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Waffles SS
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[*] posted on 9-4-2015 at 23:09
Get rid of Nitrogen dioxide


I am working on reaction that produce large amount of Nitrogen Dioxide.

I am looking for dispose or dissolve method for get rid of it.

I tried to dissolve it in alkaline water but i was unsuccessful.

Somebody has idea or experience about it?

NO2 dissolve in Nitric acid,CCl4
Mendiara, S. N.; Sagedahl, A.; Perissinotti, L. J. (2001). "An electron paramagnetic resonance study of nitrogen dioxide dissolved in water, carbon tetrachloride and some organic compounds". Applied Magnetic Resonance 20: 275. doi:10.1007/BF03162326

[Edited on 10-4-2015 by Waffles SS]
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Loptr
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[*] posted on 10-4-2015 at 04:09


Why alkaline water? I have read that dissolving NO2 in H2O2 will oxidize it to HNO3.

In fact, I think I saw this method used in a video on YT.

[Edited on 10-4-2015 by Loptr]
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[*] posted on 10-4-2015 at 04:49


@Loptr - True, but the absorption/conversion efficiency is usually low.

1. For absorption, you want think redox rather than acid/base. NO2 is a reasonably good oxidizer, so an oxygen-sensitive reducing solution will probably work well. Try a solution of sodium sulfite, sodium nitrite, etc.

2. NO2 can be condensed at ~21°C with an ice-cold, efficient condenser. For a gas, it has has a reasonably low vapor pressure at room temperature and can be stored as a pressurized liquid in a container with suitable compatibility, then released elsewhere in a remote location or used for something else.

3. Passing it through the air intake of a reducing (yellow) bunsen flame may help, with the NO2 behaving as an oxidizer, combusting the fuel and leaving only nitrogen. Catalytic converters in vehicles use a similar process over a platinum, rhenium, or rhodium catalyst to rearrange unburned hydrocarbons and nitrogen oxides.




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[*] posted on 10-4-2015 at 06:04


Sodium Hydroxide solutions are usually employed in such situations.

Nitrogen Dioxide hydrolyzes to give Nitrous Acid and Nitric Acid. These acids are immediately neutralized by Sodium Hydroxide to give Sodium Nitrite and Sodium Nitrate. Because there is never any true NO2 dissolved in water, more and more NO2 gets absorbed by the solution.

What exactly didn't work out with your alkaline solution?
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Molecular Manipulations
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[*] posted on 10-4-2015 at 06:30


I could only get around 10% of nitrogen tetroxide to liquefy at 0°C. Employing a 5-1 ratio of ammonium chloride and water ice I got a solution that always stabilizes at -17.8°C (or 0.0°F, this mixture was originally used for calibrating Fahrenheit thermometers). Using this mixture in the cooling jacket condensed the nitrogen tetroxide nearly completely, and then froze some before it could drip down (MP= -11.2°C). Adding water to the cooling bath and taking out the remaining ice brought it above N2O4's MP and it ran down the condenser. Over-all yield was ~90%.



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Waffles SS
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[*] posted on 10-4-2015 at 06:32


Thanks guys,

In my reaction NO2 suddenly produce in large amount and i am trying to absorb/dispose it.

I tried to absorb it in cold %10 Sodium Hydroxide solution but that was unsuccessful and lot of NO2 gas escaped even after 3 absorption system with gas sparging device.(according to my mentioned ref. it need ~15 atm pressure)

Now I am looking for dispose reaction that NO2 completely decompose and i didnt find good method for it yet.

Absorption in Sodium Nitrite/Sodium Sulfite solution is interesting and i found some ref for it:

Quote:

Fist stage removing nitrogen oxides (nox) by sodium sulfite reaction to sodium nitrate...A two stage method is described for the removal of NOx and SOx from flue gas. The first stage removes all NOx by sodium sulfite sorbent injection. The second stage removes SOx by sodium bicarbonate injection. The sodium sulfite product formed in the second stage is transferred to the first stage for injection

US 6214308



Quote:

Absorption of Nitrogen Oxides in Aqueous Sodium Sulfite and Bisulfite Solutions
Hiroshi. Takeuchi , Makoto. Ando , Nobuo. KizawaInd. Eng. Chem. Proc. Des. Dev., 1977, 16 (3), pp 303–308
DOI: 10.1021/i260063a010



[Edited on 10-4-2015 by Waffles SS]
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BromicAcid
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[*] posted on 10-4-2015 at 09:59


Make a packed bed wet scrubber with counter-current liquid flow. I made one for about $100 in materials, if you're really going to be making a lot of NO<sub>2</sub> it's worth the expense.

