Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
 Pages:  1  2
Author: Subject: Eliminating NO2 from HNO3
clearly_not_atara
International Hazard
*****




Posts: 1716
Registered: 3-11-2013
Member Is Offline

Mood: No Mood

[*] posted on 25-9-2017 at 09:04


Quote:
Doing nothing may be the proper action, but it is not an answer that removes NO2 and preserves the HNO3. Actually, with the ozone approach, or is it the oxygen/electric arc method, there may be even stronger HNO3 as the decomposition reaction has been reversed.


Did you read the article? NO2 will evaporate much faster than H2O or HNO3, because it has a much lower boiling point. All you need to do is allow it to evaporate under conditions that prevent anyone from inhaling it. All this fucking about with oxidizers is a total waste of time. You do not need oxidizers for this.

[Edited on 25-9-2017 by clearly_not_atara]
View user's profile View All Posts By User
Fleaker
International Hazard
*****




Posts: 1232
Registered: 19-6-2005
Member Is Offline

Mood: nucleophilic

[*] posted on 25-9-2017 at 10:45


Quote: Originally posted by clearly_not_atara  
Quote:
Doing nothing may be the proper action, but it is not an answer that removes NO2 and preserves the HNO3. Actually, with the ozone approach, or is it the oxygen/electric arc method, there may be even stronger HNO3 as the decomposition reaction has been reversed.


Did you read the article? NO2 will evaporate much faster than H2O or HNO3, because it has a much lower boiling point. All you need to do is allow it to evaporate under conditions that prevent anyone from inhaling it. All this fucking about with oxidizers is a total waste of time. You do not need oxidizers for this.

[Edited on 25-9-2017 by clearly_not_atara]


At a large Canadian producer of azeotropic nitric acid, c. hydrogen peroxide is used to decolorize their products and remove dissolved NOx.




Neither flask nor beaker.


"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
View user's profile View All Posts By User
Melgar
Anti-Spam Agent
*******




Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline

Mood: Estrified

[*] posted on 25-9-2017 at 11:05


If you can't use H2O2 for some reason, like if you're dissolving silver, adding ammonium nitrate to the solution will greatly reduce fumes. I believe that this is a result of ammonium nitrite briefly forming and then decomposing into nitrogen and water. The NO3 ion is left behind to do some more oxidizing. However, you have to keep in mind that the ammonium ions all need to be gone by the time the reaction is finished, and that can be tough to predict.



The first step in the process of learning something is admitting that you don't know it already.

I'm givin' the spam shields max power at full warp, but they just dinna have the power! We're gonna have to evacuate to new forum software!
View user's profile View All Posts By User
hissingnoise
International Hazard
*****




Posts: 3923
Registered: 26-12-2002
Member Is Offline

Mood: Pulverulescent!

[*] posted on 25-9-2017 at 11:39


Quote:
At a large Canadian producer of azeotropic nitric acid, c. hydrogen peroxide is used to decolorize their products and remove dissolved NOx.

Down with dilution by water and down with losses of fixed nitrogen, I say!


View user's profile View All Posts By User
Melgar
Anti-Spam Agent
*******




Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline

Mood: Estrified

[*] posted on 26-9-2017 at 19:46


Quote: Originally posted by hissingnoise  
Quote:
At a large Canadian producer of azeotropic nitric acid, c. hydrogen peroxide is used to decolorize their products and remove dissolved NOx.

Down with dilution by water and down with losses of fixed nitrogen, I say!



So you're saying that's a good thing that they're doing, since the H2O2 appears to oxidize NOx gases back to nitric acid?

Urea can be hydrolyzed to ammonia and CO2 in an acidic environment, right?




The first step in the process of learning something is admitting that you don't know it already.

I'm givin' the spam shields max power at full warp, but they just dinna have the power! We're gonna have to evacuate to new forum software!
View user's profile View All Posts By User
hissingnoise
International Hazard
*****




Posts: 3923
Registered: 26-12-2002
Member Is Offline

Mood: Pulverulescent!

[*] posted on 27-9-2017 at 02:45


Forget H2O2 ─ even if you could use it at 100% conc., the water it produces significantly dilutes HNO3.


