Mechanistic and thermodynamic investigation of food waste-derived engineered porous carbon through integrated kinetic modelling approach

The growing generation of food waste poses significant environmental challenges, yet its conversion into value-added products through thermochemical processes is hindered by a limited understanding of the degradation kinetics. The present study provides a comprehensive evaluation of effect of carbonization on degradation behaviour across multiple stages by combining kinetic analysis with mechanistic interpretation. In this study, raw and carbonized banana peel and potato peel were analysed using thermogravimetric analysis at heating rates 10-50 °C/min. The TGA-DTG results showed multi-stage decomposition at higher temperatures after carbonization indicating improved thermal stability. Further, activation energy obtained varied from 118-180 kJ/mol for raw biomass and 162-238 kJ/mol for carbonized samples at α = 0.1-0.9. Among model-fitting methods, Coats-Redfern showed better agreement for carbonized samples (R 2 = 0.94). Thermodynamic analysis indicated endothermic and non-spontaneous behaviour with ΔH (52-205 kJ/mol), ΔG (150-200 kJ/mol), and ΔS (-150 to -220 J/mol.K) suggesting increased structural ordering after carbonization. Criado’s plot confirmed that raw biomass followed diffusion-controlled mechanisms at early stages and nucleation at later stages whereas carbonized samples showed nucleation-dominated behaviour followed by contracting geometry. Therefore, carbonization significantly enhances thermal stability and alters degradation pathways, providing useful insights for carbon material development.