The massive generation of agricultural and post-consumer plastic waste has become a serious global environmental concern. This study presents a comparative thermo-kinetic investigation of two blended feedstocks using thermogravimetric analysis (TGA). Sample PSM was prepared in 1:1 ratio using pistachio shell and shredded surgical mask waste (polypropylene), while Sample PSMC contained the same blend incorporated with 30 wt% activated carbon. Non-isothermal thermogravimetric analysis (TGA) was performed under a nitrogen atmosphere at heating rates of 10, 15, and 25 °C/min to investigate the thermal decomposition behavior of the samples. The kinetic characteristics were analyzed using four widely adopted model-free isoconversional approaches, namely Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), Starink, and Friedman methods. In addition, important thermodynamic properties such as enthalpy change (ΔH), entropy change (ΔS), and Gibbs free energy change (ΔG) were calculated to better understand the thermal reaction mechanism.Results revealed that PSM exhibited lower average activation energy compared to PSMC. The addition of activated carbon increased char yield but slightly raised the energy barrier. The pyrolysis process was found to be endothermic and non-spontaneous in nature. The obtained kinetic and thermodynamic data provide useful insights for optimizing co-pyrolysis of biomass and plastic waste for sustainable energy recovery.

Keywords: Pistachio shell, Surgical mask waste, Polypropylene, Activated carbon, TGA, Pyrolysis kinetics, Activation energy, Isoconversional methods.