Kinetics of Pu(IV) oxidation with persulfate in alkali solutions

A 6.8 x 10(-3) M suspension of freshly precipitated Pu(IV) hydroxide in 0.5-8 M NaOH is oxidized with 0.01-0.05 M S2O82- at 23-62 degrees C to give Pu(VI); in 4-8 M NaOH Pu(VII) also appears. Dissolution of plutonium accelerates with temperature and with increasing NaOH and S2O82- concentrations. The reaction mechanism is discussed; its key stages are reaction of S2O82- with Pu(IV) and Pu(V) in the solid phase, disproportionation of Pu(V) in 0.5-4 M NaOH, and reaction of Pu(VI) with S2O82- in 4-8 M NaOH.