Production of a new second generation biodiesel with a low cost lipase derived from Thermomyces lanuginosus: Optimization by response surface methodology

Biodiesel production has received considerable attention in the recent years as biodegradable and non-polluting fuel. In this work, an inexpensive purified 1,3-specific lipase from Thermomyces lanuginosus (Lipopan 50 BG from Novozymes AS, Denmark) was utilised as biocatalyst in an alternative approach to obtain a novel second generation biodiesel-like biofuel. This novel product, which integrates glycerol as monoacylglycerols (MG) into the biofuels composition, can avoid the removal step/s of such byproduct, mandatory in the production of conventional biodiesel. A multi-factorial design and response surface methodology (RSM) were employed to evaluate the effects of several conditions (temperature, molar ratio of ethanol to oil and pH) on the conversion of sunflower oil into a blend of Fatty Acid Ethyl Esters (FAEE), MG and diacylglycerols (DG). The effects of water content and concentration of lipase on conversion into FAEE and MG were also studied. Results obtained indicate that pH, molar ratio of ethanol to oil and water content were significant factors influencing the conversion in the systems under the investigated conditions. Low temperatures (20 °C), high pH values (close to 12), and an oil/ethanol volume ratios of 3.4/1 were found to be the key controlling parameters which provide optimised results after 1 h reaction (conversions around 70%; kinematic viscosities about 8.5 mm2 s−1).