Hydrothermal nitric acid treatment for effectual lipid extraction from wet microalgae biomass

• Published in: Bioresource technology Vol. 172; pp. 138 - 142
• Main Authors: Lee, Ilgyu, Park, Ji-Yeon, Choi, Sun-A., Oh, You-Kwan, Han, Jong-In
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-11-2014; Elsevier
• Subjects: Analysis of Variance; Biological and medical sciences; Biomass; Biotechnology - methods; Cell disruption; Chlorophyll removal; Chlorophylls; Extraction; Fatty acids; Fatty Acids - metabolism; Fundamental and applied biological sciences. Psychology; Lipid extraction; Lipids; Lipids - isolation & purification; Microalgae; Microalgae - drug effects; Microalgae - metabolism; Nannochloropsis salina; Nitric acid; Nitric Acid - pharmacology; Pretreatment; Statistics as Topic; Sulfuric Acids - pharmacology; Temperature; Unsaturated; Water - pharmacology; Lipid extraction; Cell disruption; Microalgae; Chlorophyll removal; Nitric acid; Chlorophyll; Chemical treatment; Lipids; Alga; Biomass; Microorganism; Acid medium
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2014.08.101

•Hydrothermal nitric acid treatment was proposed to disintegrate the algae cell.•Optimal conditions for lipid extraction from microalgae were determined.•Chlorophyll and unsaturated fatty acids were highly removed at 2% nitric acid.
Hydrothermal acid (combined with autoclaving and nitric acid) pretreatment was applied to Nannochloropsis salina as a cost-effective yet efficient way of lipid extraction from wet biomass. The optimal conditions for this pretreatment were determined using a statistical approach, and the roles of nitric acid were also determined. The maximum lipid yield (predicted: 24.6%; experimental: 24.4%) was obtained using 0.57% nitric acid at 120°C for 30min through response surface methodology. A relatively lower lipid yield (18.4%) was obtained using 2% nitric acid; however, chlorophyll and unsaturated fatty acids, both of which adversely affect the refinery and oxidative stability of biodiesel, were found to be not co-extracted. Considering its comparable extractability even from wet biomass and ability to reduce chlorophyll and unsaturated fatty acids, the hydrothermal nitric acid pretreatment can serve as one direct and promising route of extracting microalgae oil.