# Looking for reductant option for rhodium chloride solution



## goldandsilver123 (Apr 10, 2020)

I've around 40 g of rhodium in less than 1 L of solution, I'm looking for options on reductants.

I've used NaOH and formic acid in a small portion of rhodium solution, but the precipitate isn't good. It filters well by gravity but using vacuum filtration drags the precipitate down.

There's NaBH4, Zn0, etc but I'm looking for a clean and more selective reductant, like formic acid, the solution should be 99.9% Rh and I don't want to contaminate it.


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## Lino1406 (Apr 10, 2020)

Mg, Zn. No NaOH!


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## samuel-a (Apr 11, 2020)

Hard and prolonged boiling while reducing with ammonium formate will give an adhering precipitate.

Mg also produce a very nice and clean precipitate.


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## Lou (Apr 12, 2020)

Evaporate to syrup and reduce with H2 gas in pyroceram boat.


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## goldandsilver123 (Apr 12, 2020)

samuel-a said:


> Hard and prolonged boiling while reducing with ammonium formate will give an adhering precipitate.
> 
> Mg also produce a very nice and clean precipitate.



Thanks, after boiling I acidified with sulfuric the NaOH solution, It somewhat settled better, will try with ammonium next time. The precipitate was very fine but was able to filter.









 Lou said:


> Evaporate to syrup and reduce with H2 gas in pyroceram boat.



This would be done in a stream of lit H2 flame, on top of the boat?

Can it be done in a quartz boat, inside a quartz tube with H2 atmosphere? The evaporation wouldn't splatter?


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## Lou (Apr 12, 2020)

Either way. You can add some ammonia to it and then heat it until fumes then H2 reduction.


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## zachy (Jan 27, 2022)

samuel-a said:


> Una ebullición fuerte y prolongada mientras se reduce con formiato de amonio dará un precipitado adherente.
> 
> Mg también produce un precipitado muy agradable y limpio.


también pueden llevar la solución a PH: 1.2 con NaOH, y adiciones de ácido fórmico a una temperatura de 80 grados, con ebullición prolongada se produce un polvo negro de Pd, Rh y algo de Pt, es una forma de recuperar el finamente metal dividido que persiste en las aguas madres después de precipitar el platino.


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## Yggdrasil (Jan 27, 2022)

Zachy, please in English.


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## Yggdrasil (Jan 27, 2022)

zachy said:


> también pueden llevar la solución a PH: 1.2 con NaOH, y adiciones de ácido fórmico a una temperatura de 80 grados, con ebullición prolongada se produce un polvo negro de Pd, Rh y algo de Pt, es una forma de recuperar el finamente metal dividido que persiste en las aguas madres después de precipitar el platino.


Translated:

they can also bring the solution to PH: 1.2 with NaOH, and additions of formic acid at a temperature of 80 degrees, with prolonged boiling a black powder of Pd, Rh and some Pt is produced, it is a way to recover the finely divided metal which persists in the mother liquor after precipitating platinum.


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## zacchy (Mar 3, 2022)

Lou said:


> Either way. You can add some ammonia to it and then heat it until fumes then H2 reduction.


How is the oven to reduce with H2?


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## Lou (Mar 3, 2022)

Like, you want a photo of one? Ok.


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## cGrem (Apr 7, 2022)

bring pH 14 with NaOH and then add ethanol.


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