Optimization of Base- catalyzed Biodiesel Production from waste frying oil

In this article the biodiesel production procedure of base-catalyzed esterification was studied, and the optimal conditions of preparation were brought up. By applying orthogonal design, the optimal conditions of base-catalyzed esterification from waste frying oil with acid value of 4 mg/l KOH were: methanol/oil ratio, 8:1; catalyst dose, 1% oil weight; temperature, 85 degrees C; reaction time, 1.5 h. The maximum oil conversion rate of 90% was achieved. The influence of each factor on the oil production in descending order was: methanol/oil ratio > catalyst dose > temperature > reaction time. The biodiesel refinement was carried out with three types of rinsing solutions: distilled water, satirized NaCl solvent and glacial acetic acid. Rinsing times, soap removing rate and final acid value of the biodiesel were considered as the critical factors in evaluating the effectiveness of the rinsing solution on the biodiesel refinement. The results turned out that the most suitable rinsing method for industrial application was rinsing with saturated NaCl solvent.