Preparation,Properties And Structure Characterization Of Gas Diffusion Electrodes For In-situ H₂O₂

In recent years,in-situ H₂O₂ electro-Fenton oxidation has been regarded as a more promising advanced oxidation treatment technology for refractory organic wastewater,and thus has been extensively studied,becoming a research hotspot of advanced oxidation technology.However,due to the limited performance of its electrode material,especially the cathode material,which generates H₂O₂ in situ,it has not been used in large-scale industrial applications.Improving the performance of cathode materials and developing new cathode materials and electrodes have become the key to breakthrough industrial applications of this technology.As the cathode material of electro-Fenton technology,gas diffusion electrode can generate H₂O₂ in situ of the electrode and then generate Fenton reaction to generate·OH,which is an ideal cathode material.In this paper,by screening the main cathode materials,improved electrode preparation process,in-situ H₂O₂ production experiment and material structure characterization,etc.,the gas diffusion electrode is studied in order to promote the development of in-situ H₂O₂electric Fenton technology and lay the foundation for the realization of planned application.By comparing the five carbon blacks of VXC-72R,acetylene black,SUPER P LI,VXC-72 and BP2000,Ti,Ni and stainless steel material collectors,gas diffusion electrodes made with different C/PTFE ratios can produce H₂O₂.Screening to get the best cathode material combination:（1）The strongest H₂O₂ production capacity:SUPER P LI carbon black,50 mesh stainless steel mesh,C/PTFE ratio is 4:3,the best H₂O₂yield is 18.09 mg/（L·cm²·h）;（2）The best electrode stability:VXC-72R carbon black,15 mesh titanium mesh,C/PTFE ratio is 4:3,and able to experiment 13 times（each experiment 5 h）.The preparation process was improved by modifying nitric acid,adding a certain proportion of pore-forming agent,and changing the heat treatment conditions.It was found that after nitric acid modification,VXC-72R carbon black was calcined for one hour without adding pore-forming agent and under 350℃nitrogen protection The output of electrode H₂O₂ can be increased by up to 24.36%.The operating parameters of the system were changed to conduct the H₂O₂experiment,and the operating conditions were recommended as current density 5～10m A/cm²,initial p H value 3.0～3.5,and aeration volume 120 m L/min.Through SEM image and contact angle analysis,it was found that the pores on the electrode surface were blocked by the electrolyte and the electrode contact angleθdecreased.Due to the destruction of the electrode structure and hydrophobicity,the performance and stability of H₂O₂ produced by the electrode were greatly reduced.Electrode structure characterization research can provide reference for electrode development.