The use of neat CO2 for the Post-extraction purification of Etoh and butane concentrates

The weaknesses of CO2 as an extraction solvent has become very apparent too many people. The pressures needed for CO2 extraction requires the use of pressure vessels that do not scale effectively due to the inverse Square law. This means while thin steel tubes can hold alot of pressure the bigger the diameter the thicker the metal needed needs to be able to handle the same pressure, this makes larger pressure vessels exponentially more expensive. The other most commonly addressed weakness of CO2 is a low solubility of cannabinoids relative to other solvents which results in long extractions and low yields.
Both of these issues can be significantly addressed by using it as a post extraction purification. Small pressure vessels that are cheaply available could process at least 500 grams per day and yield it’s not an issue cause nothing is lost in the system do to the tunability of co2. This type of system seems particularly useful for large-scale distillation operations who extract large quantities with ethanol or BHO and need it to be fully purged, thoroughly dewax and deterpeneate before distillation. While some distillers use crude directly and employ multiple distillation passes or post-distillation purifications, many have found the amount of distillation passes required can contributes significantly to oxidative degradation products, meaning losses of yield and purity. Many others do multiple pre distillation purifications i.e. winterisation, degumming, clarification, adsorptive filtration, liquid-liquid extraction or steam distillation in an attempt to achieve satisfactory purity after only one distillation. Most of these purification techniques only require a non-interacting “carrier solvent” to make the cannabis oil mobile. The cycle of adding and removing solvents can be costly and time-consuming especially at larger scales. CO2 a suitable replacement in all these techniques that is cheap and can quickly and easily be separated completely upon decompression.
Benefits of the, ultra-fast and efficient filtration which avoid the need of solvents and solvent recovery devices ie rotovaps. The ability to adjust the effective pH of the carrier solvent without added impurities and to modify adsorptive behavior of the entire system.

I have a design for a modular multifunction system that can: (Method I) Fractionation, the use of a chain of separation vessels that decrease Stepwise in Pressure and temperature to facilitate the separation of the three main fractions of cannabis concentrates, terpenes, cannabinoids and waxes. (Method II)It is therefore possible to get rid of trace butane on a large scale much more quickly and without the use of powerful vacuum pumps or heat. filtration, the use of activated carbon, aluminum oxide, celite, diatomaceous earth, fuller’s earth, cbleach, molecular sieves and any other filtration based purification can be done through the use of CO2 instead of other mobile solvents like ethanol or Hexane. The adsorbent media last much longer cause it can be flushed with a cleaning solvent like ethanol and then be “dried” with scCO2
These are the two that I have tested most thoroughly myself but other possible application are numerous.
For example, Butane and other short hydrocarbons are fully miscible with CO2 and ethanol is highly soluble. Both of these solvents can either be separated from the cannabis concentrate through use of liquid-liquid extraction or high pressure distillation. And liquid-liquid hexane water systems can be replaced with fully expanded ethanol and water.

This could drastically reduce solvent use and save distillers money so maybe next time u realize you need to upgrade ur rotovap again or spending hours vac filtering for winterization remember there might be a better way.
I’m building one iteration of my designs now but I am just curious what people will think about this idea. I know alot of people dislike co2 for many legitimate reasons but I think that was because of how it was sold to people.
I am currently collecting my scattered research and designs on the subject into a more coherent long-form description of what im talking about with references and personal testing. but i have alot of information on all these topics and many more if people r interested.


I love the idea! I’ve been wondering if anyone uses a CO2 extractor to dewax crude oil. Since thca is especially tough to dissolve in CO2, the theory makes sense. I haven’t found a method of cleanly loading/unloading oil in the extraction vessel, but I haven’t done much research … yet! Any ideas or suggestions are welcome. I have toys to play with and winterization/filtering/recovery is always a bottleneck.

What if u didn’t have to do a clean transfer or a transfer at all. My design u just use the collection column and redirect the plumbing.
Yeah fractioning it s possible and also just using the pressure for filtrations like a filter press.