Radiation induced redox reactions in the U(VI)-U(IV) system in aqueous H 2SO 4 solutions

Abstract

G-values for U(IV) formation in gamma-irradiated acid aqueous solutions of uranyl sulfate have been determined under various conditions. Whereas in the absence of a suitable OH radical scavenger, there is no net reduction of U(VI) to U(IV), reduction is observed in presence of OH radical scavengers such as the aliphatic alcohols, the limiting G U(IV) values being 3.6 (isopropanol), 3.2 (ethanol), 3 (methanol) and 1.3 (t-butanol). H 2O 2 added prior to irradiation did not affect the G U(IV) value in the case of isopropanol, but decreased it to almost zero in the case of t-butanol as OH scavenger. These results are explained on the basis of the redox behaviour of the hydroxyalkyl radicals derived from the alcohols and the formation of OH radicals and U(V) as intermediates in the oxidation of U(IV) by H 2O 2.