Optimization of Bio-lubricant Produced from Non-edible Jatropha curcas Seed Oil

Abstract

This paper presents the production and optimization of a bio-lubricant derived from non-edible Jatropha plant seed oil. Plant oil-based lubricants offer significant environmental benefits and are derived from renewable sources, making them an attractive alternative to conventional lubricants. They provide a potential solution for sustainable and low-cost feedstock for fuel oil and its derivatives without competing with food uses, as Jatropha oil contains toxic esters unsuitable for human consumption. Jatropha seed oil was extracted using a Soxhlet apparatus fitted with a heating mantle. A total of 500 g of the extracted oil was esterified in a round-bottom flask glass reactor with 25 wt% methanol and 1.0 wt% H₂SO₄ as a catalyst, reducing free fatty acids (FFA) to approximately 1%. The esterified oil was then subjected to transesterification in a reactor preheated to 60°C. A mixture of 1.0 wt% NaOH and methanol at a 6:1 ratio was added while stirring at 300 rpm for a reaction time of 90 minutes. The transesterification process was optimized using a 23 response surface methodology (RSM) experimental design. This design evaluated the effects of temperature (112.16°C to 160.00°C), reaction time (1.81 to 5.00 hours), and catalyst concentration (0.73% to 1.73% w/w) at a constant mole ratio of JME to TMP of 3.9:1 under vacuum conditions. The results revealed that the optimal conditions for bio-lubricant synthesis were a temperature of 130°C, a reaction time of 3 hours, and a catalyst concentration of 0.8% w/w. A second-order quadratic model was developed to predict the yield of Jatropha curcas bio lubricant based on the process variables. The model predicted a yield of 88.74% with a desirability of 0.9739 and demonstrated a high coefficient of determination (R²) of 0.9739, indicating strong predictive accuracy Keywords: Bio-lubricant, Jatropha, Esterification, Seed Oil