| Electrochemical advanced oxidation technology aims to directly and indirectly generate hydroxyl radicals,realize the mineralization degradation of persistence organics.It is highly efficient,enviromentally friendly,and has a high degree of mineralization.These advantages make them impotant technology for antibiotic wastewater treatment.Cathodic indirect catalytic oxidation(electro-Fenton/electro-Fenton-like)and anodization are two important advanced electochemical oxidation techniques.The common challenge they are facing is the development of efficient,stable,non-secondary,and economical catalytic materials.Titanium dioxide(TiO2)is a widely used semiconductor photoelectrocatalyst with high chemical stability,environmental friendliness and low cost.Its high energy band gap makes it have excellent photoelectroatalytic performance,but due to its electrochemical inetia,it is rarely used in electocatalytic systems.In this study,the conductivity of graphite was intoduced through the preparation of graphite-supported titanium dioxide(TiO2-C)composites,and its electocatalytic properties were investigated and applied to electrochemical catalytic oxidation technology.Therefore.the umain contents of this study are as follows:1.TiO2 was loaded on the surface of graphite by sol-gel method to make TiO2-C composite.Graphite was used as the carier of TiO2 to improve its electrical conductivity.The composite was then made into a heterogeneously catalyzed gas diffiision electrode.This method optimizes the disadvantages of the traditional electro-Fenton system that requires the addition of homogeneous Fe2+/Fe3+ catalysts,pH regulators,and iron slurries on the premise of high degradation efficiency.The characterization of surface structure and morphological characteristics of TiO2-C composites proves that TiO2 is successfully loaded on the surface of graphite.and the diameter of nano-TiO2 particles is about 50 nm.Cyclic voltanmmetry scan test was used to examine the electrochemical properties of the composite electrode,and hydrogen evolution:-2.65 V:oxygen evolution potential:2.25 V.2.The Ti02-C composite material was applied to the cathode-type electric Fenton system.The degradation performance test showed that the TiO2 loading was 40%,the solution pH was 3,the cathode voltage was-0.8 V vs.Ag/AgCl,and the electrode rotation speed was 400 rpm,tetracycline hydrochloride(50 mg/L)can be degraded by 93.42%after 2 h run.The degradation rate of the new electrode was only decreased by 7%at 2 h after five runs.and Ti ion concentration in the solution was about 0.10 ppm after 2 h of operation,which showed excellent stability.3.The mechamnism of TiO2-C composites applied to cathodic electic Fenton system found that:H2O2 produced by the reduction of cathode O2 can generate ·OH on the surface of TiO2,and can produce 96.8 ?M ·OH after 60 minutes of operation;Electron paramagnetic resonance spectrum of the TiO2-C composites showed that the TiO2-x structure was found after the cathodic process.The free radical species in the electrolyte solution were characterized qualitatively by electron paramagnetic energy spectrum,including ·OH.O2·-and ·OOH,in which O2·-/·OOH radicals mainly come from the cathode 02 reduction reaction.4.The Ti02-C composites were used in anodizing system.The degradation efficiency of tetracycline in the anode system was tested with range of the anode voltage:0.8-1.6 V vs.Ag/AgCl.The tetracycline hydrochloride was completely degraded under 50mg/L for 20 minutes and had excellent anodizing degradation performance on the condition of 1.4 V vs.Ag/AgCl anode potential.The main catalytic mechanism in the tetracycline anodizing system is that the anodic electrocatalysis of TiO2-C composites produces ·OH to achieve the oxidative degradation of tetracycline.At the same time,it was found that the absoption of ambient light energy by C material improves the oxidative degadation efficiency of TiO2-C anodes.The Ti02-C electrode still maintains the structural integrity after repeated use of the anodic oxidation system five times,and the degadation of the tetracycline hydrochloride after 2 hours run was only about 6%lower than the first time.It also shows good stability in the anode system. |
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