Thermal Decomposition and Non-isothermal Kinetics of Dickite
- Received Date: 2004-06-10
- Dickite, Thermal decomposition, Non-isothermal kinetics, TG-DTG, IR /
Abstract: Fourier-transform infrared emission spectroscopy was used to study the dehydroxylation behavior of the thermal decomposition of dickite from Chenxi, Hunan Province, China. Dehydroxylation of dickite was followed by a loss of intensity of the 3620.73, 3695.34 cm-1 OH-stretching bands and 916.06, 1009.33 cm-1 OHbending bands. The thermal decomposition was investigated by thermogravimetric analysis (TGA). A good agreement is found with TG curves of dickite and the mass loss is 13.7% (close to the theoretical value). The non-isothermal kinetics of the thermal decomposition of dickite was studied in TG-DTG curves over the temperature range from 298 K to 1123 K by thermogravimetry and differential thermal analysis in air. Mathematical analysis of TG-DTG data using the integral methods (Coats-Redfern equation, HM equation, MKN equation) and differential method (Achar equation) shows that the thermal decomposition of dickite accords F2 mechanism. The kinetic parameters such as the activation energy (E=131.62 kJ/mol), pre-exponential factor (A=108.30 s-1) and reaction order (n=2.1) are reported. The Ozawa method was used to analyse the activation energy of the same sample at different heating rate and gave 133.07 kJ/mol. The kinetic parameters calculated from different equation are rather close to each other.
|Citation:||Fang Zhengdong, Wang Dunjia, Zhang Chuanyue. Thermal Decomposition and Non-isothermal Kinetics of Dickite[J]. Chinese Journal of Chemical Physics , 2005, 18(4): 619-624. doi: 10.1088/1674-0068/18/4/619-624|