Electrolysis of Artefacts

[bayan92]

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1. Which one of the cathode equation is most appropriate for the electrolysis of silver?


Anode: 4OH^- _(aq) -->O_{2 (aq)} + 2H₂O _(l) + 4e^-

Cathode: AgS _(s) + 2e --> Ag _(s) + S-

OR Ag⁺ _(s) + e^- --> Ag _(s)

2. Are the following techniques correct?

- Wood --> Remove surface encrustation and bath in water
- Iron --> Remove concretion, soak in NaOH, heat in 400 degree Celsius oven and coat in protective wax.
- Lead, silver and copper --> Electrolysis in NaOH
- Copper (Method II) --> Dissolve deposits with ethanoic acid, soak in water and dry and coat in clear lacquer.

3. Can electrolysis be used on iron. If so, please elaborate on process.

[sam5]

Originally Posted by bayan92

1. Which one of the cathode equation is most appropriate for the electrolysis of silver?


Anode: 4OH^- _(aq) -->O_{2 (aq)} + 2H₂O _(l) + 4e^-

Cathode: AgS _(s) + 2e --> Ag _(s) + S-

OR Ag⁺ _(s) + e^- --> Ag _(s)

2. Are the following techniques correct?

- Wood --> Remove surface encrustation and bath in water
- Iron --> Remove concretion, soak in NaOH, heat in 400 degree Celsius oven and coat in protective wax.
- Lead, silver and copper --> Electrolysis in NaOH
- Copper (Method II) --> Dissolve deposits with ethanoic acid, soak in water and dry and coat in clear lacquer.

3. Can electrolysis be used on iron. If so, please elaborate on process.

Go the second cathodic equation for the silver electrolyte electrolysis. Just leave the other ion component as a spectator.

Yep dw its only pretyy general for those cleaning methods. Always use waxes, lacquers or PEG (polyethylene glycol) to preserve the artefact. Weak acids can be used to dissolve the deposits.

With the iron, u suggested putting it in heat. Is this the hydrogen furnace reduction method? yeah u can use that.

Yes u can electrolyse iron objects (sorry, but i thought that was obvious).

Use a dilute sodium hydroxide eletrolyte. Use the artefact as the cathode and a piece of stainless steel wrapped in steel mesh as an anode. Connect the negative terminal of a DC current to the artefact, and the positive to the anode. Electrolyse on a low voltage at first, and as salt flakes on the artefact are removed by hydrogen production, u can slowly increase the voltage. Repeart the process for days or weeks. Replace the mesh and electrolyte occasionally to prevent anion saturation, and a lowered pH of the electrolyte.

NaOH is used as it is basic, and will prevent further corrosion occuring. I assume u know why bases help prevent corrosion.

The anions will move to the anode. The iron will be reduced. Water will be oxidised at the steel and reduced at the artefact.