Sciencemadness Discussion Board - Nitrites to Nitrates

Nitrites to Nitrates

urenthesage - 12-5-2016 at 10:05

Hi, Im looking for a spot of help here. Nitrates are required for making nitric acid but alot of the major nitrate salts are on lists somewhere (because OKC amongst others). Meanwhile you can buy pounds of nitrites off of ebay for curing meat. Is there a simple process that converts nitrites to nitrates via chemistry (all I can find is biological processes)?. If so, does the process scale up to larger volumes?

hissingnoise - 12-5-2016 at 10:50

Quote:

Meanwhile you can buy pounds of nitrites off of ebay for curing meat.

Ebay has sodium and potassium nitrate!

XeonTheMGPony - 12-5-2016 at 11:00

and vast majority hard ware stores have potassium nitrate, they just call it stump remover!

urenthesage - 13-5-2016 at 07:18

Mabee where you live but potassium nitrate of almost all other nitrates have been removed from store shelves or replaced by metabisulfites here in Ontario Canada. Ive looked. Even an old haunt that used to sell the KNO3 for toothaches had to pull it off the shelf. I was able to import some calcium ammonium nitrate and I can probably make what I need from that , but I still want to know how to convert NO2's to NO3's incase that road closes too.

woelen - 13-5-2016 at 09:51

One way to convert nitrites to nitrates is to add dilute warm acid to the nitrite and bubble the gas through water, while also adding air.

NaNO2 gives a mix of NO and NO2 when acid is added. The NO + NO2 escape the liquid. NO is oxidized by oxygen from air to NO2.

When the brown NO2 gas is passed through water, then you get a solution of HNO3 and NO escapes from the liquid. The NO can be oxidized by oxygen from air and then the resulting NO2 also needs to be dissolved. So, if you mix the NO2/NO mix with excess air and bubble this through a long column of water, nearly all of the NO/NO2 can be dissolved, together with O2 to get HNO3. In this way you can get dilute HNO3. The more concentrated the solution gets, the more difficult the reaction of NO2 with water. I think that you can get 5 to 10% HNO3 in this way, not much better. But this concentration is enough to concentrate. By adding NaOH or KOH you can make nitrate and by letting the water evaporate you can get the pure solid nitrate salt.

Boffis - 14-5-2016 at 05:12

I will be the first to admit that I have no idea if this idea will work but how about oxidizing sodium nitrite with sodium hypochlorite bleach? I would envisage something along the lines of mixing fresh bleach, which is a mixture of mainly sodium hypochlorite, sodium hydroxide and salt, with a solution of sodium nitrite and boil. Cool and neutralise with hydrochloric acid and then add potassium chloride solution, evaporate down and crystallise. There is a lot of literature on the seperation of sodium chloride from potassium nitrate as this was once the main method if making potassium nitrate from Chile saltpeter.

Further more, would dilute hydrogen peroxide oxidize nitrite (it may reduce it to nitrogen and oxygen!). If it will it may still require pH adjustment to get the right outcome.

However, if you can get calcium ammonium nitrate, how about simply boiling it with excess ammonium carbonate to precipitate the calcium as carbonate. You can then filter and either evaporate down to get ammonium nitrate or treat with an appropriate alkali hydroxide to get that nitrate and ammonia which can be distilled off.

clearly_not_atara - 14-5-2016 at 09:32

H2O2 + NO2- >> H2O + ONO2- (peroxynitrite)

ONO2- + CO2 >> ONO2CO2-

ONO2CO2- >> NO2* + CO3-*

NO2* + CO3-* >> NO3- + CO2

http://en.wikipedia.org/wiki/Peroxynitrite

H2O2 converts nitrite to peroxynitrite. CO2 catalyzes the decomposition of peroxynitrite to nitrate. Some peroxodicarbonate may form as a byproduct.

Boffis - 14-5-2016 at 13:18

@clearly; that's a really interesting reaction. I wonder if you could make it work by mixing sodium nitrite, sodium bicarbonate and hydrogen peroxide. If not external CO2 isn't too difficult and probably makes for a cleaner work-up.

On my other thought, I found this:
http://www.sciencedirect.com/science/article/pii/S0045653502...

This article is about the kinetics of the hypochlorite oxidation of nitrite so it is clearly possible. So the OP now has three possible OTC route to the process of turning nitrites into nitrates.

AJKOER - 14-5-2016 at 16:08

Quote: Originally posted by clearly_not_atara

H2O2 + NO2- >> H2O + ONO2- (peroxynitrite)

ONO2- + CO2 >> ONO2CO2-

ONO2CO2- >> NO2* + CO3-*

NO2* + CO3-* >> NO3- + CO2

http://en.wikipedia.org/wiki/Peroxynitrite

H2O2 converts nitrite to peroxynitrite. CO2 catalyzes the decomposition of peroxynitrite to nitrate. Some peroxodicarbonate may form as a byproduct.

