Precipitate rhodium from platinium solution

Hi all, i want to ask Is there any way to precipitate rh from pt solution ? i use hydrogen peroxide to form pt and rh solution, and drop with saturated amonia chloride, but this method also drop rh, from what I know.

And second question is, how can i check if solution contains rh, there is different colour in stannous test ?

The co-precipitation of Rh with freshly boiled chloroplatinic acid solutions at low acidity is minimal, though your platinum salt may have a greenish twinge. By low acidity, I mean <1 M HCl. That (NH4)2PtCl6 can be redissolved in aqua regia to give H2PtCl6 that has a slight rhodium red to it and precipitated once again. That's usually sufficient to meet even the ASTM/ISO specs for 99,95 Pt.

To fully purify it, you will need to conduct a bromate hydrolysis. You can alternatively take the rhodium solution, make pH 7.5 with sodium hypochlorite, boil it briefly, and then add in a flocculant to collect the rhodium hydroxide.


The rhodium may be nearly quantitatively recovered by increasing the acidity above 6M in HCl to favor [RhCl6]3- and precipitating with ethylenediammine*HCl or some other suitable organic amine salt.


Lou

Thanks for good advice, you explain this very well. 99.95 is pretty nice fine fo me. but still is second question, how can i check if there is rd in solution ?

What do you mean about freshly boiled ? that i can add amonium to hot solution and will be better than cold ?

" i use hydrogen peroxide to form pt and rh solution," what is the source material?