Transesterification of Refined Waste Cooking Oil Using SrO-KF Catalyst Under Ultrasonic Wave

Waste cooking oil is a potential raw material for biodiesel. The use of heterogeneous catalysts and ultrasonicator will optimize the transesterification and environmentally friendly. The transesterification study with SrO-KF nano catalyst has been carried out. The objectives of this study are: (1) to determine the optimum conditions for SrOKF catalyst in the synthesis of biodiesel of the refined waste cooking oil and (2) to compare the results of the methyl ester with biodiesel standards. The steps of this study were: refinement of waste cooking oil, synthesis of SrO-KF nano-catalyst, and the transesterification. The catalyst applied ratio of 1:1, 1:2, and 1:3 of SrO:KF with concentrations of 2%, 3% and 4% by weight of oil respectively. The results of heterogeneous catalyst using XRD and SEM showed that SrF2, SrO and KF compounds had been formed. The optimum transesterification conditions were obtained on SrO-KF catalyst (1:2), concentration of 4% (w/w) with a yield of 85.12% (w/w). The methyl ester of waste cooking oil has density of 884 kg/m3, acid number of 0.48 mg/g, and viscosity of 4.2 cSt. Methyl esters of waste cooking oil were composed of 25.14% methyl palmitate and 33.65% methyl elaidate, 11.27% methyl linoleate, 10.14% methyl lauric and other methyl esters.