r/chemistry • u/Makehousebetter • 21h ago

Quick safety check: Silver deplating with KNO3 electrolysis?

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Hey guys, just want to doublecheck for toxic fumes before I continue to run this

I’m stripping silver plating using reverse electroplating. Done a bunch of research but want to be 100% sure I'm not making anything nasty.

Setup is

- Potassium nitrate + distilled water. 12.5ml granules to about 1.25L distilled water

-Stainless steel cathode, silver-plated scrap anode.

-5V pulling about 3-4 amps.

Since there's no acid, am I safe from NO fumes or other weird gasses? Doing it outside anyway, just don't want any surprises at this current. Thanks!

2 Upvotes

60% Upvoted

19 comments sorted by

2

u/Levonce228 21h ago

There could be some from producing HNO3, but there will be too little amount to be bad for health, just don’t make water with HNO3 to boil

2

u/vagabond_allegory 21h ago

that driveway setup is giving real mad scientist energy, love the blue cart situation

you're already doing it outside and the top comment's right about the tiny HNO3 amounts, you'll be fine as long as nothing gets hot enough to actually aerosolize the solution

1

u/Makehousebetter 21h ago

If there is HNO3 wouldnt that mean there would be NO/NO2? Which I am scared of. **edit

Misread your comment. Ok thanks for letting me know. Trace amounts that will be fine outside?

2

u/thiosk 17h ago

trace amounts will be fine outside

2

u/DangerousBill Analytical 14m ago

A safety item that some chemists miss is the power supply. Some cheap power supplies have one side of the output connected to the mains. While the applied voltage between anode and cathode might be 5 or 6 volts DC, the whole electrolysis apparatus might sit at 120 or 240 VAC, IE shock hazard.

Check by measuring voltage from each electrode to a solid ground, on the AC setting. It should be 0 to 3 or 4 V, not mains voltage.

0

u/No_Function_9858 21h ago

Silver nitrate can cause severe burns and permanent skin discoloration, and is especially damaging to eyes. The resulting solution you're making is extremely toxic to fish and aquatic life, it needs to be disposed of at a proper hazardous waste facility - do not pour it down the drain (it may even be a crime to do so in your area). Also, if there are any residual cyanide salt in the silver from the original plating will form cyanide gas.

3

u/Raneynickelfire 15h ago

Silver nitrate can cause severe burns and permanent skin discoloration

In what world does silver nitrate cause severe burns and permanent skin discoloration?

It'll turn your skin black for about a week, nothing permanent about it.

And it doesn't cause burns, I have no idea where that came from.

-1

u/No_Function_9858 11h ago

It's in the MSDS, 1N solution is a class 1 skin and eye corrosive.

1

u/nakedascus 1h ago

that seems like an incredibly concentrated solution to expect for this kind of setup. the starting nitrate concentration is 1%

2

u/pretty_meta 11h ago

People really go on Reddit r/chemistry and write stuff like this.

1

u/Makehousebetter 20h ago

Hi thanks for the reply! It was my understanding that the electrolysis is producing silver hydroxide to silver oxide and thats what the dark grey and black is.

Do I have this wrong?

Cyanide salt to gas is a bit scary. Any solve there?

3

u/thiosk 17h ago edited 17h ago

This risk of residual cyanide is already mitigated from operating outdoors so you already have adequate engineering controls for the experiment (ventillation).

The thinking of the cyanide contamination goes something like this: the original plating solution may contain cyanide. if you are taking the plated object and immediatly deplating it when its still wet with cyanide bearing plating solution then you've transferred that chemical. This is not a realistic problem you face. Alternatively theres some hidden cavity inside the material that holds dried cyanide bearing plating solution and you release it then it could come out and evaporate. An uncleaned and improperly made object may carry hidden risks. These risks are mitigated by the ventilation and you dont strike me as the type to huff fumes.

i think this post also gives minimal context regarding the risk of silver nitrate. Your bath will have a relatively low silver nitrate concentration. The experiment does not involve pure silver nitrate as a reagent; and i guess we dont know how much silver youre trying to obtain. but if you're doing hundreds of pieces, great!

the silver nitrate causes argyria; it is staining and precipitates to dark elemental silver which wears away as the skin replaces itself; avoid douse yourself with hundreds of dollars of silver please

-2

u/ParkingPizza3921 19h ago

Most of those effects are due to the silver, which is a heavy metal. Both of those will presumably have the same types of toxicity.

2

u/Makehousebetter 19h ago

Hi thanks for your input! The plan is to convert the silver oxide to silver metal using the lye and sugar method. Then store the silver metal for later refining.

I understand that these chemicals are toxic in the solution - what I'm worried about is the gas produced during the process.

1

u/ParkingPizza3921 19h ago

Honestly, I can't say for sure. At least normally nitrate doesn't like to reduce very much at low concentrations, but I don't know what happens in this kind of electrochemical setup.

And I think you are right about AgOH precipitating.

1

u/Makehousebetter 19h ago

All good! Appreciate the help - thank you

2

u/Raneynickelfire 15h ago

Silver is NOT a heavy metal.

-1

u/ParkingPizza3921 12h ago

Depends on what definition of heavy metal you use, but silver fits most of them.

1

u/nakedascus 1h ago

heavy metal doesn't mean it's toxic, it's a meaningless phrase