Effects of Deacidification of Low-value Plant Oils on Biodiesel Fuel Production

Abstract

Crude palm and Jatropha oils, obtained from Malaysia and Thailand, respectively, were used as low-value feed oils. To remove free fatty acid (FFA) in the feed oils, alkali or acid deacidification treatments were carried out, in which FFA was neutralized with NaOH, and esterified with methanol by H2SO4 catalyst, respectively. Both methods could reduce FFA to low levels, and the following transesterifications with alkali catalysts were successfully carried out. The yields of the treated oils were smaller with alkali than with acid deacidification. Acid deacidification required much longer treatment time than alkali deacidification. Transesterification with NaOH or CH3ONa catalyst could be conducted with the treated oil of FFA mass fraction less than 0.03. CH3ONa catalyst increased the biodiesel yields to more than 0.99 with the treated crude Jatropha oil. Crude palm oil contained more glycerides with shorter chain alkyl fatty acids, which were more reactive to saponification at transesterification, so the yields of biodiesel became lower at the transesterification.