Response surface optimization of the bio-oil yield from Jatropha gossypiifolia L. seeds through ultrasonic-assisted solvent extraction

The global challenge of energy sustainability has remained an unresolved issue up to this point. Alternatives are indeed critical in a regime dominated by non-renewable fossil fuels. The potential of Jatropha gossypiifolia L. seeds for bio-oil production was investigated in this study, as it falls under the category of nonedible second-generation feedstock. The seed kernels were oven-dried at 80 °C for 24 h, powdered, and then oven-dried again at 80 °C for 4 h to remove any remaining moisture. Using the central composite design of the response surface methodology, an optimal condition was identified as 6.86:1 n-hexane to biomass (mL g^-1), 17 min and 33 s extraction time, constant 15 g biomass, 35 m resonance amplitude, and 20±5 °C temperature. Under optimal conditions, the maximum bio-oil yield from Jatropha gossypiifolia L. was 62.98±1.81%, with physical and chemical characteristics such as a golden yellow color and a density of 0.9273 g mL^-1, kinematic viscosity of 21.6–23.2 cSt, and a high heating value of 40.80 MJ kg^-1. The FTIR analysis revealed the presence of ester groups in biodiesel’s primary component, bio-oil. The GC-MS analysis revealed significant fatty acid components, including 65.6% linoleic acid, 18.5% oleic acid, 8.64% palmitic acid, 6.0% stearic acid, and 1.26% other fatty acids. The beneficial properties and components of bio-oil established a promising benchmark for biodiesel production. Conversion of the produced bio-oil to biodiesel resulted in a 59.96% recovery rate, indicating the feasibility of using J. gossypiifolia L. seeds as a feedstock for biodiesel production.