Two-Step Reaction for Biodiesel Synthesized from a High-Free Fatty Acid Crude Palm Kernel Oil

Biodiesel was synthesized through a two-step reaction using crude palm kernel oil with high-free fatty acids (FFAs) and methanol. The two-step reaction involves esterification and transesterification. Esterification was carried out with a variation of H2SO4 (10%, 15%, and 20% w/v) at 65 °C for 120 min. Esterification produced fatty acid methyl ester (FAME) with an ester content of 67.56%. FAME was used as feedstock for transesterification. Transesterification was carried out with variations in reaction time (120, 180, and 240 min) at 65 °C in addition to NaOH 0.5% (w/w). Transesterification produced biodiesel, glycerol, and soap (side product). Biodiesel was separated using decantation and washing with warm distilled water at 40 °C. The optimum biodiesel was obtained at 180 min with 96.59% ester content. The characteristics of the optimum biodiesel were an FFAs of 0.2 mg KOH/g, iodine value of 20.12 g I2/100 g, density of 0.86 g/mL, kinematic viscosity of 2.51 mm2/s water content of 0.031%, ash content of 0.02%, cetane number of 60.8, flash point of 120 °C. Biodiesel has strong band spectra for C-H on 2,922.70 cm–1, C=O on 1,739.38 cm–1, C-H2 on 1,460.25 cm–1, C-O on 1,197.29 cm–1, and O-H on 3,425.10 cm–1. In conclusion, a two-step reaction is an effective method to synthesize biodiesel using CPKO with high FFAs as feedstock.