Extraction and separation of artemisinin by a dual-circulation CO2-switchable solvent system based on fatty acids
A dual-circulation CO2-switchable solvent system based on fatty acids was constructed by ultrasound-assisted extraction of artemisinin from Artemisia annua leaves using fatty acids as external cycle,and CO2 switching of polyether amine(D230)as internal cycle.The effects of liquid-solid ratio(mL∶g,that is,the volume of fatty acids added per gram of Artemisia annua leaf powder,the same below),ultrasound time,extraction temperature and extraction time on the amount of artemisinin extracted were investigated by single-factor experiments and orthogonal experiments.The artemisinin extracted was characterized by SEM,FTIR and 1HNMR,and its extraction and separation mechanism using a double-circulation CO2-switching solvent system based on fatty acids was further analyzed.Under the optimal extraction conditions of n-heptanoic acid(C7-FA)as extraction solvent,liquid-solid ratio(mL∶g)20∶1,ultrasonication time 1.00 h,extraction temperature 50℃,and extraction time 2.5 h,the amount of artemisinin extracted was 4.37 mg/g.C7-FA and D230/water solution formed a double-circulation solvent system with CO2-switchable ability,which could rapidly separate artemisinin and achieve solvent recovery and recycling,and the amount of artemisinin extracted in the fourth cycle was 78%of that extracted in fresh solvent.Van der Waals force and hydrogen bonds were the main intermolecular forces in extraction.
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