plante1999 - 13-5-2011 at 16:49
I have read that urea + sodium hydroxide make sodium carbonate and ammonia , but i have a question , how can i convert the ammonia to nitrate ion.
I said this because already last month i can buy ammonium nitrate from instan cold pack but now i can only buy urea as a source of nitrogen.
[Edited on 14-5-2011 by plante1999]
hyperkinetic - 13-5-2011 at 17:06
Are you thinking of the Ostwald process?
http://en.wikipedia.org/wiki/Ostwald_process
plante1999 - 13-5-2011 at 17:11
Yes , but for the catalisor does any other than Pt work ,i was thinking of new ceramic catalisor like Cr2O3, does anyone have tried the process?
redox - 13-5-2011 at 17:12
Are you asking how to convert ammonia to ammonium nitrate? Or are you asking how to convert ammonia gas to nitrate ion?
If it is the first, simply bubble ammonia into nitric acid.
If it is the second, the Ostwalt process could suffice. Burn ammonia in oxygen over platinum and rhodium catalysts, yielding nitric oxide and water.
The nitric oxide is further oxidized to nitrogen dioxide, which is dissolved in water or hydrogen peroxide. This then produces nitric acid, albeit
weak.
Distillation will concentrate to the 70% (?) azeotrope.
hyperkinetic - 13-5-2011 at 17:54
Google says:
"The kinetics of ammonia oxidation over oxides of manganese, cobalt, copper, iron and vanadium have been studied. The proposed reaction mechanism
involves oxygen adsorption (oxidation of the catalyst surface) and reduction of the surface with ammonia to form the reaction products. The latter
step consists of several stages involving the intermediate formation of nitroxyl and imide species. The interaction of imide with nitroxyl leads to
nitrogen while the reaction between two nitroxyls results in nitrous oxide. For this model rate equations have been deduced which describe the overall
process and the parallel reactions of the formation of N2 and N2O. These equations are shown to be in accordance with the experimental data obtained.
It has been found that the selectivity in mild oxidation (N2 formation) decreases and the selectivity in deep oxidation (N2O formation) grows with an
increase in the surface coverage with oxygen θ. The values of θ increase with the ratio of partial pressures of O2 to NH3 (PO2/PNH3) in the
reaction mixture. The governing role of θ has been supported by experiments in which catalysts were reduced with ammonia in the absence of O2 in
the gas phase.
The reaction mechanism involving the formation of N2, N2O and NO is also considered. The corresponding rate equations have been derived, and the
expected dependence of specificity on the reaction mixture composition and temperature has been examined."
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi...
That should be about as easy as purifying magnesium with a fractional still. 
Edit: There are threads on urea to Nitrate attempts
http://www.sciencemadness.org/talk/viewthread.php?tid=3986#p...
http://www.sciencemadness.org/talk/viewthread.php?tid=133#pi...
[Edited on 14-5-2011 by hyperkinetic]
mnick12 - 13-5-2011 at 19:20
There are some species of nitro and nitrosobacter which are able to use urea directly as their nitrogen source instead of ammonia. I use a pet store
brand of aquarium microorganisms to make yummy nitrate water from ammonia and molasses for my hydroponic system. It is really simple the only thing
you have to take into account is the size of your system, the PH ( usually around 7.5-8.5) and ammonia %. Then all you do is add an airstone and a
couple ml of bacteria solution and in about a day all the ammonia is converted into nitrate.
bacteria rule!
Melgar - 16-5-2011 at 20:13
Yeah, I did this once with bacteria scraped from the bottom of my trash can and pee. Crude potassium nitrate, for way too much effort! Also, I got a
platinum/rhodium thermocouple wire from omega.com, and heated it up, then put it above a really concentrated ammonia solution. It glowed red for a
few minutes and converted a bunch of the ammonia to nitrate. I evaporated the solution and got a little bit of ammonium nitrate, again for way too
much effort. Gas-phase reactions blow. 
Later, I wised up and just bought a couple pounds of KNO3 off eBay, then mixed it with H2SO4 from a hardware store (the drain opener that is
double-sealed in jug inside a plastic bag) and distilled off the nitric acid.
[Edited on 5/17/11 by Melgar]
AJKOER - 19-5-2011 at 15:34
I found a recent paper that discusses the oxidation of urea to nitrates using KMnO4:
"A NOVEL METHOD FOR SYNTHESIS OF Cr2O3, MnO2, MoO3 AND WO3"
by Maomen S. Refat, Sadeek and Sadr
ABSTRACT:
"Cr2O3, MnO2, MoO3 and WO3 oxides were synthesized by a new reaction of urea with (K2CrO4 or K2Cr2O7),
KMnO4, Na2MoO4 and Na2WO4, respectively, in an aqueous media at ~ 85 oC. Infrared spectra, X-ray powder diffraction,
and microanalysis of the solid products, indicate the absence of urea, and the presence of oxides. A general
mechanism describing the formation of oxides and decomposition of urea is suggested."
A basic reaction of possible interest in our case is:
2KMnO4 + CH4N2O --> K2CO3 + 2MnO2 + NH3 + NO2 + 1/2H2
See threads on preparing KMnO4.
Again more work than necessary, but at least educational.
Attachment: NH3OXISNO2BYK2CR2O7.pdf (252kB)
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