Preparation And Performance Study Of Titanium-coated Carbon Fiber-based Lead Dioxide Anode For Zinc Electrowinnin

Zinc electrowinning is one of the important processes in hydrometallurgy of zinc.The composition and properties of the anode are very important in the Zinc electrowinning,which directly affects the energy consumption of the Zinc electrowinning and the quality of zinc on the cathode.At present,the main anode material for zinc electrowinning is lead-silver alloy anode,but it has problems such as dissolution of lead anode,uneven current distribution,and contamination of zinc coating with lead.In this study,a new type of CF/Ti/β-PbO₂ composite anode was prepared by successively preparing an intermediate layer of titanium metal and a lead dioxide active layer on a carbon fiber substrate using thermal decomposition and electrodeposition methods is used to improve the oxygen evolution catalytic activity and corrosion resistance of the anode material in zinc electrodeposition solution,while reducing the energy consumption of zinc electrodeposition and the corrosion rate of the anode material,achieving the purpose of improving the service life of the anode material.Firstly,the pretreatment of hot air oxidation and liquid phase oxidation was carried out for the presence of impurities such as oil on carbon fibers.It is found that double pretreatment of hot air oxidation and liquid phase oxidation can improve the type and relative content of oxygen-containing active functional group on carbon fiber matrix,increase the O/C ratio and increase the chemical activity of carbon fiber;corrosion pits and scratches can be added on the carbon fiber to improve the interfacial roughness of the carbon fiber and the coating to enhance the interfacial bonding performance and provide more nucleation points for the coating.Next,carbon fiber-titanium composites were prepared by coating titanium hydride solution on carbon fiber using thermal decomposition method and heating it.The results show that the decomposition of Ti H₂ is not a one-step reaction,and the dehydrogenation step of titanium hydride is Ti H₂→Ti H_1.5→α-Ti→β-Ti,which belongs to the shrinkage nucleation model.When the temperature is 700℃and the content of titanium hydride is 2.5 g,the carbon fiber-titanium composite has good interfacial bonding performance,low resistivity,high catalytic activity and good corrosion resistance.Finally,theβ-PbO₂ active layer,which can serve as the catalytic active layer and electrochemical reaction interface,was deposited on the carbon fiber/titanium composite by electrodeposition.The study using the univariate method found that the CF/Ti/β-PbO₂composite anode was found to have the best interfacial bonding performance,the best electrical conductivity and the best corrosion resistance when the concentration of lead nitrate was 130 g/L,the electrodeposition current density was 40 m A·cm^-2 and the electrodeposition time was 2 h.At the same time,theβ-PbO₂ active layer grains on the composite anode surface were uniform and dense.The Ti interlayer exhibits excellent catalytic activity and electrical conductivity,and it plays a very important role in improving the stability of theβ-PbO₂ active layer and the corrosion resistance of the CF/Ti/β-PbO₂ composite anode.In comparison with the conventional Pb-Ag anode,the polarization potential of CF/Ti/β-PbO₂ composite anode was found to be 472 m V lower than that of Pb-Ag anode,and it had higher self-corrosion voltage（0.730 V）and lower self-corrosion current(2.753×10^-5A·cm^-2),the catalytic activity and corrosion resistance of CF/Ti/β-PbO₂ composite anode were better;in the simulated zinc electrowinning process,the CF/Ti/β-PbO₂ composite anode increased the current efficiency by 14.92%,the corrosion rate was only 1/60 of that of Pb-Ag anode,while its service life was 3.32times that of Pb-Ag anode,saving 22.91 k W·h per ton.