Optimization of Biodiesel Production Using Immobilized Candida Rugosa Lipase on Magnetic Fe3O4-Silica Aerogel

Hydrophobic magnetic silica aerogel was used as a support to immobilize Candida rugosa lipase by adsorption method. Physical and chemical properties of the support and immobilized lipase were determined by Field Emission Scanning Electron Microscope (FESEM), Brunauer–Emmett–Teller (BET) analysis and Fourier Transform InfraRed (FT-IR) spectroscopy and the results showed that the lipase was successfully immobilized onto the support. Biodiesel production from sunflower oil using immobilized lipase was investigated. Response Surface Methodology (RSM) was employed to evaluate the effect of process variables namely methanol/oil molar ratio (4:1-6:1), enzyme concentration (4-10 % mass fraction of oil) and water concentration (3-10 % mass fraction of oil) on biodiesel yield and predict the optimal reaction conditions. A second-order regression model with a high coefficient determination value (R2= 0.99) was fitted to predict the response as a function of reaction parameters. The results indicated that optimum values for methanol/oil molar ratio, enzyme concentration, and water concentration were obtained at 4.5:1, 9.4% and 7.4 %, respectively, in which biodiesel yield was predicted at 72.3%. As the difference between the experimental and predicted values were shown as non-significant, the response surface model employed could be considered as adequate.