CHEMICAL ENGINEERING RESEARCH & DESIGN, vol.95, pp.12-21, 2015 (SCI-Expanded)
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 Scenedesmus quadricauda was cultivated in a batch photo-bioreactor with CO2 aeration, and urea was supplied as nitrogen source (0.075 g L-1). 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. (c) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.