K2SO4

[GotTheBug]

Is there any way to remove enough of the salts from solution to process silver? Or am I bound for distillation?

Palladium has me hooked on wanting to see shiny powder out of some sterling scrap I have and I'm ready to go, except for finding out what silver sulfate looks like.

Thanks guys, can't wait to get started!

 

[solar_plasma]

I guess you mean K2SO4 contaminated HNO3.

If you add ions to a system so that an ion pair is possible forming a salt with a low solubility, it will precipitate. In this case you will make Ag2SO4 precipitate, since only 8g/l is soluble in plain water. So it will work somehow, more or less, but will not be a good choice.

The sulfate can be precipitated by Ba(NO3)2 (toxic! datasheet!). That will leave you with a solution of KNO3 in HNO3, which should not be a problem, if you only want to dissolve silver. I do not believe, that this solution would be a good choice for electrorefining.

There is an interesting thread about using Ba(NO3)2 from the beginning.

 

[GotTheBug]

Ba does not sound like a lot of "fun" to deal with. I finally got a decent process with KNO3 and H2SO4, with the sulfate crystal largely precipitating out. The problem, of course, is not getting all of it, and the corresponding effect on silver. Any other ways to rid myself of the problem, or should I just go ahead and set up the distill?

Thank You for the Ba idea also, I had not considered that.

 

[Lino1406]

Ag2SO4 has a limited solubility 2 - 5% depending on temp.
To precipitate all of it, you transform it to AgCl

 

[solar_plasma]

I have no practical experience with that, so I can't say more, than the school chemistry is teaching. I do not believe using this sulfate containing solution will yield satisfying results. Maybe someone else can say more.

Lino, the limited solubility is just the problem, so I would not use this backyard nitric for any serious silver refining.

 

[solar_plasma]

If it is not for a commercial purpose, but only for having tried to dissolve silver and cement it, you could try dissolving silver in it. Then filter off the Ag2SO4 and redissolve it in a second vessel of warm water. Then you should be able to cement with copper from nitrate and precipitate chloride as Lino mentioned from the sulfate.

 

[butcher]

Distilling has many benefits and uses in chemistry, including recovery and refining.

There are things you will need to learn to do it safely.

Take for example, lowering heat on the heated reaction vessel, where it can create a vacuum, for instance, were you can suck back the cold liquid into the boiling hot reaction vessel, and explode the vessel of hot acids.

It does take some study to learn to distill liquids and separate components successfully and safely.

The benefits and uses are very much worth the trouble of doing the study needed, you will find distilling to have many uses in the chemistry we do, it can also be helpful in reusing some of the acids that may otherwise go to waste as fumes or as toxic waste needing to be dealt with, distilling can also be useful with a scrubber to lower the fumes produced from reactions, where fumes can be either scrubbed or regenerated for reuse as acids, it can also be helpful for making reactions happen that would be difficult or even impossible in an open reaction vessels...

I say take the time to learn to distill and make your home made nitric acid more pure, you will find other uses for this very effective tool.

Just be sure to spend the needed time in study to understand the chemistry of the reactions involved, and how to distill liquids safely.

 

[GotTheBug]

I agree with all so far, and will use the method for converting the silver sulfate I've already run into later.

The core question is still, "Is there an easier way than distillation to get the K2SO4 out of the nitric?"

 

[solar_plasma]

I dare to say: NO.

There are only very few potassium compounds, that have low solubility. And then you will still have contaminated nitric.

 

[butcher]

"Is there an easier way than distillation to get the K2SO4 out of the nitric?"

In my opinion no, distillation will be the easiest.

Chilling will remove much of the sulfate salts, using a metal to react and form an insoluble sulfate like lead, barium, calcium, strontium, or silver in a chemical precipitation can also get some more of the sulfate out of solution, but even then will not make the nitric acid as pure as the distillation process can if done properly, the sulfates and nitric have such a wide range of boiling points it makes the separation fairly easy.

HCl gas has a fairly low boiling point, so that if chlorides are involved in your nitrate salts, you are using to make nitric acid from, you can distill some HCl with your nitric acid, if this is the case with your nitrate salts, you can clean up the nitric acid containing some chlorides, from your distilled nitric acid with the use of a little silver powder, saving the silver chloride precipitant.

 

[GotTheBug]

Very cool, looks like it's time to assemble the apparatus. Thank You all for the input. Perhaps when I finally reach the baggy of "diamondy" powder I'll put up a pic
and Palladium can pat me on the head.

 

[pu_239]

I know it's a little late, but, it appears you're trying to purify nitric acid contaminated with K2SO4? If that's the case then I don't see a resonable way to clean it up with out a distillation. The SO4- can be taken out with something like Ba(NO3)2, Ca(NO3)2. This will cause the Ba2SO4 to form, taking out the sulfate. But now you have a mixture of K+, NO3-,Ba2+ and so on. When you add a chemical to crash out another, you will still get a byproduct. You're just replacing one thing for another. So you can't get pure nitric acid back. So a distillation is the only way to go. Also have to monitor the temperature and make sure you got the boiling points right and boil at the proper temperature.

 

[solar_plasma]

I know it's a little late, but, it appears you're trying to purify nitric acid contaminated with K2SO4?

No, this thread is about nitric that is made of sulfuric acid and nitrate salts. For the rest you are right, depending on their solubility, low as it may be, there will always be traces of contaminants after precipitation.

 

[GotTheBug]

I decided to put this in the same thread, since it is related to the process I am currently learning.

1.45 mL of nitric to dissolve 1 gram of sterling, which I presume to mean includes the copper in the sterling.
Since we use copper to cement/drop silver out of solution, would it be feasable to simply add additional sterling, allowing the 7.75% copper it contains to drop some of the silver
while dissolving more than the 1 gram? Or would I end up with silver nitrate crystals to deal with?

 

[butcher]

It would be very hard to control the reaction, and to dissolve silver away from the copper first...

With sterling your dealing with a mixture of metals, an alloy of silver and copper.
The silver being the major component would dissolve along with the copper, although copper is slightly more reactive, as the nitric acid would come into contact with the alloy, basically attacking both metals at once as it oxidized and put the two metals in solution, as the acid attacked the metal alloy, the acid coming into contact with both metals at the outer surface of the sterling silver article dissolving them both as nitrate ions.

Although in theory it might be somewhat possible, I believe it would be basically impossible, you would be best off to just dissolve the sterling, dissolving both silver and copper from the alloy into solution, and then use the clean copper buss bar to cement the silver from solution, leaving you with your copper in solution...