Recovery of Etoh using a graham condenser distillation setup

Hello Gentleman,

I wanted to create this thread to discuss the utilization of a graham condenser in a standard lab distillation configuration to recover Ethanol from a winterized solution when creating an absolute.

I love rotovaps and do plan on eventually buying a nice Heidolph or Buchi in the future when I can spend 2K+ on a rotary evaporator but for now I would like to use this setup to do basically the same function (recovery of secondary winterizing solvent) in a static position.

Here is a pic of what I want to put together




I plan on using a hot water bath from a rotovape for my heating element on the boiling flask as I'd rather not use standard electric heating mantel with a boiling flask full of flammable solvent.

And for vac I'm still deciding and looking for input from you guys.

I have a oilless gast roc-r pump I could use. I figure I could put a valve on the the tubing line to regulate the vac pressure so it's not to extreme.

Or I've been considering a water aspirator tub style vacuum pump. I like this style pump for this application and I think it would work safely and efficiently to maintain the pressure in the apparatus. Have any of you used this type of self contained water aspirator pump on labware before?






What are your thoughts guys on this type of distillation setup?

Is it the entry model rotovap I'm in search of so to speak?

Thanks for your input!

Whatever the distillation set costs, its a ripoff - all of that looks like the most garbage-brand garbage-brand in all of China. Does that condenser even have water cooling? It it does, it still only works in a vertical position - and if you want a vertical condenser, you want a Friedrichs. A West condenser is typically used for the pictured setup, which won't produce much ethanol per hour in that size. A 3 liter with vacuum - and a good condenser or two with lots of ice - shouldn't fall too short of a basic rotavap.

Those pumps have always been much more expensive than they should be - Sigma-Aldrich will sell a Buchi, which is rebranded Brinkman, which is rebranded Sibata, who maybe buys from China for less than $100. They're great, but quiet is a sales lie. Used units on auction sites are likely defective from many years of abuse, which is why they're up for sale. You could put together a faucet aspirator, water pump, and tank instead.

You can get a used Rotovap off Ebay for under a grand usually, and it'll be far superior for the purpose. Without a magnetic stir bar in a conventional setup bumping (flash boiling) will be a problem.

The Gast will be excellent for distillation but you'll need more than a valve to regulate vacuum. A mechanical vacuum regulator can be had off ebay or Amazon for under $50.

Water aspirators don't develop very good vacuum and use a shit-ton of water...

RB

cALyXtech1 said:

Hello Gentleman,

I wanted to create this thread to discuss the utilization of a graham condenser in a standard lab distillation configuration to recover Ethanol from a winterized solution when creating an absolute.

I love rotovaps and do plan on eventually buying a nice Heidolph or Buchi in the future when I can spend 2K+ on a rotary evaporator but for now I would like to use this setup to do basically the same function (recovery of secondary winterizing solvent) in a static position.

Here is a pic of what I want to put together

View Image


I plan on using a hot water bath from a rotovape for my heating element on the boiling flask as I'd rather not use standard electric heating mantel with a boiling flask full of flammable solvent.

And for vac I'm still deciding and looking for input from you guys.

I have a oilless gast roc-r pump I could use. I figure I could put a valve on the the tubing line to regulate the vac pressure so it's not to extreme.

Or I've been considering a water aspirator tub style vacuum pump. I like this style pump for this application and I think it would work safely and efficiently to maintain the pressure in the apparatus. Have any of you used this type of self contained water aspirator pump on labware before?

View Image




What are your thoughts guys on this type of distillation setup?

Is it the entry model rotovap I'm in search of so to speak?

Thanks for your input!

Click to expand...

A lot of things will work, some better than others. The system you have pictured would work, but as noted running a Graham condenser on its side will cause it to flood and "putt."

The low section will fill with condensate, shutting off the flow, until pressure builds high enough to blow enough liquid out of the way to discharge in a putt, and then plug and shut off again.

I built my own out of a asparagus steamer and copper coil in an ice water bath, but kept the coil vertical so that it self drained.

Joe picked up a Mega Home alcohol still, which he swears by.

