Efficiency Of Photoelectrocatalytic Treatment For The Ceftazidime By 3D-TiO₂ NTs

With the large-scale application of antibiotics in the treatment of biological diseases,the composition of domestic sewage and medical wastewater is more complicated and toxic,which is difficult to be completely treated by sewage treatment plants to reach the standard.After discharge,it will cause harm to environmental water bodies and organisms.Photoelectrocatalytic technology has the advantages of strong oxidation ability,fast speed,and environmental friendliness products.Therefore,a 3D surrounding structure of titanium dioxide nanotube photoelectrode was prepared in this paper,and was modified to broaden its light response range to solve the antibiotic wastewater which is difficult to be degraded by conventional treatment methods in sewage plants.Firstly,the titanium dioxide nanotube array electrode was prepared by anodizing with titanium mesh as the substrate,so that the titanium dioxide nanotube could grow around the titanium wire to form a 3D array structure.The optimal preparation conditions obtained was oxidation voltage of 50V for 2h,and calcination at 550℃.The ultrasonic treatment of 1min after the anodization can remove the barrier layer on the surface of the electrode plate and enhance the contact of the titanium dioxide nanotubes with the light and organic matter.In order to explore the optimum conditions for doping Ag/Ag Br nanoparticles on the surface of titanium dioxide nanotubes,the method of photodeposition after precipitation was used by changing the doping concentration and doping times.The photocatalytic degradation rate could reach 75.74%by the modified electrode plate with the initial concentration of10μmol/L Rh B under visible light,and it was better than the photocatalysis without modification by the increasing of 49.85%.Characterization and analysis by SEM,EDS and XRD proved that Ag/AgBr nanoparticles were successfully doped on the surface of titanium dioxide nanotubes with orderly structure.The prepared photoelectrodes was applied to the photoelectrocatalytic oxidation of Ceftazidime（CAZ）to explored the effects of different conditions on the catalytic effect.When the p H was weakly acidic（p H=6）,the concentration of Na₂SO₄ electrolyte was 1.5g/L,the applied current was 0.03A,the distance between anode and cathode plates was 2cm,and the initial concentration of CAZ was 10mg/L,the photoelectrocatalytic degradation rate could get to 98.75%.Stacking multi-layer titanium mesh as a photoanode can effectively improve the degradation rate of the photoelectrodes.In actual engineering,stacking 3 layers of Ag/Ag Br/Ti O₂ NTs photoelectrodes is a more economical choice.After 15 runs of recycling tests,Ag/Ag Br/Ti O₂ NTs still maintained a good degradation effect.The reaction kinetics fitting of each reaction factor was all accorded with the first-order reaction kinetic characteristics.The contribution rate of the active catalytic groups in the system to the degradation of CAZ in descending order was·O₂^-,h⁺,·OH by the addition of various scavengers agent into the system.The degradation process of CAZ was monitored by UV spectrophotometer and LC-MS to infer the possible degradation pathway of CAZ.