Biodiesel production from high free fatty acids content Jatropha curcas L. oil using dual step process

Biodiesel production from Jatropha curcas seed oil with high acid value collected from different regions of Maharashtra was investigated. A two-step process compromising acid esterification followed by alkali-catalyzed transesterification was used. The free fatty acid contents of the oil (25–28 mg KOH/g) were reduced to 2 ± 0.25 mg KOH/g in acid esterification step using 0.5 % (v/v) sulphuric acid and 6:1 M ratio of methanol to oil. Effect of different variables such as methanol to oil molar ratio, concentration of alkali catalyst (KOH), reaction temperature, and time were investigated. The highest yield of the methyl ester achieved was 95 % under the optimum conditions: 9:1 methanol to oil molar ratio, 2 wt% KOH at 60 °C for 120 min. ¹H NMR profile of the oil and methyl ester demonstrated the successful conversion oil to biodiesel. The gas chromatographic analysis results revealed that amount of total monounsaturated fatty acid (oleic acid) in the oil was more compared to polyunsaturated fatty acid. The fuel properties of obtained methyl esters were studied and it indeed met the specification for biodiesel according to ASTM D6751 standards.