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Agreed, the purpose of the initial hydroxide conversion is to separate out the Silver contamination from the Palladium.
Precipitating palladium help needed
- Thread starter niels-chemist
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Since he is dissolving already pure Pd sheets, I still fail to see the purpose.
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I agree completely. On another note I'm sure Lou once told me that you can drop Pd clean, out of a Nitrate solution using Ascorbic. @Lou can you comment?
niels-chemist
Active member
The purpose of what?
Did you read the other posts?
The purpose of converting to Hydroxides.
I really can't see a benefit of that when you are dealing with a pure solution.
niels-chemist
Active member
I´m not aware that Pd will precipitate just as efficiently straight from AR as it does from a hydroxide suspension
niels-chemist
Active member
View attachment Zn.mp4
Here I added Zn powder to a pH = 1 solution with Pd2+ present. As you can see not a lot is happening. Any clue what I'm doing wrong?
Did the Pd powder dissolve?
Hard to see on a phone.
Edit to add:
I see it now, have you deNOxed it in any way?
Last edited:
niels-chemist
Active member
I first made it alkaline with NaOH....
niels-chemist
Active member
36% HCl to pH 1. Impurites: don´t know yet. Still have to have a sample analyzed. These solutions are combined reaction mixtures that should contain Na+ as the only other metal ions and some organic stuff that shouldn´t interfere and as anions only OH- / Cl-
The formate reduction you used, did not give you the purity you wanted?
I still do not see the point of dropping as Hydroxide, the only thing you accomplish is to increase the amount of Na+ ions in the mix.
Until you know the make up of the impurities and can device a plan to get rid of them, anything you do will be based on guesswork and assumptions.
niels-chemist
Active member
There are two batches:
1) Pure palladium sheet, dissolved in AR and precipitated with NaOH and formic acid to make palladium black for further chemistry
2) Palladium chemistry leftover reaction mixtures combined to recover the Pd (I heard it is expensive ;-) )
1 works fine and gives me nice black powder
2 does not work, nothing gives me precipiate: not ascorbic acid, not formic acid, not sodium formate, not sodium iodide, not zinc powder....
Have you tested if there are anything there?
Stannous or DMG will give you the answer but not concentrations.
niels-chemist
Active member
Can you say with 100% certainty that if you add SnCl2 that you will get black Pd(0) *if* there is Pd2+ in it? Or are there conditiosn (pH, temperature etc.) in which this redox reaction does not work?
The Stannous test is just an indication test.
It will form "nano" clusters of metal where the color indicates the metal in solution and the saturation indicates the concentration.
It needs to be acidic and should not have much Silver in it.
Besides that it should work well.
DMG is a very sensitive and accurate test for Pd (acidic) or Ni (base).
niels-chemist
Active member
Will try tomorrow. There's definitely no silver in it, apart from (sub) ppm levels. If both dont give any precipitate or black color you can safely assume there's no Pd in it?
Stannous will not give ppt, but create suspension of microscopic particles coloring your liquid.
DMG will give a light fluffy yellow precipitate.
Stannous is usually either done on a spoon/spot plate or on paper.
Her is an image of what to expect:
From Lazersteve:
Golddigger76
Well-known member
If all else fails and you know for a fact that you do have palladium in solution you can resort to cementing it out with copper powder, heat and stirring, lots of stirring.
You must add after you evaporate all the nitric acid and obtain a blood red color, NaOH, until PH = 2 to 3 and then you must add formic acid, slowly while boiling the solution, when you have the solution at about 60 to 70 degrees. Celsius, the solution goes from red to dark brown and then turns black. It continues boiling until all the palladium falls to the bottom in a fine black powder. You filter it, wash it with hot water and dry it, then melt it.
