Cyclic Voltammetric Studies of the Behavior of Lead-Silver Anodes in Zinc Electrolytes

W Zhang,Y F Chen,W Y Li,C Q Tu,G Houlachi

doi:10.1007/s11665-012-0456-0

Abstract

Cyclic voltammetry (CV) for lead-silver anodes has been performed in an acidic zinc sulfate solution with and without Mn2+ at 38 °C. It has been found that the most redox peaks observed at the lowest sweep rate of 3 mV/s in the sulfate solution could be characterized by the Nernst equation. Bubbling argon into the zinc electrolyte and increasing the potential sweep rates from 3 to 300 mV/s did not change the shape of the CV diagrams. It was also found that 0.7% silver as alloying element had an important influence on the reactions of Pb-Ag anodes in the zinc electrolyte. Lead-silver alloys were oxidized more easily in sulfuric acid than in the examined zinc electrolyte. The addition of MnSO4 to the zinc electrolyte decreased the numbers of the redox peaks on the curve of CV for lead-silver anode in zinc electrolyte.

Highlights

Insoluble anodes are widely used in industrial hydrometallurgical processes
The electrochemical redox behavior of lead and lead-silver alloy electrodes was investigated in sulfuric acid and zinc electrolyte using cyclovoltammetric method
After characterizing each redox peak, the following conclusions can be drawn: 1. CV technique has been used to observe redox peaks, and the associated species or products formed at these peaks could be characterized by chemical and physical methods, and x-ray diffraction (XRD) measurements confirm the results

Summary

Introduction

Insoluble anodes are widely used in industrial hydrometallurgical processes. A useful anode material must meet three requirements: electrical conductivity, electrocatalysis, and stability. Most hydrometallurgical processes use sulfuric acid solutions. The main anodic reaction is oxygen evolution by decomposition of water. In these solutions, the predominant anode materials have been different lead alloys used as anodes. Pure lead has many disadvantages: higher overpotential, and more corrosion products; pure lead is a weak material and it tends to creep and warp during use. Lead must be alloyed to improve at least its mechanical properties (Ref 1)

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