaction between H2O2 and UO2 with particular focus on the nature of the hydroxyl radical formed as an intermediate. Experiments were performed to study the kinetics of H2O2 consumption and uranium
dissolution at different initial H2O2 concentrations. The results show that the consumption rates at a given H2O2 concentration are different depending on the initial H2O2 concentration. This is attributed to an alteration of
the reactive interface, likely caused by blocking of surface sites by oxidized U/surface-bound hydroxyl radicals. The dissolution yield given by the amount of dissolved uranium divided by the amount of consumed hydrogen peroxide was used to compare the different cases. For all initial H2O2
concentrations, the dissolution yield increases with reaction time. The final dissolution yield decreases with increasing initial H2O2 concentration. This is expected from the mechanism of catalytic decomposition of H2O2 on oxide surfaces. As the
experiments were performed in solutions containing 10 mM [Inline formula] and a strong concentration dependence was observed in the 0.2–2.0 mM H2O2 concentration range, we conclude that the intermediate hydroxyl radical is surface bound rather than free.
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Document Type: Research Article
Department of Chemistry, Applied Physical Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden
Japan Atomic Energy Agency, Nuclear Science and Engineering Directorate, Nakagun, Japan
Publication date: July 3, 2018