title: Biodiesel production from Nannochloropsis gaditana lipids through transesterification catalyzed by Rhizopus oryzae lipase.
abstract: Biodiesel (fatty acid methyl esters, FAMEs) was produced from saponifiable lipids (SLs) extracted from wet Nannochloropsis gaditana biomass using methanolysis catalyzed by Rhizopus oryzae intracellular lipase. SLs were firstly extracted with ethanol to obtain 31 wt% pure SLs. But this low SL purity also gave a low biodiesel conversion (58%). This conversion increased up to 80% using SLs purified by crystallization in acetone (95 wt% purity). Polar lipids play an important role in decreasing the reaction velocity - using SLs extracted with hexane, which have lower polar lipid content (37.4% versus 49.0% using ethanol), we obtained higher reaction velocities and less FAME conversion decrease when the same lipase batch was reused. 83% of SLs were transformed to biodiesel using a 70 wt% lipase/SL ratio, 11:1 methanol/SL molar ratio, 10 mL t-butanol/g SLs after 72 h. The FAME conversion decreased to 71% after catalyzing three reactions with the same lipase batch.
authors.affiliation: Area of Chemical Engineering, University of Almería, 04120 Almería, Spain.
authors.forename: Elvira
authors.initials: E
authors.lastname: Navarro López
authors.affiliation: Area of Chemical Engineering, University of Almería, 04120 Almería, Spain. Electronic address: arobles@ual.es.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Robles Medina
authors.affiliation: Area of Chemical Engineering, University of Almería, 04120 Almería, Spain.
authors.forename: Pedro Antonio
authors.initials: PA
authors.lastname: González Moreno
authors.affiliation: Area of Chemical Engineering, University of Almería, 04120 Almería, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Esteban Cerdán
authors.affiliation: Area of Chemical Engineering, University of Almería, 04120 Almería, Spain.
authors.forename: Lorena
authors.initials: L
authors.lastname: Martín Valverde
authors.affiliation: Area of Chemical Engineering, University of Almería, 04120 Almería, Spain.
authors.forename: Emilio
authors.initials: E
authors.lastname: Molina Grima
mesh_terms: D056804:Biofuels; D018533:Biomass; D002384:Catalysis; D004951:Esterification; D008049:Lipase / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry; D012233:Rhizopus / Q000201:enzymology*; D058009:Stramenopiles / Q000737:chemistry*; D020002:tert-Butyl Alcohol
chemical_list: D056804:Biofuels; D008055:Lipids; D008049:Lipase; D020002:tert-Butyl Alcohol; D000432:Methanol
keywords: Biodiesel; Intracellular lipase; Microalgae; Rhizopus oryzae; Transesterification