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Nitrogen Generator

JJay - 19-12-2015 at 15:17

I was thinking about distilling some ether, and I don't think doing it in air is such a great idea, so I thought I would try doing it in a stream of nitrogen. I could use a nitrogen tank, but what about generating nitrogen using sulfamic acid and sodium nitrite solution? I could dry the nitrogen in MgSO4 or molecular sieves.... I believe that this sort of setup could be useful for other procedures that require inert gas.... Is there any major advantage to using a tank of gas instead?

Etaoin Shrdlu - 19-12-2015 at 15:28

Ammonium chloride and sodium nitrite, even cheaper.

EDIT: Yes, there's an advantage to a gas tank, no scrubbing and less expensive all told.

[Edited on 12-19-2015 by Etaoin Shrdlu]

subsecret - 19-12-2015 at 16:05

Distilling under nitrogen will help you just until your entire apparatus is filled with ether vapor. Then it won't make much of a difference over air. I'd just flame-dry the glassware and distill with a drying tube.

JJay - 19-12-2015 at 17:39

Quote: Originally posted by subsecret

Distilling under nitrogen will help you just until your entire apparatus is filled with ether vapor. Then it won't make much of a difference over air. I'd just flame-dry the glassware and distill with a drying tube.

That's fine, but my concern is actually oxygen, not water vapor.

JJay - 19-12-2015 at 17:57

Quote: Originally posted by Etaoin Shrdlu

Ammonium chloride and sodium nitrite, even cheaper.

EDIT: Yes, there's an advantage to a gas tank, no scrubbing and less expensive all told.

[Edited on 12-19-2015 by Etaoin Shrdlu]

Cool - I don't happen to have any ammonium chloride, but I'll keep that in mind.

Amos - 19-12-2015 at 18:33

Just distill it in air; the boiling ether pushes out the air in the apparatus anyway, and unless you have a room full of nitrogen to distill it in there's essentially no difference when you add a generator. Do the distillation outside, in a fume hood, or a very well-ventilated room. Use a warm water or steam bath as opposed putting the boiling flask very close to any hot metal surface.

JJay - 20-12-2015 at 07:14

It does appear that it isn't absolutely essential to distill diethyl ether in inert gas, although it is sometimes recommended.

The_Davster - 20-12-2015 at 09:50

If you distill under a stream of nitrogen, the ether volatility will result in the loss of the majority of your yield from the collection vessel.

JJay - 20-12-2015 at 14:58

Quote: Originally posted by The_Davster

If you distill under a stream of nitrogen, the ether volatility will result in the loss of the majority of your yield from the collection vessel.

I think it would depend on temperatures. Anyway, this thread isn't really about ether.I would definitely prefer to distill it in nitrogen if that is convenient, though.

Are there any good substitutes for sodium nitrite that are both cheap and easy to obtain?

[Edited on 20-12-2015 by JJay]

BromicAcid - 20-12-2015 at 18:48

Stream of nitrogen? You're missing some key aspects here of distillation. Look up a nitrogen bubbler. That will keep everything inerted (after initially inerting the setup) and will allow you to monitor the nitrogen flow. Producing the nitrogen in that way is an interesting way to approach it. Your drying agent all depends on how dry you want your ether in the end. Most home chemists don't have the technique or transfer capabilities to need it as dry as say magnesium perchlorate can get it.

JJay - 20-12-2015 at 19:09

I would probably prefer phosphorus pentoxide if I wanted things that dry. Also, I would probably use argon, but this discussion is about nitrogen.

ParadoxChem126 - 20-12-2015 at 19:43

Sodium nitrite is fairly cheap and easy to obtain online as a food preservative. Check Amazon, you can buy 2 pounds for fairly cheap, around 15 dollars.

JJay - 20-12-2015 at 20:35

Quote: Originally posted by ParadoxChem126

Sodium nitrite is fairly cheap and easy to obtain online as a food preservative. Check Amazon, you can buy 2 pounds for fairly cheap, around 15 dollars.

It seems like most reactions that generate nitrogen gas require expensive reagents that are only available through chemical suppliers or sodium nitrite.

I'm not sure that decomposing ammonia with bleach and bubbling the gas produced through sulfuric acid is such a great idea.

