Sciencemadness Discussion Board - Get rid of Nitrogen dioxide

Get rid of Nitrogen dioxide

Waffles SS - 9-4-2015 at 23:09

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]

Loptr - 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]

Praxichys - 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.

HgDinis25 - 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?

Molecular Manipulations - 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%.

Waffles SS - 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]

BromicAcid - 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]

NO2 Adsorption on Silica Gel

WGTR - 10-4-2015 at 12:06

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]

macckone - 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).

Waffles SS - 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?

WGTR - 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.

BromicAcid - 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.

Waffles SS - 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 ?!)

macckone - 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.

woelen - 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.

MrHomeScientist - 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.

BromicAcid - 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.

Waffles SS - 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)

[Edited on 15-4-2015 by Waffles SS]

BromicAcid - 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.

Fleaker - 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.

Boffis - 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!

)

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?

Molecular Manipulations - 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]

aga - 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.

medchemist - 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

Molecular Manipulations - 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.

AJKOER - 14-7-2015 at 17:01

With respect to scrubbing NO2, why not pass the target gases over heated Fe2O3, creating Iron nitrate in the process? This is a general technique for creating anhydrous nitrate to quote Wikipedia on NO2 (https://en.m.wikipedia.org/wiki/Nitrogen_dioxide):

"NO2 is used to generate anhydrous metal nitrates from the oxides:[9]

MO + 3 NO2 → M(NO3)2 + NO "

where the harvesting of the formed anhydrous nitrate(s) may paid for the scrubbing operation.

Here are my prior comments on SM upon my successful small scale scrubbing of the problematic nitric oxide using NaClO/HOCl. Apparently, the best pH is from 4 to 7, and not more alkaline. Please see "Oxidation of Nitric Oxide in Two Stage Chemical Scrubbers Using DC Corona Discharge" available at https://www.google.com/url?sa=t&source=web&rct=j&... which presents some comparative views on many existing routes.

However, some recent research per Atomistry.com on nitric oxide (link: http://nitrogen.atomistry.com/nitric_oxide.html ), suggests yet another possible simple route to me. To quote:

"The absorption of nitric oxide by aqueous solutions of various salts has been the subject of much investigation. In the case of ferrous salt solutions the solubility of the gas increases with the concentration of the solution. The limit is reached when the proportions of iron to nitric oxide are in the ratio 1:1, both in aqueous and alcoholic solutions. It is assumed that unstable chemical compounds are formed of the type FeSO4.NO, FeCl2.NO, etc., but the ready dissociation of such compounds under the influence of heat indicates only a feeble combination. Usher has investigated the freezing-point of such solutions, and finds that neither the freezing-point nor the pressure of the nitric oxide remained constant, and hence no conclusion can be drawn as to the nature of the compound FeSO4.NO. The absorption of nitric oxide by bivalent salt solutions of nickel, cobalt, and manganese is of a similar nature. Ferric salts also absorb nitric oxide readily, as also do many metallic and non-metallic halides. Nitric oxide dissolves in solutions of copper sulphate, producing a violet unstable compound, CuSO4.NO. "

Namely, direct absorption into an aqueous ferrous or ferric salt soution.

I also came across some interesting chemistry surrounding the production of peroxynitrite as yet another possible method which arises from the reaction of nitric oxide radical (NO.) with a superoxide radical, per the reactions below:

NO. + 02.- -------) ONOO-
ONOO- + H+ -----) ONOOH
ONOOH ------) OH.+ NO2.

See https://www.google.com/url?url=http://scholar.google.com/sch... which I find interesting based on a possible ongoing photocatalytic source of the superoxide radical via a suspension of sayTiO2 as to quote:

"A luminol chemiluminescence (CL) probe method was successfully applied to the investigation of the superoxide radical (O2−˙) formed on photoirradiated TiO2 powders. "

Reference link: http://pubs.rsc.org/en/Content/ArticleLanding/2002/CP/B10844...

which, unlike prior methods, does not require replenishing of the oxidizer and thus may be able to better address a continuous scrubbing issue.

[Edited on 15-7-2015 by AJKOER]

annaandherdad - 25-7-2015 at 21:17

Quote: Originally posted by Boffis

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?

