Co-pyrolysis behaviour and kinetic analysis of waste mango seeds and low-density polyethylene for their bioenergy potential

The increased accumulation of agricultural residues and plastic waste highlights the need for sustainable conversion methods. This study investigates the pyrolysis behaviour and kinetic characteristics of waste mango seeds (MS), low-density polyethylene (LDPE) and their co-pyrolysed blends (10–30 wt%) for bioenergy recovery. Thermogravimetric analysis revealed multistage degradation between 200 and 600 °C, with higher heating rates shifting the decomposition peaks towards higher temperatures due to thermal lag. Kinetic characteristics using KAS, OFW, FM, TG, DAEM, and VZ models revealed average activation energies of 208–215 kJ/mol for MS and 179–219 kJ/mol for LDPE. Co-pyrolysis exhibited strong synergistic effects: MS + LDPE-20 wt% blend showed reduced activation energy (105.93 kJ/mol), indicating enhanced degradation, while 10 wt% blend demonstrated the highest activation energy (268.67 kJ/mol), suggesting improved stability. Thermodynamic evaluation confirmed all reactions were endothermic and non-spontaneous. The MS + LDPE-20 wt% blend demonstrated optimal energy efficiency, reduced activation energy, and enhanced product yield, thereby supporting co-pyrolysis as a viable strategy for sustainable energy production.