[TAB]

Background info:
I read in a survival book about a makeshift distiller created using a sheet of plastic.  It suggested that in dry environments you could crush plant matter and place it under the plastic to add moisture.  It even said you could urinate under it, and that the distillate would be "pure" water.  I asked my dad (who is a retired chemist) and he said that there are chemicals in urine that are volatile and, thus, will evaporate and condense with the water.  Additionally, I read somewhere else that you mustn't use poisonous plants under the plastic, as the resulting distillate will (may?) be poisonous.  This confirms what my dad said, and contradicts the first guide I read.  Some additional research confirmed that some impurities are NOT removed by distillation.

This lead me to investigate different purification systems.  Here are some simple explanations (perhaps some are over-simplified, but I feel those details are beside the point):  Boiling will kill some (most?) living things.  Filtering will pull out "large" debris.  Distillation will leave behind debris, heavy metals, salts, and anything else that doesn't evaporate, BUT it will not leave behind certain chemicals (volatile ones).  To get those chemicals out of the water, it seems one needs to use a special filter (with some neutralizing chemical in it) or reverse osmosis where the membrane is fine enough not to allow the target chemical to pass.

My question comes with the goal of being able to purify water WITHOUT the need of special chemicals or bulky filters.

The question:
Can volatile chemicals be removed from water by open-boiling it for an extended amount of time?

Example:
Let's say I take a gallon of pure water, and mix it with a cup of hydrogen peroxide solution, and a cup of isopropyl alcohol.  Now, I wouldn't want to drink that (it'd taste nasty! ).  Can I boil that mixture and reduce it to, say, half volume, and be confident that the hydrogen peroxide and isopropyl alcohol have evaporated out of the remaining water?

The bottom line:
Can filthy water be confidently purified by first open-boiling it for a while (to remove volatiles) and then distilling it (to remove everything else)?  OR are there some chemicals that just can't be separated from water without the help of another chemical?

More thoughts:
Any chemical with a lower boiling point than water would evaporate before the water does. Adding salt to the water would increase its boiling point, thus creating a greater disparity and helping the other chemicals evaporate without losing as much water.  The salt would be left behind during the distillation process.  However, it there is a chemical in the water with a high boiling point, it would be difficult to separate it (I would think).  Anyway, sorry for my ramblings.  I just thought it would be a good skill to know how to purify water if all I had was fire and a couple of pans.  I.e. no access to a Brita filter, reverse osmosis, or activated charcoal.

Many thanks!

-Jonathan

[discodermolide]

Volatile chemicals can be removed from water by distillation or fractional distillation, providing they do not form an azeotrope (constant boiling mixture), e.g. ethanol/water.

[TAB]

Thank you so much for your reply!  You have provided me with more topics for research and study.

-Jonathan

[billnotgatez]

Research on making potable water out of non-potable water is going to cause you fits. There is a lot of good and bad information out there that is hard to sort through. This has been worked on for a long time for such projects as "safe" water in third world countries and survival in the ocean (water water everywhere and not a drop to drink).

I do not know for sure what your final goals are but below are some examples of what to think about, but note I am talking off the cuff here based on memory of things I have read some time ago. I am going to assume you do not want to set up fractional distillation since you are talking about survival techniques.

Plastic sheet and salt water or urine. --- This result may have volatiles in it but are they really harmful. Remember, this process removed the for sure harmful like salts and microorganisms.

Boil water orders with coffee filter filtering. --- The authorities are just making sure you have boiled out most of the possible volatiles, killed the microorganisms and removed particulate mater.

Water purification tablets. --- mostly used to kill off microorganisms.

If you are doing this just for home use why not just use a filter like Brea?

[vmelkon]

What about crystallizing water (assuming the water is already fairly pure)?
If you could slowly cool the water, crystals would grow and you just remove the crystals and put them in another container.

I have heard about Faraday's benzene.
Apparently, 2 bottles of benzene have been found marked as Faraday's benzene. A major oil company (I'm not sure if it was BP oil) analyzed it and found it to be purer than what they have.
It was discovered that Faraday would purify his benzene by crystallizing it.