Enzymatic transesterification of soybean ethanolic miscella for biodiesel production

Abstract

AbstractBACKGROUNDBiodiesel production is not economically competitive with petroleum diesel particularly when using virgin and refined vegetable oils. Rich‐in‐oil miscella obtained from the extraction of soybean oil with ethanol may be a promising feedstock for taking off the refining process, simultaneously introducing an environmental friendly step by replacing hexane by ethanol as a renewable solvent in the oil extraction process. The aim of this study was to investigate the production of biodiesel from the oil–ethanol miscella by direct transesterification using Novozym®435 as catalyst and ethanol as acyl acceptor; simultaneously optimizing the process by response surface methodology and enzyme reuse.RESULTSThe best experimental conditions indicated by the empirical model were temperature 40 °C, oil:ethanol molar ratio 1:4.5 and catalyst concentration 9.5% for 24 h, reaching 85.4% fatty acid ethylic esters (FAEE) yield. Tert‐butanol used as co‐solvent increased the ethyl esters yield from 18%, keeping a high FAEE yield (over 70%) for more than 3 cycles of enzyme reuse.CONCLUSIONSRich miscella has great potential as a low cost feedstock for biodiesel production when Novozym®435 is used as catalyst, simultaneously introducing an environmentally friendly step by using the renewable solvent ethanol in the extraction and transesterification. © 2013 Society of Chemical Industry