Preparation And Performance Of CeO₂/Bi₂WO₆ Photocatalyst On Degradation Of Tetracycline

Recently,the antibiotics were more frequently faced due to their extensive use in human and veterinary medicine,and their residues left in the environment can induce the development of antibiotic-resistant pathogens and cause serious problems for human health.Thus,it is importance to develop efficient and cost-effective treatment technologies to remove these pollutants left in the aquatic environment.Semiconductor photocatalysis has been recognized as an effective technology for environmental remediation of antibiotics,which can degrade tetracyclines into small inorganic molecules under solar energy conversion.Among a multitude of photocatalysts,the novel bismuth tungstate?Bi₂WO₆?semiconductor catalyst has gained extensive attention owing to its own a wide range of visible light absorption,excellent catalytic performance and enhanced stability.Nevertheless,its photocatalytic performance is still restricted by high electron–hole recombination rate in the process of photocatalytic reaction.However,the utilization of photocatalytic technology still faced separated powdered photocatalyst and wastewater that restrict its potential development and application space.Herein,we prepared a novel CeO₂/Bi₂WO₆ heterostructured microsphere with enhanced photocatalytic activity by a facile solvothermal route for degradation tetracyclines.And then,CeO₂/Bi₂WO₆ was laoded on the pumice and applied to the continuous type photocatalytic reactor.Moreover,the mechanism of high photocatalytic activity was also discussed.Such simple and highly productive route of the photocatalyst will allow CeO₂/Bi₂WO₆ to be applied for photocatalytic treatment of tetracyclines wastewater.From the above,the main works and the relevant results are as follows:1.The optimization of CeO₂/Bi₂WO₆ preparation: novel CeO₂/Bi₂WO₆ microspheres with excellent and stable photocatalytic activity for degradation tetracyclines were successfully synthesized via a facile solvothermal route.The crystal structure of the as-prepared microspheres were characterized by XRD,SEM,EDX,HRTEM,XPS,FT-IR,BET and UV-DRS.Among them,1CeO₂/2Bi₂WO₆ exhibited the best photocatalytic activity for degradation of TCH?50-2g/L?,reaching 92.1% after 90 min reaction.It was found that the high activity and stability for degradation of TCH could be attributed to introducing CeO₂ into Bi₂WO₆,which formed the particular morphological conformation of the microspheres and improved transference of the photogenerated charge carriers.Meanwhile,the heterojunction was formed by coupling CeO₂ and Bi₂WO₆ in the as-prepared microspheres,so that the separation efficiency of photogenerated electrons and holes were dramatically improved and the lifetimes of charge carriers were prolonged.2.Immobilization of CeO₂/Bi₂WO₆ catalyst and applied in the continuous tank type photocatalytic reactor: based on the special features that pumice was light and easy to be fluidized,CeO₂/Bi₂WO₆/pumice catalyst was prepared via a facile hydrothermal route.The optimum preparation conditions of composite catalyst were confirmed: the load ratio of catalyst and pumice was 1:4,load rate was 37.24%.CeO₂/Bi₂WO₆/pumice catalyst exhibited great photocatalytic activity for degradation of TCH.Under visiable-light irradiation,the photodegradation rate of TCH was 91.72% in 90 min.Meanwhile,CeO₂/Bi₂WO₆/pumice catalyst had a stable photocatalytic activity after 4 photocatalytic after four recycles,the loss rate was about 9.01%.The optimal operation parameters of reactor under the condition of 50mg/L inlet pollutant concentration were confirmed: the dosing amount of catalyst was 10g/L,the light intensity was 140000 lux,and the hydraulic retention time was over 6h,the removal rate of tetracycline in the reactor was more than 90%.Meanwhile,it had a stable photocatalytic activity in the continuous tank photocatalytic after 72 h,the removal rate of tetracycline in the reactor was more than 90%.This work provides not only a principle method to synthesize CeO₂/Bi₂WO₆ with the excellent photocatalytic performance for actual produce,but also a excellent property of the photocatalyst for potential application in photocatalytic treatment of tetracyclines waste water from pharmaceutical factory.