Continuous Solid-Liquid Home-made Extractor

[Trickster]

With some help from a chemist-friend SWIM has assembled and is about to try a home-made extractor.

As SWIM is not a chemist she doesn't know if a similar device exists and has been used before.

SWIM is just a physisist, so maybe there are some serious flaws in the design and the device would not work.

Comments will be greatly appreciated. The extractor itself is not a standard piece of lab equipment but the idea should be obvious from the attached drawing.

It is planned to do a test extraction of 30-50 g of MHRB using acidified IPA as solvent.

 

[Infundibulum]

The design has only one flaw that I can think of; the rate of condensed vapour falling onto the plant material and the rate of the flow-through through the cotton filter.

If the rate of the former is faster than the latter then the column will overflow. If the latter is faster than the former then the column may have too little to drip and may extract slower? Or the hot vapour from the surrounding vapour chamber will heat up and evaporate the (condensed) and dripped solvent from inside the plant material? Remember that the plant material + solvent will be as hot as the solvent vapour surrounding it.

In any case the soxhlet design solves all these. But in any case it would be interesting to see this simplified design work!

How does SWIY plan to tether the inner herb-holding chamber into the outer one? Just curious.

 

[Trickster]

The design has only one flaw that I can think of; the rate of condensed vapour falling onto the plant material and the rate of the flow-through through the cotton filter.

If the rate of the former is faster than the latter then the column will overflow. If the latter is faster than the former then the column may have too little to drip and may extract slower?

Good point. The issue could be resolved by ajastment of amount of heat from the hotplate.

Or the hot vapour from the surrounding vapour chamber will heat up and evaporate the (condensed) and dripped solvent from inside the plant material? Remember that the plant material + solvent will be as hot as the solvent vapour surrounding it.

Glass does not transfer heat very efficiently, besides liquid solvent needs additional energy for evaporation.

How does SWIY plan to tether the inner herb-holding chamber into the outer one? Just curious.

The cone of inner chamber does not fit snugly into the outer chamber. There are 3 beads of glass welded to the external surface of the cone of the inner chamber. The inner chamber rests on these beads and there are several millimeters of airspace between chambers at the lowest point.

Three more glass beads are welded to the outer surface of inner chamber at the top acting as spreaders. Anyway the device is already assembled. SWIM is looking for a suitable aquarium waterpump to test it.

 

[Trickster]

SWIM's setup (see picture) is running for 2 hours already. The solvent in the evaporation flask is dark purple. There are 2-3 inches of solvent above the layer of MHRB. The process seems to have stablized. SWIM's worries about possible inner chamber overflow were not confirmed.

It is a test run. Only 20 g of MHRB is loaded.

The solvent that is above the MHRB layer is not colored anymore. How do you guys familiar with soxhlet extractors decide that the extraction is over?

 

[Trickster]

Looks like SWIM messed up this extraction.

She would very much appreciate any comments on what has happened.

After extracting 20 g of MHRB in her continuous solid-liquid extractor she has got 250 ml of dark purple IPA.

She checked its pH and it was around 3. That seemed reasonable as before running the extractor she added a dozen drops of concentrated phosphoric acid to IPA

She thought it is time to basify the solution. So she added a teaspoon of lye directly to the IPA. Once lye has been added, gooey precipitate started to form. No exotermic reaction was noticed. Now at the glass bottom she has got a layer of black tar in which there are lots of small off-white crystals are embedded (most likely lye).

Is it possible to save the extraction?

 

[Infundibulum]

Sodium hydroxide is not very soluble in IPA. And even if it is, there is no much water in IPA to play with the pH value.

pH is a property of water, not alcohols. So in SWIY's case some of the NaOH dissolved in the IPA (but not dissociated so as to give OH-, hence the lack in exothermic dissolution), some precipitated and some may have also caused the precipitation of Mr. Whatever.

One should evaporate most of the IPA that came out of the continuous extractor, then add at least 2-3 times the final volume of IPA of water (or maybe more) and then basify and extract.

In this case, IPA must be evaporated to a minimum then water added to the mixture and continue as a normal extraction.

Hope that helps,

 

[Trickster]

Thanks a lot, Infundibulum,

Sodium hydroxide is not very soluble in IPA. And even if it is, there is no much water in IPA to play with the pH value.

SWIM thought that there will be enough water in the IPA. The solution pH shoot up immediately once SWIM added some water.

Hope that helps,

It may have helped, but before reading your message SWIM managed to screw up even more.

Could you please read her other thread and see if there is still some hope.

Thanks a lot.

