Kinetics of the reduction of Pu(V)O-2(+) by hydrogen peroxide

The kinetics of the reduction of Pu(V)O-2(+) by hydrogen peroxide have been studied in 1.0 m NaCl solutions at 19 +/- 2 degrees C. Experiments were co nducted over a range of pH values from 7.9 to 10.8 with variable concentrat ions of hydrogen peroxide between 1.00 . 10(-5) M and 4.00 . 10(-2) M. The concentration of plutonium in solution was (1.5 +/- 0.2) . 10(-10) M. The d ecrease of the concentration of PuO2+ in solution with time was monitored b y ultrafiltration combined with solvent extraction using TTA. Independent e xtraction experiments, using DBM as extractant, were employed to validate t he results. The reduction of PuO2+ was found to be first order with respect to hydrogen peroxide concentration and inverse first order with respect to hydrogen io n concentration With these results and assuming a first order dependence wi th respect to the concentration of PuO2+, the reaction can be described by the following rate equation: d[Pu(V)]/dt = k . [Pu(V)] . [H2O2]/[H+], with k = 3.59 . 10(-9) +/- 1.79 . 10(-9) min(-1). Using this equation, the redox half life of PuO2+ has been calculated for a range of environmentally relevant conditions.