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Author: Subject: Nitrogen Generator
JJay
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[*] posted on 28-12-2015 at 16:44


Quote: Originally posted by vmelkon  
Probably the cheapest way is to use iron + water. It will also react with the oxygen in the air and make Fe(OH)2. The left over gas will be mostly N2 and argon.
You can also heat some metal powder to react with the oxygen.


Most books I have looked at on the subject suggest using copper, which is easy to prepare in powder form and is more reactive.
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aga
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[*] posted on 20-1-2018 at 09:36


Quote: Originally posted by JJay  
Mellor vol. 8 in the ScienceMadness library lists a large number of reactions that create nitrogen. Most involve the use of an oxidizer on an ammonia salt, but one that caught my eye involves 200 mL 5% of sodium hypochlorite solution and 1.146 grams of ammonium sulfate. ...

I tried this one today after attempting to read that 1000+ page Tome.

Nothing happened.

Not even a single teensy bubble.

[Edited on 20-1-2018 by aga]




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[*] posted on 20-1-2018 at 12:02


Quote: Originally posted by aga  
Quote: Originally posted by JJay  
Mellor vol. 8 in the ScienceMadness library lists a large number of reactions that create nitrogen. Most involve the use of an oxidizer on an ammonia salt, but one that caught my eye involves 200 mL 5% of sodium hypochlorite solution and 1.146 grams of ammonium sulfate. ...

I tried this one today after attempting to read that 1000+ page Tome.

Nothing happened.

Not even a single teensy bubble.

[Edited on 20-1-2018 by aga]


How old was the bleach?
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Melgar
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[*] posted on 20-1-2018 at 12:24


I don't see how that would generate nitrogen. Seems like you'd just get a bunch of chloramine and derivatives. The only conditions that I don't think can be ruled out would be very high pH, in which case you might need to add sodium hydroxide.



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[*] posted on 20-1-2018 at 12:39


The bleach is about 2 years old.

It started at 20% so the label says. It's a 20 litre container.

I guess i need to titrate it to find out what the actual w% is.
(when i find out how that is done)

Perhaps it needs heating, so will try that too.




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Σldritch
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[*] posted on 20-1-2018 at 12:57


Please do not mix ammonia and bleach, especially if using an ammonium salt!

Most syntheses of Nitrogen Trichloride seem to use a chlorine source and ammonia in acidic conditions. Im sure you know why you do not want to make Nitrogen Trichloride in that manner.

Ex.:

"Ammonium chloride reacts with a solution of hypochlorous acid to form nitrogen trichloride, also with sodium hypochlorite, or a suspension of bleaching powder in water (calcium hypochlorite)."

[Edited on 20-1-2018 by Σldritch]
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[*] posted on 20-1-2018 at 13:09


acidic conditions ? Bleach ?

Hello ?




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[*] posted on 20-1-2018 at 13:35


Hello.
Ammonium sulphate is a weak acid.

You are almost bound to get chloramines. NCl3 isn't impossible.
The only merit of this scheme is that the reactants are cheap + easy
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[*] posted on 20-1-2018 at 13:52


Mixing bleach and ammonia is generally considered a bad idea and produces toxic byproducts.

The popular hydrazine sulfate synthesis is known to produce nitrogen as a byproduct. The safest method I know of is by mixing sodium nitrite and sulfamic acid.

I ended up just buying an argon tank, but I do think that amateur chemistry lacks a safe and clean nitrogen generator that is easy to set up with commonly available chemicals.




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[*] posted on 20-1-2018 at 13:56


the reference JJay cited says:

"Soln. of sodium hypochlorite decompose ammonia
and ammonium salts evolving all the nitrogen as a gas. J. Thiele said that hydrazine
and hydroxylamine are formed as intermediate products. T. Oryng found the
reaction is of the second order; and with the proportions 3NaOClq-2NH 3
=3NaClq-N2q-3H20, at 15°-25 °, the oxidation of the ammonia to nitrogen is
never complete."

... on page 217. It's hard reading and i could not find the bit that JJay said was there.
A page number maybe would help, pretty please ?

So far it seems that ammonium sulphate does not work.

[Edited on 20-1-2018 by aga]




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[*] posted on 20-1-2018 at 14:28


Check page 49. Alternatively, you might try Ctrl-F.



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[*] posted on 20-1-2018 at 14:41


Ctrl-F didn't work as hoped. It is a grainy scan.

I guess you mean this bit :

"F.C. Calvert used 200 c.c. of a soln. of bleaching powder containing 5 per cent. of hypochlorite, and mixed with 1.146 grammes
of ammonium sulphate"

Nothing says F.C Calvert had any joy with that method.

I certainly did not, but i've not tried heating it yet.

Edit:

Thank you for providing the page number.

Despite much reading and Ctrl-Fing i could not find it,

[Edited on 20-1-2018 by aga]




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clearly_not_atara
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[*] posted on 20-1-2018 at 17:19


What about the Hofmann degradation of urea with excess hypochlorite? If hypochlorite is used in excess, the produced hydrazine will be further oxidized to nitrogen. NCl3 and chloramines cannot be produced in this case.



