Hydrodynamic cavitation as an efficient approach for intensification of synthesis of methyl esters from sustainable feedstock

Abstract Investigations related to process intensification of synthesis of methyl esters from sustainable feedstock is gaining importance because of considerable energy requirements and higher reaction time in the conventional approach. The present work illustrates the use of hydrodynamic cavitation for intensification of methyl ester synthesis from the high acid value non-edible oil. Two-step synthesis of acid esterification followed by alkaline transesterification has been employed for obtaining the methyl esters. In first step, acid esterification is used to reduce the acid value of oil from 18.7 to less than 1.5 mg of oil/g of oil beyond which alkaline transesterification can be used without any problems of soap formation. The molar ratio and catalyst concentration have been optimized for the esterification and transesterification stages. The optimized molar ratios were 1:3 and 1:6 for esterification and transesterification respectively. Under optimized conditions, 92% conversion has been obtained in the transesterification stage. It has been established that due to the use of hydrodynamic cavitation, the energy requirement for the synthesis is significantly reduced as compared to the conventional approach. The novel route discussed in the present work provides a viable option and can be explored easily for the industrial scale of operations.