Advances in ultrasound-assisted transesterification for biodiesel production

The use of ultrasound in biodiesel transesterification has been advocated as a novel technology, which enhances mass transfer characteristics leading to reduced reaction times and potentially lower production cost. In this paper, advances in ultrasound-assisted biodiesel transesterification from different feedstocks using acid, base and enzyme catalysts are reviewed. A critical appraisal of the current technology status for each of these is provided, with focus on using ultrasound energy in conjunction with heterogeneous catalysts. For each of the technology reviewed, the interactions between reaction parameters and process efficiency as well as productivity are analysed and discussed. Overall, this review aims to impart an understanding of ultrasound use in biodiesel production and to provide insights into future developments within the field.