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Improving Marijuana Concentrate Extraction

August 3, 2015 | APPEARED IN VOLUME 93, ISSUE 31

“Making Legal Marijuana Safe” outlined many issues with the current extraction solvent known as butane hash oil (BHO) (C&EN, April 20, page 27). This method requires a large up-front investment in closed-loop, high-pressure systems to contain and recover solvents. Safety concerns include explosion and fire risks for workers.

The article then proposes a new extraction system using the greenhouse gas carbon dioxide. Although this CO2 extraction process seems to be a viable alternative, it only modestly shifts the safety risk from explosion to asphyxiation while doing nothing to eliminate the hazards of keeping gases under high pressure. Extraction by CO2 will still require closed-loop systems and large up-front capital investment to produce the desired extracts.

A new Seattle-based company called BT Ingenuity has tackled the extraction process using a green chemistry approach. The company, founded by ACS member and ACS Medicinal Chemistry Fellow Tyrell Towle, uses a solvent that is ­biodegradable, does not bioaccumulate, and is nontoxic. The patented process does not require a closed-loop system and requires only minimal postextraction processing using Food & Drug Administration-approved ingredients. This new process eliminates the risk of both fire and asphyxiation for workers. It is highly versatile and provides control over the finished product. Finally, the solvent is recovered and can be reused in multiple extractions.

The legal marijuana market will only continue to increase, and improved safety as well as green production processes will continue to be important for both producers and consumers. Innovative thinking will allow the industry to dramatically improve safety.

Duncan I. Mackie
Carrboro, N.C.



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Dave (September 6, 2017 9:28 AM)
Ha Ha, all these "extractors" are just being taken by companies looking to sell expensive equipment.

The most important part is purification, and the way to do that for such compounds is wiped film distillation.

You can extract just using a high boiling point vegetable oil or even water (by emulsion) and then do separations on the still, including removal of harmful impurities.

No need for solvents or dangerous pressurized systems.

It's obvious that very few experienced process development chemists are really involved in this given the way we see things currently being done.

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