Comparative study of biodiesel production from ethanol and babassu oil using mechanical agitation and ultrasounds

Abstract

Babassu oil is a vegetable oil extracted from the seeds of the babassu palm (Attalea speciosa), which grows in most areas of South America. Brazil is the world's largest exporter of ethanol; the advantages of this alcohol are concerned to its renewable origin and low toxicity. In this work ethyl esters of babassu oil were synthesized by alkaline catalysis in homogeneous medium. The experimental design was used as a tool for optimization of the transesterification reaction and also in identifying key factors influencing the conversion into ethyl esters. The transesterification reactions were performed using two methods-the traditional mechanical agitation and agitation promoted by ultrasound waves. The nuclear magnetic resonance spectroscopy was used to quantify the conversion of all reactions of transesterification. According to the model obtained for mechanical agitation, conversions above 99% are obtained when the stoichiometric ratio is set at 6:1, with 1.0% KOH, under stirring at 400 rpm, in 60 minutes. Alkaline transesterification assisted by ultrasound waves produced the best results with respect to time of reaction and phase separation of glycerin and ethyl esters. The experimental model showed that conversions above 99% can be obtained in 10 minutes after adjusting the other independent variables.