Comparative iso-conversional kinetics of raw and carbonized Dendrocalamus asper (Schult. & Schult.f.) Backer under inert and oxidative atmospheres

We investigated the biomass fuel characteristics, thermal degradation behaviour and iso-conversional kinetics of raw and carbonized Philippine giant bamboo ( Dendrocalamus asper ) under inert (N ₂ ) and oxidative (air) atmospheres using simultaneous TG–DTG–DSC analyses at heating rates of 5–20 °C min -1 . Carbonization significantly enhanced fixed carbon content (up to 64.60%), increased gross calorific value (26.96 MJ kg⁻¹) and energy density (4.59 GJ m⁻³), and substantially reduced volatile matter. In nitrogen, raw bamboo exhibited devolatilization within 200–400 °C corresponding to hemicellulose and cellulose degradation, whereas carbonized bamboo showed delayed and broadened high-temperature degradation (300–750 °C) associated with aromatic carbon restructuring. In air, raw bamboo underwent volatile oxidation followed by char combustion, while carbonized bamboo displayed a dominant oxidation stage attributed to char oxidation within 300–650 °C. Iso-conversional analyses using the Ozawa–Flynn–Wall, Starink and Friedman methods revealed conversion-dependent apparent activation energy ( E A ) evolution, confirming multi-step kinetics. Under inert conditions, carbonization increased E A at intermediate to high conversions ( α = 0.6–0.8), indicating enhanced structural stability of the condensed carbon matrix. Conversely, in air, carbonized D. asper exhibited markedly lower activation energies (≈42.60–98.64 kJ mol⁻¹) compared to raw bamboo (≈73.21–176.25 kJ mol⁻¹), suggesting a potential mineral-associated catalytic effects supported by Fe ₂ O ₃ enrichment in ash. Overall, carbonization induced an atmosphere-dependent shift in degradation mechanisms, and the validated conversion-dependent kinetic parameters provide intrinsic inputs for mechanistic modeling of bamboo-based biomass energy systems.