Extraction of microalgal lipids and the influence of polar lipids on biodiesel production by lipase-catalyzed transesterification.
In order to obtain microalgal saponifiable lipids (SLs) fractions containing different polar lipid (glycolipids and phospholipids) contents, SLs were extracted from wet Nannochloropsis gaditana microalgal biomass using seven extraction systems, and the polar lipid contents of some fractions were reduced by low temperature acetone crystallization. We observed that the polar lipid content in the extracted lipids depended on the polarity of the first solvent used in the extraction system. Lipid fractions with polar lipid contents between 75.1% and 15.3% were obtained. Some of these fractions were transformed into fatty acid methyl esters (FAMEs, biodiesel) by methanolysis, catalyzed by the lipases Novozym 435 and Rhizopus oryzae in tert-butanol medium. We observed that the reaction velocity was higher the lower the polar lipid content, and that the final FAME conversions achieved after using the same lipase batch to catalyze consecutive reactions decreased in relation to an increase in the polar lipid content.
Area of Chemical Engineering, University of Almería, 04120 Almería, Spain.
Elvira
E
Navarro López
Area of Chemical Engineering, University of Almería, 04120 Almería, Spain. Electronic address: arobles@ual.es.
Alfonso
A
Robles Medina
Area of Chemical Engineering, University of Almería, 04120 Almería, Spain.
Pedro Antonio
PA
González Moreno
Area of Chemical Engineering, University of Almería, 04120 Almería, Spain.
Luis
L
Esteban Cerdán
Area of Chemical Engineering, University of Almería, 04120 Almería, Spain.
Emilio
E
Molina Grima
D056804:Biofuels; D018533:Biomass; D001709:Biotechnology / Q000379:methods; D002384:Catalysis; D005591:Chemical Fractionation / Q000379:methods*; D004800:Enzymes, Immobilized; D004951:Esterification; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism; D005656:Fungal Proteins; D008049:Lipase / Q000737:chemistry / Q000378:metabolism*; D008055:Lipids / Q000737:chemistry / Q000302:isolation & purification*; D058086:Microalgae / Q000737:chemistry* / Q000378:metabolism; D012997:Solvents / Q000737:chemistry; D058009:Stramenopiles / Q000737:chemistry* / Q000378:metabolism; D020002:tert-Butyl Alcohol
D056804:Biofuels; D004800:Enzymes, Immobilized; D005227:Fatty Acids; D005656:Fungal Proteins; D008055:Lipids; D012997:Solvents; C093667:Novozyme 435; D008049:Lipase; D020002:tert-Butyl Alcohol
Biodiesel; Lipase stability; Lipid extraction; Microalga; Nannochloropsis gaditana; Polar lipid