Talk:Azeotropic distillation

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This section requires some re-writes. The ethanol-water separation is not really that sensitive to pressure. Methanol-methyl acetate is, and that would be a better example. Also, the comment that you try to make the overhead composition in pressure swing to be equal to a pure component is also wrong. You just want the azeotrope to move so you can reycle it between two columns, one at a higher pressure and a lower one. I will try and make these changes in the future.

you said it. This page is virtually incomprehensible, and the examples rarely clarify at all. It reads like it was written by a non-english speaker. —Preceding unsigned comment added by 131.172.99.15 (talk) 05:25, 2 October 2007 (UTC)


Ethanol purification[edit]

This page and the Ethanol currently seem to disagree on what distillation of ethanol-water can do. From the ethanol page:

Fractional distillation can concentrate ethanol to 96% volume; the mixture of 96% ethanol and 4% water is an azeotrope with a boiling point of 78.2 °C, and cannot be further purified by distillation.

From this page:

Ethanol is distilled to 96%, then run over a molecular sieve which absorbs water from the mixture. The concentration is now above 96% and can be further distilled.

I don't see how these can both be true. (Is this page a typo? (can't => can) Nahaj 14:09, 18 April 2006 (UTC)


I don't believe it is a typo. The second quote mentions the use of a membrane process, which does not rely on VLE to effect a separation. After the membrane stage, the mixture is now beyond the azeotropic composition and hence the mixture may be further distilled. See the main article on Azeotropes. 86.21.8.3 (talk) 00:23, 26 May 2009 (UTC)

Pressure-swing distillation[edit]

Another popular method is use of an entrainer. For breaking the azeotrope. I think there should be a discussion of what a zeotropic mixture is to help someone distinguish more easily the two. — Preceding unsigned comment added by 174.23.238.94 (talk) 16:53, 17 December 2011 (UTC)

This statement directly contradicts a statement made on the Azeotrope page:

To "jump" the azeotrope, the azeotrope can be moved by altering the pressure. Typically, pressure will be set such that the azeotrope will be closer to 100% concentration. For ethanol, that may be 97%. Ethanol can now be distilled up to 97%. It will actually be distilled to something slightly less, like 96.5% The 96.5% alcohol is then sent to a distillation column that is under a different pressure, one that pulls the azeotrope down, maybe to 96%. Since the mixture is already above the 96% azeotrope, the distillation will not get "stuck" at that point and the ethanol can be distilled to whatever concentration is needed.

From the azeotrope page:

...when distilling a mixture of ethanol and water that is richer in ethanol than the azeotrope, the distillate (contrary to intuition) will be poorer in ethanol than the original but slightly richer than the azeotrope.

—Preceding unsigned comment added by 58.111.195.249 (talkcontribs) October 16, 2007

The way I read it, if a water-ethanol mixture of greater than azeotropic ethanol content is distilled the distillate will be poorer in ethanol, but this does not stop the process from being used to produce purer ethanol: if the distillate is poorer in ethanol the residue will be richer. Casper Gutman (talkcontributions) 12:41, 20 August 2008 (UTC)

Clarify[edit]

In azeotropic distillation the volatility of the added component is the same as the mixture..

By choice of added component or by some physical principle? 84.227.245.245 (talk) 07:40, 15 September 2014 (UTC)