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Re: [Phys-l] dirty water

I think rough distillation of wine to make Armagnacs, etc. purposely done to retain some contaminants that give them the characteristic aromas and flavor; same w/ whiskeys, etc. OTOH, according to a recent New Yorker article more careful distillation is done to eliminate the poison from wormwood.

bc, who brought home a one litre bottle purchased at a wine shop in the 5th. Clipped to the box was the slotted spoon.

p.s. while at Keele one research group both did steam distillation and ion exchange, but this was to ensure the water was non-pyrogenic and sterile. (Bio-Physicists)

p.p.s. saves you the trouble:

Michael Edmiston wrote:

(1) If "dirty" means organic chemicals in the water, these usually have enough vapor pressure that what you get is "codistillation." The condensing liquid is a mixture of all the volatile components... hardly pure water. The condensate is enriched in the more volatile substance(s), which might not be water. Take "moonshiners" for example. The water/alcohol/mash from the fermentation process, when distilled, yields more-pure alcohol, not more-pure water.

(2) With mixtures of volatile compounds, to get high-purity separation you have to do repetitive distillations. You can do simultaneous repetitive distillations by the process of "fractional distillation" using a fractionating column. This is commonly done in many chemical plants, especially refineries.

(3) If "dirty" means inorganic chemicals with negligible vapor pressure (such as desalination of water) then a single distillation can get fairly pure water, but you either have to boil slowly (so you get only honest-to-goodness vapor, as opposed to droplets that can contain "dirt") or you need some baffles to prevent the droplets from getting into the condenser.

This is typically considered "physical chemistry" and is fully described in college-level physical chemistry texts. You might also Google or otherwise look up words like codistillation, fractional distillation, and desalination.

Michael D. Edmiston, Ph.D.
Professor of Physics and Chemistry
Bluffton University
Bluffton, OH 45817

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