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clearly_not_atara
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| 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]
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Fleaker
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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
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Melgar
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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!
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hissingnoise
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| Quote: | At a large Canadian producer of azeotropic nitric acid, c. hydrogen peroxide is used to decolorize their products and remove dissolved NOx.
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Down with dilution by water and down with losses of fixed nitrogen, I say!
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Melgar
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| 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.
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Down with dilution by water and down with losses of fixed nitrogen, I say!
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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.
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hissingnoise
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Forget H2O2 ─ even if you could use it at 100% conc., the water it produces significantly dilutes HNO3.
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Melgar
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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.
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clearly_not_atara
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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.
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Fleaker
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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
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Pulverulescent
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| 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
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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
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Sulaiman
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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
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Fleaker
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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
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