kemster90 - 6-1-2016 at 02:31
Can it be made with hydrogen peroxide using an iron sulfate catalysis to form hydroxyl radical to oxidize the ammonium hydroxide to ammonium nitrite
[Edited on 1-6-2016 by zts16]
MeshPL - 6-1-2016 at 06:12
I'm not sure, but I think hydrogen peroxide will oxidise nitrites to nitrates.
Bert - 6-1-2016 at 07:44
Might want to look at some pre-existing nitrite threads-
http://www.sciencemadness.org/talk/viewthread.php?tid=52&...
AJKOER - 7-1-2016 at 13:14
Not Iron based Fenton reaction, but, in my opinion, a Copper based Fenton-like reaction which I recently discussed at https://www.sciencemadness.org/whisper/viewthread.php?tid=64... to account for the apparent nitrite formation (cited in the referenced source) and
my observed decomposition of a nitrite releasing nitrogen gas as a side reaction. The addition of NaOH may stabilize the nitrite and permit a low
yield harvest.
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There is also another personally untested path with respect to yield based on a possible photolysis of an aqueous nitrate salt. As a reference see,
for example, "Quantum Yields of Hydroxyl Radical and Nitrogen Dioxide from the Photolysis of Nitrate on Ice" by Liang Chu and Cort Anastasio, 2003.
Per the abstract to quote:
"Nitrate photolysis proceeds via two major channels at illumination wavelengths above 290 nm: NO3- + hv (+ H+) → NO2 + .OH (1) and NO3- + hv →
NO2- + O(3P) (2)"
where the second equation is described as a minor reaction. Source link: https://www.google.com/url?q=http://scholar.google.com/schol...
A more recent article, "Solutions: The Role of Peroxynitrite, Nitrogen Dioxide, and Hydroxyl Radical" by Sara Goldstein and Joseph Rabani, 2007. To
quote:
"Photolysis of aqueous NO3- with λ ≥ 195 nm is known to induce the formation of NO2- and O2 as the only stable products. The mechanism of NO3-
photolysis, however, is complex, and there is still uncertainty about the primary photoprocesses and subsequent reactions. This is, in part, due to
photoisomerization of NO3- to ONOO- at λ < 280 nm, followed by the formation of •OH and •NO2 through the decomposition of ONOOH (pKa =
6.5−6.8). Because of incomplete information concerning the mechanism of peroxynitrite (ONOOH/ONOO-) decomposition, previous studies were unable to
account for all observations. In the present study aqueous nitrate solutions were photolyzed by monochromatic light in the range of 205−300 nm. It
is shown that the main primary processes at this wavelength range are NO3- +hv → •NO2 + O•- (reaction 1) and NO3- + hv → ONOO- (reaction 2). "
Link: http://pubs.acs.org/doi/abs/10.1021/ja073609+
I am assuming that any released NO2 gas is captured (perhaps using a thin plastic wrap so as not to reduce uv exposure) and dissolved via the
reaction:
2 NO2 + H2O = HNO2 + HNO3
to produce a mixture of nitrite and nitrate.
Yield versus time is the question, and I suspect, any formed nitrite may be subject to further reaction. For example, in the gas phase in presence of
water vapor:
NO2 + hv → •OH + NO
But in the presence of more NO2 and water:
NO + NO2 + H2O → 2 HNO2
I would make the nitrate source alkaline with NaOH to promote the stability of the nitrous acid/nitrite. Nevertheless, some nitrite could be loss as
in the aqueous phase:
NO2- + •OH → OH- + NO2 (source: https://www.researchgate.net/publication/222022843_Photochem... )
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Here is a link discussing a not recommended route noted among researchers as unsafe with falling pH, https://www.sciencemadness.org/whisper/viewthread.php?tid=63... , best avoided.
[Edited on 8-1-2016 by AJKOER]