Kinetics and Thermodynamic Studies on Pyrolysis Behavior of Plastic Waste Using Thermogravimetric Analysis

Abstract

The purpose of this study was to investigate the thermochemical breakdown of polypropylene grocery bags by using non-isothermal thermogravimetric analysis. The temperature was varied from room temperature to 900 °C in a series of experiments at different heating rates. Differential Friedman method (DFM), an isoconversional model, is utilized in this study to evaluate the kinetic parameters for pyrolysis of polypropylene grocery bags. According to the DFM method, the obtained values of average apparent activation energy (E_α) and pre-exponential factor (k₀) were, respectively, 158.98 kJ mol⁻¹ and $2.16 \times 10^{12}$ min⁻¹. An R² > 0.98 correlation was found in the conversion range of 0.2–0.8 for DFM technique in the kinetics analysis. The DFM approach determined an average enthalpy change (∆H, kJ/mol) of 153.12 kJ mol⁻¹ at a heating rate of 10 K min⁻¹. Master plots based on the integral form of kinetic data were used to find out the best pyrolysis kinetic model for polypropylene grocery bags. The kinetic process of thermal dehydration of polypropylene was explained by the zero-order reaction mechanism (F0), which was based on the plots between experimentally and theoretically calculated master plots.