ABSTRACT
In this study, the efficiency of esterification vs glycerolysis for the reduction of Free Fatty Acid (FFA) content of acid soapstock oil (128.8 mg KOH g−1) was studied. Further, alkaline transesterification of the pre-treated oil mixed with sunflower oil (to achieve FFA content <2%) was conducted to maximize Fatty Acid Methyl Esters (FAME) production. Homogeneous acid esterification was conducted at 65°C, using 2.0 wt% H2SO4 as catalyst and 9:1 molar ratio of methanol to oil. Glycerolysis was performed at 200°C using a 6:1 molar ratio of glycerol:oil. Both reactions lasted 6 h. Final acid value of the product was around 10 mg KOH g−1 for both processes, showing negligible differences between them. After transesterification of the mixtures it was possible to obtain biodiesel with around 90% FAME content, thus showing potential for the recovery of such waste material.
