A (likely) unsolvable problem with ethanol extraction (keep them terps!)


Adding to my last statement, there is definitely a body of work on how to minimize chlorophyll solvation in EtOH and also how to remove it via filtration. Does the use of steam first make it worse?



Cold causes less degradation than heat, heat drives endothermic reactions.

If you want to use heat to extract, you want to limit the amount of time heat is applied. A very novel way of doing this is by utilizing microwave radiation! Check out this video that explains this:


Thanks for the article but I am not seeing the connection to steam distillation first followed by a drying of the biomass. I am probably not seeing your point, sorry. I do see that structural damage and loss of essential oil does occur from freeze drying vs. pressure, but the steam distillation occurs prior, removing the essential oils. The cannabinoids should not be removed or damaged by the process.


Here is their paper: https://www.researchgate.net/publication/285643201_Extraction_Steam_Distillation


The paper shows that some of the volitiles like terpenes escape during vacuum assisted freezing. Those can be collected utilizing a cold trap .

Conversely, one can use a freezer under positive pressure after harvest to preserve volitiles and reduce damage to the plants cells. Terpene extraction can be preformed, and the material can be re frozen for use in cannabanoid extraction.


What about distilling the ethanol under vacuum, but keeping it below the boiling point of the etoh to pull the turps first? Or am I going to run into an issue that the azeotrope is at a similar boiling point to the etoh? Maybe a column style distillation under vacuum would be necessary?


Been there done that
Most terps have a higher bp than etho
And Some an aazeotroope
Has not brought me Any thing usefull so far but try Maybe You nail iT :ok_hand::+1:


There’s a small chance you could pull some monoterpenes before the EtOH came along, it’s highly unlikely you’d have anything “usable” from that. In general, azeotropes require some sort of chemical treatment to separate. Which is why benzene is needed to make 200 proof ethanol, that H2O and EtOH azeotrope is hard to break.

Obviously not all of the terpenes are lost, just a pretty big spectrum of them.


Hmm, seems like I’m gonna be stuck doing a co2 or nitrogen pull beforehand.



I’m in. Current tech is barbarian. I come from a plasma research background and there is @#%%wad of potential to build a killer, almost completely in-line, continuous process.
The tech is available. There are no technical barriers. I am certain a meeting of the right minds would produce a proposal that would work work 1st build. Extraction is the easy part and the extraction methodology is not the problem.
The objective should an automated, in-line process which delivers winterized crude ready to go into WFE or chromatography.
The possible exception of cGMP regulatory batch isolation protocols, dependent upon the upcoming USP product monogram details. This only effects cGMP operations, of which there are currently few. But it could be a game changer.


“almost” ?

I want a human to put the cannabis in the hopper, press go, and walk away. Come back to crude. I’d prefer a robot did the hopper loading too, but that’s way down the line.

Batch isolation isn’t that bad actually, it just adds a lot of pain in the ass and equipment downtime if you’re doing batches smaller than one day’s production.


The turp retention with etoh is something that isn’t going to scale super well from what I can see here.

Maybe I’ll just make giant concrete vacuum chambers lined with Teflon. Load in 500lb in mesh bag, do nitrogen pull for water and turps., fill with cold etoh, agitate. Drain. Lift off lid with crane, lift 500lb mesh bag out. Lift into centrifuge. Rinse, repeat. Giant teabag method.


A super interesting inline process is membrane filtration. The waxes don’t actually dissolve that well in etoh and are pretty easily removed with proper filters, even at room temperature

Ecosce guys are on here. They’ve got some interesting tech in that Dept.


that’s only part of it.

with terps present you’re extracting cannabinoids in solvent.

remove them, and you’ve changed the extraction kinetics.


When terps build up in my ethanol I simply run it through carbon and it’s as good as new. For small amounts I just use a Buchner, for larger amounts I built a 3"x48" column with a hopper on top. Works great.


Here’s a good read on using carbon: https://homedistiller.org/activated_book1.pdf


We’re trying to keep the turps, we’re more focused on saving the turpenes than the alcohol.


Brilliant idea. Don’t know why I never thought of this.


FYI - Try adding distilled water to your Ethanol to around 70 proof then slowly distill off (low and slow to retain as much water/terps as possible) the ethanol in your roto. At the end you will have a watery/terpy mess. Transfer to your SPD dial in the temp/pressure for the different terps you want to separate then start your temp/vac ramp. Change out your receiving flask once you get to the fraction you want to keep. You can for sure get really clean terp separation. I have seen and witnessed it first hand. My lab tech did it to prove me wrong! The terps he pulled looked, smelled and tased :fire::fire::fire: just have to have the right gear (a super solid vac controller is a must) to to dial in the right temp/pressure to fraction off the different terpenes. Not sure how scalable this is but you can at least capture some of the lost terps this way.


Just get it hella saturated over the course of a few runs. Maybe make it a monthly ethanol recharge/turp pull day or batch separation based on biomass. Run it column style with reflux to get good separation of the ethanol. Then hit the floral water with some salt or maybe try a pentane pull to get the remainder. Can probably snag 80-90% of what’s in there.

Gives a good excuse to recharge solvent as well! Especially if running live it would need a solvent recharge pretty often. And i don’t think it would take much extra energy in reflux running 85%-96% compared to 30%