ParadoxChem126 - 20-12-2015 at 23:33

Of course, for significant quantities of nitrogen, an air separation diffusion membrane is always an option, but small ones are difficult to source.

JJay - 21-12-2015 at 00:42

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. Apparently ammonium chloride can be used too.

Hypochlorite isn't cheap, but it is completely OTC, as are ammonium sulfate and ammonium chloride... I wonder what side products might be produced by this reaction.

JJay - 21-12-2015 at 00:56

Quote: Originally posted by ParadoxChem126

Of course, for significant quantities of nitrogen, an air separation diffusion membrane is always an option, but small ones are difficult to source.

Possibly several chambers could be set up separated by pinholes and evacuated... then air could be allowed to quickly diffuse into the apparatus and the nitrogen enriched gas in the final chamber removed.

[Edited on 21-12-2015 by JJay]

woelen - 21-12-2015 at 04:31

Quote: Originally posted by JJay

[...]Hypochlorite isn't cheap, but it is completely OTC, as are ammonium sulfate and ammonium chloride... I wonder what side products might be produced by this reaction.

To my opinion it is not a pleasant means of making N2. Side products are NH2Cl (chloramine) and NH2NH2 (hydrazine). Both are very toxic and hydrazine is a known carcinogen. Both are soluble in ether and will contaminate your product.
If you really want to do this, bring up the pH, before mixing NH4Cl and NaOCl. Without added acid you may also make some NCl3, although I do not really expect such quantities that it may result in explosions.

ParadoxChem126 - 21-12-2015 at 18:14

Quote: Originally posted by JJay

Most air separation diffusion membranes work on the molecular level, similar to molecular sieves. Pinholes would be too large to encourage the separation of air into its constituent components.

[Edited on 12-22-2015 by ParadoxChem126]

JJay - 22-12-2015 at 02:16

Quote: Originally posted by ParadoxChem126

Quote: Originally posted by JJay

False.

ParadoxChem126 - 22-12-2015 at 10:49

Really? Can you provide an example of pinholes being used to separate air? Diffusion membranes work on a much smaller level.

JJay - 22-12-2015 at 20:31

Quote: Originally posted by ParadoxChem126

Really? Can you provide an example of pinholes being used to separate air? Diffusion membranes work on a much smaller level.

Yeah, many Graham's Law problems in high school and undergraduate textbooks discuss using pinholes for purifying gases. I'm not saying it is the approach I would favor, but it's certainly possible.

JJay - 22-12-2015 at 20:34

Quote: Originally posted by woelen

Quote: Originally posted by JJay

[...]Hypochlorite isn't cheap, but it is completely OTC, as are ammonium sulfate and ammonium chloride... I wonder what side products might be produced by this reaction.

Sodium azide (and other azides) are said to be useful for producing highly pure nitrogen.

ParadoxChem126 - 22-12-2015 at 21:19

Quote: Originally posted by JJay

Yeah, many Graham's Law problems in high school and undergraduate textbooks discuss using pinholes for purifying gases. I'm not saying it is the approach I would favor, but it's certainly possible.

I suppose. Due to their similar molecular weights, nitrogen and oxygen would be rather ineffectively separated by simple diffusion. It seems the very low flow rates through pinholes would explain why this technique is not practical for reasonable amounts of air.

JJay - 22-12-2015 at 21:23

Quote: Originally posted by ParadoxChem126

Quote: Originally posted by JJay

Yeah, many Graham's Law problems in high school and undergraduate textbooks discuss using pinholes for purifying gases. I'm not saying it is the approach I would favor, but it's certainly possible.

Whether it is practical or not really depends on how bad you need the nitrogen....

vmelkon - 28-12-2015 at 12:15

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.

JJay - 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.

aga - 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]

unionised - 20-1-2018 at 12:02

Quote: Originally posted by aga

Quote: Originally posted by JJay

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?

Melgar - 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.

aga - 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.

Σldritch - 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]

aga - 20-1-2018 at 13:09

acidic conditions ? Bleach ?

Hello ?

unionised - 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

JJay - 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.

aga - 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]

JJay - 20-1-2018 at 14:28

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

aga - 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]

clearly_not_atara - 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.

