Catalytic Reduction of U(VI) with Hydrazine and Formic Acid in HNO3 Solutions |
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Authors: | Anan'ev A. V. Shilov V. P. Afonas'eva T. V. Mikhailova N. A. Milovanov A. I. |
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Affiliation: | (1) Institute of Physical Chemistry, Russian Academy of Sciences, Moscow, Russia |
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Abstract: | Catalytic reduction of 0.75 M U(VI) with hydrazine in HNO3 solutions was studied under various conditions. At 58°C up to 0.55 M U(IV) is accumulated within 2 h in solutions containing 1-1.5 M N2H5+ and 2 M HNO3 in the presence of 1% Pt/SiO2 (S : L = 1 : 10). The reduction is decelerated with decreasing N2H5+ concentration to 0.75 M or with increasing HNO3 concentration to 3-4 M. 1.2 mol of U(IV) is formed per mole of oxidized hydrazine. Uranium(VI) reduction with formic acid in the presence of 1% Pt/SiO2 and 1% Pt/VP-1An anion exchanger was studied. There exists a threshold N2H5+ concentration below which U(VI) is not reduced. The reduction in solutions containing 1-2 M HCOOH, 1-2 M HNO3, and 0.1 M N2H5+ is faster than in solutions free of formic acid and containing 1-1.5 M N2H5+. |
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