In this paper subcritical co-solvents extraction (SCE) of algal lipid from wet pastes of Nannochloropsis sp. is examined. The influences of five operating parameters including the ratio between ethanol to hexane, the ratio of mixed solvents to algal biomass (dry weight), extraction temperature, pressure, and time were investigated. The determined optimum extraction conditions were 3:1 (hexane to ethanol ratio), 10:1 ratio (co-solvents to microalgae (dry weight) ratio), 90°C, 1.4 MPa, and 50 min, which could produce 88% recovery rate of the total lipids. In addition, electron micrographs of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were conducted to show that the algal cell presented shrunken, collapsed with some wrinkles and microholes after SCE extraction. The main composition of total lipids extracted under the optimum conditions was TAG which represented more than 80%. And the fatty acid profile of triglycerides revealed that C16:0 (35.67 ± 0.2%), C18:1 (26.84 ± 0.044%) and C16:1 (25.96 ± 0.011%) were dominant. Practical applications: The reported method could save energy consumption significantly through avoiding deep dewatering (for example drying). The composition of the extracted lipid is suitable for the production of high quality biodiesel.

中文翻译：

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亚临界共溶剂从微绿藻湿微藻糊中提取脂质。

在本文中，亚临界共溶剂萃取 (SCE) 从 Nannochloropsis sp. 的湿糊状物中提取藻类脂质。被审查。研究了乙醇与己烷的比例、混合溶剂与藻类生物质的比例（干重）、提取温度、压力和时间等五个操作参数的影响。确定的最佳提取条件为3:1（己烷与乙醇的比例）、10:1的比例（共溶剂与微藻（干重）的比例）、90°C、1.4 MPa和50 min，可产生88%的回收率总脂质的比率。此外，进行透射电子显微镜（TEM）和扫描电子显微镜（SEM）的电子显微照片显示，在SCE提取后，藻细胞呈现收缩、塌陷、一些皱纹和微孔。在最佳条件下提取的总脂质的主要成分为TAG，占80%以上。甘油三酯的脂肪酸谱显示 C16:0 (35.67 ± 0.2%)、C18:1 (26.84 ± 0.044%) 和 C16:1 (25.96 ± 0.011%) 占主导地位。实际应用：报告的方法可以通过避免深度脱水（例如干燥）来显着节省能源消耗。提取的脂质成分适合生产优质生物柴油。