JJay - 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?

JJay - 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.

aga - 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.

Melgar - 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]

clearly_not_atara - 22-1-2018 at 12:50

Quote: Originally posted by JJay

Quote: Originally posted by clearly_not_atara

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

aga - 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]

Melgar - 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.

ninhydric1 - 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.

JJay - 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....

aga - 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 ?

Σldritch - 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?

Sulaiman - 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]

aga - 23-1-2018 at 11:00

Basically i'd like to try to fabricobble a very amateur Gas Chromatograph some day.

A FID will need hydrogen, so NaOH + Al seems to make that OK.

Hydrogen might be OK for the carrier gas, just that it'd need much less volume of Nitrogen, based on what i've managed to find in literature.

PirateDocBrown - 23-1-2018 at 12:43

Distilling under N2 is very doable. I've never done it with generated gas, only from a tank, but it should work much the same.

Sparge the cold distillate before turning on the heat, you want to drive off dissolved gases in the solvent. When the heat starts to rise, switch to a blanket, applying the gas under positive pressure from the top of the apparatus. The blanket doesn't need to actually have a gas flow, just a positive pressure. Add a bubbler at the end of the gas generating train, so the system isn't closed.

Back in grad school days, we did this exact kind of thing, with a tank feeding a drying tube, then a hose manifold, with the bubbler at the end. The bubbler had a little ball in it, making a slow constant ticking sound, so you knew when the gas was flowing and at about what rate. (Fast for sparge, slow for blanket). Hoses leading to the apparatus were terminated with Luer lock needles, and balloons of N2 (yes, actual kids toy balloons) also fitted with syringe needles could also be applied to ensure pressure.

Reagents could be transferred with syringes, or siphoned under pressure using a cannula. Apparatus was sealed with septa.

We could do most of what would otherwise require Schlenkware, and at a far lower cost. Usually faster, too.

We ran solvent stills in much the same way, while there was a departmental ether still in an unused lab, in its own hood, behind a blast shield, our group distilled our own DCM, THF, and dimethoxyethane.

[Edited on 1/23/18 by PirateDocBrown]

Melgar - 23-1-2018 at 18:12

Yeah, an oxygen concentrator will separate nitrogen and oxygen. Not perfectly, so you may need a scrubber if the goal is to get it really pure. The contents of those chemical hand warmers are a good oxygen scavenger. They're mostly reduced iron, with some salt and water as catalysts, among other things. I believe CO2 behaves more like O2 in this system, but I'm not 100% sure.

I've wanted an oxygen concentrator for a while now. It'd allow efficient ozonolysis, hotter flames, improved catalytic oxidation, and other fun stuff. It'd be good for a lot of things other than as a source of nitrogen.

JJay - 23-1-2018 at 18:26

BTW, if you have nasty deposits and stains on your glassware left by oxidizing iron on it, they come right off when you soak it in full strength muriatic acid. Of course, it might be cheaper to just replace the glass....

MrHomeScientist - 24-1-2018 at 08:47

I'm interested in generating pure nitrogen for my next element video, so it's good to see this topic resurface.

My plan was to use sodium nitrite and ammonium chloride:
NH4Cl(aq) + NaNO2(aq) → N2(g) + NaCl(aq) + 2 H2O (l)

JJay's mention of a "pinhole purification" method is very interesting. This led me down a rabbit hole of researching Graham's Law, then effusion, then mean free path, etc. A cursory look tells me that the pinhole needs to be smaller than the mean free path of air molecules to enable separation by effusion, and the mean free path for air at ambient pressure is 68nm. I guess you'd have to find a porous membrane with that pore size, then, since this is orders of magnitude smaller than any hole I can physically poke. This approach might be out of reach of the amateur experimenter. You might have to set up multiple diffusion chambers, like a uranium purification plant! Interesting idea though; I'll be sure to mention it.

[Edited on 1-24-2018 by MrHomeScientist]

JJay - 24-1-2018 at 11:36

The nitrogen isn't going to be completely pure after a single pass through a pinhole, even a 68 nm membrane. If you wanted 100% separation with a single pass through a pinhole, the pinhole would have to be smaller than the minimum free path of one of the gases; it would be essentially just filtering. Using pinholes (or 68 nm membranes) is more like chromatography.

