Multifrequency Ultrasound-Based Predictive Method for Biodiesel Production

Abstract

Fossil fuel price continuous growth invites to look for alternative solutions to fuel for internal combustion engines. One of the most accepted options is biodiesel. In the present study, the multifrequency ultrasound-assisted synthesis of Sinapis alba oil biodiesel has been tested. For this purpose, an ultrasonic probe working at 20 kHz and an ultrasonic reactor with interchangeable transducers of discrete frequencies (195, 578, 861 and 1136 kHz) have been used. For the probe, a multi-response optimization has been carried out, setting methanol-to-oil molar ratio at 5.5:1. Optimal results were provided by 1.42 % w/w of catalyst after approx. 10 min of ultrasonication. In case of transducers, oil-to-biodiesel conversion needed an ultrasonication time of 15 min. Overall, when ultrasound frequency increases, oil-to-biodiesel conversion slightly improves. In conclusion, this work provides a predictive method to produce biodiesel under ultrasonication conditions, at different frequencies, in batch mode. Resulting biodiesel meets European standard requirements.