Preparation Of TiO₂-based Nanotube Composites And Investigation Of The Activity Of The Photoelectrocatalytic In The Degration

With the increasing pollution of organic wastewater,green development makes higher demands on pollution reduction.Traditional technology of organic wastewater limits its application due to its narrow application range and easy secondary pollution.The photocatalytic technology led by TiO₂ semiconductor materials has many advantages due to no pollution,high efficiency and the advantages of green chemistry and recycling economy,and is widely used in the field of the treatment of organic wastewater.Among them,TiO₂-based nanotubes?TNT?materials have a large specific surface area,strong electron transport ability,and highly ordered array structure,so they are widely concerned.However,the visible light response problems and electron-hole recombination problems constrain the practical application of TNT materials.In order to solve the above problems,the TNT materials were modified to prepare Ag-TNT,Cu₂O-TNT and Cu₂O-Ag-TNT composites.At the same time,the applied electric field was introduced into the photocatalytic technology,and the photoelectrocatalytic activity of the degradation of methylene blue organic wastewater under visible light was studied.The main contents and results are as follows:?1?The TNT material was prepared by anodizing with F^-containing organic solution system.The optimal preparation conditions for TNT materials suitable for degrading MB wastewater were as follows:the mass concentration of NH₄F was 0.6%,and the volume ratio of EG to H₂O was 97:3,the anode-anode distance was 3 cm,the potential was 40 V,and the electrolysis time was 2 h.?2?Through the preparation of Ag-TNT composites and the investigation of photocatalytic properties,the optimal photodeposition time of Ag nanoparticles was determined to be 20 min.The deposition amount of Ag was the best deposition amount,and the mass fraction of Ag was 1.32%.Through the preparation and the investigation of photocatalytic properties of Cu₂O-TNT composites,the optimal electrodeposition charge of Cu₂O nanoparticles was determined to be 600mC.The deposition amount of Cu₂O was the best deposition amount,and the mass fraction of Cu was 12.03%.?3?The Z-scheme heterojunction catalyst CAT-4-60 consisting of TNT,Cu₂O nanoparticles and Ag nanoparticles characterizes the process of collecting and improving the charge separation from solar energy and serves as a useful strategy for extending the light absorption range of the photocatalyst.The photocatalytic results of 40mL of 5 mg/L MB dye degradation showed that the CAT-4-60 sample showed a maximum degradation efficiency of 98.58%when the kinetic rate constant was 0.04761 min^-1 under 90 minutes of illumination.The valence state analysis of Cu by XPS shows that Cu?I?in the Z-scheme heterojunction of CAT-4-60 was relatively stable,and CAT-4-60 was still stable and efficient under repeated cycles of cycling experiments.?4?The factors affecting the photoelectrocatalytic degradation of MB by CAT-4-60as photoanode were studied.The optimal conditions for the photoelectrocatalytic degradation of MB by CAT-4-60 as photoanode were established,that was,the NaCl concentration in the electrolyte was 0.2mol/L,the electrolyte pH was 9,the applied anode potential was 2V,and the initial concentration of MB was 20mg/L.In the optimal conditions,CAT-4-60 was used as a photoanode for photo-assisted catalytic degradation of MB.MB could be removed by about 95%,which was much higher than 50%of pure photocatalysis.CAT-4-60 as a photoanode for photoelectrocatalytic degradation of MB can improve the visible light response of pure TNT and the rapid recombination of electron-hole.