The study of thermal decomposition kinetics of zinc oxide formation from zinc oxalate dihydrate

Abstract

This study is devoted to the thermal decomposition of ZnC2O4·2H2O, which was synthesized by solid-state reaction using C2H2O4·2H2O and Zn(CH3COO)2·2H2O as raw materials. The initial samples and the final solid thermal decomposition products were characterized by Fourier transform infrared and X-ray diffraction. The particle size of the products was observed by transmission electron microscopy. The thermal decomposition behavior was investigated by thermogravimetry, derivative thermogravimetric and differential thermal analysis. Experimental results show that the thermal decomposition reaction includes two stages: dehydration and decomposition, with nanostructured ZnO as the final solid product. The Ozawa integral method along with Coats–Redfern integral method was used to determine the kinetic model and kinetic parameters of the second thermal decomposition stage of ZnC2O4·2H2O. After calculation and comparison, the decomposition conforms to the nucleation and growth model and the physical interpretation is summarized. The activation energy and the kinetic mechanism function are determined to be 119.7 kJ mol−1 and G(α) = −ln(1 – α)1/2, respectively.