# Palladium salt reduction using sodium hydroxide??



## NoIdea (Sep 30, 2014)

Hi All – has anyone tried the reduction of either hexachloropalladate(IV) or Ammonium-tetrachloropalladate(ii) or any other Palladium salt using sodium hydroxide, similar to that when reducing silver chloride to silver oxide?

Thanks 

Deano


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## g_axelsson (Sep 30, 2014)

Not a direct answer, but have you seen this thread about reduction with formic acid?
http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=51&t=11078

Göran


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## Lou (Sep 30, 2014)

Deano,


To clear up a miscommunication, there is no reduction occurring in the reaction

2AgCl + 2NaOH --> Ag2O + 2NaCl + H2O as no electrons are transferred and silver remains as {Ag+}
Of course there's some AgOH <-->Ag2O, but really, that's a minor species.
When you heat silver oxide, Ag2O above, oh what is it, 350 C or so, it disproportionates and you get 2Ag2O --> 4 Ag + O2. 

You will see the dark powder Ag2O turn into light gray silver.


Using NaOH (in excess) on such ammonium salts of Pd is 1.) going to produce ammonia if you vigorously boil it, and 2.) Pdx(OH)y (and hydrous, ill-defined oxides). Some small amount of Pd will remain in solution.

Of course, you can filter off these floccs of Pd (hydr)oxides and reduce them via heat to metal in a similar disproportionation reaction that occurs at 950 under a CO2 or inert atmosphere to get a Pd sponge as good as the hydroxide you put into it. Alternatively, it can be reduced at a few hundred C with hydrogen. pH 5.5-6.5 buffered formate is probably a more quantitative option.

For your purposes, melt the hydroxide with no flux and a neutral O2/H2 (or methane) flame into a button. It'll be gassy but that's palladium for you.


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## NoIdea (Sep 30, 2014)

Thanks Lou, very helpful indead. The powder is really a mixture the Palladium salt and silver chloride, I was hopeing to kill two birdies with one stone, as it turns out I can. 

I am more interested in recovery rather than refinning as it makes no different to the refinner i sell to. Ill let you know how I get on, should be allot easyer to melt with silver on boad. 

As for ammonia being released from concentrated sodium hydroxide is well know method for ammonia production, could be a great way to get ones ammonium hydroxide solution back. I precipitated by direct addition of refrigerater ammonia to the HCl solution until till the liqure takes on a slite blue haze, base metal impurities, pH slightly above 7, I know that thier will be PM's still in the filtrate after filtration, ill keep that for later.

Thanks Again  

Deano


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## Lou (Sep 30, 2014)

Your palladium is in the ammonia--Pd doesn't make hydroxide with ammonia


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## NoIdea (Sep 30, 2014)

Lou said:


> Your palladium is in the ammonia--Pd doesn't make hydroxide with ammonia




Thanks Lou, your right, and from the solution in question, i acidified it shortly after i finnished adding the ammonium hydroxide, and obtained a wee bit of precipitate where-as the filter cake, after rincing and drying came to a grand total of 23g dry weight of dark red/black powder/clumps. It was sun dried first before oven so I would say any light exposed silver chloride will have converted to it's oxide, a Plus from where i sit.

Still work to do butt happy with my progress so far.

Cheers

Deano


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