The Effect of Variations in Methanol Concentration on the Esterification Process against Quality of Biodiesel from Used Cooking Oil

Abstract

Used cooking oil has the potential to be used as raw material for biodiesel. However, the high Free Fatty Acid (FFA) content in used cooking oil can interfere with the transesterification process. This issue will affect the quality of biodiesel yields. Therefore, FFA content in used cooking oil must be reduced through a pre-treatment process by adding activated carbon adsorbent from charcoal. In this study, the adsorption process was carried out by mixing used cooking oil and activated carbon using 20% NaOH for 3 hours. Then the degumming process was carried out by adding 0.5% v/v HCl from the volume of used cooking oil. Then add 0.5% NaOH by weight of used cooking oil and distilled water gradually, accompanied by heating to a temperature of 120 °C. In the esterification stage, the variables used are the comparison of methanol with a ratio of 1: 2, 1: 4, 1: 6, 1: 8, and 1:10. In this study, the lower acid number obtained from all variables was 2,24 mg KOH/g sample. Meanwhile, the most optimal result was the 1: 2 variables with a density of 0.8531 g/ml, and the kinematic viscosity at 40°C was 4.94 mm2/s.