SFE Supercritical Carbon Dioxide.
Let’s quickly examine what SFE is, by looking at what Wikipedia has to say about it, followed by our kicking off our affordable DIY CO2 extractor design project:
Supercritical carbon dioxide
From Wikipedia, the free encyclopedia
Standard carbon dioxide pressure-temperature phase diagram from Wiki, plus another showing the droopy nose normally not shown on CO@ SCFE charts, but which can be exploited.
Carbon dioxide usually behaves as a gas in air at standard temperature and pressure (STP), or as a solid called dry ice when frozen. If the temperature and pressure are both increased from STP to be at or above the critical point for carbon dioxide, it can adopt properties midway between a gas and a liquid. More specifically, it behaves as a supercritical fluid above its critical temperature (31.1 °C) and critical pressure (72.9 atm/7.39 MPa), expanding to fill its container like a gas but with a density like that of a liquid.
Supercritical CO2 is becoming an important commercial and industrial solvent due to its role in chemical extraction in addition to its low toxicity and environmental impact. The relatively low temperature of the process and the stability of CO2 also allows most compounds to be extracted with little damage or denaturing. In addition, the solubility of many extracted compounds in CO2 vary with pressure,permitting selective extractions.