Sustainable management of plant litter and polypropylene plastic mulch residues via thermochemical recycling: Synergistic co-pyrolysis characteristics and evolved gas analysis

In agricultural fields, plant litter and plastic residues commonly coexist due to the widespread use of plastic mulching, a practice known to enhance crop yield. Following harvest, both plastic mulch and plant litter accumulate abundantly as an undesired waste. However, these materials can instead be utilized as a valuable bioenergy source, thereby addressing two critical challenges simultaneously: effective waste management and sustainable bioenergy production. In this context, the current study presents a comprehensive investigation of the co-pyrolysis behavior, kinetic and thermodynamic analyses, and detailed evolved gas analysis of a blend of plant litter and polypropylene (PP) plastic mulch. Thermogravimetric analysis (TGA) was carried out from ambient temperature to 800 °C at four heating rates (5, 10, 15, and 20 °C/min) to investigate the thermal stability of the blend. The composition of the evolved volatiles was analyzed using a TGA coupled simultaneously with Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectroscopy (GC-MS). FTIR and GC-MS analyses confirmed the dominance of alkenes and alkanes at 480 °C. However, aromatics, particularly benzene, were the predominant volatiles at 700 °C. The interactive effects between plant litter and PP promoted the formation of a diverse range of aliphatic hydrocarbons and aromatic compounds, demonstrating the potential of their co-pyrolysis as a pathway for transportation fuel production.