We later got glassware and used a boiling flask with a stirring hotplate to minimize bumping and speed up the evaporation. A little faster, but it is necessary to pour early and remove the rest of the alcohol to a container with a large enough opening to remove the purged oil when final, or chase it out with a heat gun and suffer thin film losses to the container.

Slickest yet, we are currently using a Hiedolph rotary evaporator on loan for trials and have been negotiating on a couple others for testing.

We've suggested to Hiedolph that they add a boiling flask that has a removable top for harvesting, and we will see where that leads.

We are currently either pouring early, or chasing the finished oil out of the boiling flask with a hot air gun.

Mag stirring and rotation aren't the only options for vacuum distillation - capillary inlets have been used forever. Soften a part of a borosilicate tube and pull it apart, break it, stick it in.

We have the technology.

A loose vacuum inlet connection makes a great valve. You want to do it before shutting off the vacuum anyways.

The pressure produced by aspirators - 10-30 mm. - is a good area for most solvents with both glassware like this and rotavaps. If you have a chiller tank to recirculate to, no water is lost with the aspirator unit shown. The aspirators are big, the water jets coming out of them are strong, and the water does warm a bit. The cost new reflects their common usage with rotavaps and absolutely not the cost to make. A brand new unit will run worry free for years if they're not allowed to get hot or dry or crusty and rusty.

I ordered a little piece of plastic used in hot tubs as a water aspirator for for like ten bucks. Hooked it to a hose attached to a half horsepower pump I had for watering and ran the pump recirculating in a big Tupperware - maybe 15 gallons. That provides a cheap, safe vacuum and the hot plate stirrer will make quick action of the evaporation. No need for a vacuum if you're not worried about heating the oil and you have a chilled condenser.


You could also just pour it in a Pyrex, put a screen over it and blow a fan over it and directly out the window - evaporating it surprisingly fast. But use every safety precaution, of course.

G.O. Joe said:

Whatever the distillation set costs, its a ripoff - all of that looks like the most garbage-brand garbage-brand in all of China. Does that condenser even have water cooling? It it does, it still only works in a vertical position - and if you want a vertical condenser, you want a Friedrichs. A West condenser is typically used for the pictured setup, which won't produce much ethanol per hour in that size. A 3 liter with vacuum - and a good condenser or two with lots of ice - shouldn't fall too short of a basic rotavap.

Those pumps have always been much more expensive than they should be - Sigma-Aldrich will sell a Buchi, which is rebranded Brinkman, which is rebranded Sibata, who maybe buys from China for less than $100. They're great, but quiet is a sales lie. Used units on auction sites are likely defective from many years of abuse, which is why they're up for sale. You could put together a faucet aspirator, water pump, and tank instead.

Click to expand...

Thanks for chiming in Joe, I've read tons of your posts and you always have the in depth chemistry info on the subject I figured you have had hands on most of this gear.

So first off what MFG of supplier do you recommend for quality glassware? I figured for a couple hundred if it collects my solvent I'm good but I'm all for making a quality investment as well.

So you would recommend a Friedrichs condenser under vacuum in a vertical position with a 3000ml boiling flask and a 2000ml collection? And for the pump it's a waste of a couple hundo for one off flea bay I should just put together my own?

Thanks again

Rickys bong said:

You can get a used Rotovap off Ebay for under a grand usually, and it'll be far superior for the purpose. Without a magnetic stir bar in a conventional setup bumping (flash boiling) will be a problem.

The Gast will be excellent for distillation but you'll need more than a valve to regulate vacuum. A mechanical vacuum regulator can be had off ebay or Amazon for under $50.

Water aspirators don't develop very good vacuum and use a shit-ton of water...

RB

Click to expand...

Thanks for posting up RB!

That was my original plan I order stuff off ebay daily. So my main problem has been the glassware. Anyone with it wants 1200-1400 min. I have been looking around and finally found ace glass with a database of Buchi and Heidolph glassware and it looks like 600-700 for the condenser assembly alone. So once I get the condenser assembly, vapor duct, the head, the heating mantel I'm back at that 1K + price point.

