Uranyl-catalyzed chemiluminescent reaction of U4+ oxidation by dioxygen in aqueous HClO4 solution |
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Authors: | S V Lotnik L A Khamidullina V P Kazakov |
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Institution: | (1) Institute of Organic Chemistry, Ufa Research Center of the Russian Academy of Sciences, 71 prosp. Oktyabrya, 450054 Ufa, Russian Federation |
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Abstract: | Chemiluminescence (CL) accompanying the reaction of U4+ with O2 in 0.0004–0.1M HClO4 was studied. It was found that the electron-excited uranyl ion (UO2
2+)* is the CL emitter. The fact that the reaction rate and the CL yield increase as the solution acidity decreases was explained
by different reactivities of the U
aq
4+
aquation and the products of its stepwise hydrolysis, UOH3+ and U(OH)2
2+, toward O2. Based on the results of analysis of the chain-radical mechanism of the reaction between U4+ and O2, it was concluded that transfer of an electron from the UO2
+ ion to the oxidizing agent (a ·OH radical) is the most plausible elementary step of the reaction of (UO2
2+)* formation. It was found that the reaction rate, as well as the CL yield, increase substantially in the presence of uranyl
ion. Catalytic action of UO2
2+ was explained by the formation of a UO2
2+·UO2
+ complex, which reduces the rate of the UO2
+ disproportionation reaction (UO2
+ is an intermediate of the reaction and is involved in chain propagation), and by regeneration of the active center, UO2
+, in the reaction of UO2
2+ with U4+.
Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1522–1528, September, 2000. |
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Keywords: | uranium(IV) uranyl ion (UO2 2+) complex dioxygen kinetics catalysis chemiluminescence oxidation |
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