A comparative study of non-isothermal kinetics of decomposition of calcium oxalate monohydrate

The kinetics of thermal dehydration and decomposition CaC2O4·H2O was studied using thermogravimetry at four rates of linear increase of temperature and two different sample mass. Four calculation procedures based on single TG curves and iso-conversional method, as well as 35 mechanism functions were used. The comparison of the results obtained with these calculation procedures showed that they strongly depend on the selection of proper mechanism function for the process. Therefore, it is very important to determine the most probable mechanism function. In this respect the iso-conversional calculation procedure turned out to be more appropriate. In the present work, the values of apparent activation energy, pre-exponential factor in Arrhenius equation, as well as the changes of entropy, enthalpy and free Gibbs energy for the stages of dehydration, decarbonylation and decarbonation of calcium oxalate monohydrate are calculated. All calculations were performed using programs compiled by ourselves.