Actually, a more direct path starting with an aqueous nitrite is to treat the solution with the output from an ozonizer via the reaction:

O3 + NO2- = O2 + NO3-

Source: See, for example, http://www.ncbi.nlm.nih.gov/pubmed/8185875

Or, based on more recent (2010) research, the products include primarily nitrate and singlet oxygen (96% yield). See http://www.tandfonline.com/doi/abs/10.1080/01919512.2010.522...

I would also expect employing ultrasound woud improve yield based on results with dissolved air in water. See http://www.sciencedirect.com/science/article/pii/S1350417799... . I would also try with this path adding CO2, as Singlet oxygen forms H2O2 with water.

[Edited on 15-5-2016 by AJKOER]

Boffis - 14-5-2016 at 20:38

@Ajoker, you can by 30 vols (9%) H2O2 and 5% sodium hypochlorite at my local supermarket, not so ozone or ozonizers. I don't doubt it works but...

AJKOER - 15-5-2016 at 03:34

Here is a list of price ranges https://www.google.com/search?q=ozonizer&prmd=sivn&s... for ozonizers. Assuming one invests $34 that the cost of 4 bottles of 9% H2O2 and we are not tallying the cost of generating CO2.

Whatever other use you find for the ozonizer is a bonus.

With respect to employing NaOCl directly, one may find the presence of added NaCl problematic in the final NaNO3 product depending on use.

Boffis - 15-5-2016 at 05:55

@Ajoker; look at the spec for those machine, the expensive "industrial" machine generate only 1.25g of ozone per hour thats equivalent to about 2.2 g of sodium nitrate per hour if the process is 100% efficient at every stage.

With the hydrogen peroxide route, 9% H2O2 cost about £38 for 25L here "cash-n-collect" and you only need catalytic amounts of CO2, probably just enough to saturate the solution. So if I dissolve solid nitrite in the say 8 L of peroxide in a 2 gallon bucket, I could handle about 1kg of sodium nitrite at a time even allowing for nearly 50% excess of peroxide.

The bleach route is a little trickier; however, 4.5% bleach at the local supermarket is 48pence (about 70 cents) for 2 L, say 90g of sodium hypochlorite. This should oxidize about 80g of sodium nitrite to about 100g of nitrate. The work-up would be a little more complex as I alluded to above but there is plenty of published data if you go to the KCl route.

urenthesage - 15-5-2016 at 09:32

Quote: Originally posted by Boffis

I will be the first to admit that I have no idea if this idea will work but how about oxidizing sodium nitrite with sodium hypochlorite bleach? I would envisage something along the lines of mixing fresh bleach, which is a mixture of mainly sodium hypochlorite, sodium hydroxide and salt, with a solution of sodium nitrite and boil. Cool and neutralise with hydrochloric acid and then add potassium chloride solution, evaporate down and crystallise. There is a lot of literature on the seperation of sodium chloride from potassium nitrate as this was once the main method if making potassium nitrate from Chile saltpeter.

I might try this. I found a source of saltpeter but I may have fun with some nitrites just to learn more about how they react. Thanks for the suggestions.

Further more, would dilute hydrogen peroxide oxidize nitrite (it may reduce it to nitrogen and oxygen!). If it will it may still require pH adjustment to get the right outcome.

However, if you can get calcium ammonium nitrate, how about simply boiling it with excess ammonium carbonate to precipitate the calcium as carbonate. You can then filter and either evaporate down to get ammonium nitrate or treat with an appropriate alkali hydroxide to get that nitrate and ammonia which can be distilled off.

urenthesage - 15-5-2016 at 09:33

Quote: Originally posted by urenthesage

Quote: Originally posted by Boffis

OOPS, my mesage is after the first paragraph.

urenthesage - 15-5-2016 at 09:55

Quote: Originally posted by Boffis

@Ajoker; look at the spec for those machine, the expensive "industrial" machine generate only 1.25g of ozone per hour thats equivalent to about 2.2 g of sodium nitrate per hour if the process is 100% efficient at every stage.

With the hydrogen peroxide route, 9% H2O2 cost about £38 for 25L here "cash-n-collect" and you only need catalytic amounts of CO2, probably just enough to saturate the solution. So if I dissolve solid nitrite in the say 8 L of peroxide in a 2 gallon bucket, I could handle about 1kg of sodium nitrite at a time even allowing for nearly 50% excess of peroxide.

The bleach route is a little trickier; however, 4.5% bleach at the local supermarket is 48pence (about 70 cents) for 2 L, say 90g of sodium hypochlorite. This should oxidize about 80g of sodium nitrite to about 100g of nitrate. The work-up would be a little more complex as I alluded to above but there is plenty of published data if you go to the KCl route.

Im lucky enough to be able to buy 30%H2O2 hassle free, so Ill adjust my amounts to match, but yes Ill definately give it a try.

