I’ve done a few liquid liquid extractions on cannabis oil, and I’m not sure if they’re accomplishing what I want them to - improve color.
Process so far has been to dissolve oleoresin (1st pass distillate, EHO, etc.) in pentane (trying heptane currently), transferring to sep funnel, and washing with pH 4 brine (2x), pH 8 brine (2x) and pH 7 brine (3-5x) draining aqueous layer each time. My concern is that I see no color change in the organic layer in between washes. My aqueous layer always comes out clear (maybe a little bit of color if I pull too much organic layer thru). Is this normal? Is the point of LLE to remove the impurities via the emulsion layer more so than to actually extract the colored pigmented impurities into the aqueous layer?
I was always taught in ochem to swirl gently to minimize emulsions, so I did that the first time (invert, swirl, burp, swirl, burp, repeat.) Since I still got a pretty significant emulision I figured might as well shake the shit out of it and that is how I’ve been doing it since (invert, shake like hell, burp, shake like hell, burp, repeat). Aqueous layer still always comes out clear leaving the organic phase as dark as it was originally.
sounds like your color isn’t water soluble & you need to throw magic dirt at the problem.
you won’t have sugars in your crude, and it will go through a WFE better…but if that’s not where you’re aiming, then you might want to try other approaches.
In my experience, and @Kingofthekush420 can probably attest to this, LLE is more effective at removing color when using a non polar like heptane or hexane against an alcohol such as methanol. There will be cannabinoids in both fractions but if you learn how to finesse this process you can remove the color.
Methanol/Alkane solubility is a real neat trick- and does work well even though is very inefficient unless you’re using a well engineered system.
I was able to take @Kingofthekush420 bucket/decanter tech LLE and reduce the alkane Solvent volumes by half with a continuous extraction mixer settler after reading some wise words from @Photon_noir
It’s an interesting way to clean up warm extracted crude but overall not the way unless efficiencies improve, I haven’t played with temperature variance and always ran both solvents at room temp when I was using the tek but I’d like to see how that affects the overall system, id love to play with those CINC LLE centrifuges one day and see how well they perform as they seem real, real cool.
I personally haven’t seen any benefit to LLE for color improvement. If you are doing short path distillation, doing a second pass is the easiest way to lighten the color a bit. LLE may be useful if your next step is chromatography, but doesn’t really benefit the oil if you are doing distillation anyway, in my experience. You may want to experiment with @anon42519203 hot condenser (over 120C) method if you trying to lighten the color of your distillate.
If you are doing 2 pass molecular distillation properly on a wiped film short path, you shouldn’t need any special cleanup or color changing tricks, unless the original biomass is particularly nasty or very old.
I have not been impressed by the few I’ve tried, which leads me to believe I’m doing something wrong as everyone else seems to get great results. I’m trying to lighten some first pass distillate. After I did LLE on it, I threw basically everything I had in the pentane and stirred for 2 hours at room temp. T5, T3, T41, and AC. Figured I’d give this a try as if it worked it would be so easy, lol. Well filtering over celite didn’t seem to do anything for color. So I figured I’d be more methodical. Since, I’ve put it in heptane and tried T41. Got out my reflux condenser and did a wet scrub at 80-85C for 1 hour with stirring. Filtered over celite and noticed maybe a very minor color improvement. Not much…
The only promising result I’ve had is by just saying fuck it and filtering over what was probably way to much silica gel (chroma gel). That had a big impact on color but poor yield. Figure I didn’t wash enough solvent thru.
So yeah I’m exploring the magic dirt route. Will take a look at the opaline silica. Any other pointers for me for improving color (Limited to EHO and solvents - heptane, pentane, alcohols.)
Thanks for all your contributions here. Learned a ton from you!
I could see it helping there. I guess the application question is: is it easier/faster to just clean the evaporator walls by running a water cleanout process really quick, or to go through the trouble of a LLE procedure before doing wiped film? Boiling water usually cleans out sugars and gums and gunk pretty fast and effectively, in my experience.
Basically trying to improve distillate color, yes. But also color for shatter. Water clear d9, or as close to it, being the goal. Unfortunately I can only extract with ethanol.
I have some ochem experience, so I’ve run a ton of columns and that has been my last resort. I’ve only ever run small prep scale flash columns and they’re a bit tedious. Might try dcvc fist? Definitely plan on switching over to hot condenser tek as soon as I can afford the upgrades.
So would you say it’s normal not to see the aqueous phase of LLE pull color?
Holy shite, is that Ethanol crude? But yeah, boil water in your evaporator at atmospheric pressure with the system open to the room air, it will clean out pretty fast, dry it after with ethanol boiling at atmospheric pressure, and then dry out the ethanol by pulling a vac. You’ll definitely want to disconnect the gear pumps during the water cleanout if the stuff is that chunky.
Yeah, ethanol crude run by a completely clueless operator. Apparently their understanding of winterization involved adding ethanol and putting it in the freezer for a couple of hours before solvent recovery. No filtration!!!
Had to disassemble the gear pumps to get the chunks out. Didn’t have the heaters connected yet, so filled the vessels with water and dropped a sous vide in
