Two Step Biodiesel Production from High Free Fatty Acid Spent Bleaching Earth
Biodiesel may be economical if produced from inexpensive feedstock which commonly contains high level of free fatty acids (FFA) as an inhibitor in production of methyl ester. In this study a two-step process for biodiesel production from high FFA spent bleach earth oil in a batch reactor is developed. Oil sample extracted from spent bleaching earth (SBE) was utilized for biodiesel process. In the first step, FFA of the SBE oil was reduced to 1.1% through sulfuric acid catalyzed esterification. . In the second step, the product prepared from the first esterification process was carried out transesterification with an alkaline catalyst. The influence of different variables on conversion efficiency to methyl ester, i.e., methanol/ SBE oil molar ratio, catalyst amount and reaction temperature, was studied in the esterification stage. The optimum process variables in the esterification were methanol/oil molar ratio 6:1, homogeneous catalyst conc. 1.0 wt %, reaction temperature 65o C and reaction time 45 minutes to produce low FFA oil which was further processed to make biodiesel using transesterification. Therefore, an optimized process for production of biodiesel from a low cost high FFA source was accomplished.
Keywords - Biodiesel, Esterification, Free Fatty Acids, Residual oil, Spent bleaching earth, Transesterification.