Sciencemadness Discussion Board

Purification and concentration of household ammonia

woelen - 24-5-2010 at 11:01

I have done a little experiment on concentrating and purifying household ammonia with appr. 5% NH3.

The household ammonia we have over here is fairly good, but when it is boiled down, then quite some solid matter remains behind. For this reason it may be better to purify this ammonia, using good quality distilled water for collecting ammonia gas and some glassware. The following page describes a procedure for making 40 ml of 10% ammonia from 125 ml of (impure) 5% ammonia. Some ammonia is lost in the process, but 70% of it can be recovered without any special effort.

I expect that the process easily can be extended to increase the concentration of the end product (e.g. taking 10% ammonia as starting solution and collecting more ammonia gas in that).

http://woelen.homescience.net/science/chem/exps/concentratin...

I think that this procedure may be interesting for other home chemists as well, who do not have easy access to reagent grade ammonia of high concentration.

[Edited on 24-5-10 by woelen]

UnintentionalChaos - 24-5-2010 at 11:56

I am jealous of your gas-absorbing train.

chochu3 - 24-5-2010 at 17:43

Very nice setup. I've read in one of uncle festers books household ammonia can be concentrated by placing it in ethyl alcohol, which he claimed would assorb into the alcohol and leave the water due to polarity. I have not tried the procedure but thought it was worth mentioning since this topic came up.

A procedure I have tried is to setup a trap with distilled water and drip 10% sodium hydroxide solution unto a round bottom flask containing household ammonia. I can not give a percentage yield since that was a long time ago and I've always been hesistant about keeping lab records on some of my expirements. Anyways your procedure is a good one since it uses less chemicals. Keep up the good work.

Panache - 25-5-2010 at 04:10

Is there a reason why when following the link three identical pages open, it was interesting the first time, however the second and third readings got a little repetitive.
8);)
For those less well equiped an inverted funnel into ~10mm water in a beaker works well for this system i find, the heating issue can also be alleviated by placing a few ice cubes under the funnel.
Edit-also for those without heating mantle adding solid NaOH into a NH3 solution will obviously heat it up but the dissolving NaOH also expels the gas very vigorously. just make sure the system is ready to go before you add your NaOH.

[Edited on 25-5-2010 by Panache]

not_important - 25-5-2010 at 06:55

Also a water bath, a soup pot on a hot plate, will work as a heat source in this case. I've done similar, adding enough low grade salt (NaCl) to saturate the household ammonia with salt to help drive out the NH3.

I've also done similar with a different absorption method. I lightly packed an old condenser with plastic mesh - dish scrubbers - arranged in reflux style as the exit port from the absorption chamber - a jug with a 3-hole stopper. A small pump sucked the water from the jug and pumped it into the top of the condenser, where it ran down over the plastic mesh. Ice cold water was run through the condenser jacket to keep the aqueous ammonia being formed nice and cool. Did this in winter, a large can with a nipple added near it's bottom was set higher than the condenser, water from a tap added in the top and snow added into the can as needed, as well as being packed around the receiving jug.

I used it to clean up a collection of ammonia-containing products that I'd gotten for free - blue print machine supplies, a dyed sudsy janitorial cleaner, other commercial products that were basically ammonia in water with other junk. I had quite a few liters of these that reduced down to some 15 liters of near-saturated aqueous ammonia, at the cost of a few handfuls of salt.

microcosmicus - 2-8-2010 at 00:17

As a preliminary step, perhaps concentrate the ammonia water by
partial freezing. This way, there will be less to distill, less salt
needed, and less ammonia left behind in the boiling flask.

For reference, you can find the ammonia water phase diagram
here:

http://www.ucl.ac.uk/es/research/planetary/undergraduate/dom...

As you can see, an ordinary refrigerator should be able to take you
up to 10% or 15%.

loveoforganic - 2-8-2010 at 21:03

You have the most wonderful glassware collection ever. So jealous.

grndpndr - 26-3-2011 at 01:01

Quote: Originally posted by microcosmicus  
As a preliminary step, perhaps concentrate the ammonia water by
partial freezing. This way, there will be less to distill, less salt
needed, and less ammonia left behind in the boiling flask.

For reference, you can find the ammonia water phase diagram
here:

http://www.ucl.ac.uk/es/research/planetary/undergraduate/dom...

As you can see, an ordinary refrigerator should be able to take you
up to 10% or 15%.


Acetone and dry ice bath ?

smaerd - 26-3-2011 at 11:38

amazing as always woelen. Lovely gas trap set-up as well :).

