Al / Pb-WC-CeO ₂ / PbO ₂ Research / MnO 2 Electrodes Preparation And Electrochemical Properties

In the electronwinning process of zinc hydrometallurgy, Pb-Ag alloy is the most widely used anode material. Though it can meet the basic requirements of zinc electrowinning, there are some deficiencies difficult to improve, such as easy bending deformation, causing a short circuit during use, great density makes assembly difficult, high energy consumption of electrowinning process and low electro catalytic activity, besides lead ions dissolved in the electrolyte can be produced on the cathode and contaminate the cathode zinc. In order to solve the above problems, on the one hand, traditional Pb-based alloy anode have been modified by surface doping; on the one hand, new kind of inert anode materials based on titanium have been explored, such as PbO2and MnO2anodes. However, the inherent defects of lead are inevitable and titanium substrate is expensive and short in service life.According to the above problems, we adopted the light and cheap aluminum as matrix and prepared Al/Pb-WC-CeO2/PbO2/MnO2anode by DC electrodeposition technology. The electrode was applied to zinc electro winning showing better electro catalytic activity and reducing oxygen evolution overpotential effectively, thereby reducing cell voltage and saving energy.The Al/Pb-WC-CeO2/PbO2/MnO2electrode was prepared by DC electrodeposition technology. The optimum conditions of electrodeposition that determined by orthogonal and single factor experiments were:MnSO4150g/L, H2SO450g/L,070.5g/L, temperature at80℃at the current density of3mA-cm-2, plating time75min. The electrode properties were characterized by steady-state polarization curves, Tafel curves, AC impedance spectroscopy, scanning electrochemical microscope (SECM), scanning electron microscope (SEM), energy spectrum (EDS), X-ray diffraction (XRD) and cyclic voltammetry curves (CV) methods. The results showed that coating prepared under optimum conditions had the smoothest surface, the highest content of manganese and the best catalytic activity and corrosion resistance. Main phase of MnO2electrode was y-MnO2. Roasting at120℃was beneficial to improve the crystallinity of MnO2grains, thereby refining coating grains. Anionic surfactant can refine grains and promote the deposition of Mn2+,as a result, the deposition of MnO2turned into one step process from two steps.Taking into consideration of cell voltage, current efficiency, zinc quality and service life, the Al/Pb-WC-CeO2/PbO2/MnO2electrode that had lower cell voltage, higher current efficiency and the longest service life can meet the requirements in economic and practical, but the quality of cathodic product was relatively low.