Solvent Extraction of Jatropha Oil for Biodiesel Production: Effects of Solvent-to-Solid Ratio, Particle Size, Type of Solvent, Extraction Time, and Temperature on Oil Yield

The aim of this study was to examine the effects of solvent-to-solid ratio, particle size, extraction time, and temperature on the extraction of Jatropha oil using three organic solvents, i.e., n-hexane, petroleum ether, and ethanol. The Soxhlet extraction method was used, and the parameters were varied in the following ranges: extraction temperature of 24–80°C, extraction time of 2 to 8 h, solvent-to-solid ratio of 4 : 1 to 7 : 1, and particle size of 0.5–0.8 mm. After obtaining optimal conditions, a large volume of Jatropha oil was prepared, purified, and subjected to analysis of quality parameters. It was found that the oil content of the Jatropha curcas L. seeds used was 48.2 ± 0.12% w/w. The highest oil yield of 47.5 ± 0.11% w/w corresponding to an oil recovery of 98.6 ± 0.3% w/w was obtained with n-hexane under the following conditions: solvent-to-solid ratio of 6 : 1, particle size of 0.5–0.8 mm, extraction time of 7 h, and extraction temperature of 68°C. This was followed by that of petroleum ether (46.2 ± 0.15% w/w) and lastly by ethanol (43 ± 0.18% w/w). The quality parameters of the oil extracted compared favorably well with most of the values reported in the literature, suggesting that the oil was of good quality for biodiesel production. Environmental and safety concerns over the use of hexane pose a great challenge. Thus, ethanol, which is environmentally benign, is recommended for application. The conditions for ethanol extraction that gave high oil yield were as follows: extraction temperature of 70°C, extraction time of 7 h, solvent-to-solid ratio of 6 : 1, particle size of 0.5–0.8 mm, and oil yield of 43 ± 0.18% w/w corresponding to an oil recovery of 89.2 ± 0.4% w/w.