Effect of the Acidity of the Medium on the Cathode Reactions of Sulphite and Thiosulphate Anions during Silver Extraction from Fixing Solutions
A. G. Belobaba, A. I. Masliy, D. V. Sukhorukov, Li Gan
Pages: 317-322
Abstract
Dependence of the processes involving reduction of the main components of fixing solutions (silver ions, thiosulphate and sulphite) on silver, graphite and platinum cathodes on pH is investigated. It is established that the pH value has the strongest effect on the reduction of sulphite ion; in the medium with рН ≥ 7 it does not get reduced. Quite contrary, the reduction of thiosulphate and silver is only weakly dependent on this parameter. The optimal electrolysis conditions (potentiostatic mode at the cathode potential equal to 0.85 V, and рН ≥ 7) were chosen so that they allow one to recover the worked out fixing solutions using the flow voluminous porous cathodes and to decrease the residual silver content down to 0.5-1.0 mg/l.
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