Comparative Study of the Physicochemical Characterization of Some Oils as Potential Feedstock for Biodiesel Production

Physicochemical properties of Cucurbita pepo, Brachystegia eurycoma, Cucumis melo, Luffa cylindrica, and Arachis hypogaea oils were studied to determine their potential as viable feedstock for biodiesel production. The nonedible oils were extracted by solvent extraction using n-hexane while the oil of Arachis hypogaea was procured. All the oils were characterized for specific gravity, pH, ash content, iodine value, acid value, saponification value, peroxide value, free fatty acid, flash point, kinematic viscosity, and refractive indices using standard methods. Cucurbita pepo seeds had very high oil content when compared to the others. Specific gravity and flash point of the oils were satisfactory. However, moisture content of some of the oils exceeded the stipulated ASTM standard for biodiesel production. Again, acid values of the nonedible oils were very high and exceeded the ASTM standard. They also exceeded the acid value of Arachis hypogaea oil except for Luffa cylindrica oil. Results indicate that the oils are potential biodiesel feedstocks. However, overall results indicate that the nonedible oils are not suitable for single-stage transesterification process to biodiesel but would be better suited for the two stage esterification and subsequent transesterification in order to obtain reasonable yields of the methyl esters.