Kinetics of Reaction Between Pu(Ⅳ) and Formoxime in Nitric Acid Solution

The kinetics of reaction between Pu(Ⅳ) and formoxime (FO) in nitric acid solution was determined. The rate equation is found to be -dc(Pu(Ⅳ))/dt ＝ kc(Pu(Ⅳ))c^1.61(FO)c^-0.88(H⁺) where k ＝(110.39±7.70) (mol/L)^-0.73/s at 18.7 ℃. The activation energy is found to be E_a ＝ (68.82±3.00) kJ/mol. Effects of c(FO), c(H⁺), c(Fe³⁺),c(UO₂²⁺), c(NO₃^-) and temperature on reduction rate of Pu(Ⅳ) were investigated. Pu(Ⅳ) can be rapidly reduced to Pu(Ⅲ) by FO under normal conditions. The reaction rate can be accelerated by increasing concentration of formoxime, decreasing concentration of UO₂²⁺ and H⁺, increasing concentration of Fe³⁺ and rising temperature. The influence of NO₃^- on reaction rate is negligible.