It's certainly not out of the reach of the amateur experimenter, but it's probably not something an amateur would use to produce useful quantities of nitrogen gas, even with a 68 nm membrane. I was mainly joking about the idea of producing "enriched nitrogen" by gas effusion and was surprised to see it attacked so vigorously, but it's an idea that is easy to defend....

[Edited on 24-1-2018 by JJay]

aga - 24-1-2018 at 11:49

Could someone in the USA please give these guys a call and find out about prices :

Membrane sales: +1.925.431.1030
HQ : +1.713.937.5200
https://www.generon.com/product/nitrogen-membrane-separators...

From their website :

"By simply supplying the GENERON® membrane
modules with compressed air, they will generate a
nitrogen stream"

If they are cheap enough, that'd be an attractive option.

JJay - 24-1-2018 at 12:03

They're using a 10nm membrane... that's small enough to effect a separation significantly greater than a Graham's law pinhole.

Generon deals with industry in countries all over the planet - why not just drop them an email message?

aga - 24-1-2018 at 12:11

I don't speak American well enough.

The last time i tried, they guy said "i'm travelling" so i reasoned that he was on a train or 'plane (i.e. not busy) and asked him a load more. He got annoyed and told me to f**k off.

When i asked a local natural American what the term "travelling" meant to them, it turned out that it translates to "out of the office and generally unavailable to answer questions".

I didn't know that at the time.

MrHomeScientist - 24-1-2018 at 14:43

I sent Generon a request for information on their membrane filters and how the technology works. That's incredible that you can filter gases straight out of compressed air.

NEMO-Chemistry - 24-1-2018 at 14:52

Quote: Originally posted by aga

I don't speak American well enough.

The last time i tried, they guy said "i'm travelling" so i reasoned that he was on a train or 'plane (i.e. not busy) and asked him a load more. He got annoyed and told me to f**k off.

When i asked a local natural American what the term "travelling" meant to them, it turned out that it translates to "out of the office and generally unavailable to answer questions".

I didn't know that at the time.

At least you wernt smoking Fags! and complaining about having a sore fanny.

But I do think it helps to have a native do the introduction first, otherwise you got to explain why you havnt been to tea with Liz.

aga - 24-1-2018 at 14:59

Thanks MrHomeScientist.

I still find it hard to believe that filtering Air actually works.

Please update us on what they tell you.

Melgar - 24-1-2018 at 17:22

Yeah, I've looked this up before. Trouble is, you still need two outlets, otherwise the unfiltered gas will just build up pressure. Oh, and did I mention that they're ridiculously expensive? I probably should have mentioned that part first. Thousands of dollars for the minimum-price one. Apparently, there are two types, one that uses actual filters, and one that uses columns packed with microfibers. For the microfibers, one of the gases tends to stick to the fibers more than the other, which slows that gas down. So as they move horizontally in the column, they tend to stratify vertically, and can be collected via outlets on the column.

JJay - 25-1-2018 at 02:56

It's also possible to fractionally distill liquid air.

AJKOER - 28-1-2018 at 19:12

Quote: Originally posted by vmelkon

Quote: Originally posted by Melgar

Yeah, an oxygen concentrator will separate nitrogen and oxygen. Not perfectly, so you may need a scrubber if the goal is to get it really pure. The contents of those chemical hand warmers are a good oxygen scavenger. They're mostly reduced iron, with some salt and water as catalysts, among other things. I believe CO2 behaves more like O2 in this system, but I'm not 100% sure.
.......

I remember a report of workers in a large iron pipe that did not fair well when water was drained exposing a fresh iron surface which started an electrochemical reaction that consumed all the available oxygen. Placing a burning split in a vessel also removes O2 rapidly leaving N2 with some CO and CO2.

Combines the paths by adding a mix of salt, water and fresh iron powder to a large squeezable bag/bottle, hold a lit split until it extinguishes, close vessel fitted with an exit tube and shake to dissolve CO2 gas. Let stand overnight. Compress vessel to produce a stream of N2 and impurities that are passed into a hot washing solution of say Na2CO3.