[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 21-1-2018 at 00:52


Quote: Originally posted by aga  

Nothing says F.C Calvert had any joy with that method.



*shrug* I didn't attempt it, partly because I wasn't sure about the side products. I wouldn't be surprised to learn that Calvert used an excess of sodium hydroxide when making his hypochlorite; you could pull the source document and see if he mentioned anything about that.

How badly do you need the nitrogen?




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[*] posted on 21-1-2018 at 00:55


Quote: Originally posted by clearly_not_atara  
What about the Hofmann degradation of urea with excess hypochlorite? If hypochlorite is used in excess, the produced hydrazine will be further oxidized to nitrogen. NCl3 and chloramines cannot be produced in this case.


That would likely work, but you'd have to scrub a lot of carbon dioxide.




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[*] posted on 21-1-2018 at 01:13


Quote: Originally posted by JJay  
... *shrug* I didn't attempt it, partly because I wasn't sure about the side products. I wouldn't be surprised to learn that Calvert used an excess of sodium hydroxide when making his hypochlorite; you could pull the source document and see if he mentioned anything about that.

How badly do you need the nitrogen?

No desperate need.

With the possibiity of making NCl3, that method is beyond where i would dare to go.

Wish i had the brains to think of that earlier.




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[*] posted on 22-1-2018 at 12:42


Sodium nitrite + any ammonium salt will generate nitrogen easily enough. It would seem more efficient to scrub air of oxygen and CO2 though. Maybe FeSO4 solution to scrub oxygen, then NaOH solution to scrub CO2? FeSO4 is prone to generating SO2, when made by dissolving iron in H2SO4. Iron also tends to be really impure, and dissolving it generates a lot of other crap that you probably don't want.

What about HCl over tin metal, in a dilute enough solution that HCl vapor wouldn't be a problem? Bubbling air in should promote the oxidation of Sn(II) to Sn(IV), which would then be reduced back to Sn(II) by the metal.
Just keep adding tin as needed, and evaporate the solution to get valuable stannous chloride, which you can sell on eBay to amateur gold prospectors.

[Edited on 1/22/18 by Melgar]




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[*] posted on 22-1-2018 at 12:50


Quote: Originally posted by JJay  
Quote: Originally posted by clearly_not_atara  
What about the Hofmann degradation of urea with excess hypochlorite? If hypochlorite is used in excess, the produced hydrazine will be further oxidized to nitrogen. NCl3 and chloramines cannot be produced in this case.


That would likely work, but you'd have to scrub a lot of carbon dioxide.

If there's enough alkali in the mother liquor any CO2 should be retained as bicarbonate




[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 22-1-2018 at 14:05


So, please you Proper chemistry guys: is there a safe and reliable Nitrogen generator setup you could recommend ?

I got tons of NaOH, a huge jug of bleach and a sack full of ammonium sulphate.

Very little sodium nitrite, as i made that myself and am still pondering what to do with the lead salt waste.

[Edited on 22-1-2018 by aga]




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[*] posted on 22-1-2018 at 16:49


Hmm. The only ways I know of to generate nitrogen require nitrite or hydrazine. Nitrite could be generated in situ, though, from nitrate and something that nitrates oxidize. Maybe NH4NO3 + HCl + copper metal?

There's also pressure-swing absorption oxygen concentrators, that separate N2 and O2 primarily.




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[*] posted on 22-1-2018 at 16:51


If you're lucky, your local supermarket might sell sodium nitrite as a curing salt, but probably mixed in with some NaCl and sometimes a pink dye. I was lucky to get ~100 g of it for $1 at my local supermarket.



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[*] posted on 22-1-2018 at 17:52


You can buy and fill a small cylinder for well under $200. A lot of gases are heavily restricted, but nitrogen is totally OTC (as is argon, and the price isn't really all that different). They'll ask what you are planning on doing with it, but you don't really have to tell them as long as you don't come across as a complete idiot. After all, these people sell cylinders of acetylene to high school kids every day....



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[*] posted on 23-1-2018 at 00:18


On ebay there are Oxygen concentrators for about $100.

Presumably their exhaust gas is mostly nitrogen.

Does that make sense ?




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[*] posted on 23-1-2018 at 09:31


I don't think they are that efficcient in removing Oxygen. Maybe if you put two in series? I guess it depends on what you want to use it for but i would not waste my money on trying it.

Can you not use Carbon Dioxide instead?
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[*] posted on 23-1-2018 at 10:24


Or you could use atmospheric nitrogen and argon by oxidising something to remove oxygen,
(and possibly drying the gasses)
e.g. carbon if CO2 is compatible, phosphorous or a metal if not
or as above, possibly a medical atmospheric oxygen concentrator exhaust ?

[Edited on 23-1-2018 by Sulaiman]




CAUTION : Hobby Chemist, not Professional or even Amateur
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