I was considering doing this via, NH4Cl + NaOH then bubbling that into deionized water, so that the NH4Cl could be dissolved in minimal amounts of water. This seems like a pretty good route as well :).

postart - 26-3-2011 at 14:39

Is 10% aq ammonia useful for amination?

grndpndr - 26-3-2011 at 18:18


Im sorry I cant comment on the previous post but I wanted to add what a fine lab set-up is pictured.
Its nice and Im most envious but if Im understanding the process using the 2 gas traps I should be able to accomplish the same with less.Not to denigrate what youve demonstrated mind you I just cant afford the set-up and have to improvise.Very interesting work as usual.All the fine quality lab equip is giving me a slight complex but working through what you dont have to hand is half the fun.Regards,
pndr
PS If I did manage to increase the % ammonia in the starting product
to 10%-15% could I expect a yield in the dist water of 20%<30%.

Ephoton - 27-3-2011 at 02:34

I would personaly go with an aqua ammonium salt and aqua sodium hydroxide to make the gas.
then on my first gas wash bottle I would half fill it with KOH as this will nearly dry the ammonia to anhydrous.

with this method one can obtain any concentration they want from the first reaction rather than
reworking the collected material to gain a higher concentration.

your webpage is comming along nicely there woelen you have a great number of experements
and a very nice method of showing them.

Arthur Dent - 28-3-2011 at 03:18

Quote: Originally posted by Ephoton  
I would personaly go with an aqua ammonium salt and aqua sodium hydroxide to make the gas.
then on my first gas wash bottle I would half fill it with KOH as this will nearly dry the ammonia to anhydrous.


I imagine plain NaOH in your first gas wash bottle would do the same? I have a large bottle of Ammonium Chloride that's gathering dust and I could put it to good use...

@ Woelen: I add my voice to the others on this thread... awesome website and really nice glassware collection sir! Congrats!

Robert

smaerd - 28-3-2011 at 08:22

Wow so I just used 100g of NH4NO3 with 50g of NaOH into a mason jar with a tube duct-taped into the lid. The tube was led to a mineral oil bubbler(bad choice) filled with 30mL of distilled water submerged in an ice-bath. After adding 40mL of water and quickly shutting the lid, oh boy was that vigorous. NH3 evolved and even forced 15mL of H2O out of the bubbler almost immediately. Should have seen that one coming. After the reaction settled I put the jar into a pan of boiling water and would occasionally shake it. After each shake more bubbles would go through the bubbler. Maybe for 5 to 10 minutes.

I took the bubbler to a graduated cylinder to measure it's volume 15mL remaining. Wafted the my hand over the cylinder and burnt my nose on conc NH3 fumes. Seriously awful.

Wish I could titrate but I don't have any methyl red only phenolphthalein which is bunk for this. All I know is this stuff is CONCENTRATED.

This reaction is quite nice because it's by product is NaNO3 which is perfect for whipping up some HNO3. Kind of expensive to be spending a $0.75USD for 15mL or so of conc. ammonia. Although for a home chemist who can complain once the reagent is there :P and completely OTC.

Recommendations for other experimenters: Use a gas dispersion tube or one of those super fancy gas traps that woelen has, and be prepared for suck back the bubbler prevented this quite nicely though. Use a short hose, the longer means the more fumes that will condense in it, and use a real reaction flask not a mason jar the tube popped out at the end due to pressure(no surprise there). Oh yea and out doors or in a nice fume hood unless you enjoy basking in anhydrous ammonia.

[Edited on 28-3-2011 by smaerd]

jimmyboy - 28-3-2011 at 19:27

Salt is the cheapest way to push the ammonia out but you waste alot - sodium hydroxide and heat the most complete using the common ion effect.

cyanureeves - 28-3-2011 at 19:36

has anyone heated urea and sodium bicarbonate to produce ammonia?i have plenty of dirty urea that i'm recrystalizing and i really dont want to waste my hydroxide on urea . the loss of ammonium nitrate when the cold water washed back and broke my reaction vessel has halted my ammonium hydroxide making, but not for long. it blows my mind how nitrogen and hydrogen make this stuff. recrystalizing urea is new to me, today on my second recrystalization everything fogged up and turned cold. i inadvertantly made an instant cold pack! heating urea based fertilizer until almost dryness will produced a mean ammonia gas so urea should too, wouldn't it?

cyanureeves - 28-3-2011 at 19:51

@jimmyboy salt? and you wont get any chloride contamination? the reason i'm not using the urea based fertilizer(i still got 5gal. bucket full) is because it has potassium salts in it.it produces an ammonia so strong and awful it leaves a bitter taste in your mouth,probably sulfates. first time i made it and smelled it i wanted to hit my head with a two by four to swap the hurts.scary!

