Electrochemical Degradation Of Tetracycline In Water By Modified Titanium Based Lead Dioxide Electrode

Tetracycline is a commonly used antibiotic,which is widely used in medical care,livestock and poultry breeding and other fields.In the process of livestock and poultry feeding,tetracycline is added to the feed as an important antibiotic.However,it cannot be metabolized in animals completely.The residual tetracycline flows into the natural water body with the discharge,which is harmful to the aquatic ecosystem and human health.Tetracycline has complex molecular structure and is difficult to biodegrade,and common water treatment measures are taxing to carry out.Therefore,it is essential to explore an efficient and valuable removal method.In this study,an electrochemical advanced oxidation method was designed to remove tetracycline from water.The electrocatalytic activity of the electrode was improved by introducing other substances into the Ti/Pb O₂ intermediate layer and active layer.The main research results are as follows:（1）Ti/Pb O₂,Ti/Pb O₂-La,Ti/Ni O/Pb O₂ and Ti/Ni O/Pb O₂-La anodes were prepared by electrochemical deposition（chronopotentiometry and chronoamperometry）and high temperature thermal oxidation.The electrochemical properties of four kinds of anodes were analyzed by cyclic voltammetry（CV）,linear cyclic voltammetry（LSV）and AC impedance（EIS）.The experimental results showed that doping La can significantly improve the electrocatalytic activity of the electrode in a single modification,while the intermediate layer modification alone could only slightly improve its electrochemical performance.In the synergistic modification,compared with the other three kinds of Ti/Ni O/Pb O₂-La anodes,the prepared Ti/Ni O/Pb O₂-La anodes were significantly improved in peak current and peak potential,oxygen evolution potential and charge transfer ability on the electrode surface.（2）The prepared electrode was used as anode and the polished and etched Ti plate was used as cathode.The removal effect of tetracycline by different modification methods was explored.The effects of solution p H,current density and initial concentration on the degradation process of tetracycline were investigated.The experimental results show that except for the electrochemical performance of the three modified electrodes,the condition factors have no obvious effect on the electrode degradation process.When the p H of the solution was 4.5,the current density was 20 m A·cm^-2 and the initial concentration was 10 mg·L^-1,the removal rates of TC by Ti/Pb O₂-La,Ti/Ni O/Pb O₂ and Ti/Ni O/Pb O₂-La anodes were 97.2%,94.2%and 98.4%respectively.The degradation process accorded with the first-order kinetic model.（3）The p H of the control solution was 4.5,the current density was 20 m A·cm^-2,the initial concentration was 100 mg·L^-1,and the degradation time was 90min.according to the COD removal rate,the current efficiency and energy consumption of different modified electrodes in each stage were calculated respectively.The results showed that Ti/Ni O/Pb O₂-La anode can maintain high current efficiency and low energy consumption before 60 min,and has better stability than the other two anodes.Through the accelerated life test of the electrode,it was concluded that the interlayer modification plays a key role in improving the service life of the electrode,and the service life of the electrode after synergistic modification is up to 62 hours.Under the optimum conditions,the removal rates of the three electrodes could still be maintained above 90%after being reused for 6 times.（4）Combined with free radical masking experiment,it was verified that^·OH was the main active substance in the process of electrocatalytic degradation,and the possible degradation path of TC in water was preliminarily analyzed.