Preparation And Photocatalytic Degradation Properties Of MIL-101(Fe)@BiOI Composites And Their Derivatives

The world is currently facing increasingly serious environmental pollution problems,with water resources in particular,but traditional treatment methods are not only inefficient but also time-consuming and costly.Photocatalytic degradation technology,as an emerging treatment solution,has the advantages of being energy efficient,pollution-free,highly effective and highly targeted,and is a new environmentally friendly and green solution to water pollution.However,most of the existing photocatalytic materials suffer from low charge transfer efficiency,wide band gap and low light energy utilisation.Metal-organic skeletal materials（MOFs）are a recent hotspot for photocatalytic materials research.These materials have a series of advantages such as large specific surface area,rich functional structure,interlaced and stable pore channels and active sites.Therefore,it is an urgent task to develop new MOF materials and MOF material as a template for derivative photocatalysts to combat the serious water pollution problem.In this thesis,MIL-101（Fe）@BiOI composites were first prepared by hydrothermal method,then Bi Fe O₃@Bi₅O₇I and Bi Fe O₃@Fe₂O₃composites were prepared by calcination method,and finally Bi Fe O3@Fe2O3@BiOI ternary composites were prepared by secondary hydrothermal method,and the factors influencing the photocatalytic degradation of the materials and the catalytic mechanism were investigated.catalytic mechanism.Details of the work are as follows:1.The MIL-101（Fe）@BiOI composites were made by hydrothermal coupling of BiOI with MIL-101（Fe）.Photocatalytic degradation experiments were carried out on different ratios of MIL-101（Fe）@BiOI under visible light.The experimental results showed that the addition of BiOI significantly improved the photocatalytic degradation efficiency of MIL-101（Fe）@BiOI compared to MIL-101（Fe）alone,with the best degradation effect at a ratio of1:1 of MIL-101（Fe）@BiOI and a degradation rate of k=0.00468 min^-1.The effects of p H,TC concentration and ionic strength in the solution environment on the photocatalytic degradation of the material were explored and the results showed excellent stability and environmental adaptability of the material.Through active substance trapping experiments,the active substance molecules that play a role in the degradation process were identified as superoxide radicals and photogenerated holes.2.The ratio of MIL-101（Fe）@BiOI was adjusted,and then the Bi Fe O₃@Bi₅O₇I composites with different ratios were prepared by high-temperature calcination method.The photocatalytic degradation efficiency of Bi Fe O₃@Bi₅O₇I for tetracycline under visible light was investigated.The experimental results showed that Bi Fe O₃@Bi₅O₇I has better photocatalytic degradation ability compared with MIL-101（Fe）,and the degradation rate of tetracycline molecule reached k=0.02196min^-1.In addition,by changing the solution environment of the material photocatalytic degradation experiments to determine the influencing factors and active substances,the test results show that the material still has the ability to degrade in different concentrations of p H and ionic strength,and the substances that play a role in the photodegradation process are superoxide radicals and hydroxide radicals.3.Different ratios of Bi Fe O₃@Fe₂O₃ composites were firstly prepared by calcination after adjusting the ratio of MIL-101（Fe）@BiOI,and then BiOI was loaded on Bi Fe O₃@Fe₂O₃by hydrothermal method to form Bi Fe O₃@Fe₂O₃@BiOI ternary composites.The tetracycline photocatalytic degradation experiments of Bi Fe O₃@Fe₂O₃@BiOI ternary composites were carried out under xenon lamp conditions.The test results show that the Bi Fe O₃@Fe₂O₃@BiOI composites have effectively improved the efficiency of charge transfer and achieved a photocatalytic degradation rate of k=0.03016min^-1compared to the monomeric material and Bi Fe O₃@Fe₂O₃ binary material.In addition,the materials showed stable performance and environmental adaptability in different solution environments.