Intensified transesterification of castor oil using ultrasonic horn: response surface methodology (RSM) based optimization

Abstract

ABSTRACT Intensification of synthesis of biodiesel from sustainable feedstock using ultrasound and optimization based on RSM is important to develop sustainable and economical processes as an alternative to fossil-based fuels. The current work deals with transesterification of castor oil focusing on intensification based on the application of ultrasonic horn and optimization using RSM. The parameters applied in the study for optimization are time (X1), temperature (X2), molar ratio of reactants (X3), catalyst loading (X4), duty cycle (X5), and ultrasonic power (X6). The maximum yield of fatty acid methyl esters (FAME) obtained under conditions of time of 120 min, temperature of 30°C, molar ratio of reactants as 1:15 (mol: mol), catalyst loading of 1 wt%, duty cycle of 40%, and ultrasonic power of 100 W was 99%. A quadratic mathematical model was also developed to formulate predictions about the expected yield under a set of operating conditions. The statistical analysis and analysis of variance were executed to understand the interaction of independent variables and their effect on the biodiesel yield. Intensification due to ultrasound was demonstrated based on higher yield (99%) as compared to conventional processing without ultrasound (58%). Overall, the work clearly illustrated the intensification due to ultrasound and also helped to establish the optimum conditions.