 

[ThirdEyeVision]

Did you blow that glass? If so, I'm impressed. It seems like a slightly modified soxhlet, any particular reason this would be better than the normal version? A good 1000ml soxhlet could be purchased on eBay for 100 bucks.

 

[Trickster]

Did you blow that glass? If so, I'm impressed.

No, It wasn't SWIM. A friend glass-blower made it.

It seems like a slightly modified soxhlet, any particular reason this would be better than the normal version?

SWIM thinks it is an extractor that is substantially different from Soxhlet. Two major differences are:

1. There is no cycling of solvent in this one.

2. It is a boiling solvent type of extractor. That means faster and more efficient extraction. 20 g of mhrb were extracted in less than 3 hours. Also, it is possible that boiling destroys channels of which Soxhlet is famous due to undisturbed flow of solvent.

A good 1000ml soxhlet could be purchased on eBay for 100 bucks.

Nothing to compare to as this one is a present from a friend.

There are drawbacks that Infundibulum pointed to.

The design has only one flaw that I can think of; the rate of condensed vapour falling onto the plant material and the rate of the flow-through through the cotton filter.

If the rate of the former is faster than the latter then the column will overflow. If the latter is faster than the former then the column may have too little to drip and may extract slower?

Indeed solvent evaporation rate should be over a certain limit, so that all extracted material is covered with solvent. Overflowing proved to be not an issue as with increased column of solvent in the inner chamber rate of filtration also increases. It may overflow at some point though. SWIM's hot plate was not powerful enough to reach that point.

 

[ThirdEyeVision]

No, It wasn't SWIM. A friend glass-blower made it.

They did a great job!

SWIM thinks it is an extractor that is substantially different from Soxhlet. Two major differences are:

1. There is no cycling of solvent in this one.

I was under the impression the flat bottom flask boils the solvent which vaporizes and rises up the side of the column to the condenser which cools back down to a liquid to drip into the thimble holding the MHRB then out the bottom to repeat the cycle. Is that not accurate?

2. It is a boiling solvent type of extractor. That means faster and more efficient extraction. 20 g of mhrb were extracted in less than 3 hours. Also, it is possible that boiling destroys channels of which Soxhlet is famous due to undisturbed flow of solvent.

If it's condensing back to a liquid before it reaches the MHRB it wont be extracting at boiling temps. Or is the hot solvent gas running through the MHRB before it reaches the condenser?

A good 1000ml soxhlet could be purchased on eBay for 100 bucks.

Nothing to compare to as this one is a present from a friend.

Agree. I wish I still had a friend that blew glass.
I love the experimenting with new equipment! Just curious of the proces.

 

[benzyme]

obstruction of the top of the allihn condenser also slows the process (increased pressure). there's no point in blocking the top

 

[Trickster]

2. It is a boiling solvent type of extractor. That means faster and more efficient extraction. 20 g of mhrb were extracted in less than 3 hours. Also, it is possible that boiling destroys channels of which Soxhlet is famous due to undisturbed flow of solvent.

If it's condensing back to a liquid before it reaches the MHRB it wont be extracting at boiling temps. Or is the hot solvent gas running through the MHRB before it reaches the condenser?

Before the evapped solvent reaches the condenser it passes the inner tube that is full of condensed solvent. The condensed solvent is heated to the boiling temp.

obstruction of the top of the allihn condenser also slows the process (increased pressure). there's no point in blocking the top

Thanks, benzyme, good point. The idea was to reduce possible smell (there was none). That was just a piece of cotton loosely inserted into the condenser top.

SWIM is just a lowly electronics engineer. These are her first steps in the arcane science of chemistry.

 

[Crucial]

Before the evapped solvent reaches the condenser it passes the inner tube that is full of condensed solvent. The condensed solvent is heated to the boiling temp.

I may be misunderstanding as well here, but what your describing is basically a reflux. Your biomass is in a solvent that is heated to a specific temp, with a condenser above to prevent the loss of solvent. You've just gone a very long way around, a reflux condenser above your flask with your biomateral in the flask would have achieved the same results. However I may be misunderstanding the idea here as well.

obstruction of the top of the allihn condenser also slows the process (increased pressure). there's no point in blocking the top

Thanks, benzyme, good point. The idea was to reduce possible smell (there was none). That was just a piece of cotton loosely inserted into the condenser top.

SWIM is just a lowly electronics engineer. These are her first steps in the arcane science of chemistry.

If you are getting a noticeable amount of aromatics coming out of your condenser, first try bringing your water temp down and that may solve the problem. A large beaker inside of an ice/salt bath will get Very cold.

