Co-pyrolysis of discarded disposable tableware and bamboo chopsticks: The effect of synergistic interactions on kinetic parameters and products

Abstract

This study systematically investigates the co-pyrolysis behavior of a ternary system composed of polypropylene (PP), polystyrene (PS), and disposable bamboo chopsticks (DC), focusing on its pyrolysis characteristics, kinetic synergistic effects, and product distribution mechanisms. The reaction process was analyzed using thermogravimetric analysis (TGA), tubular furnace experiments, and GC-MS combined with various kinetic methods. The results indicate that co-pyrolysis exhibits a significant synergistic effect, with an apparent activation energy of 108.98 kJ/mol, markedly lower than the theoretical value of 217.31 kJ/mol. The kinetic mechanism follows a random nucleation and growth model (A_1/2). The pyrolysis oil yield reaches 67.33 %, exceeding the theoretical value of 64.78 %. Product analysis indicates that co-pyrolysis effectively promotes deoxygenation reactions and the formation of aromatic hydrocarbons. The relative contents of naphthalene derivatives, such as 1,2,3,4-tetrahydro-2-phenyl-naphthalene, and phenyl-alkene compounds are significantly increased, with the total aromatic hydrocarbon content rising by 26.54 %, while the content of oxygenated compounds is markedly reduced. Mechanistic analysis indicates that the synergistic deoxygenation primarily results from hydrogen transfer reactions and Diels–Alder pathways, effectively enhancing the quality of pyrolysis oil. This study provides a robust theoretical basis and a feasible process route for the co-pyrolysis of multi-component waste to produce high-value chemicals.