Kinetics of intramolecular oxidation of oxalate ion in monooxalate plutonium (4) complex in nitric acid solutions

Kinetics of oxalate-ion oxidation by Pu4+ ions in nitric acid solutions is studied. It is shown that at 80-90 deg C in solutions containing approximately equimolar amounts of Pu4+ and H2C2O4, a rapid oxidation of oxalic acid is observed. It is assumed that intramolecular electron transfer to monooxalate complex is the limiting stage of the reaction. It HNO3 solutions Pu3+ formed is rapidly oxidized to Pu4+. In solutions of HCl and HClO4 in the presence of Pu4+ the decomposition of H2C2O4 is also observed, howeven, in this case Pu3+ is accumulated in the reaction mixture. The values of K ((219±44 mol/l) and k (0.08±0.02 min-1) are calculated at 98 deg C. The values of rate constants vary in the series: HClO4>HCl>HNO3. The values of activation parameters ΔH* and ΔS* in nitric acid solutions are found