Interactive co-pyrolysis of leucine amino acid and plastic wastes using TGA-IR-MS connection

Waste materials from agricultural and food packaging usage pose significant health and environmental challenges, where the main source of waste originates from plastics and protein-based amino acids, and their thermal degradation is often investigated separately for the production of waste-to-energy. Therefore, this research investigates the products of a specific amino acid called leucine and its co-pyrolysis with different plastic waste, like polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET), to recognize their interactions with the nitrogen compounds. The system used for this reaction is an integrated TGA-IR-MS that can effectively mimic the thermal degradation of these blends and their gas analysis by evaluating the pyrolysis behaviour and nitrogen emissions. Pure leucine degradation proved the production of 87% nitrogen-rich compounds like amines and nitriles with a high endothermic demand of 1009 J/g, while the PE and PP blends enhanced the degradation properties by reducing the enthalpy by 60% and suppressing the nitrogen production to 10% for PP and <5% for PE blends, while promoting the formation of rich hydrocarbons like 2,4-dimethyl heptane with over 70% relative yield. Nonetheless, PET had a different interaction since it enhanced the reaction of leucine and increased the nitrogen production while providing high oxygen content, proven by the FTIR (C=O at 1750 cm −1 ) with 15% char content. These interactions were promoted via radical mechanisms. The reported results address multiple suitability challenges that are related to clean and affordable energy. • Co-pyrolysis of pure leucine with PP, PE, and PET was studied using TGA-FTIR-GCMS. • Plastic blends (PP, PE) enhanced the leucine pyrolysis by suppressing nitrogen-rich products. • The PE blend suppressed nitrogen products from ∼ 87% to <5% relative yield. • PP reduced leucine’s enthalpy demand, while producing ∼ 70% relative yield of 2,4-dimethyl-1-heptene. • PET enhanced leucine decomposition, but increased nitrogen aromatics, leaving 10%–15% char.