Application of Taguchi Method to Investigate the Effects of Process Parameters on the Transesterification of Soybean Oil Using High Frequency Ultrasound

This paper utilizes the Taguchi optimization methodology (L-9 orthogonal array) to optimize various parameters for the ultrasound-assisted, KOH-catalyzed transesterification of soybean oil with methanol. The statistical tool used in the Taguchi method to analyze the results is the analysis of variance (ANOVA), which gives the relative contribution of the factors varied to the change in the dependent variable (i.e., FAME or biodiesel yield). It is observed that catalyst loading is the most influential parameter, with similar to 42.56% contribution toward variation in biodiesel yield, followed by ultrasonic power with similar to 39.95%, and oil/methanol molar ratio with 11.40%. Ultrasonic frequency is found to have negligible influence on the biodiesel yield in the range of the present investigation. The optimum conditions are determined to be 581 kHz, 143 W, 0.75% (w/w) KOH loading at 1:6 oil/methanol molar ratio, resulting in more than 92.5% biodiesel yield in less than 30 min. Confirmation experiments have been performed to prove the effectiveness of the Taguchi technique after the optimum levels of process parameters are determined.