Waste of Nile Tilapia (<i>Oreochromis niloticus</i>) to Biodiesel Production by Enzymatic Catalysis—Optimization Using Factorial Experimental Design

Abstract

Lipase from Thermomyces lanuginosus (TLL) and immobilized in Immobead was utilized in the transesterification of Nile tilapia’s oil. The oil was obtained using the rejects of the farming process of Nile tilapia fish (Oreochromis niloticus). The transesterification process was optimized using factorial experimental design. Quantity of the enzyme, molar ratio of methanol/oil, temperature, and co-solvent were the parameters evaluated. The response selected for optimization was biodiesel yield (%). The success of the reaction using optimized conditions was confirmed by nuclear magnetic resonance of hydrogen. The physicochemical properties determined for Nile tilapia’s biodiesel were in accordance with international standards. An enzyme concentration of 20%, a 6/1 methanol/oil molar ratio, a temperature of 33.5 °C, and toluene as a co-solvent were found as optimized parameters. The statistical data suggested the co-solvent as a factor which explains a possible deactivation of the enzyme by the addition of alcohol.