Biodiesel synthesis by enzymatic transesterification of palm oil with ethanol using lipases from several sources immobilized on silica-PVA composite

This work deals with the transesterification of palm oil with ethanol in a solvent free system using lipase from different sources (Thermomyces lanuginosus, Pseudomonas fluorescens, Burkholderia cepacia, Penicillium camembertii, and Candida antarctica, porcine pancreatic) immobilized on hybrid support polysiloxane-poly(vinyl alcohol). This is an exceptional option for the Brazilian biodiesel production, because both palm oil and ethanol are readily available in the country. The enzyme source showed strong influence on the transesterification yields, and the best performance was attained with the lipase from Pseudomonas fluorescens that reached. almost full conversion (congruent to 98 %) in less than 24 h of reaction. The purified product (biodiesel) was straw yellow in color and essentially odorless. Purity of the fatty acid ethyl ester was found to be high having no glycerol bound as verified by NMR C-13 (APT, attached proton test). In addition, the other properties such as low water content (0.02%), specific gravity (0.8), and viscosity (4.97 cSt) are in accordance with specifications recommended by the ASTM D6751 to be used as biofuel.