Erika Cristina G. Aguieiras
Federal University of Rio de Janeiro, Brazil
Erika Cristina G Aguieiras is from Rio de Janeiro, Brazil. She graduated in Biologist in 2008 from the State University of Rio de Janeiro (UERJ). In 2011, she finished her MSc studies at School of Chemistry, Federal University of Rio de Janeiro (UFRJ). Currently she is a PhD student in Chemistry Institute, Department of Biochemistry, UFRJ. Her research includes lipase production by solid state fermentation and enzymatic catalysis to biodiesel synthesis.
This study investigated a new process of enzyme/enzyme hydroesterification for biodiesel production using a low-cost acid oil (10.5 wt% acidity) from macauba (Acrocomiaaculeata) pulp as raw material. The ethyl esters were produced by the hydrolysis of the oil using vegetable enzyme (VE) obtained from dormant castor seeds followed by esterification of the released free fatty acids (FFAs) with ethanol catalyzed by fermented and dry babassu cake with lipase activity from Rhizomucor miehei. The vegetable enzyme-catalyzed hydrolysis produced 99.6% of FFAs after 6 h in a medium with high oil concentration (50% v/v) and without organic solvent and emulsifier. For the esterification reaction, the best result was attained with an ethanol:FFA molar ratio of 2:1 and 15.1 U of dry fermented solid per g of FFAs at 40ºC, which yielded 91% of conversion after 8 h in a solvent-free system. Similar esterification conversions were obtained with the commercial lipases Novozym 435 and Lipozyme RM IM and the fermented solid. The fermented solid was reusedin successive 6-h batches for esterification reactions and conversions of over 60% were maintained for eight cycles. After two consecutive esterification reactions the resulting biodiesel met important Brazilian standards such as: Density, viscosity kinematic, flash point, carbonresidue, free glycerol and total glycerol, monoglycerides and triglycerides. The ester content was of 96.7% (esters of fatty acids of 8–18 carbons). This new approach is an alternative method to lower enzyme costs and consequently make the biodiesel obtained by enzymatic route more cost competitive.