1. Production of biodiesel from vegetable oil and microalgae by fatty acid extraction and enzymatic esterification.
- Author
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Castillo López B, Esteban Cerdán L, Robles Medina A, Navarro López E, Martín Valverde L, Hita Peña E, González Moreno PA, and Molina Grima E
- Subjects
- Biocatalysis, Biofuels analysis, Biomass, Candida enzymology, Catalysis, Enzyme Stability, Enzymes, Immobilized, Esters chemical synthesis, Esters chemistry, Esters metabolism, Fungal Proteins, Hexanes chemistry, Lipid Metabolism, Methanol chemistry, Microalgae chemistry, Plant Oils chemistry, Temperature, Time Factors, Biofuels supply & distribution, Esterification, Fatty Acids, Nonesterified isolation & purification, Fatty Acids, Nonesterified metabolism, Lipase metabolism, Microalgae metabolism, Plant Oils metabolism
- Abstract
The aim of this work was to obtain biodiesel (methyl esters) from the saponifiable lipids (SLs) fraction of the microalga Nannochloropsis gaditana, whose biomass dry weight contains 12.1 wt% of these lipids. SLs were extracted from the microalga as free fatty acids (FFAs) for subsequent transformation to methyl esters (biodiesel) by enzymatic esterification. Extraction as FFAs rather than as SLs allows them to be obtained with higher purity. Microalgal FFAs were obtained by direct saponification of lipids in the biomass and subsequent extraction-purification with hexane. Esterification of FFAs with methanol was catalysed by lipase Novozym 435 from Candida antarctica. Stability studies of this lipase in the operational conditions showed that the esterification degree (ED) attained with the same batch of lipase remained constant over six reaction cycles (36 h total reaction time). The optimal conditions attained for 4 g of FFAs were 25°C, 200 rpm, methanol/FFA molar ratio of 1.5:1, Novozym 435/FFA ratio of 0.025:1 w/w and 4 h reaction time. In these conditions the ED attained was 92.6%, producing a biodiesel with 83 wt% purity from microalgal FFAs. Several experimental scales were tested (from 4 to 40 g FFAs), and in all cases similar EDs were obtained., (Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.)
- Published
- 2015
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