Polyaniline And Tungsten Carbide Enhanced Lead-based Inert Anode Materials

Non-ferrous metal resources are plentiful in our country. Although Pb-Ag alloy anodes are widely used in hydrometallurgy processes such as electrowinning Zn, Cu, Ni, Co etc. But the shortages such as high oxygen evolution potential, low mechanics property and electroconductibility, anodic dissolution pollute the electrolyte, which limits its efficient. Special attention has been paid to new kinds of composite inert anodes for the advantage of combine and synergy of the materials. This paper prepared Al/Pb-PANI-WC composite inert anodes on Al substrate by pulse electrodeposition technique.Al/Pb-PANI-WC composite inert anodes have been prepared by direct current electrodeposition, signal-pulse and double-pulse current electrodeposition in electrolyte which added conductive PANI, WC activity particles and Pb2+. The effects of electrodeposition method, conductive PANI and WC activity particles deposit individually and jointly with Pb2+ on electrocatalytic activity for oxygen evolution were studied. Anodic polarization curve, CV curve, tafel curve and EIS were tested in the solution of ZnSO4+H2SO4 and electrochemical performance parameters such as oxygen evolution kinetic parameters, electrode reaction reversibility, voltammetry charge, corrosion potential and corrosion current density of the composite inert anodes have been obtained, the surface morphology, section organization and composition distribution has been studied by means of SEM. The results show that the Al/Pb-PANI-WC composite inert anode prepared by double pulse electrodeposition possesses compact organization, composition uniformly distributed, higher electrocatalytic activity for oxygen evolution and corrosion resistance.By using double-pulse electrodeposition method, the effects of conductive PANI and WC activity particles density, temperature of electrolyte and parameters of positive pulse current on oxygen evolution kinetic parameters, electrode reaction reversibility, voltammetry charge, surface morphology and composition distribution of composite inert anode were stuied. The process of preparing composite inert anode was optimized. Compared with Pb-1.0wt%Ag alloy inert anode, PANI and WC activity particles deposited in matrix metal of Pb can be lowering the oxygen evolution overpotential in the process of zinc electrowinning and the overpotentials of oxygen evolution are reduced 243mV,207mV,183mV and 171mV when the current densities are controlled at 500A·m-2,1000A·m-2,1500 A·m-2 and 2000A·m-2. Furthermore, exchange current density and electrocatalytic surface are significantly higher than Pb-1.0wt%Ag alloy inert anode.The comparative study between Al/Pb-PANI-WC composite inert anode and Pb-1.0wt%Ag alloy inert anode on zinc electrowinning were carried out in the solution of 50g/L Zn2+,150g/L H2SO4 and 35℃, and the current density was 500A·m-2. In the course of zinc electrowinning, the cell voltage of Al/Pb-PANI-WC composite inert anode was 434mV lower than Pb-1.0wt%Ag alloy inert anode, demonstrated very good energy saving potential. The intensifying lifetime test was carried out under the current density was 10000A·m"2, the result shows that the lifetime of inert anode were 14h, convert to the lifetime under 500A·m-2 were 233 days.