Ethanol is a popular solvent for cannabis and hemp extraction. Not only is it easy to use but it can deliver an enormous diversity of desired end-products. Learn more… Ethanol alcohol can be used to make cannabis tinctures and other concentrates such as Full Extract Cannabis Oil (FECO). Learn more about alcohol extraction from Leafly. For high-volume extraction companies, ethanol can be the most efficient and cost-effective solution for separating cannabis compounds from plant matter.
5 Reasons Why Ethanol is Ideal for Cannabis Extraction
Ethanol has long been popular as the solvent of choice for cannabis and hemp extraction, and there are several very good reasons for this. Not only is ethanol easy to use but it’s also very versatile in that it can deliver an enormous diversity of desired end-products. This versatility makes it an ideal solvent for both small-scale cannabis ‘connoisseur’ processors (who may be targeting a wide array of full-spectrum cannabinoids and terpenes), and also for larger processors seeking to isolate specific cannabinoids such as THC and CBD at scale.
1. Ethanol Extraction Has Been Used for Thousands of Years
Ethanol (AKA alcohol) when used as a solvent, is one of the oldest forms of botanical extraction and has played this role for thousands of years. In fact, alcohol is one of the oldest recreational drugs used by humans and is relatively easy to manufacture. It has been a prevalent part of society for several millennia. The earliest evidence of alcohol consumption in the archeological record was pushed back 13,000 years when researchers found residue of ancient wheat-and-barley based beer in a cave in modern-day Israel.
The term ‘spirits’ is believed to come from the idea that when ancient peoples would soak high-proof alcohol solutions (wine or mead) with other plants and herbs, the alcohol would take on the properties, or the ’spirit’ of the plant or herb.
With the use of ethanol as a solvent on one hand being so primitive, and on the other hand having developed a multitude of technological breakthroughs over the past few thousand years, ethanol’s versatility places it in a uniquely good position for any type of botanical extract and none more so than cannabis and hemp extraction.
2. Ethanol is Safe and Easy to Use
When directly compared to the other two most popular solvents used to extract cannabis—CO2 and hydrocarbon—the ethanol extraction process is generally safer and easier:
- Ethanol is less explosive and toxic, and therefore largely considered safer to operate than hydrocarbon extraction systems.
- Not only must CO2 extraction systems operate under high pressure, creating another potential hazard, but the equipment cost is much higher and its throughput (how much biomass it can extract in a given period of time or batch) is much lower when compared to ethanol extraction.
- While all extraction processes have their respective intricacies, ethanol is largely considered to be one of the easiest forms of cannabis extraction to learn therefore making it easier and faster to train operators. This simplicity is primarily because an ethanol extraction process does not require the solvent to change phases, which in the case of CO2 and hydrocarbons, involves the manipulation of pressure in sealed systems requiring more in-depth training to ensure a successful result.
3. “Like Dissolves Like” (Solubility) Makes Ethanol Highly Efficient
Understanding solubility (the ability to, and the quantity of, a particular substance that will dissolve in another specific substance) and the mechanisms that underlie it, is perhaps the most crucial piece of information dictating the success or failure of designing an extraction SOP.
What does “Like Dissolves Like” mean?
This is perhaps the most useful and common piece of knowledge readily known about solubility, but what does it mean? When we look at solubility at a molecular level, there are generally two different categories of molecules: polar and non-polar.
- Polar having positively + and negatively – charged ends
- Non-polar having roughly no, or zero charge, or is balanced
It is best to view these categories as a spectrum. On one end we have a molecule that has absolutely zero charge. And on the other we have a molecule that looks like a straight line that is completely polarized with a positive charge on one end and a negative charge on the other. And in between these two extremes, with varying degrees of polarity, are all the molecules of the world.
- Polar compounds will mix, or dissolve, with other polar compounds
- Non-polar compounds will mix, or dissolve, with other non-polar compounds
So, this is what we mean when we say “Like Dissolves Like”.
