The mechanism of PuVI oxidation with ozone and other reagents in alkaline solutions

Resumo

The analysis of reported data on the interaction of ozone with alkaline solutions of Pu^VI leads to the conclusion that the process of ozonation involves reactions O₃ + OH^– → HO₂^- + O₂, O₃ + + HO₂^- + OH^– → O₃^- + O₂^- + H₂O and O₃ + O₂^- → O₃^- + O₂. The O₃^- radical ion oxidizes Pu^VI, the HO₂^- and O₂^- anions reduce Pu^VII and Pu^VI and react with O₃^-. Using persulfate instead of O₃ in aerated solution at 80—95 °C results in thermal decomposition of the S₂O₈^2- anion into radical ions of SO₄^-, oxidizing OH^– to the O^– ion, which in reaction with O₂ forms O₃^-. The oxidation of PuVI proceeds via the formation of an activated complex with O₃^-. where charge transfer occurs with the simultaneous elimination of two H⁺ ions. A similar mechanism is operating in reactions of Pu^VI with BrO^–, Fe(CN)₆^3–, Am^VI, and Am^VII. Upon the γ-radiolysis of alkaline solutions of Pu^VI saturated with N₂O or containing S₂O₈^2–, e_aq^– is converted into O^– and then into O₃^-; F₂ and XeF₂ in alkaline solutions are decomposed with the formation of H₂O₂, which prevents producing Pu^VII.