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Author: Subject: electroreduction of NO3- to NO2-?
silonyl
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[*] posted on 18-2-2006 at 19:00
electroreduction of NO3- to NO2-?


I'm not so good with electrochemistry, and searching didn't yield much on this topic. I'm interested in the possibility of electrolytic reduction of ionic nitrates, either in solution or in the melt, to ionic nitrites. Is this a reasonable idea?
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silonyl
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[*] posted on 18-2-2006 at 19:41


I suppose I should have been more specific: I'm interested in the feasibility of the specific reduction of nitrate to nitrite without significant further reduction to lower oxides of nitrogen (or to dinitrogen). I know electrode materials can significantly affect the reaction pathways, but I don't have a good understanding of how, so any insights would be appreciated.
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12AX7
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[*] posted on 18-2-2006 at 21:11


Hum... I know Al and Mg (metal) tend to reduce NO3- to NH3, in the absence of dichromate or boric acid buffer. That's too far, so mebbe you can add some acid and do a metal+HCl reduction thing (Fe or Zn)?

Electrically you should be able to do the same thing in the cathode electrolyte, but that would turn basic while the anode grabs up the nitrate ions...

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The_Davster
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[*] posted on 18-2-2006 at 22:27


I have accidently reduced nitrate to ammonia during an electrolysis, I should have tested the solution after for nitrite, it did not even occur to me then. It might be somewhere to start at least...

Checked a couple of books, see the attachment for a relavent excerpt from "the Manufacture of Chemicals by Electrolysis"

nitrite from nitrite via electrolysis.JPG - 96kB




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woelen
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[*] posted on 20-2-2006 at 12:36


I have done a lot of experimenting with electrolysis of KNO3 to see if I can get nitrite at the cathode, but all was in vain. I obtained NH3 (smell) and gas bubbles (I think H2 and maybe some N2). Now I understand what I did wrong. I used concentrated solutions and this .JPG talks about 2.3 grams of NaNO3 per litre. That is a very low concentration. I did experiments with copper wire, thin silver wire and also with aluminium strips. All experiments were without success.

From all this information I conclude that making nitrite electrolytically hardly is interesting. It is a hell of a job to isolate the small amounts of nitrite from such a dilute solution and the nitric acid formed also is a problem (it decomposes nitrite easily).

Luckily I have no need to go through all this trouble anymore :). I bought a kilo of NaNO2 for just $12.50 (excl. international overseas shipping). To thrustworthy members of this forum I'm willing to U2U the address for the source. No responses to SWIM and Co :D.

[Edited on 20-2-06 by woelen]




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Madandcrazy
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[*] posted on 4-3-2006 at 09:15


Hmm,

interested -NO3 to NO2 per electroreduction.
I know for instance NaNO2 is produced when NaNO3 is molten with lead to PbO and NaNO2 in the calculated amounts and for two hours stirred, the NaNO2 is separated with H2O from the PbO.

Maybe interrested to the topic is when the ammonium chloride is splitted per electrolysis to produce dilute ammonium hydroxide and HCl (NH3 and Cl2).

[Edited on 5-3-2006 by Madandcrazy]
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cabrero
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[*] posted on 1-12-2006 at 08:57


NO3- is electroactive in the cathode (Ni, Cu, Fe....and many others) , to get diverse reaction products; you can change Temperature and intensity (voltage) to obtain NH3, N2, oxides of nitrogen, ...
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