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Author: Subject: Purification and concentration of household ammonia
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[*] posted on 21-9-2013 at 14:54

The pyrolysis products of urea produces ammonia and ammonium carbonate. As far as I know, the carbonate salt is very weak and will break down into ammonia and carbon dioxide upon slight heating.

A solution made from pyrolysis process contains this single major impurity. Is it possible to heat the liquor up to 100C under reflux and collect the ammonia into new, cooled solution? Can anyone verify the solubility and gas pressure data for water-ammonia mixture at this temperature?
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[*] posted on 24-9-2015 at 10:00
ammonia distillation

Would not vacuum distillation work for this.
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[*] posted on 24-9-2015 at 22:41

Why would you want vacuum distillation? It works, but without it also works fine (see start of thread where I describe my own experience).

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PHILOU Zrealone
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[*] posted on 27-9-2015 at 11:39

CaCl2 is able to catch 2 NH3 as CaCl2.2NH3 and those can be set free by heating...maybe a way to concentrate NH3.

The other way is to make a salt of NH3, concentrate and evaporate to crystalization then to allow CaO or NaOH to react with the salt...the NH3 vapor must then be allowed to react with H2O...1L of water can dissolve up to 450 volumes of NH3!
(NH4)2SO4 + CaO --> CaSO4.H2O + 2 NH3(g)
NH4NO3 + NaOH --> NaNO3 + NH4OH (H2O + NH3)

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[*] posted on 8-7-2021 at 04:43

I recently needed some Ammonia.
To my displeasure I found the none of the numerous hardware stores here had concentrated ammonia, 9% was the best I could find...
So I decided to concentrate mine using woelens setup. (Thank you for your great website, by the way :))

One question concerning the setup:
I placed the thermometer in the suggested place, in the vapourstream. Shouldn't it be placed in the sump?

Using a sandbath, at about 65° centigrade I got bubbles that dissolved,
at about 85° the bubbling went down,
and at 92° the bubbling died down. But it would not get hotter.

I did not use any boiling chips what seems to have been a mistake, I got only bumping, no steady boiling.
92° was the limit.
Is that because the thermal conductivity of my setup sucks, or do I have to measure the sump (the difference should be little imho...)

Then I got a serious suckback and started again, this time added a third washbottle for catching the sucked back stuff. It was not needed though, I pulled the pipe out of my product in time...;)

I got 25% (130ml/40ml dest. water), OK, I hoped it would be more ;)

I might not have the time to repeat this every time, hence another question:
How would you store that? I know of course that the shelf life is limited, but I would use a nice laboratory flask with the expensive red teflon lids.
-Will the ammonia migrate through, in noteworthy amounts?
-Would storing in a fridge or even freezer help much to lower the vapour pressure/reduce the loss over time?
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