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Waffles SS
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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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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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Praxichys
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@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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HgDinis25
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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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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%.
-The manipulator
We are all here on earth to help others; what on earth the others are here for I don't know. -W. H. Auden
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Waffles SS
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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
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| 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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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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WGTR
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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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macckone
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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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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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WGTR
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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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BromicAcid
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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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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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macckone
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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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woelen
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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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MrHomeScientist
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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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BromicAcid
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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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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)
[Edited on 15-4-2015 by Waffles SS]
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BromicAcid
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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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Fleaker
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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.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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Boffis
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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!  )
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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Molecular Manipulations
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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]
-The manipulator
We are all here on earth to help others; what on earth the others are here for I don't know. -W. H. Auden
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aga
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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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medchemist
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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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Molecular Manipulations
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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.
-The manipulator
We are all here on earth to help others; what on earth the others are here for I don't know. -W. H. Auden
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