The importance of evaporation in CBD extraction

Medicinal and functional health products containing CBD (cannabidiol) are growing in popularity, with the Australian market now worth more than $58.6 million a year1; however, traditional extraction processes do not always take advantage of the latest evaporation technology.

The current growth of the market for legal cannabis products is exceeding even industry predictions. It has been estimated that, with adequate political support, the market could grow by 32.7% annually.

What is CBD?

CBD is a chemical extracted from the hemp and marijuana plants, and although it is an active ingredient in the drug cannabis, it does not cause the psychoactive effects associated with THC, which is also found in plants. Although medical studies are inconclusive, some of the claimed benefits of CBD include reducing inflammation, improving relaxation and focus, and slowing digestion. As such, it is often used to treat problems such as anxiety and insomnia, as well as some types of seizures and digestive problems.

How is CBD extracted?

There are several different techniques for extracting CBD from the hemp plant, although most of these require the use of solvents that are effective at separating CBD from other chemical compounds found in the plant. Once the CBD is extracted, the solvent evaporates leaving pure CBD oil.

Some methods use supercritical carbon dioxide in a closed-loop extractor to extract the CBD under pressure, resulting in a liquid mixture of CO2 and CBD, which must then be separated by evaporation, but a solvent step is usually still required alcoholics For this reason, the use of liquid solvents based on alcohols (ethanol, or isopropyl alcohol (IPA)) or hydrocarbons (butane or propane) is also sometimes used, which are much simpler and more direct. However, unless the evaporation step is performed correctly, some residual alcohol may remain in the CBD oil mixture.

It is important to remember that even when CO2 extraction is used, another step involving alcoholic solvents will still be required. Each method has its own advantages and disadvantages and the best method for one manufacturer may not be suitable for another.

Once CBD oil has been separated from the solvent, it is usually refined and distilled to produce pure CBD oil that is free of other compounds such as THC, waxes, and lipids. The exact nature of this refining process will affect the chemical profile of the resulting CBD product and depends on the extraction method used.

Considerations for evaporation

To maintain the characteristics of CBD oil, low temperature evaporation techniques must be used, often involving separate vacuum extraction systems to lower the boiling point of the solvent.

On a small scale, laboratory-based rotary evaporation systems (with or without vacuum extraction) may be adequate and are in fact one of the most common systems in use today. But as the market grows and producers need to increase production, they are likely to look to the type of low-temperature evaporator used in pharmaceutical or food production. Additionally, maximizing solvent recovery with this system requires a high level of vacuum control and therefore often requires specialized process supervision.

Rotary evaporators have limited capacity and require a lot of time and attention.

Multi-stage fallen film evaporation processes are very efficient and allow for much higher yields. As a continuous system, there is no need to disassemble and clean between each run and clean-in-place (CIP) is used to maintain hygienic conditions and prevent contamination. Having different temperature regimes in each evaporation stage improves ethanol removal and the unit is highly efficient as each evaporation stage is maintained at a lower pressure than the previous one.

The HRS K series of multi-tube heat exchangers are suitable for evaporative applications.

HRS offers equipment that meets the highest standards of hygiene and traceability and is well positioned to help the rapidly growing CBD industry fulfill its market potential.

Top image credit: iStock.com/IRA_EVVA

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About the Author: SteveSossin

Welcome! I keep up on all the latest cbd and thc news!