[redgolum]

The water/alcohol mixture has a depressed boiling point that results in the 95% limit. To get to 100% you add benzene to the alcohol. That takes the last 5% of the water away, but makes the end product toxic for human consumption.

A molecular sieve is what most places use now. Cyclohexane is to nasty to use. Very flammable. I used to work at a plant that made ethanol, and we had a few contractors that would sneak the stuff straight out of the sieves. Gave them one heck of a hangover.

[Myrddin]

A molecular sieve is what most places use now. Cyclohexane is to nasty to use. Very flammable. I used to work at a plant that made ethanol, and we had a few contractors that would sneak the stuff straight out of the sieves. Gave them one heck of a hangover.

My lab skills are a bit dated. A molecular sieve wasn't common in labs in the mid-70's. The closest approximation was Sephadex gels used to separate salt solutions from larger proteins. The Sephadex gels cause a larger included volume to be experienced by smaller salt particles. Proteins zip on past the outside of the gels due to larger physical size. I usually finished the desalting process with reverse osmosis via semi-permeable membranes.