The thermal decomposition of uranyl(VI) oxalate

Abstract

The kinetics of the thermal decomposition of uranyl(VI) oxalate have been studied as a function of temperature in the range 300–350°. In an inert atmosphere the reaction follows Prout-Tompkins kinetics with activation energy 62·4 ± 1·0 kcal./mole, and the final product is uranium dioxide. In the presence of air, the final product is amorphous trioxide. The reaction is then composed of two consecutive stages: (a) a reaction on the surface of the subgrain boundaries following Prout-Tompkins kinetics, and (b) a reaction involving isolated disc-like grains of reactant which follows an Avrami-Erofeev law with n= 2. The kinetic parameters for these last two stages are sensibly consistent with those found for the reaction in inert atmospheres.