Biodiesel production from palm oil using combined mechanical stirred and ultrasonic reactor

• A combined mechanical stirred ultrasonic flow reactor (MS–US) has been designed for biodiesel production.
• The MS–US reactor provided the highest reaction rate when compared with MS and US reactors used separately.
• The transducer power plays a relevant role in the transesterification reaction.

This paper investigates the production of biodiesel from palm oil using a combined mechanical stirred and ultrasonic reactor (MS–US). The incorporation of mechanical stirring into the ultrasonic reactor explored the further improvement the transesterification of palm oil. Initial reaction rate values were 54.1, 142.9 and 164.2 mmol/L min for the mechanical-stirred (MS), ultrasonic (US) and MS–US reactors, respectively. Suitable methanol to oil molar ratio and the catalyst loading values were found to be 6 and 1 of oil, respectively. The effect of ultrasonic operating parameters; i.e. frequency, location, and number of transducer, has been investigated. Based on the conversion yield at the reactor outlet after 1 h, the number of transducers showed a relevant role in the reaction rate. Frequency and transducer location would appear to have no significant effect. The properties of the obtained biodiesel (density, viscosity, pour point, and flash point) satisfy the ASTM standard. The combined MS–US reactors improved the reaction rate affording the methyl esters in higher yield.