In-Situ Three-steps Method for Biodiesel Synthesis from Acidified Waste Cooking Oil

Biodiesel can be obtained from waste cooking oils (WCO) and represents a promising renewable fuel alternative to fossil oil. However, its production from low-cost feedstock requires the lowering of the free fatty acids (FFAs) concentration below 1% in order to prevent soaps formation. In the present study, the biodiesel synthesis was performed from a high acidity feedstock using a three-step method: the first one is an in-situ esterification using sulfuric acid as catalyst, the second one is the neutralization and the third one is the transesterification. The last two processes were performed using lime stone as neutralizing agent and basic catalyst, as well. The neutralization was the crucial step and the aim of the present work was the optimization of the reaction parameters. The results showed that the conversion was almost complete in the three-step method. The H-1-NMR, FT-IR, GC and TGA analyses of the final product confirmed that the purity of the biodiesel produced by such in situ three-step method and that its properties satisfy the European standards.