Identification and Separation of hydrophilic emulsions in crude extract

The centrifuge definitely helps to break the emulsion, but it does take 2 - 3 cycles this way before the resin is fully separated, at least as far as I can tell.

One of the greatest issues I face in my region is that many regulatory bodies and companies don’t allow the use of many alkane solvents. Even if the state does, many out here are fearful of alkanes and other solvents with high volatility, and if I’m doing a project for them I have to mostly work with alcohols and other more hydrophilic solvents.

That being said, I’m not opposed to using non-polars in my hemp project in Vermont. The color retention of the method does seem to be effective, but not to the level of being ready for single pass distillations without some chromatography.

I appreciate your assessment of the method. Now the real question, is it worth it and is it scale-able?

is it scalable? maybe. How far?

does this look anything like a sep funnel to you?

image

they come much bigger. does it help that it has a glycol jacket, so you can warm it to get your extract out the bottom?

you’d need an air powered agitator.

are you recovering your solvent? because a no there might make the process less feasible.

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At 8000 rpm, you may be hard pressed to find equipment for pilot scale, but large industrial scale is probably available.

So you are actually separating milky water from ethanol using a centrifuge? I did not even realize that was possible, but with enough water-soluble & alcohol-insoluble material in the water, I guess it can happen. However, the only naturally plant-derived extractable compounds I can think of with those properties are mineral (inorganic) salts. What do you think is in that “milky water” layer? It is my experience that the milk is largely comprised of the cannabinoids themselves, so throwing away the milk sounds incorrect to me, but if your alcohol is somehow centrifugally separating from the water, then it makes sense that the cannabinoids would migrate back into the reconcentrated ethanol.

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I’ve realized I forgot a crucial piece of SOP.

After step 3, wax filtration, we do use a 20L RV to recover most of the EtOH. Once its down to a somewhat…slurry I suppose we then start step 4, liquid-liquid. I realized this is probably creating some confusion, my apologies.

@cyclopath
That sure does look like one to me, I never made the connection myself to look into jacketed system like that from the brewing industry. I know we have taken a lot of tech from them and modified it, but haven’t looked into brew tech to modify for my own purposes much. Our MA project might be interested in such a thing, VT definitely. At the moment I suppose scale would be 10-50gal of EtOH winterized solution.

@Photon_noir
I was assume that since EtOH can undergo some hydrogen bonding that it was possible some of the remaining EtOH would be migrating over to the ROH2O

I’ve been separating the milky water and usually just putting it in its own waste container in case it required further examination, so I suppose we haven’t technically thrown it away yet. We were speculating that maybe salts or sugars, haven’t gotten that far. Our R&D at that project has been halted by an influx of contracts needing to be dealt with, and those are being done on our older SOP.

I plan on running some HPLC on the milky water on Monday and see if any THCA is remaining.

Thank you both

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Ah, okay. I guess it makes more sense now. I think you will find a little of your resin compounds in that milk, but it is possible you are grabbing mostly colored materials, especially if your resin is coming out of this process very clean.

Something else I wondered about. I would think just extracting as cold as you do should suffice to keep waxes if not also most vegetable oils out of your extract. Are you grinding the material up a lot? I ask because I have found no precipitated material upon leaving cold 190p ethanol extract solution to sit in the cold, out of plant contact. The only thing I ever see is plant sediments, which are normally easily filterable with cotton wadding or similar 3D filter matrix.

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@Photon_noir When performed correctly the wash does leave a reasonably clean resin.

Our cryo EtOH method is still in development, it works in conjunction with a piece of equipment a peer of mine is developing, I unfortunately don’t have his permission to go into that much. I’m guessing that when he gets that process dialed in the water wash would only be necessary for color or salt, though I’ve never really had an issue with that once I’m at distillation.

The wash originally started as a way to help ensure no solids were getting into feedstocks marked for WFE. I find that with WFE any vegetable oils just run to raffinate during the first pass, then the second pass removes most of the color. Personally I always liked a little gold tint to my distillates.

I’m using a large pore table top Buchner with a cake to deal with most of those sediments. The bottom line is that I’m trying to decide if my reccomendation to the group is to cease this R&D or scale it. I don’t have much time for R&D right now so I need to pick and choose what I work on.

Thanks

I do not intend to press you for information you are obligated to keep confidential, so no worries. I can still likely help you without knowing it. :blush:

I will also not try to convince you not to do something you believe has merit, even if it seems to differ from my understanding through my own empirical data. In this case, it would be your Winterization process after cryo-ethanol extraction of your biomass. However, since all that really entails or requires is the separation of the bulk of the marc (solvent-wet biomass) from your solution, I adamantly recommend you use nylon mesh filter bags (generic all-mesh Bubblebags) to pull the bulk marc out of the solvent, let it drain a bit, then centrifuge it to get the vast majority of your ethanolic solution out of the marc. Speaking of which…

CENTRIPETAL FILTRATION TEK
…a photon_noir production, exclusively published here on future4200.com:grin:

Since you should be using a large basket centrifuge to get all your ethanolic extraction solution out of the marc, you could ostensibly utilize that large artificial gravitational force more efficiently by lining the basket with a few concentric layers of filter paper or membrane material. The finest pore material would be against the metal interior wall of the basket, and successively larger pore size materials would follow over it and one another. Cut each membrane a little long so it overlaps itself a bit, and place this seam away from your last seam by 180° if using only 2 layers, 90° for 4 layers, 45° for 8 layers, etc. (Just divide 360° by the number of layers you will use to find the degree offset for the seams.) to balance the weight distribution around the basket.

