Non-isothermal decomposition kinetics of diosgenin

Abstract

The thermal stability and kinetics of isothermal decomposition of diosgenin were studied by thermogravimetry (TG) and Differential Scanning Calorimeter (DSC). The activation energy of the thermal decomposition process was determined from the analysis of TG curves by the methods of Flynn-Wall-Ozawa, Doyle, Satava-Sestak and Kissinger, respectively. The mechanism of thermal decomposition was determined to be Avrami-Erofeev equation (n = 1/3, n is the reaction order) with integral form G(α) = [−ln(1 − α)]1/3 (α = 0.10–0.80). Ea and logA [s−1] were determined to be 44.10 kJ mol−1 and 3.12, respectively. Moreover, the thermodynamics properties of ΔH≠, ΔS≠, and ΔG≠ of this reaction were 38.18 kJ mol−1, −199.76 J mol−1 K−1, and 164.36 kJ mol−1 in the stage of thermal decomposition.