提升微藻油脂萃取效率以製備生質柴油

Enhancement of lipid extraction from microalgae for biodiesel precursor.

楊易閎(Yang, Yi Hung)

指導教授 ： 談駿嵩

國立清華大學/工學院/化學工程學系/碩士(2015年)

摘要

本研究使用國立成功大學以開放式大規模培養之學名為Chlorella vulgaris的微藻作為生質原物料，進行生質柴油前驅油脂之萃取。研究中以超臨界CO2前處理技術、萃取溶劑篩選以及萃取操作條件最適化等三個方向以增進微藻油脂萃取製程之效率。
結果顯示超臨界CO2前處理於壓力為20.7 MPa下，不論操作溫度高或低皆無法有效提升萃取產率。經萃取溶劑篩選之結果顯示CO2膨脹甲醇(CO2-expanded methanol)為最有效之微藻油脂萃取溶劑，接著再以實驗設計-反應曲面法進行CO2膨脹甲醇萃取微藻油脂操作條件最適化之探討。CO2膨脹甲醇之最適化操作條件壓力為5.5 MPa、溫度為358 K、CO2流速為3 ml/min及甲醇流速為1 ml/min。於最適化操作條件下，以CO2膨脹甲醇萃取未經前處理之微藻可以得到高達84.8%的萃取產率。再以實驗結果搭配Aspen Plus計算比較CO2膨脹甲醇與丙烷膨脹甲醇(C3H8-expanded methanol)作為萃取溶劑時於生質柴油製程中所需能耗之差異。結果顯示CO2膨脹甲醇以及丙烷膨脹甲醇兩者於後續轉酯化製程所需之能耗並無太大差異；然而，當使用CO2膨脹甲醇作為萃取劑時，萃取過程中所需之能耗僅為丙烷膨脹甲醇所需之2/5，又因為CO2膨脹甲醇被視為一綠色溶劑而且操作上較丙烷膨脹甲醇安全，在安全及綠色製程之考量下，以CO2膨脹甲醇萃取微藻中油脂可視為一極具發展潛力之綠色萃取製程。

關鍵字

微藻 ； 二氧化碳 ； 膨脹溶液 ； 生質柴油 ； 油脂萃取

並列摘要

The purpose of this study is to enhance the efficiency of lipid extraction from Chlorella vulgaris for biodiesel precursor by supercritical CO2 (scCO2) pretreatment, CO2-expaneded alcohol extraction and optimization of extraction.
Supercritical CO2 pretreatment was used to disrupt the cell wall of microalgae to enhance the extracted lipid yield; however, scCO2 pretreatment was ineffective when it was operated at a temperature range of 313 to 353 K and at a high pressure of 20.3 MPa. The CO2-expanded methanol (CXM) was a superior solvent to methanol, ethanol, pressurized methanol and ethanol, and CO2-expanded ethanol for lipid extraction from the microalga Chlorella vulgaris (a total lipid content of 20.7% of the dried biomass was determined by Soxhlet extraction with methanol at 373 K for 96 h) in continuous mode. The effects of operation variables, such as temperature, pressure and CO2 flow rate, on extraction performance were examined using response surface and contour plot methodologies. The optimal operating conditions were a pressure of 5.5 MPa, a temperature of 358 K, a methanol flow rate of 1 mL/min and a CO2 flow rate of 3.0 mL/min, providing an extracted lipid yield of 84.8 wt% over an extraction period of 30 min. Compared with PM, CXM was safer and more energy efficient for lipid extraction from Chlorella vulgaris.

並列關鍵字

microalgae ； CO2 ； expanded liquid ； biodiesel ； lipid extraction

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