deplating silver from silverplated items

hello everyone,

i will share an experiment, to deplate silver from plated items, with you:
it´s not from me, i have found a little about the experiment, and now i will reproduce this.



You need:

distilled water
cooperplate
silverplated items
sodium persulfate (Na2S2O8)
electro cell like silvercell

60g sodium persulfate per liter
Voltage 5-12 V

i testing some setups, here are the results:

first i dissolving some copper in sodium persulfate solution.
next i start the cell with silver plated items as anode
and a copperplate as cathode.
after the solution is saturated, some removing of copper from cathode is needed,
you can cement the silver with a copperplate from solution out.

i testing some setups, and i have now not the 100% right way, but you can see the results.

you can test this and try make the process better, perhaps we can find the best way?!

mocodos

next pictures:







mocodos

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mocodos

next pictures:



i testing some of setups, so if i find a new better configuration, i´ll post it here.

mocodos

Very nice, Mocodos!

Phil

so if im not mistaken, your electrolyte is copper sulfate? you first saturate the sulfate solution with copper?

yes, first i add some copper to the sodium persulfate solution, after the solution is
saturated, (it turns blue color, and no more copper is dissolving) you remove the undissolved copper and can start the process.

mocodos

That's an interesting experiment.

How many pieces can be stripped before you need to cement?

Is this solution reusable?

i started the experiment with 0,5 liter. after the solution is not transparent, dark blue/green, and you can´t look through,
i started the cementation part.
now i have a 6 liter plastic bowl, it turns longer to saturate the solution, but you have more dissolved silver in it.
the cementation need some hours, but with larger pieces of copper, you can get more silver at one time.

the solution is reusable, ("endless" i think) but little goes away, from filtering, removing cooper from cathode,...

mocodos

Would a copper bar hung from the glass, not part of the electrical circuit, cement silver while this is running?

how is the silver in suspension? is it converted to silver sulfate? after it is cemented what would the purity be? many questions. i, mistakenly apparently,believed sulfuric acid could not hold silver in suspension and that it would self precipitate at a certain point.

qst42know said:

Would a copper bar hung from the glass, not part of the electrical circuit, cement silver while this is running?

Click to expand...

yes, it would, you can see it here

in the right side is a copper bar, as a not a part of the electrical circuit, and cementing starts immediately

mocodos

Geo said:

how is the silver in suspension? is it converted to silver sulfate? after it is cemented what would the purity be? many questions. i, mistakenly apparently,believed sulfuric acid could not hold silver in suspension and that it would self precipitate at a certain point.

Click to expand...

i´m not a chemist, i thing it is presented as silver oxide and in a colloidal form (after dissolving from anode) here.
i did at test, 100 ml distilled water, 20g sodium persulfate, 1g silver from cementing, after adding silver
to the solution, the reaction starts, silver was converted to silver oxide, it was dark on the ground, after few minutes, the solution
was gray/black in color an was not transparent. after adding a copper piece, the cementing starts, after the solution is saturated from the copper piece.

if the cell have no current, or you have only a anode or only a cathode in the solution, the cementing process start immediately.

in future i will test few grams, but after reading about this process, the purity would be about 99% -99.9%.

mocodos

but after reading about this process, the purity would be about 99% -99.9%.

Click to expand...

Is there a web document to read?

qst42know said:

but after reading about this process, the purity would be about 99% -99.9%.

Click to expand...

Is there a web document to read?

Click to expand...

here is the source, but it is in german
http://www.experimentalchemie.de/versuch-051.htm

"Nach etwa 20 Minuten hat sich auf der Elektrode ein ocker-farbener Überzug gebildet, der nach weiteren 2 Stunden zu einem fein verästelten Gebilde ("Dendriten") herangewachsen ist ("Silberbaum"), welcher jetzt etwa die Grösse eines Tischtennisballes erreicht haben kann.
Dieser Silberbaum kann sich rund um die Elektrode verteilen, er kann auch wie ein Vorhang bis zum Gefässboden hängen. Das Resultat besteht aus elektrolytisch reinem Silber und wird in einem weiteren Gefäss (altes Trinkglas) unter dest. H2O gelagert."

translated with google:

"After about 20 minutes has on the electrode an ocher-colored coating formed, which is after another 2 hours to a finely branched structures ("dendrites") grew up ("Silver Tree"), which may have now reached about the size of a ping pong ball.
This silver tree can be distributed around the electrode, it can hang like a curtain to the vessel bottom. The result consists of electrolytically pure silver and distilled into another container (old drinking glass) below. H2O stored."

mocodos

Roughly how long would it take to deplate a single silver plated spoon in this set up? a few seconds/few minutes/few hours ?

what is the voltage that your setup is using?

thank you for the great pictures they answer a few questions

I used sulfuric acid 37% as electrolyte and a 5V/25A PC power supply for 6 spoons and 6 forks (appr. 30g fine).
The other electrode was stainless steel. Sulfiric acid has its highest conductivity at 37%.
I let it in the acid for 4 hours and the result was 35% silver. I wanted to be sure that I got all the silver, I think 50% are also possible.

The method described above says "some removing of copper from cathode is needed" - the layer on the cathode is also partly silver.
You only extracted the silver that is still in the solution, which is less than 4g/l because silver sulfate is not easily dissoluble.
I hope you did not throw the "copper" away
The silver you extracted may have a purity of around 98-99%. Pure silver can not be refined by cementing with copper.

hello goldfinger4,

thanks for the info

this way that I write is only one way, must not be the best,
I wanted to reproduce this from an experiment.

I think in order to process the mass of silver items, silver items must be melted as anode and processed in sulfuric acid cell/copper cell.
like in the industry.
the higher the voltage the higher the contamination of impurities at the cathode.

mocodos

If you have any more pictures of your setup or while your cell is running I would love to see them

thanks Ian

most of my silver plated item are silver over zinc and not silver over copper ,did you have probleme with the zinc(i think it is reacting with sulfuric acid)...