Nannochloropsis gaditana and Dunaliella salina as Feedstock for Biodiesel Production: Lipid Production and Biofuel Quality

Abstract

Introduction: Microalgal lipids have a wide range of applications, from biodiesel manufacture in the energy industry to the production of polyunsaturated fatty acids for the pharmaceutical industry. Microalgal lipid productivity and quality, however, vary greatly depending on cultivation parameters.
 Aims: In this study, we investigated the potential of two marine microalgae, Nannochloropsis gaditana and Dunaliella salina, to be used as feedstock for biodiesel production.
 Methodology: A Taguchi L4 orthogonal array design was applied to understand the effects of sodium acetate (0 or 2 g L−1), sodium bicarbonate (0 or 2 g L−1), and sodium nitrate (25 or 75 mg L−1) concentrations on biomass and lipid productivities. Fatty acid methyl ester (FAME) profiles of microalgal lipids obtained under the best conditions were determined, and FAME results were used to predict biodiesel properties.
 Results: Both carbon sources (sodium acetate and sodium bicarbonate) improved biomass productivity. Lipid productivity was enhanced only by sodium acetate. The highest lipid productivities obtained were 10.25 ± 1.02 and 12.12 ± 0.28 mg L−1 day−1 for N. gaditana and D. salina, respectively. Palmitic (C16:0), stearic (C18:1), oleic (C18:1), linoleic (C18:2), lauric (C12:0), and myristic (C14:0) acids were the major components of D. salina oil. The major fatty acids in N. gaditana oil were C16:0, C18:0, and C18:1.
 Conclusion: The great differences in FAME profiles resulted in different biodiesel properties. Biodiesel from N. gaditana oil was predicted to have a higher cetane number (73.20) than that derived from D. salina oil (59.59). D. salina oil biodiesel, however, was predicted to have better properties than N. gaditana oil biodiesel, including lower cloud point (0.46°C) and cold filter plugging point (−7.27°C).

Assessing the application of marine microalgae Dunaliella salina in a biorefinery context: production of value‐added biobased products

“…The D. salina biomass was obtained by flocculation and filtration of 7 day batch cultures under laboratory conditions described. At the end, the biomass concentration reached 1.15 gL −1 and the volumetric productivity was 164.28 mg·L −1 ·day −1 , a value that is about 1.6 higher than the productivity reported by Bredda et al 24 . who cultivated D. salina in f/2 with 2 g·L −1 sodium acetate and sodium bicarbonate and 25 g·L −1 sodium nitrate in 4 L phtobioreactors (15 cm wide and 33 cm high), at 24 ± 1 °C under 150 klux for 7 days, and almost 4 times the productivity reported by Fawzy et al 25 .…”

“…Finally, a low percentage of PUFAs also favors the oxidative stability, increasing cetane number and other properties that improve fuel quality. Among the polyunsaturated fatty acids, linolenic acid (C18:3) stands out, as its maximum percentage is set as 12% (w/w) by the EU, because it contains many unsaturated bonds, it is prone to polymerization when subjected to high temperatures, and therefore increases the accumulation of solids in the engine 24 …”

“…Among the polyunsaturated fatty acids, linolenic acid (C18:3) stands out, as its maximum percentage is set as 12% (w/w) by the EU, because it contains many unsaturated bonds, it is prone to polymerization when subjected to high temperatures, and therefore increases the accumulation of solids in the engine. 24 In Table 2, the fatty acid profile obtained in this work is compared with those obtained by other researchers for D. salina microalgae. It was observed that, even when there was variation in the culture medium or when the microalgae were subjected to certain stress conditions, the microalgal oil was mostly composed of palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1), linoleic(C18:2), and linolenic (C18:3) acids.…”

Liquens artificiais e a integração de produtos de alto valor agregado a uma biorrefinaria

“…Das diversas fontes disponíveis para produzir biolubrificantes, os óleos vegetais são uma primeira alternativa (MOBARAK et al, 2014;BOLINA;GOMES;MENDES, 2021), contudo, diversos óleos vegetais possuem quantidades excessivas de ácidos graxos poliinsaturados, o que reduz a estabilidade térmica do biolubrificante resultante (DE SOUZA et al, 2012;. O óleo de microalgas apresenta-se como uma boa alternativa aos óleos de origem vegetal, por apresentar diferentes tipos de composição, dependendo da espécie de microalga e dos parâmetros de cultivo (BREDDA et al, 2018;HAWROT-PAW et al, 2021;PATEL et al, 2021). Esta variação de composição é possível também em óleos extraídos de biomassas liquenizadas.…”

“…A reação de transesteficação in situ efetuada com a biomassa de D. salina com o mesmo catalisador, empregando também óleo fúsel simulado, resultou em um teor de ésteres de 97,58% e 2,42% de MAG (DAG não detectado) e viscosidade de 5,0 mm 2 /s. Em comparação aos resultados encontrados para esta microalga, cultivada porBredda et al(2018), a qual contém uma composição em ácidos graxos com elevados teores de ácidos graxos saturados (34,27%) e monoinsaturados (46,74%) e um menor conteúdo de ácidos graxos poliinsaturados (18,99%), os resultados alcançados com a biomassa do consórcio microbiano são bastante promissores à aplicação como biolubrificante.…”