Rhizomucor miehei lipase supported on inorganic solids, as biocatalyst for the synthesis of biofuels: Improving the experimental conditions by response surface methodology

Abstract

Two inorganic solids have been evaluated as supports of Lipozyme RM IM, a Rhizomucor miehei lipase immobilized on a macroporous anion exchange resin, in order to improve its application as a biocatalyst in the synthesis of biofuels. The experimental conditions have been optimized to get the selective transesterification of sunflower oil, by using a multi-factorial design based on the response surface methodology (RSM). In this way, the effects of several reaction parameters on the selective ethanolysis of triglycerides to produce Ecodiesel, a biodiesel-like biofuel constitute by one mole of monoglyceride (MG) and two moles of fatty acid ethyl ester (FAEE), have been evaluated. Thus, it was obtained that a 6:1 oil/ethanol molar ratio, 0.215 g of biocatalyst supported in silica-gel (0.015 g Lipase/0.2 g silica-gel), 50 µL of 10 N NaOH, together with previous optimized reaction parameters, 35 ◦ C reaction temperature and 120 min of reaction time, gave the best results (conversions around 70%; selectivity around 65%; kinematic viscosities about 9.3 mm 2 /s) in the reaction studied. Besides, Lipozyme RM IM, supported on silica-gel, biocatalyst exhibited a very good stability, remaining its activity even after 15 cycles.