Cryogenic Ethanol Extraction
Ethanol extraction is very commonly used when dealing with cannabis, CBD, and even THC production. The reason why it is called cryogenic ethanol extraction is that it uses ethanol as the solvent to soak and extract cannabis/plant leaves under a very low temperature for ethanol's low boiling point and easy volatility.
With that being said, the machine to proceed with ethanol extraction is often called centrifuge extractor, and it is usually used by connecting with chillers to keep the temperature inside the machine down so as to fully soak and extract cannabis in a stable state. The centrifuge extractor only washes, agitates, soaks, and then spin-drys to get the most initial crude oil which contains a bit of solvent and needs further steps for refining treatment.
Ethanol extraction can not remove all of the ethanol out of the initial crude oil, so it needs further steps for refining treatments. It will then be proceeded with ethanol recovery by evaporation machines, such as the rotary evaporator, wiped film evaporator, and falling film evaporator. Also, ethanol extraction is mainly used in the cannabis industry.
Supercritical Fluid Extraction
Supercritical fluid extraction uses carbon dioxide (CO2) as the solvent. In a normal situation, carbon dioxide stays in a gaseous state. However, under the specific condition, the carbon dioxide will change into a both-gas-and-fluid state. More precisely, when the temperature is higher than 31-celsius degrees and the pressure is higher than 1071 PSI, CO2 steps into the supercritical phase, meaning it becomes fluid featuring the gaseous property.
CO2 is powerful and cheap as the solvent, and its price is so much lower than ethanol, leading to a drastically decreased maintenance cost. When stepping into the supercritical phase, it is time for the CO2 to sparkle its advantages. Since it features both gas and fluid properties, the supercritical CO2 can easily flow through the solids and space due to the gaseous quality and dissolve the materials by the benefit of its fluid attribution. CO2 gains the qualities of low viscosity and no interfacial tension, so the solubility capacity and extraction efficiency are thus improved. Moreover, it will not damage the flavonoids and essences of the material for extraction, which enables it to be largely applied in many industries like coffee, pharmaceuticals, cosmetics, essential oil, and perfume.
Unlike ethanol extraction, supercritical extraction does not require the further solvent recovery step because in the final step the chilling effect will make the temperature drop, and the fluid CO2 will instantly change back to gas, thus separating the crude oil and solvent without effort. What's more important is that the supercritical extraction can focus on extracting the specific particle you favor and you have more controlling abilities about the selective compounds you target by changing the pressure and temperature, which the ethanol extraction and BHO extraction are not able to do.
Closed Loop Butane Extraction
Closed-loop butane extraction is also called hydrocarbon extraction since it uses hydrocarbon as the solvent, such as butane and propane. The extraction runs in a closed-loop system that does not require further solvent recovery and the solvent will be recovered and collected in a storage tank within this system.
Like the supercritical extraction, the butane stays in a gaseous state under the normal situation. It will turn into a fluid state, too, if the temperature and pressure change. That is to be said it needs to connect with a chilling machine to keep the inside temperature down, and usually, when the solvent is injected into the storage tank, it is added with enough pressure.
The big difference compared with the other two techniques is this one has a CRC device, which can remedy the color of the cannabis oil. So the extracted oil color looks brighter, clearer, and more transparent. Another point to notice is that the safety requirements and compliance are much stricter than the other two because of the high instability and volatility of butane.
Conclusion
In general, all three extraction ways require solvent and chilling machines to continue the extraction process. Ethanol extraction and BHO extraction are usually used in the cannabis industries, however, ethanol extractors can deal with much larger cannabis processing and have higher capacity, if you are a manufacturer or plant, it's better to choose ethanol extraction.
Unlike those two, supercritical extraction can be applied in much more industries as mentioned above besides cannabis industries due to its excellent compounds and particle targeting abilities. If you are in the pharmaceutical industry, food industry, cosmetics industry, and perfume industry, and want purer extracted materials, including cannabis oil, this is your best choice.