Visible-light Photoelectrocatalytic Removal Of Mixed Water Pollutants Based On Titanium Dioxide Nanotubes Composite Film

As a new advanced oxidation technology,photoelectrocatalysis technology combines electrocatalysis on the basis of photocatalysis.It also has the advantages of photocatalysis and electrocatalysis,and is widely used in the field of water pollution treatment.However,there is only a single pollutant in the environmental water body,which is more common in the form of mixed pollutants.The treatment of mixed pollutants is more difficult and worth studying.In this paper,Ti O₂ nanotubes are used as the matrix,and composite film electrodes with visible light absorption are prepared through different modification methods.The photoelectrocatalytic removal efficiency of organic-heavy metal ion mixed pollutants on the composite Ti O₂ nanotube film electrode was studied.The main research content includes the following two parts:（Ⅰ）Ag/Ag Cl-Ti O₂ NTs composite film electrode was prepared by anodic oxidation and electrochemical deposition,and used to synergistically remove tetracycline-Pb²⁺mixed pollutants.Compared with photocatalysis and electrocatalysis technology,photoelectrocatalytic technique exhibited the highest visible removal efficiency for tetracycline-Pb²⁺mixed pollutants..Tetracycline and Pb²⁺undergo oxidation and reduction reactions at the anode and cathode respectively.The results after optimizing the electrode preparation process and experimental conditions show that when the electrodeposition time is 60 s and the applied voltage is+3 V,the removal efficiency of tetracycline and Pb²⁺are the best,which are 83.2%and 94.6%,respectively.And the results of four cycles experiment show that Ag/Ag Cl-Ti O₂ NTs composite film electrode has excellent stability.Tetracycline and Pb²⁺have mutual influence in the removal process,which shows that tetracycline promotes Pb²⁺removal and Pb²⁺inhibits tetracycline removal.（Ⅱ）Bi/Bi₂O₃-Ti O₂ NTs composite film electrode was prepared by anodic oxidation,immersion-decomposition and electrochemical deposition,and used to synergistically remove oxytetracycline-Cu²⁺mixed pollutants.First,using oxytetracycline as a simulated pollutant,the degradation efficiency of visible light PEC on different composite electrodes was studied,and the electrochemical deposition time was optimized.The results show that when the electrodeposition time is 60 s,the prepared Bi/Bi₂O₃-Ti O₂ NTs film electrode has a 46.3%degradation efficiency for oxytetracycline in 120 min.Then the optimized Bi/Bi₂O₃-Ti O₂ NTs film electrode was used to treat the mixed contaminant of oxytetracycline-Cu²⁺,and the removal efficiency was 76.1%and 96.5%after PEC treatment for 5 h.The mutual influence of oxytetracycline-Cu²⁺mixed pollutants were explored.In addition,high performance liquid chromatography-mass spectrometry technology was used to explore the mechanism of the PEC co-treatment process of oxytetracycline-Cu²⁺mixed pollutants.