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thrival
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How to concentrate an ammonia solution via distillation?
Is it possible to concentrate ammonia via simple distillation? If yes, which fractions (the beginning or end) should I throw away? I simply want to
get rid of unnecessary water. Please don't suggest I buy more concentrated solution, this is about DIY; Thanks!
[Edited on 12-3-2013 by thrival]
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GammaFunction
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Drive out ammonia using heat (not boiling), and redissolve in small amount of cold water. Problem is that at 100C water still holds 7% ammonia, which
is more than household ammonia (but janitorial ammonia is 10%).
With a big-container-hot-side / small-container-cold-side apparatus, an equilibrium should be established with more concentrated ammonia in the cold
side.
Maybe one could consume the water in the hot side with a desiccant?
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sbbspartan
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There are a number of threads on the forum on the subject of concentrating ammonia. You should read them first before posting a new one...
[Edited on 12-3-2013 by sbbspartan]
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thrival
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So I need to have a cold side and the ammoniated gas will move in that direction?
How do I know when the reaction is done or the most possible ammonia has been transferred? ...or how much cold water to start with?
Yes I've seen other threads about concentrating ammonia but they were not useful to me. My specific request was for methods using distillation, not
others.
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Mailinmypocket
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Check this page here, unless you already have of course:
http://woelen.homescience.net/science/chem/exps/concentratin...
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thrival
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Thank you, the last link was very useful. But again, how do I know what amount of ammonia I have to begin with (unknown sample) or when the
concentration has gone as far as possible?
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sbbspartan
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You can find out the original concentration of the ammonia by titrating it with HCl. I've never done it, but it should be farely easy. I think you
would use methyl orange as an indicator.
I think you can tell when you get as much ammonia out of the original solution as you can (or when the % is as high as it goes in the new solution),
when it stops being absorbed into the water as well as it does originally. When bubbling pure ammonia into the water, barely any bubbles will reach
the surface, it gets absorbed into the water so well, whereas after driving the majority of the ammonia out of the water, water vapor will start to
come over and will not get absorbed as well.
This is my understanding at least, I may be wrong. I hope that is not very confusing... 
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Fantasma4500
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wouldnt it be possible to lead ammonia gas through an solution already containing ammonia to get higher concentrations faster?
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woelen
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Yes, that is possible. If you have very pure household ammonia, then you can start with that instead of distilled water. In my experiment I did not do
that, because I wanted the ammonia to be pure and I do not know what kind of crap there may be in the household ammonia. Household ammonia looks clear
and colorless, but it may contain all kinds of dissolved salts.
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m1tanker78
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I've taken dilute clear ammonia and distilled it straight. A rough titration put it at 37% IIRC(while still very cold). As it warms to RT, it's happy
to release ammonia and wreak havoc with the mucous membranes and eyes so be careful.
If you pump too much heat into the boiling flask, it tends to bubble/foam up the condenser. Even 'clear' ammonia seems to contain surfactant. I don't
remember the reason I used a flood light for heat source. I used boiling chips and a TALL column composed of a liebig + graham IIRC. Cool water
through the condenser and receiving flask immersed in ice. Takes a while and volume yield is low but the product is obviously concentrated and free
from surfactants, salts and so forth. The storage container builds up a fair bit of pressure unless you live in Antarctica or store it in the freezer
(don't).
It's interesting watching the bubbles in the boiling flask 'grow' at the bottom then become partially reabsorbed as they work their way up. This is
about how much heat you should aim for. Less and you'll get slow or no distillate. More and you'll have the foam and more water in the distillate.
Tank
Chemical CURIOSITY KILLED THE CATalyst.
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thrival
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Back to original question: In distilling/concentrating ammonia, which part, the beginning fraction, or end(?) ...should be tossed ...to get highest
concentration. I've got about 20 gallons of dilute solution to go through. (Not using a bubbler or cold-water receiver.)
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ElectroWin
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the ammonia comes off first. however, i've tried to do this with simple kitchen equipment and had problems. dont allow the vapours anywhere near your
skin as they are very corrosive. my cuticles cracked and bled right away. you will want to cool your receiving vessel and keep it at below zero
celsius.
if you want industrial scale, check here
http://chemistry.stackexchange.com/questions/174/why-is-dist...
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aliced25
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You would be better served doing what Woelen did, but using a basic chemical to drive ammonia from its salts - NaOH/KOH, will drive ammonia from its
salts and gaseous ammonia, will be driven off. It will be hot, so put it through a condenser on the way to the wash bottle.
From a Knight of the Realm: "Animated movies are not just for kids, they're also for adults who do a lot of drugs." Sir Paul McCartney
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hyfalcon
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If you really want to concentrate it you can condense it straight by cooling the receiver with dry ice and acetone. If you have a means to contain it
you can achieve anhydrous ammonia in this fashion.
