Utilization of Supercritical Fluids for the Effective Extraction of Waxes and Cannabidiol (CBD) from Hemp Wastes

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Utilization of Supercritical Fluids for the Effective Extraction of Waxes and Cannabidiol (CBD) from Hemp Wastes

1. This study seeks to establish an effective method of isolating Cannabidiol (CBD) from the hemp dust that is produced during fiber production using supercritical CO2 extraction.

2. The economic potential of this process is significant, because, quote – up to 33 percent of hemp by mass can be lost in the form of dust during the processing for fiber production – unquote. This offers the opportunity to turn a significant waste product into a viable revenue source.

3. As a field crop, Hemp offers many advantages including, quote – pest and disease resistance, weed control and improvement of soil properties due to crop rotation – unquote. Increasing utilization of hemp and improving its crop value will offer farmers more opportunity to vary and improve their production.

4. Hemp fiber is well know for its quality and versatility. Its use is widespread in the textile, paper, manufacturing, and construction industries.

5. Cannabidiol (CBD) is a non-pychotropic cannabinoid found in hemp and has recently, quote – been given considerable attention over the past few years due to its plethora of therapeutic properties and pharmacological activities – unquote.

6. Due to its low toxicity, CDB has been used in clinical-level trials relating to nervous system disorders including Alzeimer’s.

7. Savitex, a phytocannabinoid drug, was the first CBD based treatment approved in the UK in 2011 for use with multiple sclerosis muscle spasms.

8. Hemp dust also contains lipids and waxes which, quote – are an important and valuable class of compounds that can be extracted – unquote, via supercritical CO2 extraction.

9. Historically, hexane was used to extract wax from biomass, but hexane poses toxicological and environmental issues that are not present in supercritical CO2 extraction.

10. This study collected dust samples from multiple locations throughout a hemp fiber facility. Both Heptane soxhlet and supercritical CO2 extractions were performed to identify target compounds.

11. The hemp samples used in this investigation were of the variety santhica and were grown, quote – on 80-acres of arable land, in North Yorkshire – unquote.

12. The facility involved with the investigation produced, quote – approximately five tonnes of hemp … and approximately 900 – 1,650 kg of hemp dust weekly – unquote.

13. Dust samples were extracted via supercritical CO2 extraction over the temperature range of 35C to 65C and pressures of 80 bar to 400 bar for a period of 4 hours. Samples were also extracted via Soxhlet was.

14. For both extraction setups, the crude extract was filtered and solvent removed via vacuum. The resulting extract was used to calculate percent yield.

15. Extract composition was then analyzed via high temperature – gas chromatography and high temperature – gas chromatography mass spectrometry.

16. Sample number 8 was found to have a significant concentration of CBD (5,832.5 ug/g of dust) which was surprising given that these cannabinoids, quote – are normally found in the hemp flowers and not in the fiber – unquote, which indicated that, quote – during the mechanical extraction and separation of the fiber from the woody core, there was an accumulation of CBD at one stage of the process – unquote.

17. Sample 8 was collected from the rotary screen duster. Other samples showed some presence of CBD, but in much lower quantities. As a result, sample 8 was selected for further study to determine ideal extraction parameters.

18. Higher pressures and temperatures offered the greatest extraction yield. At 65C and 400 bar, supercritical CO2 extraction yielded 1.57 percent crude oil mass. The greatest CBD yeild occured at 350 bar and 50C. 

Source: Attard TM, Bainier C, Reinaud M, Lanot A, Mcqueen-Mason SJ, Hunt AJ. Utilisation of supercritical fluids for the effective extraction of waxes and Cannabidiol (CBD) from hemp wastes. Industrial Crops and Products. 2018;112:38-46. doi:10.1016/j.indcrop.2017.10.045.

Review by: SP


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