View user's profile View All Posts By User
Melgar
Anti-Spam Agent
*******




Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline

Mood: Estrified

[*] posted on 27-9-2017 at 06:05


Quote: Originally posted by hissingnoise  
Forget H2O2 ─ even if you could use it at 100% conc., the water it produces significantly dilutes HNO3.

So? Metal salts of the variety you use nitric acid to dissolve are all much less soluble in water than concentrated nitric acid is, so you'd have to dilute it anyway or you'd get metal nitrate crystals shielding the metal from further oxidation.




The first step in the process of learning something is admitting that you don't know it already.

I'm givin' the spam shields max power at full warp, but they just dinna have the power! We're gonna have to evacuate to new forum software!
View user's profile View All Posts By User
clearly_not_atara
International Hazard
*****




Posts: 1716
Registered: 3-11-2013
Member Is Offline

Mood: No Mood

[*] posted on 27-9-2017 at 12:27


Also dilute HNO3 is more efficient in some cases. Eg:

8 HNO3 (conc) + 2 Cu (s) >> 2 Cu(NO3)2 (aq) + 4 NO2 + 4 H2O

vs

8 HNO3 (aq) + 3 Cu (s) >> 3 Cu(NO3)2 (aq) + 2 NO + 4 H2O

Re-oxidation of nitric oxide by HNO3 results in loss of nitrogen, basically.
View user's profile View All Posts By User
Fleaker
International Hazard
*****




Posts: 1232
Registered: 19-6-2005
Member Is Offline

Mood: nucleophilic

[*] posted on 1-10-2017 at 06:45


Quote: Originally posted by hissingnoise  
Forget H2O2 ─ even if you could use it at 100% conc., the water it produces significantly dilutes HNO3.




For industrial purposes this "significant" dilution is absolutely meaningless. Every bit I've bought from commercial suppliers at work has been colorless and ranged from 66-68 wt % but was all called 42 deg Baume.




Neither flask nor beaker.


"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
View user's profile View All Posts By User
Pulverulescent
International Hazard
*****




Posts: 792
Registered: 31-1-2008
Member Is Offline

Mood: Torn between two monikers ─ "hissingnoise" and the present incarnation!

[*] posted on 1-10-2017 at 07:39


Quote:
Every bit I've bought from commercial suppliers at work has been colorless and ranged from 66-68 wt % but was all called 42 deg Baume

Well yeah, the azeotrope is what's commonly available from ammonia oxidation but WFNA is often more desirable...




"I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones"

A Einstein
View user's profile View All Posts By User
Sulaiman
International Hazard
*****




Posts: 2760
Registered: 8-2-2015
Location: UK ... on extended Holiday in Malaysia
Member Is Offline


[*] posted on 1-10-2017 at 11:32


About 10 months ago, in a >250ml clear glass bottle, I stored c100ml RFNA that I distilled from H2SO4 plus Ca(NO3)2
I thought that the NO2 would 'vanish' due to leakage and oxidation by the atmosphere ... wrong.
My HNO3 looks exactly as it did 10 months ago.
In the intervening time I used a little to attempt the nitration of cellulose
... almost no residue on ignition, so for 'rough' nitrations etc. the NO2does not seem to be problematic,

I like the excess NO2 in solution and in the bottle headspace,
it warns me of its potential 'evilness' :)




CAUTION : Hobby Chemist, not Professional or even Amateur
(suffering from separation of me and my chemistry stuff)
View user's profile View All Posts By User
Fleaker
International Hazard
*****




Posts: 1232
Registered: 19-6-2005
Member Is Offline

Mood: nucleophilic

[*] posted on 1-10-2017 at 12:19


I have seen RFNA and anhydrous HF cause blistering of FEP bottles that they were stored in from gas diffusing through the polymer.

I have no need for RFNA or WFNA of that concentration. I will say this, in terms of skin damage, the difference between azeotropic HNO3 and RFNA is HUGE. Same deal with H2O2 (35% of commerce vs the 90% stuff), same deal with perchloric (70% vs near anhydrous), and so on.




Neither flask nor beaker.


"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
View user's profile View All Posts By User
 Pages:  1  2

  Go To Top