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Dissimilatory nitrate reduction to ammonium is a two step process, reducing NO 3 − to NO 2 − then NO 2 − to NH 4 +, though the reaction may begin with NO 2 − directly. [1] Each step is mediated by a different enzyme, the first step of dissimilatory nitrate reduction to ammonium is usually mediated by a periplasmic nitrate reductase.
When a solution of nitrate ions is mixed with aqueous sodium hydroxide, adding Devarda's alloy and heating the mixture gently, liberates ammonia gas. After conversion under the form of ammonia, the total nitrogen is then determined by Kjeldahl method. [7] The reduction of nitrate by the Devarda's alloy is given by the following equation: 3 NO −
Direct reduction from nitrate to ammonium, a process known as dissimilatory nitrate reduction to ammonium or DNRA, [6] is also possible for organisms that have the nrf-gene. [ 7 ] [ 8 ] This is less common than denitrification in most ecosystems as a means of nitrate reduction.
Ammonium nitrate is an important fertilizer with NPK rating 34-0-0 (34% nitrogen). [17] It is less concentrated than urea (46-0-0), giving ammonium nitrate a slight transportation disadvantage. Ammonium nitrate's advantage over urea is that it is more stable and does not rapidly lose nitrogen to the atmosphere.
The first step is the partial nitrification (nitritation) of half of the ammonium to nitrite by ammonia oxidizing bacteria: 2 NH + 4 + 3 O 2 → 2 NO − 2 + 4 H + + 2 H 2 O. The remaining half of the ammonium and the newly formed nitrite are converted in the anammox process to diatomic nitrogen gas and ~15 % nitrate (not shown) by anammox ...
[12] [13] Complete nitrification, the conversion of ammonia to nitrate in a single step known as comammox, has an energy yield (∆G°′) of −349 kJ mol −1 NH 3, while the energy yields for the ammonia-oxidation and nitrite-oxidation steps of the observed two-step reaction are −275 kJ mol −1 NH 3, and −74 kJ mol −1 NO 2 − ...
The term "calcium ammonium nitrate" is applied to multiple different, but closely related formulations. One variety of calcium ammonium nitrate is made by adding powdered limestone to ammonium nitrate; [1] [2] another, fully water-soluble version, is a mixture of calcium nitrate and ammonium nitrate, which crystallizes as a hydrated double salt: [3] 5Ca(NO 3) 2 •NH 4 NO 3 •10H 2 O.
The calcium nitrate mentioned before, can as said be worked up as calcium nitrate fertilizer but often it is converted into ammonium nitrate and calcium carbonate using carbon dioxide and ammonia. Ca ( NO 3 ) 2 + 2 NH 3 + CO 2 + H 2 O 2 NH 4 NO 3 + CaCO 3 {\displaystyle {\ce {Ca(NO3)2 + 2 NH3 + CO2 + H2O -> 2 NH4NO3 + CaCO3}}}