Sciencemadness Discussion Board

separating Toluene from the azeotrope with Ethanol

stoichiometric_steve - 29-10-2007 at 09:59

since i'm left with a lot of the azeotrope from solvent recycling, i have yet to find a convenient method to break it up. anybody?

Phosphor-ing - 29-10-2007 at 10:27

You could try 4a molecular sieves to absorb the ethanol. Just a thought.

evil_lurker - 29-10-2007 at 14:17

Add enough water to the azeotrope to cause the toluene to float to the top. Seperate then add some calcium cloride to dry the toluene. The CaCL2 will form the addition product with any remaning ethanol. Work up the products by distillation.

stoichiometric_steve - 29-10-2007 at 22:20

Quote:
Originally posted by Phosphor-ing
You could try 4a molecular sieves to absorb the ethanol. Just a thought.


with a mole fraction of 80% for ethanol, this would need a ridiculously huge amount of mol sieves.

Mumbles - 29-10-2007 at 22:27

Just out of curiosity, but do you desire both compounds back, or just the toluene? The thought of addition of water, and extraction with hexane or ether or something crossed my mind, but that probaby just introduces new azeotropes, and is less than efficient. Evil_lurker's suggestion is probably far better than my half-brained idea, and would be cheaper and less complex.

evil_lurker - 30-10-2007 at 00:00

Well my method works for E85 gasoline.

It just takes a long time and a lot of fractionating to recover the ethanol. I usually shoot for over 90%, then dry it with sieves and redistill.

stoichiometric_steve - 30-10-2007 at 12:01

evil_lurker, are you using a column to fractionate the EtOH?