Talk:Steam distillation

message: Just a note: the article previously attributed the boiling point depression to colligative properties.  Colligative properties generally apply to nonvolatile solutes, and as such lead to a boiling point elevation.  The boiling point depression is related to the immiscible liquids contributing to the total vapour pressure as if each was the only liquid present.  In this manner the total system can reach a combined vapour pressure equal to ambient at a temperature lower than the boiling points of the individual liquids, and thus the system can come to a boil.  At least that's how I understand it.
--199.126.26.202 01:48, 26 April 2006 (UTC)
thread_title: comments

message: I removed the following:
Other industrial uses of steam distillation include the production of consumer food products such as sprayable or aerosolized condiments such as sprayable mayonnaise.Purves, ER. (1972), Method for producing mayonnaise. U.S. Patent No. 3,804,957. Washington, DC: U.S. Patent and Trademark Office.
I read the patent, and it says nothing about steam distillation at all! --Slashme (talk) 20:07, 20 December 2010 (UTC)
thread_title:  Mayonnaise? 

message: The "Principle" section makes it seem that steam distillation is based on the existence of azeotropes with lower boiling point than water.  I believe that is incorrect.  Whether there is an azeotrope or not, it makes no significant difference.Any substance has some vapor pressure even below its (1 atm) boiling point, but that would not allow effective distillation because a layer of vapor-rich air would form over the liquid and prevent further evaporation.  The vapor would flow down the condenser only by diffusion, which is an extremely slow process.Simple distillation is generally done by boiling, because once the vapor pressure exceeds 1 atm, there will be a steady flow of vapor from the boiling flask to the condenser.In steam distillation, the flow of steam carries with it the vapor of the substance of interest, even if the latter itself is not boiling.  It suffices that the substance has significant vapor pressure at 100 C.Makes sense? --Jorge Stolfi (talk) 20:30, 16 March 2020 (UTC)
replies: text: Good eye.  That section is misleading and the azeotrope of PhBr and water seems irrelevant (probably written by someone who never ran a steam distillation - but no one does these anymore).  The relative vapor pressures near the temperature of the steam is key.  Another aspect is that the materials that steam distill are almost always hydrophobic, so they are easily separated from the huge amt of water that comes over.--Smokefoot (talk) 12:10, 17 March 2020 (UTC)
replies: text: OK. Refurbished the article, correcting that section.From some Google hits, I suspect that steam distillation is (or could be) also used for solid substances, like naphthalene or iodine.  Is that so?Also, it seems that the same principle could be used with other solvents besides water.  In my teens I prepared Eau de Cologne, sort of, by distilling orange peel and ethanol; that would be "ethanol steam distillation", no? And also I gather that one can remove water from a mixture by distilling with a solvent of lower boiling point; would that be "reverse steam distillation"?Just wondering... --Jorge Stolfi (talk) 00:44, 18 March 2020 (UTC)
thread_title:  "Principle" is incorrect? 

message: The article needs better images.  The current photo and diagram at the top right (presumably done by the same person) show the condensation happen in two steps: the aniline is condensed first in the middle flask, with no condenser, and the the water is then condensed through the Liebig into the flask at right. That does not seem to be the typical setup; is it? In fact, the setup seems to fictional, rather than having been actually used for steam distillation.  Being a simple "water distillation", the steam with the product of interest leaves the boiling container at 100 C.  Even if the middle flask is somehow kept just above 100 C, most of the desired product should go through it and condense with the water.  No?--Jorge Stolfi (talk) 00:56, 18 March 2020 (UTC)
replies: text: Yes, I'm going to remove this pic.  Look at its comment: "Note: This diagram seems incorrect: the vessel in the middle should not exist, and both liquids should be collected in the flask at right."  38.73.253.217 (talk) 10:46, 24 August 2021 (UTC)
thread_title:  Suitable images