Get rid of NOx fumes and get stronger nitric acid

[Noxx]

The real patent title is Metal dissolution Process but the patents speaks about how to prevent evolution of NOx gases. By adding Hydrogen Peroxide, the gases redissolve in your solution and make new nitric acid ! :lol:

VERY interesting.

 

[scavenger]

Hi Noxx, I know that low percent peroxide will kill HCL fumes but I read somewhere that peroxide was incompatible with nitric. I couldn't understand why it wasn't but I didn't want to risk it. If u have tested this please share the results. Cheers Dave

 

[goldsilverpro]

Noxx,

I worked some numbers out for you.

This system is claimed to work on all "mineral acid solutions of nitric acid".
This would be any nitric solution that put out brown fumes - aqua regia, 50/50 nitric acid, etc. It probably will work on HCl/sodium nitrate.

In the examples given, it shows that, for each gram of copper dissolved, in whatever solution, it will require 2.4 - 3.4 mL of 30% hydrogen peroxide (H2O2) to totally suppress the fumes. For 35% H202, it will take 2.1mL - 2.9 ml per gram of copper.

If the H2O2 levels are maintained at the solution make-up level, the acid will be twice as efficient. Instead of it taking 1 gallon of 50/50 nitric to dissolve 1# of copper, it will only take 1/2 gallon.

With no preservative, the H2O2 decomposes quickly, especially in the presence of copper. To combat this, ethylene glycol (common anti-freeze) is used as a preservative.

Experiment! I would first try a small piece of copper in aqua regia, just to get the hang of it. Graduate to gold later. Weigh it before and during and after, to figure out how fast the copper is dissolving and how much H2O2 is being used up.

Use a fume hood, even though there's not supposed to be any fumes. Like anything else, anti-freeze is poisonous. It's especially dangerous around small children and dogs, because they like the sweet taste of it.



STARTING FORMULA FOR 1000 mL OF SOLUTION:

This starting formula is for 1000 mLs to make it easy. If you only make 100 mLs, divide everything by 10.

The acid solutions with the additives, should work the same as without the additives. If fact it may work faster, with all that oxygen from the H2O2 present.

(1) 57 mL of 30% H2O2 or, 49 mL of 35% H2O2. Using 3% H2O2 (570 mL) might add so much water that the acid performs too poorly. However, 3% may work for certain metal combinations.

(2) 22mL of the old standard, green, ethylene glycol anti-freeze. Read the label to make sure it's only ethylene glycol. The EG is probably stable and won't need replenished.

(3) The remainder is either aqua regia, 50/50 nitric, or HCl/sodium nitrate.

The solution could be heated, if desired.

You should use enough copper, in several small batches, to require you to replenish the H2O2. It would be be best to break up the H2O2 additions into increments. I don't know what would happen if you added too much peroxide

For a large setup, I would continously meter the peroxide in with a peristaltic chemical metering pump.

I would start with copper first. Then, silver. Finally, karat gold. I would also try the HCl/sodium nitrate.

Keep records! Write down your observations. Collect and compare data.

 

[Noxx]

Thanks very much for this informations.

Will be very useful !

 

[lazersteve]

Noxx,

Be very careful with ethylene glycol and oxidizers. Here are a few MSDS for you:

Two MSDS

Be sure to read these thoroughly.

Steve

 

[Noxx]

Thanks Steve.
But I think I'll use Glycerin instead.

 

[aflacglobal]

What's the chemistry behind that chris. Chain of event wise.

 

[Noxx]

The H2O2 makes the gases to redissolve in the solution thus not having any NOx fumes and making new nitric acid.

Why does it do that ? No idea.

 

[aflacglobal]

How about a little cheaper Yet :idea:

Oh here he goes again. :wink:

How about capturing the fumes, subject them to Ozone and passing them thru cold water until the concentration build up :?:

Will it work :?:

http://www.fas.harvard.edu/~scdiroff/lds/Geophysics/SmoginaBottle/SmoginaBottle.html

 

[goldsilverpro]

Here's another patent on the subject, #3367874.

This patent's purpose is to mainly speed up the dissolving of base metals in nitric acid. He uses 80/20 nitric acid, or higher. He could have gone faster if he had started with 50/50 nitric or, added a little heat, but, I guess he didn't think of these things.

