Co-pyrolysis of waste tires and Platanus orientalis leaves: thermogravimetric characterization, kinetic modeling, and resource valorization potential

This study investigates the co-pyrolytic behavior of waste tires (WT) and Platanus orientalis leaves (SL) as hybrid feedstocks for thermochemical valorization. Pyrolysis experiments were conducted under nitrogen atmosphere using thermogravimetric analysis across a temperature range of ambient to 745 degrees C, with heating rates of 5, 10, 15, 20, and 25 K min-1. Five blend ratios (100% WT, 75/25, 50/50, 25/75, 100% SL by mass) were assessed to evaluate thermal degradation profiles and kinetic characteristics. A Box-Behnken experimental design within the response surface methodology (RSM) framework was employed to optimize the effects of temperature, heating rate, and blend ratio on pyrolysis performance. The statistical model showed a high predictive capability with R 2 >0.995. Kinetic parameters were calculated using Coats-Redfern, Flynn-Wall-Ozawa, and Kissinger methods, with activation energies for the major decomposition stage (Stage 3C) ranging from 114.3 to 125.2 kJ mol-1. A significant negative correlation was found between activation energy and SL content (r = -0.82), while WT content showed a positive correlation (r = 0.87), indicating that biomass reduces the energy barrier for thermal degradation. Fourier transform infrared analysis confirmed the breakdown of functional groups such as -OH, C-O, and aromatic C-C after pyrolysis, indicating extensive structural transformation. Scanning electron microscopy imaging revealed morphological changes from fibrous structures in SL to carbonized, fractured surfaces in the char. Energy-dispersive X-ray spectroscopy analysis indicated a high carbon content (91.2%), supporting the suitability of the product for energy applications. Overall, the study demonstrates the synergistic potential of WT and SL in co-pyrolysis, improving thermal behavior, reducing activation energy, and yielding carbon-rich products. These findings support the development of integrated waste-to-energy strategies aligned with circular economy principles.