For instance I see a decent Heidolph Laborota 4000 for under 700 with the head and waterbath on ebay. I wanna click buy it now but being that I'm not that familiar with lab glassware suppliers.
I'm a bit unsure and apprehensive I might buy it and find I need 1000+ worth or glassware or ancillary items to start distilling with it.

Thanks for bring up the bumping with a standard setup.

Is there a particular vaccum regulator you could like me to or recommend for using my Gast with labware.

Thanks man!

Gray Wolf said:

A lot of things will work, some better than others. The system you have pictured would work, but as noted running a Graham condenser on its side will cause it to flood and "putt."

The low section will fill with condensate, shutting off the flow, until pressure builds high enough to blow enough liquid out of the way to discharge in a putt, and then plug and shut off again.

I built my own out of a asparagus steamer and copper coil in an ice water bath, but kept the coil vertical so that it self drained.

Joe picked up a Mega Home alcohol still, which he swears by.

We later got glassware and used a boiling flask with a stirring hotplate to minimize bumping and speed up the evaporation. A little faster, but it is necessary to pour early and remove the rest of the alcohol to a container with a large enough opening to remove the purged oil when final, or chase it out with a heat gun and suffer thin film losses to the container.

Slickest yet, we are currently using a Hiedolph rotary evaporator on loan for trials and have been negotiating on a couple others for testing.

We've suggested to Hiedolph that they add a boiling flask that has a removable top for harvesting, and we will see where that leads.

We are currently either pouring early, or chasing the finished oil out of the boiling flask with a hot air gun.

Click to expand...

Thanks for outlining why the graham condenser in this configuration is not the best option.
I do see that the supplier I posted the pic from does have it available in a vertical configuration as well. Here is a pic


You mention you guys moved to glassware later with a mag stir plate to minimize bumping what kind and size of condenser did you use?

I remember you mentioned you were testing a Hiedolph.
What are your thoughts on glassware pricing and availability and weather or not I should just try to piece together one from ebay?

That's a great idea on the two piece boiling flask. Like you mentioned I figured I would just be chasing it out with a heat gun.

cALyXtech1 said:

So first off what MFG of supplier do you recommend for quality glassware? I figured for a couple hundred if it collects my solvent I'm good but I'm all for making a quality investment as well.

So you would recommend a Friedrichs condenser under vacuum in a vertical position with a 3000ml boiling flask and a 2000ml collection? And for the pump it's a waste of a couple hundo for one off flea bay I should just put together my own?

Click to expand...

There's a bunch of recommending I don't know where to start. The beginning?
https://archive.org/details/TheOrganicChemLabSurvivalManual
There's fine print in there on topics like vacuum distillation, and there's even a picture of a really complicated improvised vacuum regulation device.

Joint sleeves, and wire rather than plastic joint clamps. Fisher hardware. Water bath heating and overhead stirring. Relying on magnetic stirring to control bumping isn't something that many people recommend. You'll get impatient and crank up the heat, and even with the stirring, bumping will happen and the stir egg will go off-center and then just fly around the flask of increasingly superheated flammable organic solvent.

For this use, used and slightly abused glass from the major US brands is probably just fine - Ace and Kimax are as good as the Pyrex and Duran that costs more. Synthware is the best Chinese glass brand. I would not spend a lot, because you'll be disappointed in how slow, tedious, and unexciting distillation really is, until everything is covered with fire.

Used, unwanted pumps cannot be trusted. You could see how tough Harbor Freight's Chinese HVAC pumps are or aren't. I've got it all from faucet aspirator to turbovac and still can't tell anyone exactly what is best for them.

The Friedrichs only came up because it's a much better condenser than that kind, and vertical. I could have said if you want a condenser with coils, you want one with water going through the coils. If the long downward slope is not a problem, a meter's worth of West or Liebig condensensers in series should be plenty. The kind of glassware set you need is one sold as a set by the manufacturer, not a retailer, except you want larger flasks. If you had that kind of set you'd have a West or Liebig condenser and also a fractionating column, which when not packed doubles as a condenser. And you'd have a 3-way or thermometer adapter, other handy adapters, and the standard vacuum adapter.