Sodium sulfite: A promising reagent in the electrochemical oxidation of metallic silver

Among the complexing agents suitable for the electrochemical silver recovery, a promising one is sodium sulfite forming silver complexes with high stability constants: according to our data, log β₁ ∼ 5.3, log β₂ ∼ 8.2. This reagent is accessible and cheap, but nevertheless it almost never has been used for these purposes. We studied the stability of the sodium sulfite solutions in air and showed a possibility of using them for a long period. Using the methods of potentiodynamic polarization and potentiostatic electrolysis, we have studied characteristics of the process of metallic silver oxidation in the sulfite media. The anodic polarization process of the silver dissolution is shown to occur with 100% yield with respect to the consumed current. Simultaneously, on the cathode deposited up to 90% of dissolved silver.