A new method, which uses exact formula involving the E2-function, is proposed for the determination of the kinetic parameters of calcium oxalate from non-isothermal thermogravimetric analysis (TGA) data. There are three consecutive pyrolyzed stages in the decomposition of calcium oxalate. In the first stage of the reaction (splitting water), we obtained the possible domain of reaction orders ranging from 0.7 to 0.9. It was observed that the kinetic reaction model best fit a 0.7-order reaction model, and the activation energy was found to be 77.1-119.0 kJ/mole. In the second stage of the reaction (splitting carbon monoxide), among reaction orders ranging from 0.35 to 0.5, the best fit was an order of 0.5, and the activation energy was found to be 203.5-218.9 kJ/mole. In the third stage of the reaction (splitting carbon dioxide), among reaction orders ranging from 0.45 to 0.6, the best fit was an order of 0.45, and the activation energy was found to be 167.6-199.8 kJ/mole. The results were somewhat lower than the data obtained in similar studies reported in the literature. We believe that the proposed methodology has the merits of both accuracy in calculation and simplicity in formulation.
Journal of the Chinese institute of chemical engineers=中國化學工程學會會誌 34(2), pp.247-254