Scale-up and economic analysis of a supercritical CO2 plant for antimalarial active compounds extraction

Artemisia annua L. is characterized by a strong antimalarial activity due to the presence in its aerial parts of artemisinin and its derivative compounds: dehydroartemisinin and artemisin. These compounds are also antiulcerogenic, antifibroric and antitumoral against P-388 (murine lymphocytic leukemia), A-549 (human lung carcinoma) and HT-29 (human colon adenocarcinoma) cells. A. annua extract is generally obtained by N-hexane extraction; but, this process is not selective, can induce extract degradation and requires post-processing to eliminate the organic solvent used. In this work, supercritical CO2(SC-CO2) extraction coupled to fractional separation of a solvent extract is proposed as an eco-friendly alternative to overcome these limitations. In particular, a semi-solid, waxy product (i.e., concrete) from ground A. annua leaves is obtained by hexane extraction; then, it is treated by SC-CO2selective fractionation and extraction at 90 bar and 50 °C, using a CO2flow rate of 0.8 kg/h. Operating in this manner, storage and transportation costs can be reduced since the simpler parts of the process (organic solvent extraction and drying) are performed in the area where A. annua is cultivated and the intermediate product (i.e., A. annua concrete) is subsequently delivered to the SC-CO2plant. Moreover, the volume of the high-pressure extractor is 20 times smaller with respect to the one used to treat the equivalent quantity of vegetable matter by direct SC-CO2extraction since, in this case, the feed is the organic solvent extract. Therefore, the high-pressure pilot plant will be about 7 times less expensive in terms of equipment involved, if compared with the direct supercritical processing of the ground vegetable material.