# Rejuvinating Nitric



## Joe (Sep 23, 2007)

How do I recycle Nitric Acid? I've read through most of the posts, but I am still a little unclear. I hope I am not duplicating a previous post.

Bubbler-putting a fish bubbler in nitric will restore it.

Sodium Nitrate - what happens if I add sodium nitrate to used nitric?

Peroixide - will adding hydrogen peroixde rejuvinate nitric? If peroxide is aded would it also dissolve the gold?

It seems like at some point the nitric becomes saturated with metal and won't take anymore on. Is there a good way to completly remove all debris. Also, how does one go about adjusting PH?

I have little chemistry background. I plan to gain some education in the near future. In the meantime, thanks for the help.


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## lazersteve (Sep 23, 2007)

Joe said:


> How do I recycle Nitric Acid? I've read through most of the posts, but I am still a little unclear. I hope I am not duplicating a previous post.



Actually only a portion of the nitric will be recyclable, some of it goes up in smoke (NOx fumes- red vapors). If you have a vapor trap you can capture this and convert it to nitric also. The part that gets "stuck" to the metals is the part I'll focus on for purposes of this post.



Joe said:


> Bubbler-putting a fish bubbler in nitric will restore it.


Wrong, but this is how you rejuvenate Acid Peroxide solutions that are saturated with Copper I ions and have become ineffective at dissolving copper. The air converts the Cu+ into Cu++ so it can react with more Cu0 (copper metal) again. A little HCl is required in the solution to jump start the reaction.



Joe said:


> Sodium Nitrate - what happens if I add sodium nitrate to used nitric?


Wrong again, you would do nothing more than add more nitrate ions to the soup. You still need hydrogen to convert the nitrate ions back to nitric acid.



Joe said:


> Peroxide - will adding hydrogen peroxide rejuvenate nitric?


See answer #1 above except substitute Peroxide for air.



Joe said:


> If peroxide is added would it also dissolve the gold?


Peroxide in the presence of HCl will dissolve gold under the right conditions.

So the question remains, How does one rejuvenate nitric acid from spent solutions? The spent solutions are typically composed of various nitrates which can liberate the NO2 when heated or electrified. This NO2 can then be passed directly into distilled water to reform the nitric acid again.

Another set of methods involves replacing the metal that is bound to the nitrate ion with Hydrogen via distillation or controlled precipitation. The acid of choice for either of these reactions is Sulfuric Acid. 

I'm planning an entire post topic on this fascinating subject soon so stay tuned... :wink: 

As a side note, remember you will never get *all* the nitric acid back that you started with due to losses.
Steve


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## Patrick_R (Feb 20, 2012)

Steve,

Have you posted a system/way to recycle nitric. Or made a movie?  I would gladly pay to watch a couple different methods of Nitric recovery. If there is a new topic, can someone please link it. I apologize in advance for missing it.

Comrade


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## Geo (Feb 20, 2012)

Patrick_R said:


> Steve,
> 
> Have you posted a system/way to recycle nitric. Or made a movie?  I would gladly pay to watch a couple different methods of Nitric recovery. If there is a new topic, can someone please link it. I apologize in advance for missing it.
> 
> Comrade



butcher has posted pictures of his pickle jug distillation kit. just think of it as capturing the NOx fumes and converting it back into a usable acid. passing these fumes through water will capture the gas and convert it into nitric acid, albeit weak, but still usable. even more effective by adding a little H2O2 to the water and chilling it in an ice bath.


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## maynman1751 (Feb 20, 2012)

> butcher has posted pictures of his pickle jug distillation kit. just think of it as capturing the NOx fumes and converting it back into a usable acid. passing these fumes through water will capture the gas and convert it into nitric acid, albeit weak, but still usable. even more effective by adding a little H2O2 to the water and chilling it in an ice bath.



Geo, can you direct to this post? I searched, but didn't find pics. Thanks in advance!


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## Geo (Feb 20, 2012)

its been awhile since i saw it last. i'll see if i can locate it, but you might find it quicker when butcher is on and see if he will post it again.


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## butcher (Feb 20, 2012)

There are several posts of this, and other techniques to reusing or making nitric acid, this is a process to make nitric acid at the same time as you de-plate the gold from pins, but the principles are here that can be used in other processes.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=38&t=6199&hilit=killing+two+birds+one+stone


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## maynman1751 (Feb 20, 2012)

Thanks Geo and Butcher. I already have that page bookmarked . I was hoping for some pics...hint,hint!


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## luigi2004 (Feb 28, 2012)

Dear friends of the forum:
Please, I would like to know if I am right with these formula:

3 Ag2S + 8 HNO3 = 6 AgNO3 + 4 H2O + 2 NO + 3 S

AgNO3 + ClH = ClAg + NO3H
My goal is to re use the nitric acid used in the first step of the reaction.
Could it be possible ?
With my best regards
Luigi


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## butcher (Feb 28, 2012)

"AgNO3 + ClH = ClAg + NO3H"

I would write it differently:

AgNO3 + HCl --> AgCl + HNO3


The thing is we lost a little nitric to gases when we dissolved silver, also we have water involved, and normally we do not dissolve pure silver in nitric acid, so actually we would end up with copper nitrate solution Cu(NO3)2, the nitric acid can be recycled (you will not get all of it back), they are several ways to reuse or recycle the nitric acid, or copper nitrate, but it is not as easy as the formula above suggests.

You can also make sodium nitrate salts by using table salt in the above formula, and then make nitric from the crystallized salts.


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## doctor (Jun 25, 2012)

Hi - can anyone tell me how long it takes for Nitric to derogate ?
I have some that I used about 7 years ago.
Is it still good to go?
Thanks
Gerry


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## FrugalRefiner (Jun 25, 2012)

If it's been tightly sealed and not exposed to a lot of light it should be fine. I'm using some that was stored for close to 40 years. The plastic bottle caps were brittle and crumbled when I tried to replace the first one but the acid is still fine.

Dave


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