The most common non-polar molecules we encounter are lipids and fats. Like cooking and motor oils. The most common polar molecule we encounter is water.
Hence you will also find these categories referred to as:
- Water-soluble (polar)
- Fat-soluble (non-polar)
So, what is ethanol, polar or non-polar?
4. Ethanol is both Polar and Non-Polar
Ethanol can be both polar and non-polar, and this is one of the reasons it is so useful and herein lies its versatility.
Ethane (C2H6), is an alkane or hydrocarbon molecule composed of 2 carbons and 6 hydrogens. It is very non-polar.
Ethanol on the other hand (C2H6O) is an alcohol and is classified as such because of its oxygen atom containing alcohol, or hydroxyl, (OH) group on the end, which causes a slightly negative charge. This is because oxygen atoms are more electronegative. They have a higher affinity for the electrons, which are negatively charged, and which tend to ‘hang around’ the oxygen atom more than the carbons and hydrogens. This results in a partial negative charge.
Hence, H2O is quite a polar molecule. The oxygen being slightly negative (-) and the hydrogens being slightly positive (+).
What this all boils down to is this; ethanol is in a uniquely good position to dissolve most slightly non-polar and slightly polar molecules, which turns out to be a lot of different molecules!
And primarily because it’s a non-viscous liquid at atmospheric pressure and ambient temperatures, it can do the job of dissolving (dissolution) quickly and easily.
5. Ethanol is Ideal for Cannabis and Hemp Oil Extraction
Now how does all of this coalesce to make ethanol a great solvent for extracting botanicals, most specifically for hemp and cannabis extraction? The target compounds (the molecules we are attempting to extract and separate from the rest) typically include cannabinoids like THC and CBD as well as terpene compounds. These are all fat soluble.
Which is ideal because ethanol will dissolve them quite well.
However, for those extractors and manufacturers whose goal is to isolate and extract these compounds exclusively, ethanol can present a challenge.
Because ethanol also picks up polar, or water-soluble compounds, it will draw out other compounds we don’t necessarily want like chlorophyll. Conversely, if you’re intending to make ingestible, full-spectrum, end-products this ability can be an advantage.
However, herein lies the flexibility of ethanol making it extremely suitable for extracting botanical compounds: the polarity of ethanol can be slightly modulated / adjusted simply by changing temperature.
The colder the ethanol, the higher its affinity for fat soluble compounds, and therefore a more efficient extraction of cannabinoids and terpenes.
And if extraction is performed with warm or room temperature ethanol however, the ethanol will not only grab the cannabinoids, but also a wider spectrum of terpenes as well as water soluble compounds.
A versatile solvent indeed!
In Summary:
Ethanol’s versatility places it in a uniquely good position for any type of botanical extract and none more so than cannabis and hemp extraction because it…
May dissolve most slightly non-polar and slightly polar compounds.
Has an affinity for polarity because it can be adjusted via temperature.
Is a non-viscous liquid at atmospheric pressure, so it extracts quickly.
Boils at relatively low temperatures which allows for the efficient recapture of the ethanol and the subsequent separation of the extracted compounds.
Alcohol extraction
Ethanol alcohol can be used to make cannabis tinctures and other concentrates such as Full Extract Cannabis Oil (FECO). Isopropyl alcohol can be used to make hash, but many are shy away from it because of concerns of its toxicity. Denatured alcohol is toxic and should not be drunk or used to make cannabis concentrates at all.
“When a product was made with alcohol extraction, it’s a good idea to ask what type of alcohol was used.”
What is alcohol extraction?
Ethanol alcohol can be used to make cannabis concentrates. It’s important to note there are different types of alcohol, all with their own uses:
- Ethanol, also called drinking alcohol because it’s the only alcohol that’s safe to drink, is the active agent in alcoholic drinks, such as beer, wine, and spirits. It is safe to use for making cannabis concentrates.
