What is CO2 Extraction?

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What is CO2 Extraction?

Cannabidiol (CBD) products for pets are more popular than ever. Pet products made with CBD, a natural ingredient derived from hemp, account for up to 5 percent of all hemp CBD sales within the US, according to the 2020 Pet Industry Green Paper.

Pet parents who give their pets hemp-derived CBD oil tinctures to help with a range of health conditions are curious about how these CBD products are manufactured and CO2 extraction is one of the most common methods used to create these products. 

What is CO2 Extraction?

CO2 extraction uses pressurized carbon dioxide to pull desired compounds from the hemp plant. 

The temperature and pressure of the carbon dioxide can vary as it runs through the extraction machine, allowing the gas to be used as a solvent to separate compounds like cannabinoids, terpenes and waxes. This creates the amber-colored liquid that is used in products such as CBD tinctures for pets.

CO2 extraction became the go-to method for extracting cannabidiol from hemp because it is safer than other methods such as butane extraction and ethanol extraction that utilize solvents. It is also more environmentally-friendly.

The CO2 Extraction Process: Understanding the Steps

woman holding hemp plant

 The process requires several steps: 

Step 1: A pump forces pressurized carbon dioxide gas into the extractor chamber where it is cooled to super low temperatures. The high pressure turns the gas into a liquid. 

Step 2: An extractor chamber is filled with ground hemp material, which is called trim.

Step 3: The CO2 passes through the chamber, dissolving the cannabinoid compounds, including CBD. 

Step 4: The CO2 carries the CBD particles past a pressure release valve to a cyclonic separator chamber where the pressure is lower. This allows the gas to separate from the oil.

Step 5: The CBD, waxes and resins move from the separator into a collection vessel and the CO2 is routed back to the tank where it is recycled. This process is called closed loop extraction.

Step 6: The CBD is processed further into different products such as CBD oil for both pets and humans.

CO2 Extraction Equipment: A Closer Look

The equipment used for his process varies depending on the batch sizes, which can range from 10 grams to hundreds of kilograms. 

Most of these high-tech machines are used in laboratories and their fully automated settings do not require operators to remain in the room during the extraction process. 

The CO2 extraction process takes longer than other methods, requiring four to six hours to extract CBD and other compounds from 20 pounds of plant material, but the machines yield higher amounts of oils than other forms of extraction.

The Benefits of CO2 Extraction

Woman playing with dogs outside

CO2 extraction is more expensive than other methods but offers significant benefits that make it a popular option for manufacturers making CBD products.

Unlike other methods that rely on toxic solvents such as butane and ethanol to extract compounds from cannabis and hemp plants, manufacturers prefer using carbon dioxide because it creates a pure quality oil that requires almost no post-processing. 

The ability to control the temperature and pressure also allows manufacturers to target specific compounds such as cannabinoids or terpenes to customize their formulations for truly unique products. 

Carbon dioxide can also be recycled, making it a “greener” option than other methods and the gas acts as a cleaning agent that kills microbial bacteria, mold or mildew during the process. In the absence of bacteria, CO2-extracted CBD oil has a longer shelf life than products extracted using other methods.

Supercritical Vs. Subcritical Extraction

bottle of CBD oil

There are two different processes used to separate cannabinoids, terpenes and other compounds from pressurized carbon dioxide—supercritical CO2 extraction and subcritical CO2 extraction. Both methods use heated, pressurized carbon dioxide to separate compounds from both marijuana and hemp plants, but the specs and results are varied.

Subcritical CO2 requires less pressure and lower temperatures than supercritical CO2 extraction. The lower temperatures protect fragile constituents from denaturing such as specific terpenes that work synergistically with the cannabinoids (like CBD) to produce medicinal benefits. The process takes longer and produces smaller yields than supercritical CO2 extraction. 

Supercritical CO2 extraction uses higher pressure and temperature so the gas becomes a liquid—called a supercritical fluid—that acts as a solvent to separate the desired compounds from the hemp plant. This high-heat, high-pressure process produces a thicker substance than subcritical CO2 extraction and preserves both CBD and additional cannabinoids. It is faster, more efficient and produces greater yields than subcritical CO2 extraction.

CO2 Extraction vs. Butane Extraction

Using carbon dioxide is just one of the options for extracting CBD and other compounds to make tinctures. Some manufacturers also use solvents like butane to extract compounds. 

Butane extraction is also called hydrocarbon extraction. The solvent passes through the raw plant matter, collecting cannabinoids. The cannabis is heated to evaporate the butane until only the extracted oils remain. 

Terpenes, the aromatic compounds in plants like cannabis, that remain after butane extraction are often stronger than those remaining after CO2 extraction.  

But the compounds extracted with butane often contain residual solvents which can be toxic to animals. Lastly, butane gas is flammable, increasing the manufacturing risks. 

In contrast, CO2 extraction uses high carbon dioxide gas under high pressure and low temperature to isolate the medicinal oil, producing a safe, potent CBD oil. 

Is It Safe?

This method is considered one of the safest ways to extract CBD. Compared to other methods, including butane extraction, CO2 extraction has a lower risk of residual solvents, producing a “cleaner” product that is both non-flammable and recyclable. 

Dr. Trina Hazzah, DVM, DACVIM (Oncology), CVCH