초록
<P><B>Abstract</B></P> <P>Superparamagnetic Fe<SUB>3</SUB>O<SUB>4</SUB> sub-microspheres with diameters of approximately 200nm were prepared via a solvothermal method, and then modified with epoxychloropropane. Lipase was immobilized on the modified sub-microspheres. The immobilized lipase was used in the production of biodiesel fatty acid methyl esters (FAMEs) from acidified waste cooking oil (AWCO). The effects of the reaction conditions on the biodiesel yield were investigated using a combination of response surface methodology and three-level/three-factor Box–Behnken design (BBD). The optimum synthetic conditions, which were identified using Ridge max analysis, were as follows: immobilized lipase:AWCO mass ratio 0.02:1, fatty acid:methanol molar ratio 1:1.10, hexane:AWCO ratio 1.33:1 (mL/g), and temperature 40°C. A 97.11% yield was obtained under these conditions. The BBD and experimental data showed that the immobilized lipase could generate biodiesel over a wide temperature range, from 0 to 40°C. Consistently high FAME yields, in excess of 80%, were obtained when the immobilized lipase was reused in six replicate trials at 10 and 20°C.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sodium glutamate was used to get larger specific surface Fe<SUB>3</SUB>O<SUB>4</SUB> sub-microspheres. </LI> <LI> The surface of Fe<SUB>3</SUB>O<SUB>4</SUB> sub-microspheres was decorated with epoxy groups using epoxy chloropropane. </LI> <LI> Immobilized lipase is favorable to generate biodiesel over a wide temperature range. </LI> <LI> Immobilized lipase improves the reusability of biodiesel production at lower temperature. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Immobilized lipase on epoxy-group modified superparamagnetic Fe<SUB>3</SUB>O<SUB>4</SUB> was used to produce biodiesel from acidified waste cooking oil at a wide range of temperature and showed a good reusability at 10 and 20°C.</P> <P>[DISPLAY OMISSION]</P>