Study On The Preparation Of FeWO₄ Based Nanocomposites And Their Sonocatalytic Removal Of Tetracycline

The rapid development of modern biomedicine has resulted in the generation of a large amount of organic drug waste liquid in the environment.Tetracycline（TCL）is the most widely produced and used drug in the world.TCL is not easy to be absorbed and degraded by organisms,which will lead to continuous accumulation of TCL in the environment,resulting in the generation of drug resistance and resistance genes to TCL in the biological world.In the end,the organism will have malformation,mutation,cancer and other adverse effects,so it is necessary to explore effective methods to remove TCL.The semiconductor-based sonocatalytic degradation technology used to remove TCL is a method with high removal efficiency and no secondary toxic pollution.At the same time,it also has the advantages of simple operation and strong practicability.FeWO₄ is a common metal tungstate with a band gap energy of about 2 e V.However,the high electron-hole pair（e^--h⁺）recombination rate is the disadvantage of FeWO₄.High e^--h⁺recombination rate will limit the catalytic performance of FeWO₄.Studies have found that the e^--h⁺recombination rate can be reduced by constructing heterojunction,while producing more active materials and further improving the degradation efficiency of the catalyst.In this study,FeWO₄ was used as a sonocatalyst to explore its sonocatalytic activity after combined with ultrasonic technology.Furthermore,the sonocatalytic activity of FeWO₄ was improved by constructing complex.The research contents are as follows:Firstly,FeWO₄ nanosemiconductors were prepared by hydrothermal method.CuS/FeWO₄ catalysts were prepared by hydrothermal synthesis method by changing the addition amount of reaction raw materials to adjust the morphology of FeWO₄ and using FeWO₄ as the substrate.The catalysts were used to remove TCL by sonocatalysis to explore the sonocatalytic performance of CuS/FeWO₄.The removal rate of TCL can reach 99.0%by CuS/FeWO₄ catalyst combined with ultrasonic technology under optional experimental conditions.The kinetics of sonocatalytic removal of TCL by CuS/FeWO₄ was studied,and it was proved that the combination of CuS and FeWO₄could greatly improve the ability of sonocatalytic removal of TCL by FeWO₄.The hole（h⁺）,superoxide anion（·O₂^-）and hydroxyl radical（·OH）were identified as the active substances causing the degradation of TCL by radical trapping experiments,and the S-type heterojunction mechanism of CuS/FeWO₄ was proposed.Finally,the four reusability experiments of CuS/FeWO₄ catalyst and the XRD and XPS images before and after the reaction using CuS/FeWO₄ also proved that CuS/FeWO₄ could maintain high sonocatalytic activity and good stability in the process of removing TCL.It was proved that the addition of H₂O₂ could greatly improve the efficiency of CuS/FeWO₄in removing TCL by exploring the influence of H₂O₂ on the reaction.The intermediate products and degradation pathways in the process of removing TCL using CuS/FeWO₄were proposed by Q-TOF HPLC-MS technology.Secondly,using FeWO₄ as substrate,a new BiOBr/FeWO₄ sonocatalyst was successfully prepared by hydrothermal synthesis method.The sonocatalytic activity of BiOBr/FeWO₄ removing TCL was significantly higher than that of only BiOBr or FeWO₄ under the action of sonocatalysis.The BiOBr/FeWO₄ complex with 15%mass ratio had the best sonocatalytic activity and the degradation rate of TCL reached 86.5%.The kinetics of sonocatalytic removal of TCL using BiOBr/FeWO₄ was studied.It was proved that the combination of BiOBr and FeWO₄ could greatly improve the ability of sonocatalytic removal of TCL using FeWO₄.The free radical trapping experiments proved that various active free radicals（·OH,·O₂^-and h⁺）were the main active substances causing the degradation of TCL.The S-type heterojunction mechanism of BiOBr/FeWO₄ was proposed.Finally,it was concluded that BiOBr/FeWO₄ could maintain high sonocatalytic activity and good stability in the process of removing TCL according to four reusability experiments of BiOBr/FeWO₄ catalyst,ICP test results and XPS images of BiOBr/FeWO₄ catalyst.It was proved that the addition of K₂S₂O₈could greatly improve the efficiency of removing TCL using BiOBr/FeWO₄ by exploring the influence of K₂S₂O₈ on the reaction.The intermediate products and degradation pathways in the process of removing TCL using BiOBr/FeWO₄ were proposed by Q-TOF HPLC-MS technology.The above experimental results show that the sonocatalytic performance of FeWO₄ can be effectively improved by constructing heterojunction.It is expected that the results of this study will provide useful reference for further research and practical application of FeWO₄ and its complex in the treatment of organic pollutant wastewater by sonocatalysis.