The Importance of Evaporation in CBD Extraction

The Importance of Evaporation in CBD Extraction

Functional and medicinal health products containing CBD (cannabidiol) are growing in popularity, and the Australian market is now worth more than $58.6 million annually1; however, traditional extraction processes do not always capitalize on the latest evaporation technology.

The current growth of the legal cannabis products market exceeds even industry forecasts. It has been estimated that with the right policy support, the market could grow by 32.7% per year.

What is CBD?

CBD is a chemical extracted from hemp and marijuana plants, and although it is an active ingredient in cannabis drugs, 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 issues such as anxiety and insomnia, as well as certain types of seizures and digestive disorders.

How is CBD extracted?

There are several different techniques for extracting CBD from the hemp plant, although most of them require the use of effective solvents to separate the CBD from other chemical compounds present in the plant. After the CBD is extracted, the solvent is evaporated to leave pure CBD oil.

Some methods use supercritical carbon dioxide in a closed-loop extractor to extract CBD under pressure, resulting in a liquid mixture of CO2 and CBD, which must then be separated by evaporation, but a step involving alcoholic solvents is usually still necessary. 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 and is much simpler and more straightforward. However, unless the evaporation step is done correctly, some alcohol residue may remain in the CBD oil blend.

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

After the 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 impact the chemical profile of the resulting CBD product and depends on the extraction method used.

Evaporation Considerations

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

On a small scale, laboratory rotary evaporation systems (with or without vacuum extraction) may be suitable – and indeed are one of the most commonly used systems today. But as the market grows and producers need to increase production, they are likely to switch to the type of low temperature evaporator used in pharmaceutical or food production. Additionally, maximizing solvent recovery with such a system requires a high level of vacuum control and therefore often requires skilled process monitoring.

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

Multi-stage falling film evaporation processes are very efficient and allow much higher throughputs. As a continuous system it does not need to be disassembled and cleaned between each cycle and cleaning in place (CIP) is used to maintain hygienic conditions and avoid contamination. Having different temperature regimes at each evaporation stage improves ethanol removal and the unit is very 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 provides equipment that meets the highest standards of hygiene and traceability and is well placed to help the rapidly growing CBD industry realize its market potential.


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