Has anyone ever come across, used, or seen one of these Aldrich glass falling films?
Description from sigma-aldrich,
“Similar to the standard one-piece design with the added efficiency of water-cooled jacketing. Water-cooled jacketing efficiently condenses volatile heat-sensitive compounds.”
Falling Film Technique
- Flask A is
filled with the solvent desired and heated to reflux. The boiling
solvent vapor maintains a constant temperature at the center finger. The
temperature is the boiling point of the solvent.
- The material to
be distilled is placed in the addition funnel and allowed to drip slowly
onto the heated center finger. The volatilized material will condense
on the outer air-cooled wall and collect in Flask B. The high boiling material will remain on the center finger and flow down the spiral into Flask C.
- Any pressure-equalizing funnel, standard condenser, and flasks can be used.
https://www.sigmaaldrich.com/catalog/product/ALDRICH/Z516163?lang=en®ion=US
There’s a 580mm, jacketed version for $2050 that looks like it might be an interesting way to do some light volatile stripping on a budget. This scale would obviously be for a small bench top scale lab, I was considering getting one just for research. One limiting factor I don’t like about the default setup would be selecting the solvent for the boiling flask. I suppose one could find several ways of modifying this.
Thoughts?
Haven’t tried myself, but there has been a few Kontz brand on Ebay, and may still be available. Might have some utility for bench/headstash work. Interested to see it applied
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I had one of these built for me in ~1980. It was based on the Kontes design, but about 4X bigger. It was useful, but at that time I had no access to analytical methods, so though the products I produced were quite active, in retrospect I suspect we were only producing a high-sesquiterpene fraction, and didn’t pull out high cannabinoid levels. The biggest limitation was the temperature that could be reached in the hot finger, that was constrained by the boiling point of solvents in the boiling flask at the bottom of the apparatus. If memory serves, I was using n-butanol (b.p.: 117° C), that only would have taken off terpenes. A more suitable solvent (e.g.: dimethyl formamide, b.p.: 153°) might have given a better temperature. I used a DuoSeal pump, and an air-cooled diffusion pump. A tilting (mercury-filled) McLeod gauge is visible in the photos. Pressures were in the 25 mTorr ballpark.
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@drPaul
That’s really cool, it’s good to see that in action, especially during the 80s. I’m actually looking to use the falling film to help with decarb and strip things like terpenes. If you were successful in doing that then that’s the idea.
I’m working on a thin film, but this is more of a fun benchtop project for me. Do you feel you had to be in the 25mTorr ballpark to achieve separation, or were you using a diffusion pump and higher vacuum to just lower your chances of degradation and get better performance?
The photos are really cool, thank you!
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You’re right on target…all the reading I had done (way before the internet!) indicated the need for lowering temperatures as much as possible to avoid thermal degradation. The main thing I missed was hard data on the boiling points of the cannabinoids under those low pressures.
If you’re thinking of having one of these built, jacketing the body to ease product flow would be a great idea. With the right solvent (e.g.: DMF), the existing heating method would even allow cannabinoid distillation, though electrical heating of the ‘finger’ should also be possible, maybe preferable.
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