Low tech with safe, available and inexpensive reagents, but may have some CO impurity in the nitrogen gas. The carbon monoxide, if a problematic presence, can be removed with FeI2 via the reaction:

FeI2 + 4 CO → Fe(CO)4I2

[Edited on 29-1-2018 by AJKOER]

Pumukli - 29-1-2018 at 12:33

A year ago I systematically hunted "oldies but goldies" - looking articles from JACS. You can find some really interesting (not to mention: fairly amateur friendly) articles which were cutting edge science a century ago. Now you can do them in the garage.

Anyway, among others, I saved the following one:

A Nitrogen generator
by Chas Van Brunt, received May 4, 1914.
from the research laboratory of General Electric Company, Schenectady, New York.

Enjoy!

Attachment: nitrogengenerator.pdf (187kB)
This file has been downloaded 467 times

edited typo

[Edited on 29-1-2018 by Pumukli]

aga - 29-1-2018 at 12:49

Awesome Pumukli !

Many thanks for that Gem.

MrHomeScientist - 29-1-2018 at 12:52

I'm emailing with a guy at Generon; they offered to send me a free module to demo in a video! I'm going to ask about what their requirements are for using their product in my video. I'm worried they'll want to restrict what I can and can't say about it, and I don't want this to turn into like a product review where I can only say positive things or something.
In the meantime, here's a patent for the filtration system that explains it pretty well: https://www.google.com/patents/US7517388 (also attached below for posterity)

Turns out, the guy I'm talking to is the inventor!

Attachment: US7517388.pdf (883kB)
This file has been downloaded 349 times

aga - 29-1-2018 at 13:22

WTF ?!?!?!

Superb stuff MrHomeScientist !

Fantastic that they are sending you the Real Deal, and for Free !

Being in touch with the inventor is, well, AWESOME ! I guess any questions you have can be answered.

Now, You may be getting one for free, but is there any indication of how much they normally sell for ?

You definitely have to make that video. Most definitely.

MrHomeScientist - 30-1-2018 at 09:32

In one of the patents cited by the one I linked above, US 9034957, it lists the type of polymer used in the membrane fibers:

Quote:

The composition is a spin dope including tetrabromo bis-phenol A polycarbonate (TBBA-PC) and tetrabromo bishydroxyphenylfluorene polycarbonate (TBBHPF-PC), in proportions, by weight, ranging (in percent) from about 60/40 to 40/60, and n-methyl pyrrolidinone (NMP) and triethylene glycol (TEG), wherein the ratio of the amounts of NMP to TEG, by weight, is in the range of about 1.6-2.5. The spin dope is used to make hollow fibers for use in gas-separation membrane modules.

For those that didn't read the patent, the "filter" consists of a bundle of hollow polymer fibers that pressurized air is passed through. Different gases permeate through the membrane at different rates, so oxygen and water vapor pass through the walls of the fibers while nitrogen continues down the tubes. Nitrogen is collected from the bottom of the fibers while oxygen is drawn off from the space surrounding the fibers. That also suggests that enriched oxygen gas can also be obtained from such a filter.

According to Wikipedia, it works because there is a chemical potential between the inside and outside of the fibers caused by the pressure difference. So oxygen passes through the membrane faster than nitrogen, and the pressure in the system drives the nitrogen out the bottom before it can also diffuse out.

MrHomeScientist - 20-2-2018 at 07:46

It has arrived!

I got the tubing and Swagelok fittings from McMaster at the same time. Now, I'll order the compressed air tank from AirGas and I should be good to go.

Here's the plan for the setup:

The permeate is the filtered oxygen, at up to 50% concentration, and the retentate is pure nitrogen, collected in an open flask at the end. I included a flowmeter (rotameter) to help gauge the purity; the spec sheet for the 210 module relates purity to output flow rate. Slightly concerning that I'll be pushing the rotameter close to its max 100 PSI rating, but here's hoping nothing explodes!

