Continuous liquid/liquid extraction

[IridiumAndLace]

For those who don't know, continuous liquid/liquid extraction is an extraction technique where your solvent is boiled in a receiving flask, travels up into a condenser, and then drips down into your extraction vessel. Once the solvent reaches a particular height in the extraction vessel, it overflows through a tube back into the receiving flask (taking the extracts with it), creating a closed loop. In theory, you could extract virtually all of the spice in the starting material using such an apparatus.

I recently came across the opportunity to obtain the glassware for a continuous liquid/liquid extraction, at a very good price. I've read people talking about this several times, but has anyone here actually attempted it?

Seems like while the crude product would likely be heavily contaminated and would most certainly need a mini a/b and re-x, in theory one could remove virtually all of the spice from an MHRB solution this way, with minimal effort (and cleaning glassware). Plus, there's a theory going around that boiling in heptane is good for yields and quality.

Are there any pitfalls to this that I ought to know about before I give this a try?

Edit: Here's a schematic diagram of how this extraction works. The boiling flask and condenser are separate pieces, the rest is all one (elegant) piece of glass.

 

[Tony6Strings]

Are you talking about a soxhlet?

 

[Dirty T]

I haven't tried a "continuous loop" extraction but I have tried extracting by reusing the same boiling solvent over and over on one jar of soup until the solvent gets so dark it turns brown. The increase in yields is barely noticeable. I don't think there is an easier or automated way to do this. It's just overcomplicating an easy simple way of doing things. It's akin to the "automated mushroom environment boxes" that used to be so popular on Myconet, they usually lead to tiny or no fruits and mold plus a big waste of time setting it up and money spent on the unneeded components. In my experience each jar takes a total of about 15 minutes of work to get every last bit of spice that Naphtha will collect using a mason jar and pippette.

There is another thread where someone was playing with a sohxlet but I think he was about as successful as the guy on Shroomery with the mush Sohxlet, it's just extra steps and unnecessary equipment for lower yields than the more widely accepted extraction techniques. That's the beauty of this site, most people have tried a lot of ideas before and have solid information as to how well they work.

 

[IridiumAndLace]

Are you talking about a soxhlet?

Close, but not quite. Whereas a Soxhlet uses NPS to extract from solid matter via repeated washings, a continuous liquid-liquid extraction uses a steady stream of solvent extracting from an aqueous solution. I edited my initial post to include a schematic diagram.

It's worth noting that this type of continuous extraction is usually done using a heavier-than-water solvent such as DCM, and the solvent crosses over from the bottom of the liquid rather than spilling over from the top. Finding the glassware for a lighter-than-water solvent is particularly rare and usually has to be custom ordered (which these were, at great expense).

I haven't tried a "continuous loop" extraction but I have tried extracting by reusing the same boiling solvent over and over on one jar of soup until the solvent gets so dark it turns brown. The increase in yields is barely noticeable. I don't think there is an easier or automated way to do this.

So, just removing and re-adding the same NPS over and over? I'm not sure what the advantage there is, once the DMT concentration is in equilibrium with the soup it's going to stay that way.

 

[downwardsfromzero]

It will be nice to see some pictures of your kit in action once it arrives. What volume extraction flask does it have?

The main thing to note - which I didn't see in your diagram - is that for lighter-than-water congeners it should (or can) include a dip tube to deliver the condensate to the bottom of the extraction flask. The dip tube should have a rotating end-cap that disperses the condensed solvent at the bottom of the aqueous phase. This, of course, enhances the efficiency of the extraction in a similar manner to magnetic stirring.

I've attached a picture of a more flexible set-up which is configurable to use both heavy or light congeners with omission or inclusion of the dip tube, respectively, and opening or closing the valve of the bottom outlet as appropriate.

 

[Dirty T]

It will be nice to see some pictures of your kit in action once it arrives. What volume extraction flask does it have?

The main thing to note - which I didn't see in your diagram - is that for lighter-than-water congeners it should (or can) include a dip tube to deliver the condensate to the bottom of the extraction flask. The dip tube should have a rotating end-cap that disperses the condensed solvent at the bottom of the aqueous phase. This, of course, enhances the efficiency of the extraction in a similar manner to magnetic stirring.

I've attached a picture of a more flexible set-up which is configurable to use both heavy or light congeners with omission or inclusion of the dip tube, respectively, and opening or closing the valve of the bottom outlet as appropriate.

It did increase yield but no enough to warrant the extra work involved. I'm interested to find out how your set up works. I personally don't have any equipment in my home that could be confused with anything not used for cannabis extraction myself. I have a still system for both Cannabis ethanol extracts and vacuum powered for psilocybin water based extracts but with MHRB I just use the good old mason jar and shake approach.

 

[IridiumAndLace]

It will be nice to see some pictures of your kit in action once it arrives. What volume extraction flask does it have?

I believe the extraction flask has a 1L capacity plus 200ml of solvent, for a total of 1.2L. I'll check once it arrives.

The main thing to note - which I didn't see in your diagram - is that for lighter-than-water congeners it should (or can) include a dip tube to deliver the condensate to the bottom of the extraction flask. The dip tube should have a rotating end-cap that disperses the condensed solvent at the bottom of the aqueous phase. This, of course, enhances the efficiency of the extraction in a similar manner to magnetic stirring.

I thought about that, and concluded a dip tube wouldn't provide anywhere close to enough agitation in a vessel this large, especially if I'm not filtering the soup. (And that's assuming I could find one of the appropriate size anyway.) What would be helpful is overhead stirring; I've learned that my MHRB has just enough sand in it for the stir bar to produce a dull spot on the bottom of the beaker. That'd be prohibitively complex and expensive for this setup though, so I might just filter my soup like always until such time as I get different MHRB, hopefully without any grit.

Alternatively, I wonder if a small piece of hardened glass (like a smartwatch screen protector) on the bottom could protect the vessel from marring? What kind of adhesive do those use?

Edit: Looks like they're typically silicone-based adhesives, which are not compatable with heptane. But at the bottom of the flask I don't imagine it would come into much contact with the floating solvent. Might have to look into this....

 

[IridiumAndLace]

Check it out, I finally got all my glassware!

I did a dry test fit, and let me tell you, this apparatus is a thing of beauty. Small issue though... Does anyone know where I can get a 48 inch lab stand?? Asking for a friend... :lol:

 

[benzyme]

get a Glas-Col mantle and an input controller (ex. Thermolyne)

 

[IridiumAndLace]

get a Glas-Col mantle and an input controller (ex. Thermolyne)

It's not clear in the picture, but that's a 250ml flat-bottom boiling flask, not an RB flask. Still not ideal, but if I find I'm overstressing the hot plate, I can easily swap in a PG bath for boiling the heptane. Might do that anyway just so I can use my 500ml RB flask and have the extra headroom.

Do they make adjustable heating mantles for use with multiple sizes of RB flasks? All the mantles I can find only seem to fit a single size flask, and they're all expensive so I can't exactly buy a separate heating mantle for every flask I own.

 

[benzyme]

yeah, doesn't matter. The mantle will equally distribute heat regardless. There are various sizes...250 mL, 500 mL, 1 L, 2 L, 5 L, etc

 

[Hailstorm]

Aluminum heating blocks work well with hotplates and RB flasks (a hundred dollars from the Chinese retailer, they last a lifetime). Just be careful not to cool it down with your flask sitting in it.