Optimization of transesterification process by the application of ultrasound energy coupled with diesel as cosolvent

The present investigation deals with the homogeneous alkali catalyzed transesterification of soybean oil in the presence of petrodiesel as a cosolvent and applying ultrasound energy. The effects of the various reaction parameters on transesterfication such as the methanol/oil molar ratio, concentration of the cosolvent and amount of the catalyst used were investigated. An excellent yield of 92% fatty acid methyl esters FAME was achieved within half an hour using stoichiometric amount of alcohol (alcohol/oil molar ratio 3:1), 1 wt.% catalyst and ultrasound energy of 20 kHz and 30 wt.%(with respect to oil) of the cosolvent diesel. Under similar reaction conditions, transesterification without cosolvent yielded a mere 46% of methyl esters. The biodiesel blends B05, B10 and B20 were tested for their performance in an unmodified compression ignition (CI) engine and were found to be suitable. The use of diesel as a cosolvent has further decreased the step of removal of cosolvent during the purification process making the process more efficient, economical and time saving.