Boffis - 15-5-2016 at 10:25

@urenthesage, If you use 30% H2O2 I would dissolve the sodium nitrite in water, mix in the peroxide diluted with some water in a heavy glass bottle for the first attempt until you see how it goes, cool to below freezing to increase the solubility CO2 in the solution and bubble in CO2, or add a litle hydrochloric acid and some bicarbonate of soda and then screw down the lid to keep the CO2 in. I have no idea if the reaction is rapid or exothermic so let us know how you get on!

AJKOER - 15-5-2016 at 16:47

I believe a significant benefit from my ozone/air treatment on carbonated aqueous nitrite can be achieve by introducing strong sunlight into the process. This is based on my examination of the photolysis of just an O2 and CO2 rich nitrite solution, from which I suspect the eventual creation of a predominately nitrate solution.

First, we have the photolysis products of aqueous nitrite and future nitrate:

NO2- + H2O + hv → NO + OH· + OH-
NO3- + H2O + hv → NO2 + OH· + OH- (around 100 times slower than nitrite reaction above)

Reference: https://books.google.com/books?id=RAJMmvbfyzgC&pg=PA383&...

Then, the oxidation of the formed NO from the photolysis of aqueous nitrite with air bubbles:

Reaction: NO + O2 + NO → .NO2 + .NO2

Solvent: H2O, k = 2.3 × E06(L2 mol−2 s−1), pH = 7.0

Reference: Mayer, B.; Klatt, P.; Werner, E.R.; Schmidt, K. , J. Biol. Chem. 270, 655-659 (1995)

Next, the creation of the carbonate radical anions from the photolysis produced hydroxyl radicals and the interaction of CO2 and water forming largely the bicarbonate ion:

CO2 + H2O → HCO3- + H+
OH· + HCO3- → H2O + CO3·- (see https://www3.nd.edu/~ndrlrcdc/Compilations/Hydroxyl/OH__21.H... )

Next, reaction of nitric oxide with carbonate radical anion, regenerating the nitrite:

Reaction: .NO + CO3·− → CO2 + NO2−
Solvent: H2O, k = 3.5 × E09(L mol−1 s−1), T = 296K

Source: Czapski, G.; Holcman, J.; Bielski, B.H.J. J. Am. Chem. Soc. 116, 11465-11469 (1994), link: https://www3.nd.edu/~ndrlrcdc/Compilations/Ino/INO_745.HTM

Also, the reaction of any formed nitrogen dioxide with carbonate radical anion:

Reaction: CO3·− + .NO2 → CO2 + NO3−
Solvent: H2O, k = 1.0 × E09(L mol−1 s−1), pH ~11

Source: Lilie, J.; Hanrahan, R.J.; Henglein, A. , Radiat. Phys. Chem. 11, 225-227 (1978)

This last reaction preserves existing nitrate and any recently formed NO2 (from the action of oxygen on NO).

So, even with a poor quality ozone generator, the action of air and sunlight alone on the CO2 rich aqueous nitrite mix may increase nitrate yield.

[Edit] If my supposition is correct, then there should be a reference that this photolytic conversion of nitrite should be observed in natural waters with sunlight. There is, see https://books.google.com/books?id=RAJMmvbfyzgC&pg=PA383&...

[Edited on 16-5-2016 by AJKOER]

yobbo II - 16-5-2016 at 05:35

Could the nitrites be converted to nitrates by popping in an anode (mmo say) and running power?
Electricity is a cheap (otc as it were) source of oxidization.

[Edited on 16-5-2016 by yobbo II]

Boffis - 17-5-2016 at 16:20

@yobbo; probably but I don't know much about electro chemistry but it seems reasonable. I don't see any reason why with a divided cell and the right electrodes it wouldn't work.

Eddygp - 18-5-2016 at 03:18

Oxidation of the nitrite with H2O2 under a CO2 atmosphere (and/or bubbling CO2 through it), with stirring, should do the trick. CO2 is rather readily available in small gas canisters.

EDIT: clarifying ox agent

[Edited on 18-5-2016 by Eddygp]

woelen - 18-5-2016 at 03:59

CO2 used as oxidizer for nitrite? I do not expect any reaction.

Eddygp - 18-5-2016 at 05:10

Quote: Originally posted by woelen

CO2 used as oxidizer for nitrite? I do not expect any reaction.

Not as an oxidiser. Refer to a previous comment, use H2O2 as an oxidiser and CO2 catalyses the isomerisation of peroxynitrite to nitrate.

woelen - 18-5-2016 at 06:04

OK, after the edit of your post it is clear to me.
I, however, think that it hardly is necessasry to use CO2 as catalyst.
I once experimented with H2O2, added to nitrite solutions, just for experimenting with the peroxynitrite ion. In my experience, this ion isomerizes to nitrate very quickly, within seconds. I could not do any experiments with peroxynitrite, all of it was converted to nitrate before I could do something interesting with it. I could observe a transient orange/red color though, when the solutions were freezingly cold.

[Edited on 18-5-16 by woelen]