Originally Posted by whatthe215
Both. My recommendation for flasks with a large enough opening (China 20L and 50L flasks) is this:
- Buy arm gloves, the kind for inseminating cows and some rubber bands to hold it at shoulder. Have silicone spatulas.
a) Finish rotovaping @ ~60c, kill vac, stop rotation, insert stopping key (so it doesn't rotate when you unscrew,) then let sit for 10-15min so oil can collect from walls and get to temperature 60c.
b) Remove evap flask and pour out as much oil as you can. Let sit upside down for 5-10min dripping into collection container. Use heat gun carefully if desired.
c) Turn evap flask so that you can reach in with arm glove and spatula and scrape out as much as you can. After the first time you'll probably dial in the method. I scrape the top first so I can see inside. Scrape upwards and then pull the oil covered spatula out and deposit into collection container.
** You'll dial in time to wait before starting spatula scraping depending on oil consistency/type. Too early = too hot for your arm and oil will fall right off spatula, too late = very difficult to scrape, more left behind. There's a perfect 5 or 10 min window. **
d) Use minimum amount of ethanol/solvent required to dissolve left over oil in flask. Save it for rainy day, put it in your ultrasonic solvent bath, whatever. Rotovap once you've got enough and need the solvent back. Squirt bottles help. Using arm gloved hand to swish solvent around and rub sides helps tremendously.
Done properly and with fresh arm gloves, I can't imagine a cGMP inspector or whatever having much of an issue with this method, although it may seem a bit ghetto.
Alternatively, throw away the rotovap and get an industrial solvent recycling machine.
Originally Posted by SkyHighLer
"Alternatively, throw away the rotovap and get an industrial solvent recycling machine."
There is no
reason to use a rotovac to rip solvent when the oil is going to be fractionated.
Rotovacs are extremely dangerous, and extremely expensive, and are invaluable in the lab, where they belong, these are not generally meant for production situations when viable alternatives exist.
Rather than step all the way up to industrial solvent recovery systems, there is a line of common commercial solvent recovery systems that should do nicely, they are referred to as solvent recyclers.
The smallest, 3-5 gallon units are used for such things as automobile paint shop in-house solvent recovery, machine shops, etc.
Much larger sizes, and various options, including vacuum/feed/removal are available.
The smaller units use nylon or Teflon bags, remove the bag, cut a corner, and let it drain, squeegee all but the very the last out.
These units have advanced controls to allow the use of solvents with various boiling points. (The new controllers with both power and temperature control would be better yet, recently I've proven to myself that floating the temperature at the boiling point, and adjusting the boiling level by regulating the power available to the heater is far smoother than trying to control the boiling with PID temperature control alone. This goes for your Buchi and Heidolph rotovapes too, lol.)
BECCA SS17.5 (17.5 Gal) Solvent Distillation Recycler - Features
BECCA HC (6 Gal) & SC (3 Gal) Solvent Distillation Recycler - Features
Sidewinder Model M2 Presentation
I've been try to stoke up interest in commercial/industrial solvent recovery machines for a couple of years here at ICMAG Concentrate Forums...
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I mentioned in the quote there are better controllers with both power and temperature controls now available that would provide smoother distillation. Shouldn't take an electrical genius to figure out how to swap out the controller, here's a post explaining the new controllers,
The Auber controller referred to (either the DSPR220, or DSPR440 with relay output) drives a solid state relay, or two, or three, it can drive up to 5 or 6. The solid state relays are available in 3-Phase configuration, here's an 80A per Phase device from Auberins,