Influence Of Preparation Process Of Gas Diffusion Electrode On Its Performance And Its Application In Zinc Electrowinning

Zinc occupies an important position in the modern industrial system,However,hydrometallurgy which is the main refining method exists serious problems,such as high energy consumption,serious pollution,and poof product quality.Introducing the gas diffusion electrodes instead of traditional alloy anodes is an effective method to address these problems in industrial production.The gas diffusion electrode can effectively reduce the energy consumption of zinc refining,environmental pollution,and improve the quality of products through the change of the anode reaction.Therefore,exploring the application of hydrogen diffusion anode in zinc electrodeposition is crucial.In this thesis,the influencing factors of the preparation of gas diffusion electrodes and their relation with the performance of the electrodes were studied.Starting from the electrode slurry,the two dispersion methods of ultrasonic dispersion and shear stirring were combined to prepare a stable gas diffusion electrode catalytic layer slurry by optimizing the process.The particle size results showed that the slurry had excellent dispersibility and stability with average particle size of the slurry was 977.5 nm and the particle distribution index was 0.203,when the ultrasonic power was 80 W,the ultrasonic dispersion time was 40 min,the shear rate was 3000 rpm,the shear time was 50 min,and the dispersant added was 2.5%PEG-10000.The gas diffusion electrode was prepared by spraying method with commercial carbon cloth as the current collector,20wt% platinum carbon as the catalyst,and polytetrafluoroethylene as the binder.The performance differences of gas diffusion electrodes were explored and determined the best process as follows: the hot-pressing pressure was 2.0 MPa,the hot-pressing temperature was 350 °C,the hot-pressing time was 60 s,and the PTFE content was 50%.The electrode had suitable hydrophilicity,hydrophobicity and conductivity in above optimal conditions.Zinc electrowinning experiments were carried out with the prepared electrodes,and determined the optimized electrolysis process as follows: the hot-pressing temperature was 350°C,the hot-pressing pressure was 2 MPa,the hot-pressing time was 60 s,and the PTFE content was 50%.In this optimal conditions,the gas diffusion electrode had the best performance with the average cell voltage was 1.112 V,and the current efficiency was 95.20%.Significantly,the power saving rate reached as high as 69.11% and the surface of the electrolytic product was smooth when the current efficiency was close to the industrial production efficiency.Meanwhile,the current efficiency was94.20% and the electricity saving rate reached as high as 56.96%,under the simulated industrial operating conditions for 50 hours,with the average cell voltage was 1.533 V,showing that the electrodes we prepared have great industrial application prospects.