Impact of chemical treatment on the energy potential of Pachira aquatica A. fruit peel during pyrolysis

Sustainable methods for producing fuels and chemicals are essential for addressing global warming and environmental damage. Biomass pyrolysis is a sustainable thermochemical process that converts biomass into fuels and valuable chemicals, potentially replacing fossil fuels. This study investigates the influence of acid treatment on the pyrolysis of Pachira aquatica A. (P) peel with phosphoric and sulfuric acid generating Pap and Pas respectively to produce energy or value-added chemical products. Slow pyrolysis was performed under non-isothermal conditions with heating rates of 5, 10, and 15 °C min⁻¹. Thermokinetic parameters were determined using the Friedman, KAS, FWO, and Starink isoconversional methods. All methods showed high correlation indices (R²) with the experimental data. Thermodynamic parameters calculated using the FWO method indicated greater spontaneity in the pyrolytic process for chemically treated samples. Acid treatment promotes partial removal and cracking chemical bonds, favoring greater conversion of lignocellulosic components such as cellulose and hemicellulose. Chemical treatment significantly enhances thermal decomposition and reduces the activation energy, following the order: E_A(Pap) > E_A (Pas) > E_A (P). Pyrolysis process results showed that the untreated sample was predominantly rich in phenolic compounds indicating extensive lignin depolymerization, in contrast both acids treated samples showed a shift toward furans, furfural and levoglucosenone, pointing to enhanced degradation of hemicellulose and cellulose.