초록
<P><B>Abstract</B></P> <P>Enzymatic transesterification reactions for biodiesel production require harsh conditions, which require methods of enzyme stability enhancements. In this study, we present covalently immobilized lipase on the biosilica-polymer composite as a viable method to obtain enzymes with enhanced stability in such harsh conditions. The fresh water microalgae <I>Scenedesmus quadricauda</I> was cultivated in a batch photo-bioreactor with CO<SUB>2</SUB> aeration, and urea was supplied as nitrogen source (0.075gL<SUP>−1</SUP>). Under optimized conditions, the amount of extracted oil was around 29.6%. Finally, the algal oil was utilized for production of biodiesel via enzymatic transesterification reaction which were performed in n-hexane using the free and immobilized lipase preparations. Fatty acid methyl ester (FAME) components were determined using gas chromatography–mass spectrophotometry (GC–MS). The conversion of algal oil to biodiesel was found to be 85.7% and 96.4%, with the free and immobilized enzyme, respectively. The immobilized lipase was highly stable and only 17% of activity was lost after 6 cycles repeated uses.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Lipase was immobilized on biosilica-polymer particle for biodiesel production. </LI> <LI> <I>S. quadricauda</I> oil was used to produce biodiesel at 35°C for 24h reaction time. </LI> <LI> 96.4% yield of biodiesel from crude algal oil with immobilized lipase. </LI> <LI> The activity retention was 76% after six cycles of transesterification. </LI> </UL> </P>