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Author: Subject: Nitrogen Generator
aga
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[*] posted on 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.




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[*] posted on 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]




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For all your phlogiston needs.
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[*] posted on 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.




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[*] posted on 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....



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[*] posted on 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:
NH<sub>4</sub>Cl(aq) + NaNO<sub>2</sub>(aq) → N<sub>2</sub>(g) + NaCl(aq) + 2 H<sub>2</sub>O (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]
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JJay
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[*] posted on 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]




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[*] posted on 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.




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[*] posted on 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?




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[*] posted on 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.




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[*] posted on 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.
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[*] posted on 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. :D

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.
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[*] posted on 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.




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[*] posted on 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.



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[*] posted on 25-1-2018 at 02:56


It's also possible to fractionally distill liquid air.



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[*] posted on 28-1-2018 at 19:12


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.


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]
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[*] posted on 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 53 times

edited typo

[Edited on 29-1-2018 by Pumukli]
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[*] posted on 29-1-2018 at 12:49


Awesome Pumukli !

Many thanks for that Gem.




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[*] posted on 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 26 times
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[*] posted on 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.




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[*] posted on 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.
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[*] posted on 20-2-2018 at 07:46


It has arrived!

210.jpg - 518kB

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:

Generon plan.jpg - 82kB

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!
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[*] posted on 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]
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[*] posted on 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.



[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 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.




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[*] posted on 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]
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