I have one month to use the filter before I need to return it to Generon, so the pressure is on! Pun intended!

sclarenonz - 20-2-2018 at 14:34

good evening
I'm grateful for so much information. but I have a doubt, after purifying nitrogen, how do I fix nitrogen, is there any substance that can react with nitrogen by making a nitride, I'm using iron oxide(I saw in wikipedia that iron oxide is a photoanode when exposed to the sun?), along with magnesium oxide inside a copper tube and a heated candle, does it work?
I saw in the previous comments that iron and water works, but I live in a forest, far from the city, and still can not make a tool to extract the iron from the minerals, I can only extract the iron oxide with caustic soda and peroxide of hydrogen

[Edited on 20-2-2018 by sclarenonz]

clearly_not_atara - 20-2-2018 at 20:39

Nitrogen is an active area of modern chemical research because it's incredibly difficult. You could use the Ostwald process, with terrible efficiency, or you can absorb the nitrogen onto metallic lithium. That's about it; there are some very complex catalysts which fix nitrogen, some of which you might be able to buy, none of which are cheap... Or fast.

BaFuxa - 23-2-2018 at 08:16

Quote: Originally posted by sclarenonz

good evening
I'm grateful for so much information. but I have a doubt, after purifying nitrogen, how do I fix nitrogen, is there any substance that can react with nitrogen by making a nitride, I'm using iron oxide(I saw in wikipedia that iron oxide is a photoanode when exposed to the sun?), along with magnesium oxide inside a copper tube and a heated candle, does it work?
I saw in the previous comments that iron and water works, but I live in a forest, far from the city, and still can not make a tool to extract the iron from the minerals, I can only extract the iron oxide with caustic soda and peroxide of hydrogen

[Edited on 20-2-2018 by sclarenonz]

Magnesium nitride works. See the Serpek process.

sclarenonz - 24-2-2018 at 04:40

Good day

I found this video interesting.

https://www.youtube.com/watch?v=ZRFai58q1J8

because of the inverse effect

MgO + NH3 = Mg + N2 + H2O

Al + MgO = Al2O3 + Mg

if magnesium is a great fixative of nitrogen, I am now looking to isolate magnesium, and I saw that it is possible with ammonia, is it possible?

[Edited on 24-2-2018 by sclarenonz]

[Edited on 24-2-2018 by sclarenonz]

MrHomeScientist - 5-3-2018 at 07:37

After much frustration getting all the right pieces for my input gas, I finally got everything I needed to test the Generon membrane filter and set it up this weekend.

Compressed air from the yellow cylinder is reduced to 100 PSI through the regulator, which flows into the input port of the filter. The filter splits this into permeate (oxygen-rich, exits out the side) and retentate (nitrogen-rich, exits through a needle valve at the other end) gas streams. Permeate is led away from the setup and any potential ignition sources. Retentate passed through a rotameter flowmeter, and then on to an open collection container.

The major annoyance was that the regulator is meant for nitrogen, so I needed to get special fittings for it to attach to the compressed air tank. The people at AirGas were nice enough to put those on for me, though. I think every single different gas has its own fitting system :mad:

The flowmeter is there to help gauge purity. The spec sheet for the 210 module relates output flow rate to nitrogen gas purity, so i.e. if I tweak the needle valve to output 5.9 SCFH I should be getting 99.5% pure nitrogen. (The real purity is actually about 1% lower, because the membrane only separates oxygen; other atmospheric gases pass through along with the nitrogen.)

I tested it out and it works really well. The nitrogen stream extinguishes flames, and the oxygen stream relights them. I tested the concentration of the oxygen stream and it's close to 50%, which is itself a useful product. Now, on to video production!

BaFuxa - 7-3-2018 at 04:18

Quote: Originally posted by sclarenonz

Good day

(...)

if magnesium is a great fixative of nitrogen, I am now looking to isolate magnesium, and I saw that it is possible with ammonia, is it possible?

[Edited on 24-2-2018 by sclarenonz]

[Edited on 24-2-2018 by sclarenonz]

Get a magnesium salt, dissolve in minimum amount of water, mix with ascorbic/ citric acid dissolved in minimum amount of water with a 2.2 molar ratio acid to magnesium salt. Heat up to a boil, magnesium will fall out of solution. Wash on a bushner with water and ethanol. Let dry at RT.