cyanureeves - 29-3-2011 at 14:21

well heating baking soda and urea does produce ammonia alright. i'm doing it right now and threw in a little of the potassium hydroxide liquid that was in the center of an everlast battery that i saved when i did the manganese dioxide extraction shown by nurd rage.i'm using a thermos bottle with a punched out whole in the center and its catching ammonium hydroxide pretty good.now i'll wait for some cheap MEK on the reduced price section at the hardware store and make some hydrazine sulfate.

jamit - 4-10-2011 at 09:22

What is the maximum concentration of ammonia solution thAt can be made using an ammonium salt and sodium hydroxide? I want 20 or 30% ammonia solution... Is that possible just by bubbling ammonia gas into either cold water or into a dilute sol of ammonia water? Any help will bE appreciated.

bbartlog - 4-10-2011 at 17:57

Fusing NaOH and NH4Cl would give you equal (molar) amounts of NH3, H2O and NaCl. But unless you have low-temperature gear or a way of capturing the ammonia gas, this mostly means you will produce a cloud of unpleasant vapors. Basically, the colder you can get water the more ammonia you can dissolve in it, so it comes down to how good your cooling is. Anyway, you should be able to get to 20-30% if you can keep your water at 0C.

jamit - 4-10-2011 at 20:19

Have you tried this bbartlog yourself or is this a guess?

Chemistry Alchemist - 4-10-2011 at 20:51

In the production of Sodium Nitrate via Ammonium Nitrate and Sodium Hydroxide, that also produces alot of ammonia instantly, i bubbled it though water, didnt smell any sign of ammonia... what does it mean when your ammonium hydroxide is cloudy? whats the difference to clear ammonia?

peach - 5-10-2011 at 04:16

Nice job Woelen.

I too like that gas chain, the only thing that'd improve it (if it's not already there) is an antisuck back valve before the chain, so it's never going the wrong way. An empty bottle in the way helps, but it's not the best - since then it all needs resetting if something does happen to go awry.

Did you make the stand yourself or buy it all as one chain? And if so, where from?

I have seven or eight wash bottles and a quite a few heads, but it'd be neat to have them all in a rack like that.

I also have some curious looking heads, whose precise purpose in life I am still wondering about. They turned up in a box of glass I got. Check these out;

----------------------------------------------------------------

The two side arms are connected to the vent. That's normal, they just have some extra connections and a tap.

But the top port (the one that extends down into the bottle) has a tiny valve sitting in there. What makes this more odd is that the valve functions backwards to the typical mode of operation. E.g. if I blow into the top port, the valve closes. If I suck, it opens. Wash heads typically blow gas into the solution below, so I am a little confused as to what's going on here.

This could be designed for flasks. That tap on the side could be for a vacuum connection. The other two on the side could be for inert gas. The valve would close under vacuum, but then, what is is purpose after that? Nothing can get into the dip tube via that valve, and any solution in the bottle would be pushed out of it if any positive pressure built up in the thing below or was applied via the two side arms.

Evolved gas from a solid? Or with the dip tube above the solution? Why even connect it to a dip tube if the goal is to not have the contents below travel up through it? It doesn't even seem right if it was solely designed for handling gases.





[Edited on 5-10-2011 by peach]

watson.fawkes - 5-10-2011 at 13:03

Quote: Originally posted by peach  
But the top port (the one that extends down into the bottle) has a tiny valve sitting in there. What makes this more odd is that the valve functions backwards to the typical mode of operation. E.g. if I blow into the top port, the valve closes. If I suck, it opens. Wash heads typically blow gas into the solution below, so I am a little confused as to what's going on here.
It's a one-way valve, that's right. But it looks like it was for handling liquid. The discoloration of the glass inside the valve hardly extends above the weir (the level of the side arm). It's much like a percolator; that might have been the actual mode of operation. The one-way valve is enclosed rather than open to the atmosphere. Since that's hard to clean, there must have been a reason for it, instead of just putting a stopper on the top. I'd guess there to have been a bit of pressure manipulation going on.

Can't say that I can think of an example reaction where this would be useful, though.

#maverick# - 5-10-2011 at 15:06

that looks like something off of a bong peach honestly

testimento - 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?

ammonia distillation

billybonkers - 24-9-2015 at 10:00

Would not vacuum distillation work for this.

woelen - 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).

PHILOU Zrealone - 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)

Gargamel - 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?