Kinetics of thermal decomposition of some metal oxalates

Abstract

The thermal decomposition kinetics of oxalates of Zn II Ni II and Th IV have been studied in air by isothermal and non-isothermal thermogravimetry. The isothermal kinetic results suggest that the mechanism of decomposition of the zinc compound invoives rapid nucIeation followed by two dimensionai growth in the acceleratory region, while in the case of thorium oxalate, the initial nucieation occurs by a chain mechanism on the surface of the reactant foilowed by the growth of the product from the surface towards the interior. The results on nickel oxalate could not be interpreted in an unambiguous manner. The activation energy and the frequency factor obtained from TG curves compare we11 with those obtained from the isothermal method. The activation energies for the dehydration of these oxalates have also been evaluated from the thermogravimetric curves.