Thermochemical conversion of Nahar non-edible oilseed and garlic husk: a kinetic and thermodynamic analysis

Biomass as a sustainable source of energy has motivated this study to use renewable feedstocks, which have the potential to minimise greenhouse gas emissions. Two waste biomass (Nahar de-oiled cake (MDC) and garlic husk, GH) were considered to determine the pyrolysis behaviour and kinetic parameters using model-free methods. Further, this study examines the thermodynamic functions associated with the thermal and co-pyrolysis of MDC and GH. The biomass was physiochemically characterised by using a bomb calorimeter, FTIR, TGA, and proximate/elemental analysis. Additionally, the kinetic parameters of MDC, GH, and co-feed (1:1 w/w) were performed at 10–30 °C min⁻¹ in a thermogravimetric analyser (TGA). Model-free methods, such as differential Friedman (DFM), Ozawa–Flynn–Wall (OFW), Kissinger–Akhaira–Sunose (KAS), Starink method (STK), and distributed activation energy model (DAEM), were used to estimate the activation energy (E), frequency factor (A), and thermodynamic parameters [(ΔH (kJ mol⁻¹), ΔG (kJ mol⁻¹), and ΔS (kJ mol⁻¹ K⁻¹)]. The feedstocks’ heating value was found to be 15.48 MJ kg⁻¹ and 12.01 MJ kg⁻¹ for MDC and GH, respectively. The combined kinetic and thermodynamic analysis reveals how compositional differences between Nahar de-oiled cake and carbohydrate-rich garlic husk influence their pyrolysis behaviour. It demonstrates the applicability of such parameters for process design and scale-up in sustainable bioenergy systems.