# Pd extraction from Pd/C



## zephler (Apr 3, 2014)

Hi there!

I have some Pd on carbon; I would like to extract the Pd from it. The analysis came back as:

Ag	0.1
As	0.01
Bi 0.3
Ca	0.04
Ga 0.1
In 0.3
Na 17.05
Pb	0.1
Pd	0.8
Ti	0.2

So not much Pd. The material has been soaking in AR for quite sometime, and the filtrate will be used. I have access to DEHPA and am wondering if someone has a reference or can comment on what pH I should adjust to to get selective chelation of Pd (if that is possible), from the AR media.


Thanks!


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## Lou (Apr 3, 2014)

Might consider incineration first.


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## zephler (Apr 3, 2014)

Not really an option - the carbon can be separated via filtration, I would also be nervous about vaporizing Pd. However, since you mentioned it, how would one incinerated the material without industrial equipment? Would a torch and a crucible do the trick?


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## Lou (Apr 3, 2014)

Not unless you like blowing it all over the place and possibly into your lungs.

Best to put it into a pan at a dull red heat. Carbon holds values very well, so it's imperative that you remove it one way or another before doing acid digestion.


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## zephler (Apr 3, 2014)

Thanks for the info. What is the temperature min and max that I should aim for, and when do I know that the incineration is complete?


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## freechemist (Apr 3, 2014)

Before asking for incineration- / leaching-conditions, you have to make clear for us - and not last - for yourself, what you expect, are dealing with.
The only information you give us, is a row of 10 different chemical elements, which have apparently been detected by some unknown method, together with some meaningless numbers, as long as no information exists about their dimensions. E.g.: What does 0.8 Pd mean? 0.8 g Pd in the whole sample?; 0.8% of total sample-weight?; 0.8 ppm Pd in the examined sample?;...?


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## joubjonn (Apr 3, 2014)

Do you really know how DEHPA works in refining?
I read a paper on it from searching it and it seems extremely advanced. Organic membrane's and cloud points and a bunch of stuff that belong with people in high dollar labs with white coats. Know what I mean?


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## zephler (Apr 4, 2014)

Apologies for lack of detail.

The values listed are in % terms 

Ag	0.1%
As	0.01%
Bi 0.3%
Ca	0.04%
Ga 0.1%
In 0.3%
Na 17.05%
Pb	0.1%
Pd	0.8%
Ti	0.2%

Determined with ICP.

I am looking to extract Pd as PdCl2.

Yes, I know how DEHPA works, and have a pH for stripping from DEHPA, but not one for extracting into DEHPA.

Thanks!


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## Lou (Apr 4, 2014)

If you really want to use S/X, I recommend incineration first.

That wouldn't be the solvent I would use, either.

FYI, ICP on PGM/C is always low for the aforementioned reason of it holding values.


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## zephler (Apr 4, 2014)

Thanks Lou. Well then, what solvent would you use? Also, when do I know incineration is complete? Colour change? No more weight change? I don't want to vaporize all the Pd off of it looking for a coloour change that never happens. Thanks!


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## Lou (Apr 4, 2014)

Weigh it before and after, heat til constant mass, post reduce with pH 6 formate to make the Pd soluble, then dissolve, then di hexylsulfide or other akylsulfide will work.

The Pd isn't going to vaporize off unless there is halogen or sufficient carbonyl to remove it.


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## freechemist (Apr 6, 2014)

Hi Zephler,

Thanks for clarifying. Like Lou I recommend incineration first. In my practice this was best done in a wide open fire-resistant dish or pan, giving free access to air. On heating the powdery mix to red heat, with occasional stirring up to give intensive contact with the air, the carbon-mix quite often begins to burn down spontaneously by itself. As soon, as there is no more visible reaction on stirring up the red glowing mixture in open air, the dish can be covered with a fire resistant ceramic plate and then be heated, under exclusion of air, to 800oC - 1000oC, resulting in a dull-darkgrey, powdery material. If there is still too much carbon left, the whole procedure - 1.) oxidizing on red heat, 2.) thermally reducing at 800-1000oC can be repeated, resulting in raw metallic Pd, ready to digest in an appropriate medium without preliminary treatment with formate-solution.


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