Preparation of biodiesel from jatropha hybrid seed oil through two-step transesterification

Seed oil of 15 jatropha hybrids along with their parents were converted into biodiesel through a two-step process: acid-catalyzed (H2SO4) esterification process followed by base-catalyzed (KOH) transesterification. A pre-esterification operation was applied to reduce free fatty acid content and increase the yield of biodiesel. The transesterification of seed oil yielded only 21 to 26% fatty acid methyl ester before acid pretreatment. Gas chromatography analysis after transesterification showed conversion to fatty acid methyl ester was achieved ≥90% for most of the oil samples. The biodiesel yield varied from 4.45 to 4.85 g/5 g oil among the hybrids. Oil to biodiesel conversion efficiency was observed to be ≥90% for most of the oil samples. After conversion biodiesel from all hybrids were characterized for their density, specific gravity, acid value, and iodine value. All of the biodiesels in this study have compatible properties with the international standards of EN 14214, DIN 51606, and ASTM D 6751-02 s...