Mechanisms of Pu(VII) reduction in aqueous alkaline solutions in the presence of catalysts

Abstract

Published data on the Pu(VII) stability in alkaline media suggest that one-electron oxidation of OH− ion or H2O with Pu(VII) ions is thermodynamically impossible. The more probable pathway of Pu(VII) reduction is formation of a dimer from thermodynamically excited and nonexcited Pu(VII) ions, followed by decomposition of the dimer into two Pu(VI) ions and H2O2 molecule, which reacts with Pu(VII) and Pu(VI). The released energy is spent for Pu(VII) excitation. In the presence of difficultly soluble hydroxides of Fe(III), Co(III), and other d elements, and also of Pt and PbO2, hydroxides of elements in higher oxidation states appear at the surface of colloidal particles and electrode materials under the action of Pu(VII). The neighboring OH groups dimerize and are eliminated in the form of H2O2.