Study On Sonocatalytic Degradation Of Organic Pollutants In Water By BiFeO₃ And Its Complexes

With the development of science and technology,the types and toxicity of organic pollutants in pharmaceutical wastewater have gradually increased,so it is necessary to explore an effective way to treat pharmaceutical wastewater.Sonocatalytic oxidation is an emerging technology for the treatment of organic pollutants in water,which has the advantages of simple operation,strong practicability,and no secondary pollution.Bi Fe O₃ is a ferromagnetic material with a unique structure,which is widely used in photocatalysis,energy storage and other fields,but its research in the field of sonocatalysis has not been carried out.In this study,Bi Fe O₃ was used as a sonocatalyst to explore its sonocatalytic activity when combined with ultrasonic technology,and to further improve its sonocatalytic activity by constructing a complex.The research contents are as follows:First,a 3D flower-like Bi Fe O₃ nanosemiconductor was prepared by a hydrothermal method,and the morphology of Bi Fe O₃ was adjusted and characterized by a synthesis process.Combining Bi Fe O₃ with ultrasonic technology,the sonocatalytic oxidation of simulated pollutant methylene blue（MB）was carried out to explore the sonocatalytic performance of Bi Fe O₃.Under the optimized experimental conditions,the removal rate of MB by Bi Fe O₃ sonocatalyst combined with ultrasonic technology reached 94.3%.Hydroxyl radicals（·OH）,superoxide anion radicals（·O₂^-）and holes（h⁺）were identified as the active species leading to MB degradation by radical trapping experiments.After four cycles of use,Bi Fe O₃ could still maintain high sonocatalytic activity and good stability.Secondly,the Cu₂O/Bi Fe O₃ composite was prepared by compounding Bi Fe O₃nano-semiconductor material with Cu₂O and characterized to explore its sonocatalytic degradation effect on simulated pollutant tetracycline（TET）in water.The results showed that compared with pure Bi Fe O₃,the prepared Cu₂O/Bi Fe O₃ heterojunction had better sonocatalytic activity for TET,and the Cu₂O/Bi Fe O₃ composite ratio of 3%had the best sonocatalytic degradation effect.Under the optimized experimental conditions,the degradation rate of TET reached 98.0%after 3%Cu₂O/Bi Fe O₃sonocatalyst combined with ultrasonic technology.The active substances produced by the sonocatalytic reaction were identified by scavenger experiments as·OH,·O₂^-and h⁺,and their possible sonocatalytic degradation mechanisms were proposed.The results of repeated used show that Cu₂O/Bi Fe O₃ had good stability and reusability.The results of the inhibition experiment of TET degradation products on Escherichia coli showed that the sonocatalytic oxidation method can effectively relieve the biological toxicity of TET.Finally,the degradation products of MB and TET were investigated by high performance liquid chromatography-mass spectrometry（HPLC-MS）,respectively,and possible degradation pathways were proposed.The above experimental results showed that the sonocatalytic performance of Bi Fe O₃ could be effectively improved by both morphology control and construction of heterojunction.It is expected that the results of this study could provide useful reference for the further research and practical application of Bi Fe O₃ and its complexes in the sonocatalytic treatment of organic pollutant wastewater.