Acidity reduction of enzymatic biodiesel using alkaline washing

The aim of this communication is to report the reduction of biodiesel acidity by wet washing using aqueous/methanol NaOH solutions. For this purpose, some assays were carried out, varying temperature, methanol concentration, molar ratio of NaOH to FFA and the amount of NaOH solution, with results expressed in terms of final acidity and process yield. It is shown that 35 °C, 1 wt% of methanol, 1 NaOH:FFA molar ratio (i.e., 1 eqv, the stoichiometric relation), and 3 wt% of base solution in relation to crude biodiesel, resulting in a final FFA content of 0.19 wt% and around 96% of product yield.