Preparation Of MIL-88(A)-based Composite Catalysts And Their Photocatalytic Degradation Of Tetracycline In Water

Conventional semiconductor photocatalysts suffer from poor visible light response,easy compounding of photogenerated electron-hole pairs and poor photocatalytic performance.In this study,MIL-88（A）,a typical MOFs material,was modified with Ce VO₄,Zn S and Bi₂S₃nanomaterials to prepare a series of heterojunction photocatalysts to overcome the problems of high photogenerated electron-hole pair complexation and low migration efficiency,taking advantage of its high visible light responsiveness and large specific surface area.New photocatalytic treatment materials were provided for the treatment of tetracycline hydrochloride（TC）pollution.Details of the study and the results are as follows:（1）Zero-dimensional（0D）CeVO₄ nanoparticles were wrapped onto the surface of spindle-shaped（3 D）MIL-88（A）using a solvothermal method to form Ce VO₄/MIL-88（A）p-n heterojunction photocatalysts,which effectively increased the active sites of the materials.The composite catalyst with a Ce VO₄ mass ratio of 20%（i.e.CVM2）was used to catalyse the degradation of tetracycline hydrochloride in water under visible light,showing an optimum photocatalytic performance with a degradation efficiency of 81%for TC（10 mg/L）in water over 120 min.Cations such as Ca²⁺,Na⁺,K⁺,Mn²⁺and anions such as Cl^-and CO₃^2-,as well as natural organic matter FA did not have a significant effect on the degradation of TC.（2）The Z-type heterojunction composite photocatalyst Zn S/MIL-88（A）was constructed by loading Zn S nanospheres onto the surface of MIL-88（A）using a simple solvothermal method.ZSM-20%showed the best photocatalytic degradation performance for TC（10 mg/L）in water,with a TC degradation efficiency of 94.4%over 120 min.Ca²⁺,Na⁺,K⁺,Mn²⁺and anions such as Cl^-and CO₃^2-did not have a significant effect on the degradation of TC,but the presence of FA inhibited the degradation of TC by Zn S/MIL-88（A）.（3）The type II heterojunction photocatalyst Bi₂S₃/MIL-88（A）was prepared by loading Bi₂S₃ nanosheets onto the surface of MIL-88（A）using a combination of low-temperature hydrothermal and low-temperature water bath methods.BM-0.2 is a composite with excellent photocatalytic performance and can degrade 93%of TC（10 mg/L）within 120 min,and the photocatalytic activity is significantly higher than that of pure Bi₂S₃/MIL-88（A）.The photocatalytic activity was significantly higher than that of pure Bi₂S₃ and MIL-88（A）.The superoxide radical is the main active species in the photocatalytic reaction system,and h+participates to some extent in the photocatalytic reaction,playing a secondary role.The three catalysts prepared not only have good photocatalytic activity,but also can be reused many times with good recyclability and have bright prospects for application in TC pollution treatment.