The book on nitric gases in the forum library gives some information about this. Water floats on liquid NO2, and of course the NO2 reacts with it to make HNO3 and NO. But unlike the case of passing NO2 gas through water (or over it in a tower) apparently in the presence of oxygen this combination of liquids is capable of reaching any concentration of HNO3, up to 95% or more.

I'm in the process of trying this out. I made NO+NO2 by HCl+NaNO2 (the latter very cheap on Amazon), and fed the combination of gases into a RBF with another tube leading in from a balloon filled with oxygen. I got the idea for doing this from Woelen's description of the NO+O2 reaction. I put the flask in an ice bath, no salt, just at 0 degrees. As the NO reacts with the oxygen and the NO2 condenses to a liquid, the vacuum sucks more oxygen from the balloon as needed. The balloon is mylar, so it holds the oxygen at almost zero pressure (above atmospheric). It's a fairly big balloon, I put maybe 50 liters of oxygen in it.

Here are the photos: http://bohr.physics.berkeley.edu/lab/lab1.html

The blue thing in the first photo is the mylar oxygen balloon. The second photo shows the liquid NO2. Tomorrow I'm going to add some water (again with the oxygen from the balloon) and see what I get.

battoussai114 - 26-7-2015 at 08:04

It seems the reaction of NO2 with H2O2 proceeds rapidly if booth are in gas phase: http://ntrs.nasa.gov/search.jsp?R=19730009428
By quickly glossing over the article it seems it might be an option for removing the gas in your case... passing the NO2 stream by a vessel with heated H2O2 and then condensing the nitric acid in another flask. The nitric acid formed is a useful reagent. But before trying you'd better check the vapor pressure of H2O2 in different temps for designing the equipment.

annaandherdad - 26-7-2015 at 16:03

Continuing from above....

Added some cold water to my flask of NO2/N2O4, with a connection to the oxygen balloon which the flask was free to draw on. The book, "Absorption of Nitrous Gases" in the library speaks of bubbling oxygen through the mixture, but I didn't want to do that in order to keep down the fumes, so I just sloshed the mixture around. It definitely started drawing oxygen from the balloon, and I figure I was making nitric acid because it started to attack the rubber stopper pretty badly.

Kept this up for a while then let the thing sit for 4 hours in an ice bath. Then I poured off the liquid into a graduated cylinder. It showed two layers, both red brown but different shades. I believe the upper layer was RFNA, that is, a higher concentration than can be achieved by bubbling NO2 through water. I say this, not because I measured the percentage of HNO3, but because I tested it on copper. There was no or very little reaction at first, but when I added some water it instantly started a vigorous reaction with the liquid turning blue.

Here is what the book says:

"By adding an excess of liquid nitrogen tetroxide to water,
the concentration of nitric acid present may be made to reach
any desired figure, even at ordinary temperatures (less than
20° C.)- Furthermore, by bubbling oxygen into the mixture,
the nitrogen trioxide present is slowly oxidized to the tetroxide
so that the ultimate product may consist of nitric acid containing
dissolved nitrogen tetroxide." (Webb, Absorption of Nitrous Gases, p. 122).

I don't think this method of making HNO3 is competitive with the saltpeter route, but I was curious to try it. However, dealing with NO2 is a pain, and I don't have a fume hood (just an open garage, a fan, and the great outdoors).

franklyn - 27-7-2015 at 06:48

I thought it was common knowledge Urea and NO2 mutually annihilate in solution.
One mol of Urea destroys two mols of nitrous acid , the reason this is used to purify nitric acid.
(NH2)2CO + 2 HNO2 => CO2 + 3 H2O + 2 N2

2 NO2 + H2O => HNO3 + HNO2

On balance you'll also get some Urea Nitrate as a product
(NH2)2CO + HNO3 => (NH2)2CO•HNO3

.

Boffis - 27-7-2015 at 15:45

@annaandherdad. These are a really interesting series of experiments and thank you for sharing them with the community.

I notice in the pictures there is a drying tube, can I ask what is in it?

Another idea occurred to me, could you use 30% H2O2 to get rid of the NO2 from the nitric acid or how about condensing the NO2 directly into ice cold H2O2 solution. With 30% H2O2 you should end up with >61% nitric acid.