If your still sensitive to the escaping odors, try placing a fairly large party type balloon over the top of the condenser. It may need a little tape to hold it in place but if you look around you could likely find one that will fit snugly. The small amount of vapor or aroma escaping will go into the ballon with out causing as much positive pressure as simply stopping up the condenser. It will rob you of a tiny amount of efficiency, but too much if you use a good size balloon.

 

[benzyme]

cool avatar, plastikman is d0pe.

the condenser should be obstructed as little as possible.
any apparatus using liquid-vapor transition conditions should be free flowing, as the transition is dependent on vapor pressure.

to deodorize, one could run tubing to an AC (activated carbon) trap.

 

[Crucial]

Thanks benzyme,
I've been a fan of Richie for quite some time... He puts on one hell of a show too.

 

[benzyme]

so i've heard.
he's been a fav of mine for a little over a decade, him and speedy j. they know techno.

+8/m-nus

 

[Crucial]

I think I came into Plastik in the mid 90's my self. I've seen him a couple times a Coachella and his live sets are different, but definitely Richie/Minus style.

 

[Trickster]

SWIM run several extractions with IPA as extracting solvent. She noticed that it pulls all sorts of unwanted stuff. Later she was told that it is a well known fact. In all the above experiments it was necessary to do A/B twice on the goo, that resulted from IPA extraction. Yields were decent (0.7% - 0.8%) but the process was quite time consuming.

Last time SWIM used acidifed water (pH~2.8) as the CSLE solvent.
She used 50 g of prepowdered mhrb and ~450 ml of dH2O.

Immediately she noticed that the extractor flow-through rate has dropped down significantly. Soon the extractor clogged completely and had to be reloaded. To loosen finely powdered mhrb a few tablespoons (one would suffice) of perlite were added. Total extraction time ~10 hrs, comparing to ~2hrs with IPA.

Acidified solution was left to sit overnight. Next day it was decanted, filtered, defatted once and basified to pH=12.5 with lye.

SWIM did 4 heptane pulls. Collected and combined heptane was clear and colorless. It was reduced from 120 ml to 20 ml and freezed for 3.5 hours. Result: 670 mg of white spice that does not require further cleaning.

Yield - 1.34%. Could be higher. SWIM is checking if there are any goodies left in the Heptane left from freeze-precip and in the basified aqueous solution. Total time - ~16 h. This could be improved.

Conclusions:
1. IPA is fast working but non-selective solvent.
2. It should be diluted to 91%.
3. If you use IPA it takes 2 A/B cycles to obtain clean spice.
4. Water is much less efficient but very selective extraction solvent.
5. If acidified water is used, additional cleaning may not be required.
6. Extractors are fun to experiment with and save a lot of chemicals.

 

[ThirdEyeVision]

SWIM run several extractions with IPA as extracting solvent. She noticed that it pulls all sorts of unwanted stuff. Later she was told that it is a well known fact. In all the above experiments it was necessary to do A/B twice on the goo, that resulted from IPA extraction. Yields were decent (0.7% - 0.8%) but the process was quite time consuming.

Last time SWIM used acidifed water (pH~2.8) as the CSLE solvent.
She used 50 g of prepowdered mhrb and ~450 ml of dH2O.

Immediately she noticed that the extractor flow-through rate has dropped down significantly. Soon the extractor clogged completely and had to be reloaded. To loosen finely powdered mhrb a few tablespoons (one would suffice) of perlite were added. Total extraction time ~10 hrs, comparing to ~2hrs with IPA.

Acidified solution was left to sit overnight. Next day it was decanted, filtered, defatted once and basified to pH=12.5 with lye.

SWIM did 4 heptane pulls. Collected and combined heptane was clear and colorless. It was reduced from 120 ml to 20 ml and freezed for 3.5 hours. Result: 670 mg of white spice that does not require further cleaning.

Yield - 1.34%. Could be higher. SWIM is checking if there are any goodies left in the Heptane left from freeze-precip and in the basified aqueous solution. Total time - ~16 h. This could be improved.

Conclusions:
1. IPA is fast working but non-selective solvent.
2. It should be diluted to 91%.
3. If you use IPA it takes 2 A/B cycles to obtain clean spice.
4. Water is much less efficient but very selective extraction solvent.
5. If acidified water is used, additional cleaning may not be required.
6. Extractors are fun to experiment with and save a lot of chemicals.

Great info! Thx.
Was vinegar the acid used?

 

[Trickster]

........
Great info! Thx.
Was vinegar the acid used?

Yes. Distilled white variety. Other acids could be used as long as their boiling temps are lower than that of water. Otherwise they will just stay in the boiling flask.

Although this lady uses a rather unique extractor, she is sure her results are of use for all experimenting with Soxhlet and other similar extractors.