The CO2 used in supercritical extractions can be recycled?
If yes, for how long can we use the same CO2?
If no, do we despose the same amount used in the beginning? Does it have the same chemical and physical structure?
Dear Guilherme, Yes it is! But you need intelligent engineering and detailed productivity evaluations. Under certain constellations, it is the most productive technology. See https://chromatographyshop.com/instruments-tools/pic-solution-sfc-sfe-systems/
It depends on how much CO2 is used in a lab. It isn't very feasible to recycle carbon dioxide from a single analytical system in a lab. The gas needs to be cleaned of residual co-solvents and then recompressed. It is is done in larger labs with many systems and large-scale preparative systems.
Depends what you are using it for and how clean you can get it. I used to work in an SCE pilot plant which would run in campaigns. We would recycle the CO2 within a circuit while treating a single product (i.e. sage, cinnamon, vanilla). Whether we could keep re-using it for the next campaign would depend on how distinct and tenacious the compounds were. To go from sage to rosemary or oregano, for instance, keeping it was ok. To go from black pepper to anything was a problem. Most of the extracted compounds were recovered by pressure let-down (which drops to gaseous state and lowers solubility) but some of the extracted compounds can be very hard to fully remove.
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