One other point, you mentioned 10% NaOH, which would on the surface seem to be mighty concentrated, but I remember looking at a graph depicting concentration of NaOH vs ability to neutralize phosgene and the ability shot up greatly as you were approaching 20%. I have been told that as the concentration gets to that sort of level the characteristics of the solution allow it to better dissolve non-polar components and once they are in solution the NaOH takes care of the rest.

[Edited on 4/10/2015 by BromicAcid]




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[*] posted on 10-4-2015 at 12:06
NO2 Adsorption on Silica Gel


I suppose you've already seen this?

https://www.sciencemadness.org/whisper/viewthread.php?tid=48...

and this:

https://www.sciencemadness.org/whisper/files.php?pid=397137&...

[Edited on 4-10-2015 by WGTR]
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[*] posted on 11-4-2015 at 08:01


Getting a catalytic converter for a car is one good idea.
Junk yards have them buy the ton literally.
But they have to be hot to be active so heat it up
and pump the NO2 through it with some
vaporized methanol. You should get plenty of CO
and CO2 with nitrogen as the result.
Of course you don't want CO in a confined space
so do it outside.

Another option would be pumping the NO2
into an active charcoal burner (BBQ pit).
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Waffles SS
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[*] posted on 11-4-2015 at 10:20


Thanks again,

@Macckone, it seems i have more chance for life if i dont use catalytic converter(CO is more toxic than NO2)

@BromicAcid ,"packed bed wet scrubber" ? may i see pic of it?i have not seen it so far !

@WGTR , that is interesting but i think absorption of NO2 in Sodium Sulfite solution should be easier.am i wrong?
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[*] posted on 11-4-2015 at 13:01


Quote: Originally posted by Waffles SS  
@WGTR , that is interesting but i think absorption of NO2 in Sodium Sulfite solution should be easier.am i wrong?


I'm not experienced with the reaction of NO2 with sodium sulfite solution. Dry silica gel adsorbs NO2 directly, though. It's a relatively quick and effective process. The saturated gel can be stored in a glass jar, and reheated later to regenerate the NO2 if desired.

When I made NO2 in a previous effort, NO was led into a large glass container to allow the air to auto-oxidize the NO to NO2. From there, the gasses were led to another glass container, but through a silica gel adsorption column. While the first container was brown from NO2, the second remained clear, indicating almost total adsorption.

Silica gel doesn't adsorb NO, however. If any is present in the product gasses, time must be given for it to react with air and form NO2 before trying to adsorb it. A large glass bottle usually does the trick.

My system was small, and used very low gas flow rates. I don't know how much gas you'll be producing at one time. It may take a large column to both minimize back pressure, and give enough surface area for the NO2 to be adsorbed quickly enough.

Since different forms of silica gel may have different properties, here is the type that I used:

Fisher S161-500 Silica Gel Dessicant Reagent A.C.S. 10-18 mesh

Since this product is expensive, another idea would be to use it as a backup to other methods. In other words, remove the bulk of the NO2 with cheaper methods, remove the water with Drierite, and scrub the dilute gas stream with silica gel.
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[*] posted on 11-4-2015 at 13:30


Waffles, here is a link to my scrubber image:

https://www.sciencemadness.org/whisper/viewthread.php?tid=29...

Basically vapors are sucked into the bottom of the column, NaOH solution sprays in from the top of the column and coats the packing and the vapors are drawn through this mass of packing and NaOH. Large surface areas and long contact times are keys to success. This is basically a scaled down version of an industrial scrubbing system. The bottom portion is the reservoir where the NaOH accumulates, the cap at the end removes and the pH can be checked, as necessary additional NaOH is added and spent scrubber solution is removed. Of course you can also run sulfuric acid through it if you want to scrub amines / ammonia. I made it to be versatile.




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Waffles SS
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[*] posted on 12-4-2015 at 08:19


Thanks,

@BromicAcid,that is interesting but i dont know can i scale up it easily or not.

@WGTR ,really cool
If i find "Fisher S161-500 Silica Gel Dessicant Reagent A.C.S. 10-18 mesh" sure i will use it.

What about common silica gel?what is your idea about molecular sieve?(i dont know 4A is effective for it ?!)
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[*] posted on 12-4-2015 at 13:17


You could use a catalytic decomposer consisting of titanium oxide and copper oxide. I am not sure how well it would work without something to oxidize but it should be worth a try. It is going to take a high temperature though. So it would need to be heated.
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[*] posted on 13-4-2015 at 01:25


The problem is not the presence of NO2, but the presence of NO. NO does not dissolve in water and it also is not absorbed (or only very slowly absorbed) by alkaline solutions. The production of NO2 usually is combined with production of NO and the scrubbers described above only absorb the NO2 and at best part of the NO.

