Producción enzimática de ésteres etílicos del aceite de ricino

biodiesel synthesis through transesterificación of castor oil with ethanol using n-hexane as a solvent and a lipozyme tl im commercial lipase as a biocatalyst was studied. the effect of ethanol molar relation to oil (3:1-10:1), temperature of reaction (35-65°c), initial enzymatic charge (5-20% p/p) and amount of water (0-10% p/p) was investigated. the maximum percentage of bio-diesel (ethyl-esters) was obtained at a temperature of 35°c, a 5:1 ethanol to oil molar ratio, an initial enzymatic charge of 15 % p/p and an initial water concentration of 2% p/p, both of them based on the castor oil weight. a simplified model was proposed to describe the enzymatic kinetics of castor oil transesterification with ethanol, based on the ping-pong bi bi mechanism with competitive inhibition for alcohol. the kinetic parameters of the model were estimated graphically and parametrically; a good approach among the results foreseen by the model and experimental data was found at low ethanol concentration (40-80 mol kg-1).