The speed of the dissolving was increased by adding small amounts (about 1 gram/liter) of urea and sulfamic acid. In the chart, it also mentions using urea alone. Sulfamic acid is a fairly common white powder and, as far as I know, it is fairly inexpensive. Like all of the things we use, it has it's dangers - read the MSDS. I have used it a lot. An old Bureau of Mines Report of Investigation used it to dissolve silver solder from jet airplane flaps. It was used electrolytically, like strong sulfuric but, safer. I can't remember how much silver is on a set of flaps but, the number, several 100's of ounces, sticks in my head.

At page 2, lines 37 thru 46, of the patent, it says that the "evolution of oxides of nitric is substantially prevented". To do this, it would have to perform the same function as the hydrogen peroxide. This is sort of an afterthought in the patent but, for us, it's the only important thing.

To me, the H2O2 patent, discussed in the above posts, is not very practical. The more I study it, the more I think that heat will decompose the H2O2 very rapidly, no matter how much glycol or other preservative is used. And, a lot of heat is generated by the dissolving action. I think you will need enormous amounts of, not cheap, 35% H2O2.

Were I you, I would play around with urea, at about 1 gram/liter ( the patent says from .05 to 10 gms/liter), in the following solutions: aqua regia, 50/50 nitric, and HCl/sodium nitrate. Watch and see if any brown fumes are evolved. If it works but, not 100%, try to get hold of some sulfamic acid. In the patent, the best results came from using both urea and sulfamic acid, at the same time and of the same strength. Also, since these chemicals speed up the reaction, you should watch the acid additions and metal additions, in order to avoid foamovers.

 

[lazylightning]

Thanks Steve.
But I think I'll use Glycerin instead.

:roll: gee guys, this is a no brainer, aren't you afraid to get a little nitro in that mix? ethylene glycol is the contemporary substitute for glycerin in making nitro. That's cause the glycerin is way too unstable to sensibly make nitro, and becomes even more unstable at about 13.5 C when it begins to freeze-half frozen. If it goes up to 20 C then it starts giving off nitric tetroxide, decomposing, and can explode at any moment. The ethylene glycol will start to do the same at slightly higher temps though it doesn't have a problem with freezing. Better do that one outside with goggles. :wink:

 

[peter i]

Production of nitroglycole requires concentrated nitric acid and an extra addition of concentrated sulphuric acid to absorb the water present in the nitric acid. Unless the acids ar concentrated, no significant amount of nitro-compound is produced.

(This is mentioned on regular intervals, now it became my turn to do it)

 

[dallasgoldbug]

Also, very impressive work, keep it up.

DallasGoldBug

 

[goldenchild]

I have tried this and confirmed it works. My vid is under Learning>Tutorials Questions/Comments>"NOx supression and nitric recycling confirmed!"

Enjoy :mrgreen:

 

[leavemealone]

:shock: :shock: :shock:
I revived a 1 year old thread once and I know that was a record.But I think goldenchild just smashed the h*ll out of that record.
Johnny

 

[Irons]

How about a little cheaper Yet :idea:

Oh here he goes again. :wink:

How about capturing the fumes, subject them to Ozone and passing them thru cold water until the concentration build up :?:

Will it work :?:

http://www.fas.harvard.edu/~scdiroff/lds/Geophysics/SmoginaBottle/SmoginaBottle.html

Actually, it's a lot easier than that. Plain old O2 will oxidize the NO to NO2. The NO2 combines with water vapor in a refluxer and they condense into Nitric acid. All you have to do is provide a continuous flow of Oxygen to the reactor and the Nitric Acid keeps being regenerated. The best part is that it doesn't add any additional water to the reaction.All you need then, is to feed in some HCl vapor to top it off. :idea:

 

[samuel-a]

i have done a little test of my own:

8.5 ml 70% nitric
8.5 ml 3% H2O2
8 grams of mixed pins

no heat.

result:
in one hour the reaction ceased, dissolving 3.5 grams of the pins.
no NOx gasess was visible, only when beaker disturbed and shaken.

i guess with silver, much more metal wlould ehve gone into solution...

anyway, just thought i will share with you

 

[philddreamer]

Hi samuel_a!

I have a question. By add'n H2O2 the nitric stays in the solution instead of losing it in red fumes? No need to distil?

 

[samuel-a]

Hi samuel_a!

I have a question. By add'n H2O2 the nitric stays in the solution instead of losing it in red fumes? No need to distil?

as i understand it, NOx that forms in stu by the reaction with the metals is dissolving back by the H2O2 until it consumes all of the peroxide.

 

[philddreamer]

Thank you!