Purification of Triglyceride from Used Cooking Oil for Biodiesel Feedstock Using Batchwise Solvent Extraction

Green economy and blue economy are essential to applicate. One of the mandatory programs from the Indonesian government is B30, a specification of diesel fuel that has 30 percent of biodiesel content. Based on the biodiesel feedstock specification standard, the free fatty acid content is below 1%. The aim of this research was to produce biodiesel feedstock with high purity of triglyceride from used cooking oil by using batchwise solvent extraction. Batchwise solvent extraction involves the polarity of oil and solvent to separate polar and non-polar lipid fractions. The target of this research was the lowest percentage of free fatty acid and the highest percentage of triglyceride. This method also skipped the general method of refined oil products, such as degumming, neutralization, bleaching, and deodorization. The used cooking oil was mixed with a binary solvent (n-hexane and technical grade ethanol) and a single solvent (food grade ethanol 96% only). Each mixture was stirred at 300 rpm for 15 min and then poured into a separator funnel for 15 min. Polar and non-polar lipid fractions were separated. The non-polar lipid fraction was processed in the same procedure until eight stages. It was found that the batchwise binary solvent extraction produced a non-polar lipid fraction with triglyceride and free fatty acid purities of 88.81% and 2.06%, respectively. Moreover, the batchwise single solvent extraction produced a non-polar lipid fraction with triglyceride and free fatty acid purities of 95.89% and 0.93%, respectively, which is suitable with the standard of biodiesel feedstock below 1%.