The power of CO2 Extraction
What is CO2 extraction? CO2 is considered to be a safer method of extraction because the solvent is non-volatile. The extract is purer because no trace of the solvent is left behind. It is also versatile and helps protect sensitive terpenes, by allowing cold separation. It’s very adjustable – the operator can select custom pressures and temperatures to achieve desired results. Best of all, CO2 is environmentally friendly!
With CO2 as a solvent for oil extraction, no toxins, heavy metals or hydrocarbon materials come in contact with the extracted oils. Generally Regarded as Safe (GRAS) by the FDA for use in food products and commonly found in carbonated beverages. Our bodies produce it when we breathe!
Extracted material is free of residual solvents.
Other extraction solvents, such as hydrocarbon-based propellants like propane and butane, hexane and pentane, or ethanol/alcohol mixtures, require additional distillation or purging beyond the extraction process to separate the solvent from the extracted oil. CO2 has a very low boiling temperature and wants to be a gas at room temperature, so it naturally separates from the extracted oil, the same way a soda goes “flat.”
Does not require costly explosion-proof facilities like flammable solvents do.
CO2 extractions can be done at temperatures native to the plant, minimizing thermal degradation of the plant material and the extracted oil.
The solvency power of CO2 can be adjusted simply by increasing or decreasing pressures and/or temperatures. The ability of the CO2 to selectively extract affords the ability to create unique extractions that have varying levels of desirable oils and waxes. Additionally, less desirable plant constituents, like chlorophyll, can be “de-selected”.
CO2 is readily available and widely used throughout a number of industries. Apeks CO2 oil extraction systems recirculate and subsequently recover 95% of the CO2 used in each extraction.
Industrial CO2 for extractions comes from byproducts – primarily hydrogen and ammonia manufacturing and fermentation for ethanol. CO2used for extractions does not contribute to the overall atmospheric CO2 levels.
Comparing CO2 extraction vs. butane or propane? Don’t forget to include the facility cost for processing with a compressed flammable gas.
SUB VS. SUPER
CO2 is unique because its solvency power can change by simply adjusting the temperature and pressure during the extraction. When the pressure and temperature of the CO2 are above 1083psi AND 88F, the CO2 is considered supercritical. If the temperature is drops below 88F, the CO2 changes to a liquid and is referred to as subcritical.
Both supercritical and subcritical CO2 act like a solvent and can extract oil from plant materials. When the pressure of the CO2 is decreased (generally to below 600psi) it converts to a gas and loses its ability to hold oils in solution and separates the extracted oil from the now gaseous CO2.
With respect to plant oil extractions, subcritical CO2 has lower solvency power and thus tends to pull mostly lighter oils and leave behind most waxes, paraffin and resins. Subcritical CO2 is also relatively cold and therefore very effective in extracting temperature-sensitive volatile oils and terpenes. Subcritical CO2 is ideal for extracting and preserving light oils from the plant material. Extraction times can be longer and yields are generally lower due to the fact that there will still be residual waxes and resins that are left behind in the plant material.
Supercritical CO2 can be a much stronger solvent than subcritical CO2. In addition to extracting lighter oils, supercritical CO2 can extract the higher molecular weight materials (like waxes, paraffins, lipids and resins) from the plant, allowing for higher yields and a more complete extraction. The stronger solvency power also makes the extraction times faster. Supercritical CO2 extractions at very high temperatures and pressures (higher than 120F and 5000psi) can cause thermal degradation of the oils, and when extracting green plant materials can have the potentially negative consequence of extracting chlorophyll.
Apeks Supercritical 2000psi and 5000psi Production Series systems all have the ability to run both subcritical and supercritical extractions. This allows the user to perform a “fractional extraction” by first extracting at lower temperatures and pressures to remove the lighter, temperature sensitive volatile oils, and then subsequently extracting the same material at a higher pressure and temperature to remove the remaining oils, waxes, etc. This approach is better than fractional separation (where extractions are done at high temperature and multiple separators have cascading pressures) because the temperature sensitive volatile oils and terpenes are never exposed to high heat.
Heat is the enemy of any botanical oil. Cold separation is critical for maintaining THCA or CBDA of cannabis extraction because cold separation will not decarboxylate extracted oils in the separator. Transparent glass-like cannabis shatter requiring only vacuum oven post-processing can also be made. Apeks Supercritical systems are designed so that the extracted oil stays cold (less than 40F) after it has been removed from the plant material to minimize thermal degradation. Learn more about how cbd oil is made.
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