A Brief Review on the Application of Ultrasonic Technique in Biodiesel Production

The increasing pollution levels, rising energy demand, and the inadequacy of conventional fuels have spurred interest in alternative sources of fossil fuel supply and demand. This problem has shifted the focus towards the examination of a promising sustainable alternative for diesel fuels. In this sense, biodiesel can be a more suitable candidate for energy, environmentally harmless, and cost-competitive approach to respond to the energy demand. The application of ultrasonic energy in biodiesel production via transesterification has been endorsed as an efficient approach that improves mass transfer factors resulting in decreased reaction times and potentially lower process expense. This study investigates the advancements in ultrasonic energy for biodiesel generation from various raw materials utilizing different catalysts. A critical assessment of the current approach is furnished, emphasizing the application of ultrasonic irradiation. Besides, in order to better understand ultrasonic energy, each ultrasonic cavitation (UC) and hydrodynamic cavitation (HC) is discussed. Regarding each approach, the fundamental concepts are discussed in detail. Generally, the present study aims at conveying a comprehensive overview of ultrasonic energy usage in transesterification reactions and furnishing an outlook on prospective developments in the technology.