Optimisation of Biodiesel Production from Jatropha curcas Seed Oil Using Response Surface Methodology in Kogi State, North Central Nigeria

Jatropha curcas is widely recognised as a promising non-edible feedstock for biodiesel production due to its high seed oil content, adaptability to marginal lands, and cultivation potential across the Guinea savanna zone of Nigeria, yet process optimisation studies using statistically robust methodologies are limited for locally sourced Nigerian Jatropha germplasm. This study optimises the transesterification of Jatropha curcas seed oil extracted from seeds collected in Kogi State, North Central Nigeria, using response surface methodology based on a central composite design. The effect of methanol-to-oil molar ratio, catalyst (potassium hydroxide) concentration, reaction temperature, and reaction time on biodiesel yield and quality is systematically investigated. Seed oil is extracted by cold-press and solvent methods, and the fatty acid profile is determined by gas chromatography-flame ionisation detection of fatty acid methyl esters. The optimised biodiesel product is characterised according to European Standard EN 14214 and American Society for Testing and Materials D6751 specifications, covering cetane index, kinematic viscosity, density, flash point, cloud point, pour point, acid value, iodine value, and methyl ester content. Engine performance testing is conducted using a blend comparison between B20 biodiesel and conventional diesel. The optimised process conditions are subjected to scale-up assessment, and a preliminary techno-economic analysis evaluates production cost competitiveness. Findings contribute process design knowledge for decentralised biodiesel production facilities applicable to agro-industrial zones in the North Central geopolitical zone. Keywords: biodiesel, Jatropha curcas, response surface methodology, transesterification, Kogi State