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How Does CO2 Extraction for CBD Oil Work?

Green Shoppers Written by Green Shoppers
Updated on November 3, 2018

Cannabidiol, or CBD, is one of the compounds that can be found in the cannabis plant, known as cannabinoids. Over the years, scientists have found various cannabinoids to have a range of effects on the human body, with research still ongoing into this matter. CBD is one of the most researched elements of the cannabis plant, and it is now being sold in mainstream markets throughout the Western world.

In the UK, CBD oil is legal for sale despite the strict illegality of the cannabis plant, and you can find these products and similar ones on the shelves in health stores such as Holland & Barrett. Aside from oils, you can purchase edibles, vape cartridges, and even lotions infused with the CBD compound.

With its growing popularity, there are a lot of questions surrounding CBD. One of the queries at the forefront of many people’s minds is how the compound is extracted from the cannabis plant, and how this is done without the accompaniment of other, illegal substances like THC. In this article, we will talk about how CBD is extracted, namely through the process of CO2 extraction. But first, let’s talk a bit more about what CBD is.

What is cannabidiol?

When people think of cannabis – and consequently marijuana, even though this is just one type of cannabis plant – they think of recreational drug use and people getting ‘high.’ This occurs because of a cannabinoid called tetrahydrocannabinol, or THC. While cannabis and THC are heavily stigmatised and notorious for psychoactive properties, CBD is actually not the same.

Cannabidiol affects our body differently to its mind-altering counterpart. Whenever cannabinoids are ingested, they interact with the endocannabinoid system (ECS) in our body, which refers to a network of cannabinoid receptors and endocannabinoids – compounds that we produce naturally. THC predominantly interacts with CB receptors in the brain, leading to those intoxicating effects it is known for. While CBD also interacts with the CB receptors in the brain, it is primarily focused on other receptors found abundantly in the immune system, tissues, and organs.

In other words, although it is a cannabinoid, CBD will not get you high. Furthermore, there have been claims that CBD could help to balance out the THC high during marijuana consumption. Regardless of whether this is true, you can rest assured that ingesting CBD oil is not going to affect your mind.

CBD is also legal in the UK. The only complication here is that CBD sold in the UK must be extracted from hemp, not marijuana. Hemp is another member of the cannabis family, but this plant contains less than 0.03% THC, which complies with the legal limit for CBD oils sold in the UK.

Why do people use CBD?

People purchase CBD oils to use as a food supplement, adding the oil to their daily routine in order to promote general wellbeing.

CBD interacts with the endocannabinoid system, as we mentioned. The ECS’ primary role is to maintain homeostasis within the body. In other words, it makes sure all the conditions within our bodies remain within the right parameters, keeping us healthy and, above all, alive. This makes the ECS crucial to our survival, which is why it is essential for it to function normally.

The body does produce its own endocannabinoids to keep the ECS in check, but it can sometimes fail to produce enough. If you’re feeling ill or under the weather, something is off with your homeostasis, and your ECS will be fighting to get your body back on track.

By taking CBD oil, you can add some extra cannabinoids into your body to promote wellbeing and a healthy lifestyle, which is why a growing number of people are adding it into their routine.

CBD extraction methods

In order to meet a growing demand of oils, companies need a way to actually get the cannabinoid out of the cannabis plant in a concentrated form that is fit for human consumption.

In order to do this, the company needs to have access to hemp. We briefly mentioned this, but marijuana is obviously very much illegal in the UK, meaning that CBD cannot be extracted from it. Hemp is also under restriction due to its relation to cannabis, but its low levels of THC mean that special permission can be granted for cultivation of hemp crops. It is legal under EU law, so many manufacturers grow their hemp crop in clean soils across Europe.

Containing less than 0.03% THC, hemp plants are a great option to use in extraction, as it means that only negligible amounts of THC will be extracted, and what is extracted can be removed if the company wants to sell an oil with absolutely 0% THC.

Without further ado, let’s look at the 4 most common extraction methods for CBD.

1. Olive oil extraction

A very cheap, easy method of extracting cannabinoids is by using olive oil. Before the oil comes into play, the dry, raw plant material is decarboxylated, which means it is heated at a specific temperature for a certain length of time in order to activate the chemicals in the plant. Generally, this is done at 120˚C for 60 minutes, or at 140˚C for 30 minutes.

