ABSTRACT
Biodiesel production methods include acid, alkaline, two-step, supercritical methanol, and ultrasonic methods. Transesterification of the vegetable oil with the help of catalysts reduce the reaction duration but promotes complications in purification of biodiesel from catalysts and saponified products. Purification of biodiesel and separation of glycerol from the catalyst are necessary, but it would increase the cost of overall production process. With increasing the chain length, the miscibility between the oil and alcohol increases, thus, decreasing the reaction time but also making the separation of the esters difficult. The ultrasonic aided biodiesel production method can be a valuable tool for the transesterification of fatty acids. Ji et al. developed an alkali-catalyzed biodiesel production method with power ultrasonic that allows a short reaction time and high yield because of emulsification and cavitations of the liquid-liquid immiscible system. Contaminants and other minor components, due to incomplete reaction, are the major issues in the quality of biodiesel.
