# Pallaspeed - need suggestions on recovering palladium ethylenediamine sulfate plating solution



## Grimster (Jan 12, 2020)

I know that trying to recover elemental metal straight from a plating solution isn't something that is normally done, but I figured I'd ask. I have probably 10 liters of Pallaspeed plating solution (some containers say 3.963 grams/liter, others say 25 grams/500mls), so you can see why Im interested. 

From what I can tell from my searching :

https://products.riogrande.com/content/Safety-Data-Sheets/335013-SDS.pdf

This is telling me that the solution is Palladium ethylenediamine sulfate. 

I found this patent 

https://patentimages.storage.googleapis.com/44/95/fe/bc6a35cccfc90b/US20030047460A1.pdf

This is saying that they used Palladium Nitrate and mixed it with sulfuric acid.

nitric acid and water is removed by distillation

residue is evaporated and redissolved into water to make palladium sulfate

palladium sulfate is then mixed in solution with ethylenediamine

filtration and drying creates this complex palladium salt

That is then used to make the plating solution

So my question is really - what is the best way to recover the palladium? Is is best to just use it as a plating solution and plate several items and then try to recover the palladium? Or since I have so much solution, is there a multi-step way to precipitate out the metallic palladium, dry it and then melt into a button?

That is really the goal, to recover the palladium into a (hopefully) big button

The solutions all have an expiration date of around 2012, so I would probably have a difficult time trying to sell it outright to someone that would use it as a plating solution. And since we aren't planning on plating anything again, we have no use for it in it's current state. 

I have access to many different chemicals that can be used as reagents in this exercise (DMG, sodium borohydride, etc). Im not a chemist by trade, so if anyone has any guidance on where to start my research that would be extremely helpful. 

Thanks.


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## Lino1406 (Jan 12, 2020)

Possibilities:
1. Electroplating solution is cyanide base, and probably contains ammoniac, you need a fume hood and drop the palladium by aluminum or zinc. Occasionally you'll have to increase alkalinity once in a while
2. Electroless plating is acidic all you need a fume hood and drop the palladium by aluminum or zinc. Occasionally you'll have to increase acidity once in a while


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## Grimster (Jan 13, 2020)

once cemented with zinc powder or aluminum powder, what acid and strength should i use to dissolve the zinc or aluminum without dissolving the palladium? If I use muriatic acid, wont that dissolve the palladium too? Or is that only an issue if substantial heat is applied?


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## Lino1406 (Jan 13, 2020)

If rinsed thoroughly, palladium does not dissolve in muriatic


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## Grimster (Jan 13, 2020)

Ok. I will work with the plating solution in the next day or so and report back with what I find out

Thank you for the suggestions. I really do appreciate it


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## snoman701 (Jan 13, 2020)

Lino1406 said:


> If rinsed thoroughly, palladium does not dissolve in muriatic



Is the dissolution when not rinsed well just changing of oxidation states of other metals still present? 


Sent from my iPhone using Tapatalk


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## Lino1406 (Jan 13, 2020)

Sorry for being misunderstood, what I meant by thorough rinsing is assuring absence of NO3- ions


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## Grimster (Apr 7, 2020)

Wanted to come back and share the findings. 

All of this was done under a hood.

I did two experiments: one using zinc powder and one using aluminum powder. I just used 100ml of plating solution and just dumped in ~10 grams or so of aluminum powder and zinc powder for these two batches. I think both worked well, but I prefer the zinc powder. 

After the powder has reacted with plating solution I used dilute HCL to eat away the zinc, leaving me (hopefully) with palladium. Both the aluminum and zinc reacted quite vigorously to the acid, but zinc seemed to react more quickly. 

after the reactions completed, I would decant off the liquid into my liquid waste and reapply dilute hcl and get the reaction going again. Definitely used too much metal powder, but wanted to make sure I captured all the palladium...and hcl is cheap anyway.

After no more reaction from the HCL applications, I washed the remaining powder several times. I then proceeded to do the zinc powder route for the remainder of the palladium plating solution. Same deal, zinc powder, mix mix mix, wait, mix mix mix, hcl to eat away the zinc. wash wash wash, dry, done.

Used an oxy-acetylene torch in a thick crucible to melt the palladium. Tricky metal. It was "ok" to melt into a button when the sample size was ~1-2 grams or so. I made one button that was just over 10 grams and as I was waiting for it to freeze so I could grab it with the tweezers and dunk it in the water, it started to grow and swell. Molten Palladium sure does love oxygen. 

So, all said and done I ended up with some nice looking palladium. Little over 20 grams all said and done. So some of the plating solution might have been already used. Either way, super happy with how things went. 

I did have some borax stick to some of the palladium after melting. I believe I can process it the same as silver/gold/platinum and just use a dilute sulfuric bath and dissolve the borax away. I think as long as I don't get the solution too hot or the sulfuric too concentrated I should be fine. Think that is a good path forward?


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## Lino1406 (Apr 7, 2020)

Borax is soluble in hot water, ethylene glycol


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