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Supercritical CO2 is heavy like a liquid, with weird and useful properties

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Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#11

Post by jchallis »

Martyn Poliakoff of Periodic Videos fame has done a lot of work with supercritical CO2, particularly in the context of more environmentally friendly organic solvents.

This 5 minute video provides an excellent summary: https://www.youtube.com/watch?v=yBRdBrnIlTQ

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#12

Post by gene-h »

Venus' lower atmosphere is actually composed of supercritical CO2 at 90 atm and ~450°C which makes corrosion interesting[0]. sCO2's property of acting like a solvent works against us in this case. Copper grows a hair copper sulphide from the trace amount of sulfur dioxide and other sulfur compounds present. Hydrofluoric acid, even though it's present at part per billion concentrations, cause corrosion problems too. While we now have interesting silicon carbide integrated circuits like image sensors[1] and 555 timers[2] capable of operating at Venusian temperatures, it's challenging to actually use them on Venus because of corrosion of the bonding pads.

[0]https://www.researchgate.net/publication/325521557_Chemical_...

[1]http://kth.diva-portal.org/smash/get/diva2:1303493/FULLTEXT0...

[2]http://www.diva-portal.org/smash/record.jsf?pid=diva2%3A1317...

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#13

Post by hrdwdmrbl »

grawprog wrote: post #7
mikeyouse wrote: post #6

It's amazing how wide the applications of supercitical CO2 can be -- we used it as a solvent to extract high-value lipids from algal biomass at a biofuel company I worked for: https://en.wikipedia.org/wiki/Supercritical_fluid_extraction But it can also be used as a 'solvent' in non-toxic and low/no-water laundry systems: http://e3tnw.org/ItemDetail.aspx?id=512 In addition to all of the benefits it can provide for ene…

It's also being used as a solvent to make high quality cannabis concentrates and extracts in place of butane or alcohol that's more commonly used now. I haven't tried them, but I know the CO2 extracted products are being used more in edibles as toxic solvents aren't used in the extraction process.

Yes. The advantage as I've heard is that the extract is flavourless.

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#14

Post by selimthegrim »

neltnerb wrote: post #3

Couldn't comment to the author without paying for an account there, but as someone who has actually built sCO2 reactors -- you can get away with a much lower cost HPLC pump to pressurize the CO2 if you can force it to be a liquid at the inlet side using an eductor tube and slightly heating the tank to guarantee that the slightly cooler HPLC pump head won't cavitate. It worked pretty well, though I had to stick a TEC…

Does cavitation depend on temperature in like submarines too?

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#17

Post by h2odragon »

grawprog wrote: post #7
mikeyouse wrote: post #6

It's amazing how wide the applications of supercitical CO2 can be -- we used it as a solvent to extract high-value lipids from algal biomass at a biofuel company I worked for: https://en.wikipedia.org/wiki/Supercritical_fluid_extraction But it can also be used as a 'solvent' in non-toxic and low/no-water laundry systems: http://e3tnw.org/ItemDetail.aspx?id=512 In addition to all of the benefits it can provide for ene…

It's also being used as a solvent to make high quality cannabis concentrates and extracts in place of butane or alcohol that's more commonly used now. I haven't tried them, but I know the CO2 extracted products are being used more in edibles as toxic solvents aren't used in the extraction process.

Such extracts are too pure imo. Especially for edibles, I'd rather have an ethanol extract that got a run of related chemicals and some other stuff that came along for the ride... aka "flavor".

Super pure extracts that then have added back flavorings, or even blended concertos of specific chemicals, miss the charm and much of the value of taking the "light oils" off the plant. Flower is hard to fake, home extracts are easy to do, and who knows what's in that commercial oil, really?

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#18

Post by grenoire »

Holy moly, until now I had absolutely no idea about the existence of supercritical CO2. And now all the comments here are making me so incredibly fascinated and excited about the potential utilities for stored CO2. I am thinking not in terms of the science, but actually making a business case for CO2 storage beyond just CSR projects!

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#19

Post by at_a_remove »

From what I can gather, the chambers are quite small due to the pressure issues. This has the result of making aerogel, typically produced with supercritical carbon dioxide, come in comparatively small chunks, especially at the hobbyist level. It's a pity.

Re: Supercritical CO2 is heavy like a liquid, with weird and useful properties

#20

Post by grawprog »

h2odragon wrote: post #17
grawprog wrote: post #7

Earlier quoted context omitted.

It's also being used as a solvent to make high quality cannabis concentrates and extracts in place of butane or alcohol that's more commonly used now. I haven't tried them, but I know the CO2 extracted products are being used more in edibles as toxic solvents aren't used in the extraction process.

Such extracts are too pure imo. Especially for edibles, I'd rather have an ethanol extract that got a run of related chemicals and some other stuff that came along for the ride... aka "flavor". Super pure extracts that then have added back flavorings, or even blended concertos of specific chemicals, miss the charm and much of the value of taking the "light oils" off the plant. Flower is hard to fake, home extracts ar…

Ah yeah, the terpenes in the strains do more than add flavour too. Different terpenes in different strains have been found to have different effects in combination with the cannabinoids in the strain. I doubt re-adding terpenes and flavouring after the fact has the same effect. I suppose I have tried CO2 extract, I have tried the prefilled oil carts with the added flavour. I don't like them. The high from them feels weird and the taste isn't great.
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