Make the electrodes part of the design

To purify copper, use impure copper as the anode, pure copper as the cathode, and aqueous copper(II) sulfate as electrolyte. At the anode, Cu(s) -> Cu²⁺(aq) + 2e^-. At the cathode, Cu²⁺(aq) + 2e^- -> Cu(s). Copper transfers from the impure electrode to the pure one; some impurities collect as anode sludge. Detailed industrial operation is not required.

The anode loses mass and the cathode gains mass. Copper ions removed at the cathode are replenished at the copper anode, so concentration remains approximately constant in the simple model. This contrasts with an inert anode, where oxygen forms and the blue solution fades.

For copper electroplating, make the object to be coated the cathode, use copper as the anode, and choose a solution containing Cu²⁺. Clean the object first so the coating adheres. Electroplating can improve appearance or provide a protective surface; the coating metal and intended use determine the benefit.