Non-isothermal kinetics of the thermal decomposition of sodium oxalate Na2C2O4

The thermal transformation of Na2C2O4 was studied in N-2 atmosphere using thermo gravimetric (TG) analysis and differential thermal analysis (DTA). Na2C2O4 and its decomposed product were characterized using a scanning electron microscope (SEM) and the X-ray diffraction technique (XRD). The non-isothermal kinetic of the decomposition was studied by the mean of Ozawa and Kissinger-Akahira-Sunose (KAS) methods. The activation energies (E-alpha) of Na2C2O4 decomposition were found to be consistent. Decreasing E-alpha at increased decomposition temperature indicated the multi-step nature of the process. The possible conversion function estimated through the Liqing-Donghua method was 'cylindrical symmetry (R-2 or F-1/2)' of the phase boundary mechanism. Thermodynamic functions (Delta H*, Delta G* and Delta S*), calculated by the Activated complex theory and kinetic parameters, indicated that the decomposition step is a high energy pathway and revealed a very hard mechanism.