Ultrasound assisted intensified production of biodiesel from sustainable source as karanja oil using interesterification based on heterogeneous catalyst (γ-alumina)

Intensification of interesterification of karanja oil in the presence of gamma-alumina as a heterogeneous catalyst using ultrasound (US) was performed in the current study. Effect of reaction conditions as reactant molar ratio, catalyst loading, duty cycle and temperature on the yield of FAME has been investigated. The catalyst used in the work, gamma-alumina, is an acidic catalyst and hence is resilient to high FFA and water content, making it as an efficient catalyst as no pretreatment is required even for karanja oil as sustainable feed stock. Optimum conditions established in the work for interesterification are 1 wt. % catalyst loading, duty cycle of 60%, reactant molar ratio of 1:9 and temperature of 50 degrees C resulting in FAME yield of 69.3% in 50 min. Reusability studies also confirmed that gamma-alumina can be reused for six cycles without much loss of activity. It was also demonstrated that conventional stirring based approach gave only 50.8% which is much lower than that obtained in the presence of ultrasound. The present study clearly demonstrated that use of ultrasound gives process intensification benefits and there are no negative effects on the gamma-alumina used as catalyst as demonstrated by the reuse for six cycles.