Kinetic analysis of thermal decomposition reactions: Part 5. Gamma irradiation effects on the thermal decomposition of potassium nickel oxalate

Abstract

Differential thermal analysis-thermogravimetry techniques were used to study the thermal decomposition of potassium nickel(II) oxalate hexahydrate crystals and the effects of 60Co gamma irradiation on the kinetics of the decomposition in air of K 2Ni(C 2O 4) 2 to NiO, K 2C 2O 4 and CO 2. The kinetics of the isothermal decomposition were studied over the temperature range 310–350°C, both for irradiated and non-irradiated K 2Ni(C 2O 4) 2·6H 2O crystals. Kinetic analysis of the results according to the various theoretical models of solid state reactions showed that the best fit is obtained for the first-order and the diffusion models. There is a decrease in both the energy of activation and the frequency factor with increasing radiation dose. The mechanism of the thermal decomposition and the effects produced by radiolysis were discussed.