Radiolytic Yield of UIV Oxidation into UVI: A New Mechanism for UV Reactivity in Acidic Solution

The yields of the radiolytic oxidation of UIV and of the UVI formation, measured by spectrophotometry, are found to be the same (G(−UIV)N2O = G(UVI)N2O = 8.4 × 10−7 mol J−1) and almost double the H2 formation yield (G(H2) = 4.4 × 10−7 mol J−1) in the 60Co γ radiolysis of N2O-aqueous solutions in the presence of 2 mol L−1 Cl− at pH = 0 (HCl). According to the mechanism of UIV radiolytic oxidation, we show that under the conditions of our experiments the UV ions do not disproportionate, but undergo a stoichiometric oxidation into UVI by H+ with forming H2.