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Author: Subject: Is it possible to build a DIY supercritical CO2 extractor?
S.C. Wack

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[*] posted on 2-10-2012 at 13:11

Little dissolves in liquid CO2 at room temp. If you could just add chunks of dry ice, you'd be able to buy such a system, or read about it in the journals.

IIRC the coffee is extracted while wet with water. It's done because it's "green", no one wants tolucoffee.

"You're going to be all right, kid...Everything's under control." Yossarian, to Snowden
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Hazard to Others

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[*] posted on 2-10-2012 at 17:53

caffeine alone is dangerous enough =D
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[*] posted on 3-10-2012 at 02:47

Quote: Originally posted by watson.fawkes  
Quote: Originally posted by encipher  
You see, the real benefit of supercritical CO2 is the ability to tailor the solvent power by varying the temperature/pressure. See the image below: [...]
Thus, by choosing the appropriate conditions, you can increase the solubility of a particular component.
That diagram is density vs. pressure, with isothermal lines. How does that relate to solubility?

It shows the ability to change the T&P to regulate density, which regulates the solvent power of a supercritical fluid. The solvent strength of a supercritical fluid increases dramatically when it's compressed to liquid-like densities.

This is important because the difference between ScCO2 and LCO2 at the same density is the fact that ScCO2 has like one or two orders of magnitude higher diffusivity (read: gas-like) and the same applies for lower viscosity, while having zero surface tension. Hence the appeal of supercritical extractions.

Of course there are situations were even these properties present no real benefit versus a traditional solvent. It depends on the application.
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[*] posted on 13-3-2015 at 07:28

Yes it is possible, it is very practicle, and very promising technology for now. Co2 is used because its supercritical temperature and pressure is relatively low at 31C and 73 atmosphere is easily achieved. Anyone w a pressure vessel rated at least 1073psi can do the extraction.
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