- Isopropyl alcohol has been used by some hashmakers but it can be toxic at certain levels, and many in the cannabis community shy away from it.
- Denatured alcohol is poisonous if consumed and should only be used for cleaning tools or surfaces. It should not be used for making cannabis concentrates.
How to make an alcohol extraction
When using ethanol alcohol to make extracts, many extractors use something close to 100% pure ethanol. Most spirits, such as rum, vodka, gin, tequila, whiskey, etc., have around 40% alcohol by volume (ABV), or are about 80 proof. If making a cannabis extract, 190 proof or stronger (95-100% ethanol) is ideal.
There are various ways alcohol can be used to extract cannabinoids, and the simplest method is to make an alcohol-based tincture, where cannabis is soaked in alcohol at room temperature for weeks. Alcohol tinctures are common in herbalism with non-cannabis herbs and usually have around 40% ABV. Since only a few drops are consumed at a time, it is not enough for one to feel drunk.
Alcohol is considered a polar solvent, which makes it wonderful for extracting cannabinoids, alkaloids, and other chemicals from cannabis and other herbs, although it also extracts chlorophyll, usually giving alcohol extracts a deep green color. Alcohol tinctures are usually consumed under the tongue but can also be added to drinks or food and consumed like an edible, or even rubbed into the skin like a topical.
Ethanol, and all other types of alcohol, are highly flammable as liquids and vapors, so alcohol extraction should be done in a well-ventilated area.
An alcohol extraction can also be heated or left out to let the alcohol evaporate. The result will be a dark, tar-like substance rich in cannabinoids with no residual alcohol—this is often called Full Extract Cannabis Oil (FECO).
Ethanol Extraction for Cannabis and Hemp
Ethanol has a long history of extracting oil from plant materials for therapeutic use. In today’s highly competitive marijuana extraction sector, extraction artists have a wide range of extraction solvents to choose from such as carbon dioxide, light hydrocarbons (propane and butane), and ethanol. These solvents are used to extract the cannabinoids and terpenes from the cannabis or hemp resin.
What Is Ethanol Extraction?
Ethanol is more common than you think. Ethanol can be found in grain alcohol made by fermenting plant sugars from agricultural crops. Ethanol (C2H5OH), also known as ethyl alcohol, is a colorless and flammable liquid that can produce intoxication, be used for fuel, and also be used as a solvent. Ethanol can be fermented from different crops, but corn is the main source of ethanol in the U.S.
Ethanol extraction can be performed under warm or cold temperatures. Generally, raw and ground-up cannabis material (dry or frozen) is soaked in pre-chilled ethanol for a certain amount of time to separate the plant’s trichomes from the plant matter. Warm ethanol extraction has been a staple in amateur home extractions. For larger batches, room temperature or cooled ethanol can improve the quality of cannabinoids and terpenes in cannabis and hemp extraction.
After the initial extraction process using food grade ethanol, the solution is filtered and the ethanol is purged from the extract. Post-processing techniques gently remove ethanol from the extracts through evaporation. Ethanol may be removed with rotary evaporators, falling film evaporators, or a vacuum distillation system.
Winterization is a term used to describe the process of removing impurities such as plant lipids, chlorophyll, waxes, and fats from the oil. Chilling the oil and ethanol solution can cause these undesirable compounds to separate (precipitate) and rise to the top for easier removal. The cooling process can be performed in freezers, cold rooms, or other cooling equipment.
Keep in mind, ethanol has a higher boiling point than butane or propane. Because of its relatively higher boiling point, many of the terpenes that give cannabis the desirable flavors and aromas that many consumers enjoy, are lost in the ethanol extraction process. The inevitable loss in terpenes from the ethanol process also diminishes the entourage effect of the final ethanol extract product when compared to BHO extraction. Regardless of ethanol’s weaknesses, large-scale throughput and financing can easily overcome equipment limitations.