You can use a stainless steel screen fitted to perfectly cover (preferred) or very slightly overlap the inside circumference of the cylinder, which will be slightly smaller as the thickness of your filter cake increases, and rolled into a C shape a bit larger than your basket interior to form a flat spring brace. Also use a neoprene (foam is probably easiest to find and best to work with), buna (nitrile), viton, silicone or other ethanol-resistant rubber slip-over gasket strip (you can make one out of tubing, but solid core is best) to line the bottom edge of the screen, and the top edge if you want to be thorough, effectively gasketing your filter cake against particle leaks around the sides of the membranes. You should also gasket the inner overlapping edge of the screen if you overlap it, so as to avoid the sharp edges cutting your filter bags. Your coarsest filtration will be performed by the mesh bag (or multiple, successively smaller pore size bags) containing the herb.

The more layers, the faster the filtration, but also the greater the holdup loss of solution, so you will find a good balance. Much of the holdup loss can be mitigated by using the right materials, however. It can be initially costly, but using PTFE or other ethanol-proof polymer (like nylon) fabrics and membranes instead of cellulose or paper reduces holdup and they can be reuseable by careful washing from the opposite side… One way to clean is to place each membrane alone in the centrifuge basket, with the originally inner surface now facing out against the metal wall (or better would be a thin towel or sheet of fabric), brace it with the screen, turn on the spinner, and spray down the membrane with clean ethanol while it spins.

Think of it as an organized or structured filter cake using gravity instead of vacuum (atmospheric pressure) as the force driving the liquid through it. Gravity (centripetal force) is excellent for filtration, because, unlike vacuum, it does not cause your solution to evaporate underneath the finest pores or within the filter layercake. It is similar to pressure filtering, but actually more perfectly tuned to your incrementally smaller pores by the simple fact that the material furthest from the center has the most angular velocity and thereby force applied to it.

And in case you were wondering, yes, you should be able to use this in place of a Buchner, Nutsche, or other pressure filtration device to filter the bulk of your extract solution. :grin:

Using this method, the ethanolic solution obtained from the centrifuge should be free of all plant (or other???) sediments and ready for solvent recovery, but if you think Winterizing it will precipitate something, by all means, refreeze it… Just do NOT add it back to the extraction cryo-vessel full of sedimenty ethanol. Maybe just put it in a cryofreezer to check if it truly has dissolved material you can cold-precipitate.

Just fyi, centrifugation can cause evaporation by multiple effects: One is the physical force of momentum being greatest on the densest matter (solids, lower temperature liquids) and weakest on the least dense matter (vapors, higher temperature liquid). Another is the air vortexing in the center and around the basket, forcefully blow-drying everything.

Consolidation of processes, improving efficiency is one of the hallmarks of effective scaling. :wink:

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@Photon_noir
You are truly a scholar and a friend, I will be going over your tech on Monday when I can give it a try, I believe I should have all the materials to attempt at least a rudimentary whack at it.

I have been trying to bring more membrane based techniques into our methodologies, unfortunately I’m far more a student of sample prep than some of my colleagues. Some believe that distillation is a end-all, beat-all solution to separation, without making a proper analysis of how poor sample prep is affecting throughput time.

Thank you again for your input, it is truly appreciated, this community is going to produce great things.

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Yea, I’m hoping to not have to deal with too much more of this material. But yea, Western Colorado clay soils are no joke. Some of the slickest stickiest mud I’ve ever come across.

@Photon_noir

Update: We haven’t been able to get HPLC done yet, however I have made a few observations.

  1. Turns out I had a confused technician, some extracts that were thought to have been winterized/cryo extracted were actually just 100% crude and were going into the water wash that way, most likely accounting for the sediments and correlating to your expectation of little precipitate after cryo processes
  2. Batches that were washed post cryo ethyl and winterized seemed to have little to no milky water. I believe the sediments were removed during filtration.
  3. We used a 3d filter of filter sand → 220um mesh → two stage flat paper filters. Waxes seemed to stay in the sand as expected and the fine “silts” were on the first stage paper. The filtered material then went for solvent recovery and the attempted water wash.

The cryo seems to take care of most of the milk, however I did note the observation of some resin globular bits floating in the ROH2O. The H2O seemed slighty cloudy, perhaps salts?

Not sure at this point if it’s really necessary or worth scaling, but I have a better idea for my reccomendation to the group

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Very cool! Thank you for the update! Things make a lot more sense, now! :sweat_smile:

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@Photon_noir

I took a sample i scraped off the paper filter and took a look under the microscope. They seemed a bit translucent, but still somewhat opaque. Considering the green tint in the images is most likely chlorophyll from extraction, it seems possible it’s fairly clear, like wax or fat.

Edit: pictures look yellowish, however they are quite green in real life. Same photo, 3 different magnification levels.

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Yep! Pigmented vegetable oil and epicuticular wax!

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