NO, however, can be removed, because it quickly and completely reacts with O2 at room temperature.

If you want to get rid of the NO and NO2, then you need to mix the gas with a lot of air, such that all NO is oxidized to NO2 as well and this mix then must be bubbled through a fairly strongly alkaline solution. Passing NO2 through water is not enough, because that will produce HNO3 and NO, the latter escaping from the liquid.




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[*] posted on 14-4-2015 at 10:51


Bromic what forum is your link posted under? I don't appear to have access. If it's whimsy, this really sounds like a post that deserves to be in Technochemistry.
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[*] posted on 14-4-2015 at 13:38


Yes, it was posted in Whimsy. I never completed the project beyond the testing phase. Being somewhat of a perfectionist I wanted to have it perfect before I unleashed the diagrams on the world but I got tied up on my third type of column packing.



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Waffles SS
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[*] posted on 14-4-2015 at 19:16


Thanks,

@woelen ,you are right.

Yesterday i used aquarium pump for bubbling air in my reaction flask and gas absorbed in two trap contain dilute nitric acid.
(I did this reaction outside of lab)

I have to say this worked but some NO2 escaped

I think strong Sodium Hydroxide / Sodium Sulfite solution work better(i have to try)

Photo0030.jpg - 351kB


[Edited on 15-4-2015 by Waffles SS]
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[*] posted on 14-4-2015 at 19:25


A fritted disk will increase your surface area of your bubbles and help with the absorption but will also increase the back pressure of the system or even having stirring in one of the traps.



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[*] posted on 2-5-2015 at 11:37


First scrub with H2O2 35% to reclaim your NOx as HNO3 then pH 10.5 sodium sulfite in NaOH to get what NOx makes it through that. Difficult material to scrub. Works best if you recirculate counter current like a wet fume scrubber.



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[*] posted on 29-5-2015 at 09:49


I have the same issue that Waffles SS has but I quite like the idea of recovering some of nitrogen dioxide as liquid but I can see that my "off gas" from dissolving silver and oxidizing selenium is both damp and full of acid spray which will also carry silver or selenium. Washing the gas with through a little brine will remove the spray but any ideas how to dry it? I have it in my head that NO2 reacts with or is at least soluble in sulphuric acid. How about P2O5 supported on an inert carrier like "perlite" (available here from garden centres).

WTGR above suggests "Drierite" (what is this? I thought Drierite was anhydrous magnesium perchlorate, sound v expensive! :o)

Molecular Manipulations: did you dry yours prior to condensing it? How does the presence of wáter effect the condensed product, do you get ice crystals in the liquid NO2 or is ice soluble in liquid NO2?
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[*] posted on 29-5-2015 at 12:15


Yes the vapors were dried first. I probably used conc. sulfuric acid to dry it as I used it to protonate nitrite to generate nitrogen dioxide in the first place.
I never tried condensing it wet, so can't answer from experience, but I bet ice would dissolve in liquid nitrogen dioxide (dinitrogen tetroxide) - with the evolution of nitric oxide.

[Edited on 30-5-2015 by Molecular Manipulations]




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[*] posted on 29-5-2015 at 12:40


Quote: Originally posted by Waffles SS  
I have to say this worked but some NO2 escaped

If you calculate the volume of gas that your reaction will produce, use a Balloon of a big enough size to keep it inside the reaction system.

I did this with Cl2 and the only Gas escape happened when i took the apparatus apart - most of it reacted as it was trapped.




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[*] posted on 12-7-2015 at 14:56


let the NO2 flow over NaOH/KOH solid, it will self moisten being hydroscopic and if you have a tube packed with ~15cmof NaOH/KOH then the gas should all absorb; check the stoichiometry to see how much NaOH/KOH is needed and add another 10% for good measure. you then reclaim most if not all NO2 as useful nitrate. ;) what ever you do, I recommend wearing a respirator regardless, you can get them form building supply shops; most supply ones that resist most chemicals. NO2 will easily cause chemically induced pneumonia, I had a horrible cough for months after a brush with a very small amount. stay safe
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[*] posted on 12-7-2015 at 20:30


Quote: Originally posted by medchemist  
you then reclaim most if not all NO2 as useful nitrate. ;)

Emm, not quite, you need oxygen to balance that equation, without it you'll end up with a one to one (molar) mixture of nitrate and nitrite.

6 NO2 + 6 KOH --> 3 KNO2 + 3 KNO3 + 3 H2O

Of course nitrite is considered more useful than nitrate by some, so it ain't all bad.:D




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