Dave Schneider   |   August 09, 2019

CO2 and Ethanol Extraction: Technology and History

When it comes to processing cannabis, two methods are the most effective: CO2 extraction and ethanol extraction. Also known as solvent extraction, these processes are used to extract essential oils from the cannabis plant by separating it from the plant matter.
Dave Schneider is the marketing consultant at CapnaSystems.com, an efficient extraction equipment with zero post-processing. He also enjoys traveling the world and has visited over 65 countries.

There are pros and cons to both extraction methods, so when deciding which one to opt for, you need to consider how the two different approaches work and what kind of result they produce. After all, these two are also used in the production of entirely different products, so it would be best to take a look at both.

The History of CO2

CO2, better known as carbon dioxide, is a naturally occurring compound that is found all around us. It’s essentially a gas that covers the entire planet and protects it from the Sun’s rays. Plants require a certain amount of CO2 to grow with the help of photosynthesis.

Even though its natural state is gaseous, it can be frozen and compressed into a liquid. In 1835, CO2 was liquefied for the first time by Humphry Davy and Michael Faraday. Nowadays, CO2 has found its place in the chemical, oil, and food industries.

The History of Ethanol

Ethanol is a chemical compound which is produced by yeast fermentation. Ethanol is better known as alcohol, and it can occur naturally, but most of the world’s ethanol is artificially produced.

Ethanol has a lot of different uses, and it’s used in many various industries. However, pure ethanol can be harmful to the eyes and skin. That’s why it’s important to remember always to be careful when working with non-purified ethanol. This chemical can also be used in botany when a plant gets too large, and its growth needs to be stunted.

CO2 Extraction

The extraction of CO2 occurs when carbon dioxide is exposed to the correct pressure conditions and temperatures. CO2 extraction is a prevalent method in acquiring essential oils, as it has an extremely low risk of toxicity.

When CO2 is pressurized and cooled, it becomes a supercritical liquid. This means that its state becomes something between gaseous and liquid. When a substance is in this state, it’s much easier to separate structures and extract essential oils. Supercritical extraction was first used somewhere during the 1990s as an alternative and safer method of extraction.

The Process of CO2 Extraction

A special machine is used in CO2 extraction, which is both costly and complicated. It can cost up to hundreds of thousands of dollars and can be used only in laboratories by highly trained professionals. This machine consists of three different chambers:

  • one pressurizes and cools down the CO2
  • the second stores the plant material
  • the third chamber recaptures and reuses the CO2

In the first chamber, the CO2 is exposed to extremely low temperatures and high pressure, which will turn the gas into a fluid. When this fluid is reheated, it becomes supercritical, and it can pass through the chamber holding the plant material. There, it will extract and capture the plant’s active compounds.

Finally, the remaining CO2 is transported into the third chamber, where it is stabilized back into a gaseous state.

The most significant advantage of this method is its customizability. Since the pressure and temperature can be customized, various CO2-based products can be produced. Even though it’s not the most cost-effective method of producing cannabis concentrates, it’s still one of the safest and most popular ones.

Ethanol Extraction

It’s hard to pinpoint the exact moment when people first started using ethanol extraction for cannabis, but we do know it’s been around for a while now. Some records show ethanol-based cannabis extracts had been sold in the US up until cannabis was outlawed in 1937.

Ethanol extraction is done with the use of alcohol as a solvent. Unlike other solvents such as butane, the advantage of ethanol is that it poses almost no risk of toxicity to the user.

Alcohol is often used as a solvent, and unlike CO2 extraction, ethanol extraction can be done without the use of expensive machinery. You can do it in your own home, but machines for ethanol extraction would provide you with a higher-quality product.

The Process of Ethanol Extraction

In this process, cannabis is soaked in ethanol and left to sit for a certain amount of time (usually for an hour). Since it’s a bipolar solvent, meaning it can mix with elements which do and do not blend well with water, it’s believed to be a better solvent than CO2.

After that amount of time passes, the plant material is removed from the container. The next step is to use evaporation to remove the alcohol and filter the remaining liquid.

One of the downsides, since ethanol pulls all sorts of materials from the plant, is that at-home production will usually leave you with a bitter-tasting product which is a darker green color.

Since ethanol is extremely flammable, this method should be performed with extreme caution. The temperature needs to be carefully controlled during the entire process, but especially during evaporation. Advanced machines will be able to control this easily, but people who try this method at home should be careful.

CO2 or Ethanol?

Which method is “better” depends on your budget and desired product. If you’re willing to invest in large-scale production, the CO2 method is preferable. If this is a business opportunity, it would be much better to invest in a good machine which will pay for itself in due time.

On the other hand, if you’re looking for a small-scale project and something you can do in the comfort of your own home, ethanol extraction would be a better choice. It’s a safe option that doesn’t require much investment, but it wouldn’t be suitable for a business opportunity.

 

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