Preparation Of MgFe₂O₄ Composites And Research On Sonocatalytic Activity Of Degradation Tetracycline

In recent years,the massive use and discharge of antibiotics has caused a huge threat to the environment and human production and life.In order to find an efficient and green method to treat antibiotic wastewater,many researchers have conducted in-depth studies on advanced oxidation methods.Ultrasonic catalytic oxidation method is one of the advanced oxidation methods.Due to its safety,simple operation,environmental friendliness and high decomposition efficiency,etc.,it has received extensive attention in the removal of antibiotic pollution in wastewater.As an n-type semiconductor material,MgFe₂O₄ not only has a narrow band gap,but also consists only of earth-rich elements,which can be produced at low cost.In addition,due to its ferrous magnetism,it can be quickly separated by magnets after treating antibiotic wastewater.Therefore,it is a good catalyst material.However,pure MgFe₂O₄ has disadvantages such as low charge separation efficiency and short carrier lifetime.In order to improve and overcome its shortcomings,we eventually modify it to improve its sonocatalytic performance.In this paper,tetracycline solution（TET）was used as an antibiotic model,and three MgFe₂O₄ composite materials were prepared by investigating the removal rate of TET solution.And by investigating the doping ratio of MgFe₂O₄,the amount of catalyst,ultrasonic time,ultrasonic power and other influencing factors,the sonocatalytic performance and mechanism of the three MgFe₂O₄ composite materials were discussed.Firstly,the Fe₂O₃/MgFe₂O₄ composite material was synthesized in one pot by hydrothermal synthesis.By changing the Na OH solution concentration and the Mg²⁺/Fe³⁺ratio during the synthesis process,XRD and SEM characterization proved that Fe₂O₃/MgFe₂O₄ with different morphologies and pure phase structures were synthesized.Composite materials.In addition,using the change in absorbance of TET solution as an indicator,the sonocatalytic activity of Fe₂O₃/MgFe₂O₄ composites was investigated under different experimental parameters,and combined with oxidation extraction spectroscopy to verify the generation of ROS in the sonocatalytic process,the results found that the best degradation process under these conditions,the removal rate of TET can reach 80.1±1.41%.Finally,the scavenger experiment proved that hydroxyl radicals（·OH）and holes（h⁺）are the main active substances in Fe₂O₃/MgFe₂O₄ catalytic degradation of TET.Secondly,in order to improve the lifetime of charge separation efficiency carriers,we constructed a p-n heterojunction structure composed of BiOBr and MgFe₂O₄.The results of XRD,SEM,XPS,UV-vis diffuse reflectance and other characterization techniques show that BiOBr is attached to the surface of MgFe₂O₄ in the form of particles.When the doping ratio of BiOBr/MgFe₂O₄ is 20%（BM-20）,the rate of degradation of TET is 13.44 times that of pure TET,and the amount of NO₃^-in the solution before and after degradation is detected by ion chromatography experiments,which proves that TET molecules are indeed broken down.Decomposed in the process.Finally,repeated use experiments and scavenger experiments prove that BiOBr/MgFe₂O₄ composites have good chemical stability,and the active species in the sonocatalysis process are·OH,·O₂^–and h⁺.Finally,in order to improve the efficiency of sonocatalytic decomposition of MgFe₂O₄,we searched for other nano/semiconductors with balanced E_g for coupling,so we constructed another p-n heterojunction—Cu₂O/MgFe₂O₄ composite material.We synthesized Cu₂O/MgFe₂O₄ composite materials by hydrothermal synthesis and chemical precipitation methods,and also used XRD,SEM,XPS and BET techniques to characterize them.Subsequently,the sonocatalytic activity of Cu₂O/MgFe₂O₄ was investigated under different experimental parameters.The results showed that when the doping ratio was 10%,the amount of catalyst added was 5 mg,the initial solution concentration of TET was 20 mg/L,and the ultrasonic power was 500 W and ultrasonic time is 60 min,the removal rate of TET can reach 91.93±1.08%,and the scavenger experiment proves that the active species in the sonocatalysis process are·OH,·O₂^–and h⁺.It shows that Cu₂O/MgFe₂O₄ composite material is also a promising sonocatalytic material.In summary,MgFe₂O₄ and its composite materials have good sonocatalytic activity in decomposing antibiotics in wastewater.In this paper,through the investigation of sonocatalytic activity factors and the study of sonocatalytic mechanism,it provides a new type of sonocatalyst theoretical basis for the application of ultrasonic catalytic oxidation method.