Ethanol extracts can also undergo a final polishing phase where adsorbents can be used to lighten the oil’s hue and improve the translucence of the extract. Popular adsorbents such as activated charcoal and bleaching clays can improve not only the color but also the quality of ethanol concentrates.
The residual ethanol is evaporated, condensed, and reused in the closed-loop extraction system to increase cost-efficiency and throughput. All of these operations take place in a lab-grade facility with adequate ventilation and storage areas.
Why You Should Choose Ethanol Extraction Over CO2?
Every extraction company favors one solvent over another for various reasons. Butane is the most common solvent used for cannabis extraction and CO2 extraction has also been touted as safe and eco-friendly. Ethanol extraction, however, offers both safety and efficiency when extracting cannabis or hemp on a large scale.
For high-volume extractions, ethanol can be the most efficient at separating cannabis compounds from the plant matter. Ethanol is an extremely polar solvent that can bind to cannabinoids, terpenes, but also chlorophylls and other water-soluble undesirable compounds. Many terpene boiling points are about the same as ethanol’s boiling point, thereby, increasing the risk of terpene loss when removing the ethanol solvent.
Ethanol’s polarity problem can largely be overcome with chilled ethanol (-40ºC or below) to bypass most of the chlorophyll, lipid, and other unwanted compounds. Under the proper conditions, ethanol extraction can produce isolate or limited full-spectrum concentrates with cannabinoids, and some terpenes, flavonoids, and other therapeutic compounds.
Ethanol can be easy to scale because using this solvent becomes cost-effective at a higher volume (1,000 to 5,000 pounds per day) compared to CO2 extraction, for instance. As hemp farming heats up across the nation, growers and extractors are looking for the most versatile and cost-efficient to reap CBD for a variety of infused products, not just CBD flower.
Is Ethanol Safer?
Ethanol extraction is no safer than hydrocarbon and CO2 extraction, that is to say, all extraction methods are safe for production under the approved building requirements. In fact, the Food and Drug Administration (FDA) has classified ethanol as a Class 3 solvent with low toxicity. Ethanol is one of the safest solvents for food grade and pharmaceutical extraction processes.
In pharmaceutical manufacturing, residual ethanol below 0.5 percent or 5,000 parts per million (ppm) is considered generally safe. Some legal cannabis states, however, have enacted stricter cutoff residual solvent levels based on recommendations from the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH). Residual cutoff levels vary by state.
While ethanol extraction may not be any more dangerous to use than light hydrocarbon extraction or CO2 extraction, the building requirements for ethanol extraction are less stringent than hydrocarbon extraction approval. Jurisdictions are familiar with approving distilleries that use ethanol compared to approving propane and butane facilities that elicit negative images based on a lingering stigma from black market extractions.
On top of receiving quicker approval by local governments, storage limits for ethanol are much more lenient compared to other solvents. That means an extraction facility can store more ethanol in the facility and use large volumes of ethanol at one time for cannabis or hemp extraction. Storing large volumes of solvent can keep the continuous extraction going without missing a beat.
Ethanol extraction systems are the go-to solution for large-scale commercial operations that process a high volume of cannabis or hemp. Ethanol is fast, reliable, and efficient at extracting low to mid-quality oils from cannabis and hemp for companies looking to scale. With the proper ethanol extraction system, cannabis companies can process hundreds of pounds of material per hour and gain a competitive edge.
Cut Labor Costs
Automated controls eliminate weeks or months of apprenticeship training required for manually controlled hydrocarbon systems.
Eliminate Operator Error
Pre-programmed recipe-monitoring system checks pressures and temperatures hundreds of times per second to remove risk of operator error.
Increase Capacity
Process 18 pounds of dried plant material or 25 pounds of fresh-frozen material per run. Single operator can process 400 pounds of biomass in a single day.
Improve Run Time
50-minute average run time with a 10-minute soak. Run-to-run changeover times of two minutes.