Ultrafast Biodiesel Production Using Ultrasound in Batch and Continuous Reactors

Biodiesel is produced in multi-stage batch reactors in which mass transfer is a rate limiting step. Mass transfer rates may be accelerated with ultrasound (US). In this paper, the performance of continuous flow US reactors, a Rosett US cell reactor, and a batch US reactor are compared to a conventional mechanically stirred batch reactor. The Rosett cell reactor combines acoustic cavitation and turbulence and achieved biodiesel yields greater than 90% in 5 min, whereas the same level of performance in the conventional reactor took more than 90 min. The most significant result of this work lies in achieving biodiesel yields greater than 90% after a single passage of the reagents in a continuous flow reactor in the presence of pulsed ultrasound. This corresponds to a reaction time of 18 s and a rate 300 times faster than the conventional process.