Ultrasonic enhancement of lipase-catalysed transesterification for biodiesel synthesis

The production of biodiesel was carried out from canola oil and methanol catalysed by lipase from Candida rugosa under different ultrasonic experimental conditions using horn (20 kHz) and plate (22, 44, 98 and 300 kHz) transducers. The effects of experimental conditions such as horn tip diameter, ultrasonic power, ultrasonic frequency and enzyme concentrations on biodiesel yield were investigated. The results showed that the application of ultrasound decreased the reaction time from 22-24 h to 1.5 h with the use of 3.5 cm ultrasonic horn, an applied power of 40 W, methanol to oil molar ratio of 5:1 and enzyme concentration of 0.23 wt/wt% of oil. Low intensity ultrasound is efficient and a promising tool for the enzyme catalysed biodiesel synthesis as higher intensities tend to inactivate the enzyme and reduce its efficiency.