[Edited on 7-3-2018 by BaFuxa]

weilawei - 13-3-2018 at 15:21

I've been trying to rig up a nitrogen generator, with no obvious success yet. In my first attempt, I put a pressure equalizing addition funnel onto a filter flask. In the flask, I put 0.5g of ammonium chloride in 100mL of water. In the addition funnel, 0.5g of sodium nitrite in 100mL of water. The filter flask connected to an oil bubbler with a balloon over the outlet.

I added the sodium nitrite solution slowly (~1 drop per second), but no bubbling was observed. After the addition, I began heating slowly. The bubbler began bubbling slowly (~1 bubble/2 seconds), picking up a little as the solution began to boil. Finally, no more bubbling was observed at the oil bubbler despite boiling continuing. The meager (barely inflated) contents of the balloon would not put put a candle, and a lit splint held in the addition funnel did not go out.

Well, that's round #1. Does anyone have experience with this reaction or references?

[Edited on 14-3-2018 by weilawei]

MrHomeScientist - 14-3-2018 at 09:57

Quote: Originally posted by BaFuxa

Do you have a reference for that? I highly doubt magnesium metal can be made from any aqueous reaction.

MrHomeScientist - 19-3-2018 at 14:58

My video on the filter is up: https://www.youtube.com/watch?v=4-bbAwoG4Z8

Very cool technology, and it works well as far as I could test it. You can get both very pure nitrogen gas and oxygen-enriched air from it, both of which would be useful for amateur chemistry. I measured the oxygen side to be about 45% O₂, but my method was pretty crude. Generon said they would expect about 40% max with my particular setup.

I could see this being especially useful if you hook it up to an air compressor for extended use. I used a cylinder because it was a lot simpler to set up for a quick test. With a compressor you need to condition your input air to remove oils, moisture, etc. A little pricey to get started, but once set up it's essentially free to run since the feedstock is just air!

Ubya - 19-3-2018 at 16:12

Quote: Originally posted by MrHomeScientist

My video on the filter is up: https://www.youtube.com/watch?v=4-bbAwoG4Z8

Very cool technology, and it works well as far as I could test it. You can get both very pure nitrogen gas and oxygen-enriched air from it, both of which would be useful for amateur chemistry. I measured the oxygen side to be about 45% O₂, but my method was pretty crude. Generon said they would expect about 40% max with my particular setup.

I could see this being especially useful if you hook it up to an air compressor for extended use. I used a cylinder because it was a lot simpler to set up for a quick test. With a compressor you need to condition your input air to remove oils, moisture, etc. A little pricey to get started, but once set up it's essentially free to run since the feedstock is just air!

just watched your video, this would be a perfect piece of apparatus for an inert gas glove box, 800$ for unlimited N2 supply, but if someone just needs (almost) pure N2 a few times for small projects (purging vials or general glassware) i would still prefer just a simple N2 cylinder

JJay - 19-3-2018 at 17:32

Quote: Originally posted by weilawei

I've been trying to rig up a nitrogen generator, with no obvious success yet. In my first attempt, I put a pressure equalizing addition funnel onto a filter flask. In the flask, I put 0.5g of ammonium chloride in 100mL of water. In the addition funnel, 0.5g of sodium nitrite in 100mL of water. The filter flask connected to an oil bubbler with a balloon over the outlet.

I added the sodium nitrite solution slowly (~1 drop per second), but no bubbling was observed. After the addition, I began heating slowly. The bubbler began bubbling slowly (~1 bubble/2 seconds), picking up a little as the solution began to boil. Finally, no more bubbling was observed at the oil bubbler despite boiling continuing. The meager (barely inflated) contents of the balloon would not put put a candle, and a lit splint held in the addition funnel did not go out.

Well, that's round #1. Does anyone have experience with this reaction or references?

[Edited on 14-3-2018 by weilawei]

I have not tried it, but my guess is that the dilute solutions are not reacting very quickly or producing much gas.

There are dozens of papers on the reaction. This one looks good: Reaction of Sodium Nitrite and Sulfamic Acid

MrHomeScientist - 20-3-2018 at 05:40

Quote: Originally posted by Ubya

Definitely agree. Thanks for the support!

sclarenonz - 20-3-2018 at 08:36

the price of the 222 kit is very expensive, it was logical to be cheap because it is only a menbrane 226 us can be very ship to american, but is expensive to one simple worker