The next question is could you use waste NO2 to up grade azeotropic nitric acid by mixing liquid NO2 with Ice cold nitric acid and then exposing it to oxygen? Or is this just wishful thinking.

annaandherdad - 27-7-2015 at 16:34

Quote: Originally posted by Boffis

@annaandherdad. These are a really interesting series of experiments and thank you for sharing them with the community.

Thanks!

Quote: Originally posted by Boffis

I notice in the pictures there is a drying tube, can I ask what is in it?

It has sand in it. I plugged the hole with a little glass fibers. The purpose is to remove the little droplets that are produced in the reaction making the NO2. I can't bubble it through water for this purpose, sand works very well. I've used the same technique with HCl gas.

Quote: Originally posted by Boffis

idea occurred to me, could you use 30% H2O2 to get rid of the NO2 from the nitric acid or how about condensing the NO2 directly into ice cold H2O2 solution. With 30% H2O2 you should end up with >61% nitric acid.

I haven't tried H2O2 but the point of these experiments was to get a higher concentration of nitric acid than is available by just bubbling NO2 through water (or even using an absorption column). The maximum concentration obtainable this way is less than the 68% azeotrope (I'm recalling this from the book on nitrous gases, cited above). But I hadn't tried to calculate the percentage one would get from concentrated H2O2. It's an interesting idea. If need be, one could obtain more concentrated H2O2 (for example, by freezing). I got my oxygen from H2O2, one might have said that it would have been easier to react the NO2 directly with the H2O2, except as I explained I was interested in getting more concentrated HNO3.

Quote: Originally posted by Boffis

The next question is you use waste NO2 to up grade azeotropic nitric acid by mixing liquid NO2 with Ice cold nitric acid and then exposing it to oxygen? Or is this just wishful thinking.

Yes, it sounds to me like that would work perfectly well, and would be a good economy on the oxygen, which is some trouble to make.

I have another comment to make about this experiment. I explained previously that my nitric acid behaves as concentrated in terms of its action on copper (passivating until water is added).

But today I tried another test, namely, pouring some on nitrile gloves. I only had a few ml left, but it was enough. The gloves smoked and fumed quite a bit, and then burst into flames. Impressive for the neighbors. Ordinary concentration HNO3 (68%) won't do this.

annaandherdad - 28-7-2015 at 10:17

Hi, Boffis, I repeated your calculation, and got 61% HNO3 from passing NO2 through 30% H2O2, same as you. What interested me is that in this process overall the water doesn't change, that is, the reaction is

2NO2 + H2O2 --> 2HNO3

(with no water on either side). Once you have converted all the H2O2 to HNO3 then you might think that more NO2 would react with the water to make more HNO3 (plus NO). If you're using NO2 gas, then Webb says you won't, not above 68.4%, anyway.

Here are the passages from Webb that I was thinking about :

"When nitrogen tetroxide is led into water, nitric acids
containing (60-65 per cent. HNO3 can readily be obtained.2
It was shown by Koerster and Koch3 that nitric acid containing
68.4 per cent. HNO3 can be realized experimentally
under these conditions, and is the maximum concentration
obtainable in this way.

When liquid nitrogen tetroxide is added to a small quantity
of water a separation into two layers occurs. The upper
layer consists of nitric acid containing dissolved nitrogen
tetroxide, while the lower bluish-green layer consists mainly
of nitrogen trioxide
2N2O4 + H2O <--> N2O3 + 2HNO3
If, however, oxygen is bubbled through the mixture, the
latter assumes an orange-yellow colour and the upper layer
is found to contain nitric acid of 95-99 per cent. HNO3—
while the lower layer contains nitrogen tetroxide with 5-10
per cent. HNO3" (Webb, op cit, p. 38)

A comment on the balloon method: You have to have quite pure oxygen in the balloon (in particular, air won't work). That's because if you used air, after a while the reaction chamber would have only nitrogen and nitrogen oxides in it, and pushing more NO into it would just force those gases back into the balloon. I was pretty careful to make my oxygen dry and as pure as possible.

Earlier in Webb's book he talks about either using all glass equipment (which I don't have) or using paraffin to protect cork and rubber. At least he says this when things are exposed to NO2; as for HNO3, I'm not sure if concentrated HNO3 will attack paraffin, perhaps violently.