| Pb-Ag (0.7-1.2%) alloy anodes have been commonly used at Non-ferrous metals zinc electrowinning process, which was easy to be manufactured and simply to be formed. However, there were also some shortcomings, such as short lifetime, high cell voltage, low current efficiency and mechanical properties. At present, A great interest was attracted in the improvement of lead dioxide as zinc electrowinning anode material, owing to its good corrosion resistance, highly electrical conductivity, good catalytic, low cost, and so on.First of all, the anodic coating ofα-PbO2-Co3O4-CeO2 on stainless steel was prepared by DC deposition in this paper. The effect of different conditions and solid particles on the binding, appearance and deposition rate of the composite were researched. The results determined the optimum conditions for electrode preparations: the current density 1.5 A/dm2, electroplating time 2 h, temperature 40℃, and Co3O4 30 g/L and CeO2 15 g/L. SEM,XRD and linear sweep voltammetry(LSV) were used for the analysis of the surface structure, phase composition and oxygen evoluction potential analysis in zinc sulfate electrolyte. The results showed that the particles of depositing can not only improve electrode surface area but also reduce the granularity of pellet. Adding Co3O4 and CeO2 coating electrode restrained the preferential growth and weakened diffraction intensity ofα-PbO2.Theα-PbO2-CoaO4-CeO2 electrode has an lower oxygen evolution potential and higher electrocatalytic activity than PbO2 electrode.With the different dosage of CNT in Pb(NO3)2 electroplating solution,β-PbO2-CNT were prepared on stainless steel/α-PbO2-Co3O4-CeO2 composite coatings. It can be seen from electrochemical analysis that doped with different concentrations of CNT,20 g/L was determined as the optimal doping CNT concentration. It indicates from the anode polarization curves that kinetic parameters a and b values of stainless steel/β-PbO2-CNT composite coating was smaller than that of without adding CNT and has better electro-catalytic activity. Tafel curve shows that the doped CNT can improve the corrosion resistance of the electrode, but the effect is not obvious.It can be seen from cyclic voltammetry that doped CNT does not change the reaction mechanism ofβ-PbO2, the reduction peak is not shifted and reduced. SEM images show that grain morphology ofβ-PbO2 coating without adding CNT was octahedral shape and coarse grains, relatively. The grain surface ofβ-PbO2 coating with CNT was not uniform. There were octahedralβ-PbO2 particles, the CNT distribution surface and the small octahedralβ-PbO2 particles at the surface by the impact of CNT.PbO2 particles were prepared withα-PbO2-Co3O4-CeO2/β-PbO2-CNT Composite coating, then PbO2 particles were pressed into Pb-(1%) Ag anode surface as a new type of anode material, compared to Pb-(1%) Ag anode in zinc electrowinning process, this anode material has lower cell voltage and high current efficiency... |
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