Research On Quinoline Degradation With The Established Photoelectrocatalysis System

Quinoline is a typical refractory organic substance in the secondary effluent of coal chemical wastewater.It is widely present in surface water and soil.The traditional physical adsorption method and biodegradation method are faced with the problems of high cost and long processing cycle,which are difficult to put into practical application.Therefore,it is urgent to seek a stable and efficient quinoline advanced treatment method.Photoelectrocatalytic(PEC)oxidation technology is a branch of advanced oxidation technology.It combines the photocatalytic process with the electrochemical process to produce strong oxidizing·OH for non-selective and efficient oxidation of pollutants.Based on photoelectric catalytic oxidation technology,this thesis developed a metal oxide catalyst based on titanium mesh copper mesh,designed a 3D stacked photocatalytic reactor based on the principle of Z-Scheme semiconductor heterojunction,and investigated the degradation of quinoline in the photocatalytic reaction system.Then we explores the factors that affect the degradation reaction,which lays the foundation for the subsequent enlargement of the system and the advanced treatment of actual coal chemical wastewater.Ag-TiO₂/Ti photoanodes were prepared by anodizing method and photoreduction deposition method,and Cu₂O/g-C₃N₄ photocathode were prepared by wet chemical oxidation method and hydrothermal method.The catalyst was characterized from the aspects of surface morphology,crystal structure,chemical bond composition and photoelectrochemical performance.Based on the principle of Z-Scheme compound semiconductor heterojunction and the structure of traditional supported photoelectric catalytic reactor,combined with the mesh catalyst structure,a 3D stacked photoelectric catalytic reactor was built,which successfully achieved the simultaneous anode-cathode photocatalytic oxidation and reduction.It effectively solves the problems of low light utilization rate of traditional photocatalytic reactors and difficulties in separation and recovery of powder catalysts,and provides the possibility for practical application of reactors.In order to determine the optimal operating parameters of the photocatalytic system,the effects of operating conditions such as the number of stacked layers,applied bias voltage,and cathode materials on the degradation efficiency of the system during pollutant degradation were studied.The results show that in the constructed 3D stacked mesh photocatalytic system,the applied bias voltage is 1.5V,and the 7-layer metal catalyst mesh has the best photocatalytic performance.The reaction rate constant is 0.00871 min^-1.Cu₂O/C₃N₄ is the most effective electrode among cathode materials.The 3D stacked photoelectric catalytic reaction system was applied to the degradation of the target pollutant quinoline.The experimental results show that the 3D stacked photoelectric catalytic reaction system has the ability to efficiently degrade quinoline.During the 90 min degradation period,the degradation rate of quinoline reached 77.6%,the TOC removal rate reached 71.5%,and the reaction rate constant was 0.01656 min^-1.Cu₂O/g-C₃N₄ cathode basically degraded 50 mg·L^-1 quinoline completely within 90minutes after aeration,the rate constant increased from 0.01681 min^-1 to 0.04412 min^-1,and the TOC removal rate increased to 81.5%.The increase in initial concentration increases the solution mass transfer resistance,resulting in a decrease in reaction rate and degradation rate.The Langmuir-Hinshelwood model was used to fit the reaction kinetics of the photocatalytic degradation of quinoline.The quasi-first-order reaction kinetics was best fitted,and the reaction rate constant was 0.01656 min^-1.From UV-Vis full-wavelength scanning and liquid chromatography,it is speculated that quinoline degradation process has more polar intermediate products.