Ultrasonic-assisted production of biodiesel from Manilkara Zapota (L.) seed oil

This paper investigates a novel method for the intensification of biodiesel production via alkali-catalyzed transesterification of an underutilized feedstock, Manilkara Zapota (L.) seed oil (MZO) using ultrasonic energy. The effects of the oil to methanol molar ratio (1:5–1:7), catalyst concentration (0.5–1.5 wt%), and reaction temperature (30–50°C) have been investigated using an ultrasonic frequency of 20 kHz and an ultrasonic power of 50 Watt. Optimal conversion of 97% was achieved in 20 min in an ultrasonic cavitation reactor with 1:6 molar ratio of oil to methanol, 1 wt% of catalyst, and 50°C of reaction temperature. The transesterification process is repeated with a conventional (mechanical stirring) method at optimum conditions (1:6 molar ratio, 1 wt% catalyst concentration, and 50°C reaction temperature). Biodiesel obtained from the ultrasonic method and the conventional method was then compared for their percentage yield and physicochemical properties. Ultrasonic transesterification process gave a maximum yield of 97% by weight of M. zapota biodiesel along with enhanced physiochemical characteristics. Therefore, it is concluded that ultrasonic process is the most effective method for converting MZO into biodiesel. The major properties of M. zapota oil methyl ester (MZME) met the requirements of EN 14214 biodiesel standard and therefore M. zapota (L.) seed oil can be a possible substitute to petro diesel.