Investigation of Kinetic and Thermodynamic Parameters of Sapodilla Leaves Pyrolysis Using Coats Redfern Model

Abstract The determination of the energy potential of indigenous biomass waste is primarily the focus of every country in its quest to meet the energy demand via clean and sustainable sources. The objective of the current study is to investigate the thermo-kinetic behavior of the sapodilla leaves with thermogravimetric analysis to analyze its potential utilization for energy production through the thermochemical conversion process. Sapodilla leaves were dried, pulverized, and heated non-isothermally from room temperature to 900°C at different heating rates in an inert environment. Thermogravimetric results indicated that the Sapodilla leaves pyrolysis is divided into three stages. The Coats-Redfern integral model was applied in the 2nd and 3rd stages to estimate the numerical value of thermo-kinetic parameters, using five major solid-state reaction mechanisms. The low-temperature stable components (LTSC) degraded in the temperature range of 250–550°C while high-temperature stable components (HTSC) decomposed in the temperature range of 550–850°C. About 45-50wt% degradation in the first temperature range of 250–550°C and about 15-17wt% degradation was observed in 2nd degradation temperature range of 550–900°C. According to the results, the diffusion model D₃showed the highest regression coefficient in the first degradation stage while in the second degradation stage, the nucleation models N1.5and N₂showed the highest regression coefficient. The activation energy of sapodilla leaves degradation was found in the range between 30–32 kJmol⁻ ¹for best-fitted models in low-temperature regions and 8–12 kJmol⁻ ¹in high-temperature regions. The positive value of change in enthalpy and Gibbs free energy showed that the reaction is endothermic while the negative value of entropy showed the more regular arrangement of the products. Thermo-kinetic behavior of sapodilla leaves hints toward their huge potential for bio-oil and syngas production through pyrolysis and gasification processes.