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thrival
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OK I've gathered from the above that simple distillation will work and if I just throw away the last
half by volume I will at least have doubled the concentration from what I started with. I'm using
simple cooling coil (nylon pneumatic hose sold at truck stops, HarborFreight, etc.) that cools to
ambient. I think this way is a lot cheaper, easier and less heroic than some of those mentioned
above.
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testimento
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Get some urea and calcium hydroxide and make water solution and distill it with steel vessel and bubble to water to get good ammonia. Household
ammonia is PITA and strongest I can find in my totalitarian country is something like 3-5%.
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hyfalcon
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Wow that's easy and available. Fertilizer and pickling lime.
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Zyklon-A
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Quote: Originally posted by m1tanker78  | I've taken dilute clear ammonia and distilled it straight. A rough titration put it at 37% IIRC(while still very cold). As it warms to RT, it's happy
to release ammonia and wreak havoc with the mucous membranes and eyes so be careful.
If you pump too much heat into the boiling flask, it tends to bubble/foam up the condenser. Even 'clear' ammonia seems to contain surfactant. I don't
remember the reason I used a flood light for heat source. I used boiling chips and a TALL column composed of a liebig + graham IIRC. Cool water
through the condenser and receiving flask immersed in ice. Takes a while and volume yield is low but the product is obviously concentrated and free
from surfactants, salts and so forth. The storage container builds up a fair bit of pressure unless you live in Antarctica or store it in the freezer
(don't).
It's interesting watching the bubbles in the boiling flask 'grow' at the bottom then become partially reabsorbed as they work their way up. This is
about how much heat you should aim for. Less and you'll get slow or no distillate. More and you'll have the foam and more water in the distillate.
Tank |
Can someone explain how this works? 37%? From household ammonia? That is very concentrated, at 100°C water dissolves only 7% NH3, so I
guess the NH3 gasses off while very little water evaporates and re-dissolves as it's cooled. Can someone confirm this?
If water dissolves 7% at 100°C, why would 5% solution off gas NH3 at <100°?
[Edited on 22-4-2014 by Zyklonb]
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macckone
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| Quote: Originally posted by Zyklonb |
Can someone explain how this works? 37%? From household ammonia? That is very concentrated, at 100°C water dissolves only 7% NH3, so I
guess the NH3 gasses off while very little water evaporates and re-dissolves as it's cooled. Can someone confirm this?
If water dissolves 7% at 100°C, why would 5% solution off gas NH3 at <100°?
[Edited on 22-4-2014 by Zyklonb] |
The physical act of the water vapor moving through the solution
picks up ammonia and concentrating it, would be my first guess.
Argon gas bubbled through dissolved gas solutions tends to
entrain the gas from the solution, I am assuming the same thing
happens with water vapor.
calcium chloride or magnesium sulfate in the vapor path
will also preferentially absorb water over ammonia. You should
use the minimum possible to absorb the water as they will
also complex with ammonia.
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Zyklon-A
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Ok thanks, I'll try this tomorrow and report my progress.
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Mildronate
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Boil your solution with reflux condenser and disolve gas from condenser in water!
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Praxichys
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| Quote: Originally posted by testimento | | Get some urea and calcium hydroxide and make water solution and distill it with steel vessel and bubble to water to get good ammonia. Household
ammonia is PITA and strongest I can find in my totalitarian country is something like 3-5%. |
A concentrated solution of ammonium sulfate fertilizer onto NaOH, KOH, or Ca(OH)2 works as well, no external heating required... This method is a bit
more compact and the ammonia is less wet and can be dried with a reasonably sized drying tube, if you are trying to condense it for instance. It is
also easily built with aquarium tubing and soft drink bottles, in the event that there are budget constraints.
I gave up distilling "household ammonia" years ago. The foaming is unmanageable. Maybe if you had some silicone oil as a defoamer?
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Zyklon-A
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Ok, I don't have a reflux, only a Liebig. I have some "drain cleaner", which contains 30-60% NaOH, 30-60% NaNO3 and about 5% aluminum (
the rest is coloring I guess.) If I mix this stuff with more aluminum shavings, and add some water, it gives off crazy amounts of ammonia gas. I once
made the mistake of using aluminum powder, the reaction was way too fast, my garage was completely fumigated with ammonia... Anyway, this
will be the key to concentrated ammonia solution, I'll just bubble the gas through cold water, or maybe distill it - which would be better?
[Edited on 22-4-2014 by Zyklonb]
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Texium
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| Quote: Originally posted by Praxichys |
I gave up distilling "household ammonia" years ago. The foaming is unmanageable. Maybe if you had some silicone oil as a defoamer?
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I agree with you on that… a few weeks ago I tried distilling some cheap 'clear' ammonia that I bought at the hardware store (first thing I tried in
my new apparatus), and the bubbles were extremely out of control and just carried right over into the condenser along with the ammonia. The silicone
oil is an interesting idea though. I think I'll try that. It would be nice to be able to purify that ammonia without having all those surfactants
carry over.
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Mildronate
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use liebig as reflux, some NaOH
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