Sciencemadness Discussion Board

NH3 Extraction from Mixed Gases

Waitey - 26-10-2022 at 04:45

Hello All,

I'm looking for a reliable way to extract NH3 from a gas mix made up of the following:

Nitrogen
Nitrous Oxide
Oxgen
Carbon Dioxide
Ammonia

The Ammonia fraction is roughly 1% of the mix.

Would using water to create an Ammonia solution be best?

If I wanted to liquify the ammonia, would it be best to compress the gas mix, as a separation method.

Alkoholvergiftung - 26-10-2022 at 04:59

Make Ammoniumsulfate. Let the gas mix bubble throught gypsom mud the CO2 reacts with it to form CaCO3 and NH4(2)SO4.

Waitey - 26-10-2022 at 05:07

Quote: Originally posted by Alkoholvergiftung  
Make Ammoniumsulfate. Let the gas mix bubble throught gypsom mud the CO2 reacts with it to form CaCO3 and NH4(2)SO4.


Great idea, I hadn't thought of that.

Assuming I'm looking to capture 100g of NH3, how much gypsom would I need?

Alkoholvergiftung - 26-10-2022 at 05:55

if you use used gyps dihydrade 505g.

Waitey - 26-10-2022 at 06:18

Quote: Originally posted by Alkoholvergiftung  
if you use used gyps dihydrade 505g.


Would passing through a mist of H2S04 also work?

Alkoholvergiftung - 26-10-2022 at 07:41

yes or easier bubbling throught h2so4 but why waste such an chemical? with gyps you would also remove co2.

[Edited on 26-10-2022 by Alkoholvergiftung]

Mateo_swe - 25-11-2022 at 12:18

Is it a must to extract the ammonia from that specific mix of gases or are you just looking for collecting some ammonia gas?
If you just want to collect ammonia gas you could generate that by mixing an ammonium salt and a alkaline hydroxide.

From wikipedia
For small scale laboratory synthesis, one can heat urea and calcium hydroxide:
(NH2)2CO + Ca(OH)2 → CaCO3 + 2 NH3

Ammonia boils at −33.34 °C so if you can lower the ammonia gas temps below that the ammonia should go into liquid state (in theory at least, i have not tried it).
Some freezing mixtures go below that, dry ice and alcohols get quite low temps.
If you need ammonia for a reaction it would be easiest to make a gas generator and lead the ammonia gas into your reaction mixture.
Making it liquid seem hard and you need a pressure vessel to contain it if its going to be above -33°C.

Remember that concentrated NH3 gas is very dangerous and that it forms explosive compounds when mixed with halogens.
Do your homework so you know what is dangerous and what is doable.

Sulaiman - 25-11-2022 at 15:54

100g ammonia = 5.87 moles
about 130 litres of gas
If ammonia is 1% then
13 cubic metres of gas total?
That's a lot of gas!

I'd consider recycling water mist first
sure to get almost all of the ammonia
(plus small quantities of the others)
into a solution of manageable volume.
(a few litres)
.... Just guessing...

P. S. one large batch or slow flow?

[Edited on 26-11-2022 by Sulaiman]

Johnny Cappone - 25-11-2022 at 19:01

Quote: Originally posted by Waitey  
Hello All,

I'm looking for a reliable way to extract NH3 from a gas mix made up of the following:

Nitrogen
Nitrous Oxide
Oxgen
Carbon Dioxide
Ammonia




In this mixture, wouldn't the ammonia react with the CO2 to form ammonium carbonate?
Would you mind saying why capture the ammonia from this particular mixture of gases rather than generating it by more convenient means? Where is this mixture of gases coming from? At what temperature and pressure?
It certainly can be done, but it seems like a lot of work.


[Edited on 26-11-2022 by Johnny Cappone]

clearly_not_atara - 26-11-2022 at 18:20

I think you would probably prefer magnesium sulfate (Epsom salt) for sequestering ammonia, since CaSO4 likely has poor reaction kinetics.