Spectrophotometric investigation of plutonium(IV) oxidation by cerium(IV)

In order to prepare a pure Pu(VI) solution, the oxidation of Pu(IV) to Pu(VI) by cerium(IV) was investigated with a UV–Visible spectrophotometer equipped with a 0.5 m liquid core waveguide. The degree of the oxidation of Pu(IV) was studied as function of the Ce(IV) concentration and the reaction time. The study showed that in 1 M HNO 3 solution, 1.2 × 10 −3 M Ce(IV) can oxidize Pu(IV) with concentration of 4.3 × 10 −5 M to Pu(VI) completely within 40 min, while 2.4 × 10 −3 M Ce(IV) can do it within 15 min. The oxidation reaction of Pu(IV) by Ce(IV) is a first order process with respect to Pu(IV) according to the data analysis. From a thermodynamic point of view, the reaction can proceed almost completely provided that amount of the Ce(IV) is greater than stoichiometric amount.