Extraction lipids from chlorella vulgaris by supercritical CO2 for biodiesel production

Abstract

This study investigated the impact of supercritical CO2 lipid extraction method (SCCO2) from Chlorella vulgaris microalgae for biodiesel production. In this research Chlorella vulgaris oil extracted using SCCO2 and conventional solvent (n-hexane and ethanol). Extraction method was carried out using high pressure CO-solvent the extraction experiments were conducted at (12L: 12D) light/dark regime in 8 treatments, including: T1 (without any shock), T2 (acidity shock, pH:11), T3 (salinity shock, 1 molar NaCl), T4 (nutritional shock, depletion of nutrition), T5 (acidity+salinity shock), T6 (acidity+nutritional shock), T7 (salinity+nutritional shock) and T8 (acidity+salinity+nutritional shock). For each experiment used 10 g algae biomass. The results of growth performance indicated that different medium conditions such as salinity, acidity and nutritional terms with light and dark time shocks can enhanced the Chlorella vulgaris biomass productivity (SGR (0.17±0.00), biomass productivity (0.34±0.05) and CO2 consumption rate (629.97±34.62). The major FAME profile of the obtained oils were (C16:0) palmitic, (C18:0) Stearic, (C22:1n9) ercucic, (C24:1n9) nervonic, (C22:6n3) DHA and (C20:3n3) eicosatrieonoic acids. The measured saponification value (SV) and iodine value (IV) showed no significant differences between the experimental samples (P<0.05). The best results of cetane number (CN) and degree of unsaturation (DU) values was recorded in TL7 (5062.04±23.14) and TL8 (40.93±1.20), respectively. At least, fatty acids content and lipid extracted by SCCO2 method under different pressure and temperature had the best results in 370 bar and 40 °C, while lowest restitution was seen in 200 bar and 40 °C, respectively. The results of this study illustrated that SCCO2 method had positive impact on oil extraction from Chlorella vulgaris had desirable properties.