Valorization of Potato Peel Waste through Pyrolysis: Thermal decomposition, Kinetic, and Thermodynamic Analysis

This study investigates the thermal degradation, kinetics and thermodynamics of potato peel (PP) pyrolysis. Thermogravimetric analysis was conducted from ambient temperature to 900 ºC under an inert atmosphere at heating rates of 10, 20, 30, 40, and 50 °C/min. The activation energy (Ea) was determined using four isoconversional methods: Friedman, FWO, KAS, and Starink. The pre-exponential factor (A) was derived using the Kissinger method, and thermodynamics parameters such as changes in enthalpy (ΔH), gibbs free energy (ΔG), and entropy (ΔS) were estimated using the kinetic data. Results indicate that peak temperature, and maximum decomposition rates and solid residues. The peak temperature, and maximum decomposition rates and solid residue, increased with heating rate. Ea values ranged from 114.40 to 452.42 kJ/mol (Friedman), 119.46 to 446.59 kJ/mol (FWO), 116.85 to 454.34 kJ/mol (KAS), and 117.10 to 454.55 kJ/mol (Starink). The KAS and Starink methods yielded nearly identical Ea values across all conversion levels. Initially, Ea remained relatively constant up to α =0.7, beyond which this it increased significantly. A values derived from the Friedman, FWO, KAS, and Starink methods ranged from 1.26×107 to 1.09×1037 s-1, are 4.34×107 to 3.44×1037 s-1, 1.87×107 to 1.61×1037 s-1, and 1.99×107 to 1.65×1037 s-1, respectively. A linear trend between Ea and lnA with a high regression coefficient was observed across all methods, indicating a strong kinetic compensation effect. Thermodynamic parameters such as ΔH, and ΔG showed positive values which indicate all reactions were endothermic and non-spontaneous nature. Moreover, ΔS values found negative at the starting of each reaction and were changed to positive at the end of conversion indicating the more ordered state at the starting followed by increase in entropy of the system due to further decomposition of biomass feedstock.