Dynamics of the codeposition of metals in a porous electrode in the presence of an oxidant

Abstract

The oxidant effect on the codeposition of two metals in a porous electrode (PE) was studied experimentally and by numerical calculations. The presence of an oxidant in a solution always leads to degradation of the dynamics and final characteristics of the target process, namely, to a decrease in the current efficiency, the final mass, and the average rate of metal deposition and to a less uniform distribution of metals in the PE. The effect depends on the PE operating conditions and involves less uniform potential distribution in PE and anodic dissolution of metals. The former component of the effect dominates when the concentrations of the metal ions and oxidant are comparable. A considerable deceleration of silver deposition in the presence of an oxidant and anodic dissolution of copper at the first stage of the electrolysis of the second and subsequent portions of solution were confirmed experimentally using as an example Ag and Cu extraction from an alkaline thiosulfate solution in the presence of a Fe³⁺ trilonate complex used as an oxidant.