Next, the plant material is placed in olive oil and heated to 100˚C for between 1 and 2 hours. The cannabinoids are sapped out of the plant material and into the oil, meaning that the end result is a ready-made cannabinoid oil.

Although this method is simple and inexpensive, the resulting oil is highly perishable and tends to not have very high yields of cannabinoids. In other words, it’s not exactly profitable for companies to use it.

2. Dry ice extraction

Another simple method, extracting cannabinoids using dry ice is only slightly more complicated and expensive than olive oil extraction. It is quite time-consuming and labour intensive but gives a much larger yield.

First, the hemp is cut up into small pieces and placed in a large bucket. Then, it is covered with around 3 pounds or so (depending on how much plant matter there is) of dry ice and is left for around three minutes. The resins on the plant are frozen through this method.

Next, a mesh bag is fit over the bucket, and the ice/hemp combo is shaking around for a few minutes, knocking the frozen resin off the plant matter. The bucket is turned upside down, filtering the frozen chunks of resin through the mesh bag onto a flat surface such as Plexiglas.

As you can see, this method is really quite simple, and it does produce a decent yield. However, shaking the product too much can actually ruin the quality of the resulting cannabinoids, so it is important to take caution. Furthermore, it is very labour intensive.

3. Solvent extraction

Solvents such as low-grade alcohol, ethanol and butane are great at extracting cannabinoids. This method does extract the full range of cannabinoids and terpenes from the plant, allowing for the entourage effect to take place; This refers to the phenomenon in which the chemical compounds in cannabis work better when all used together.

However, while ethanol and other solvents can thus result in a high-quality product, they also extract chlorophyll from the plant. Chlorophyll is not completely safe for human consumption and can cause some very nasty side effects. Fortunately, chlorophyll can be filtered out, but unfortunately, this filtering reduces the potency of the oil.

This method involves adding the solvent to the plant material. The liquid strips away the cannabinoids and terpenes from the hemp, along with some of the chlorophyll. Then, the mixture is heated to evaporate the liquid until only CBD base oil is left.

Again, this is a very simple method, and it can produce decent yields. However, solvents are not great for human health. Butane, for example, is more effective at extracting cannabinoids, but it is more likely to irritate the lungs. So, it is best to avoid this method as it can be harmful.

4. CO2 extraction

The most commonly used method for CBD extraction is CO2 extraction. There are actually different ‘levels’ of CO2 extraction, including subcritical and supercritical. Generally, manufacturers of CBD oils will use supercritical CO2 extraction, as it is highly effective.

This method requires a lot of specialised equipment and knowhow. It works by using a closed loop system, meaning that the process takes place in an entirely separate circuit to anything else. First, CO2 is cooled to -56˚C, while the pressure is increased to 75 pounds per square inch (psi). This puts the CO2 into a ‘supercritical’ state, meaning that the boundaries between liquid and gas are blurred and it behaves like both at the same time.

While in this state, the CO2 behaves a bit like a solvent. It is passed through a chamber containing the plant material. It is still dense like liquid, but can fill the entire chamber like a gas. This is ideal for extraction, as it does not lead to any denaturing or damage.

The CO2 pulls the cannabinoids and terpenes out of the plant. This is then passed into a separator and broken down into different parts. The extracted compounds are sent to a collection container, while the CO2 goes through a condenser and is converted back to its original state. Here, it can be recycled and used over and over again in the process.

Subcritical CO2 extraction is a similar process, but it involves a lower pressure and is thus less expensive. However, this produces a smaller yield and takes longer to complete.

CO2 extraction creates a safe, high-quality, pure oil, which is why companies tend to favour this technique. The expense and technical ability required does drive up the price of the product, but it’s worth it for something so safe.

Final thoughts about CBD extraction

If you were wondering how CBD was removed from the cannabis plant, then now you know! There are several ways that this can be done, but commercial manufacturers tend to use CO2 extraction due to the quality of the oil that it produces. Sure, it is enormously expensive and technical, but it is a very safe and efficient method.

When shopping around for CBD products, look out for the company stating where they source their CBD – most companies will boast that they use CO2 extraction, and now you know that these are the reputable sources you should be buying from.