Preparation And Photocatalytic Properties Of MOFs/CeO₂ Composites

With the widespread application of antibiotic chemicals in the pharmaceutical industry and the livestock and poultry breeding industry,because of their incomplete metabolism,some antibiotics will remain in the water environment,leading to an increasingly serious aquatic environment.In recent years,tetracyclines,the most typical organic pollutants in antibiotics,have accumulated in the water environment,posing a serious threat to the natural environment and human health.Photocatalytic technology is superior to the traditional water treatment technology in the removal of this kind of organic pollutants.The development of efficient and stable photocatalyst is the core of the development of photocatalysis technology.Metal organic frameworks（MOFs）,as a new type of photocatalyst,are widely used in the treatment of organic pollutants.In this study,tetracycline hydrochloride was used as a model pollutant.Two kinds of classical MOFs（UIO-66 and MIL-53（Fe））were synthesized based on the principle of crystal engineering,and CeO₂ with nanosheet structure was prepared by room temperature synthesis.Based on the principle of making full use of sunlight,MOFs/CeO₂ composite photocatalysts with rich activity and low resistance interface,namely UIO-66/CeO₂ and MIL53（Fe）/CeO₂,were prepared by mechanical ball milling method.The photocatalytic degradation effect of tetracycline hydrochloride was studied,and the corresponding mechanism was explored.The main contents of this paper are as follows:1.Firstly,the super stable three-dimensional metal organic framework material UIO-66 was prepared by simple hydrothermal method.Meanwhile,CeO₂ nanorods were synthesized by room temperature synthesis method,and a series of UIO-66/CeO₂ composites were prepared by mechanical ball milling method.It was characterized by XRD,FT-IR,XPS,UV-vis DRS,electron SEM,TEM,HRTEM and photoluminescence spectra（PL）.Tetracycline is the target pollutant.The results showed that UC100（the mass ratio of UIO-66 to CeO₂ was 1:1）showed the best photocatalytic activity.Photocatalytic removal rate of tetracycline hydrochloride（30 mg/L）in 120 min by UC100（20 mg）was 86.5%.Meanwhile,the effects of catalyst dosage and initial pH on the degradation of tetracycline were investigated.The experimental results of three cycles show that UC100 has good reusability and stability.2.A series of direct Z-type heterojunction photocatalysts were prepared by using visible light excited metal organic framework material MIL-53（Fe）and inorganic semiconductor material CeO₂ as raw materials.The results were also studied by XRD,FT-IR,XPS,UV-vis DRS,SEM,TEM,STEM,PLand EIS were characterized.The results of tetracycline degradation experiment showed that mc80 had the best photocatalytic activity when the mass ratio of MIL-53（Fe）to CeO₂ was 2:3.After 120 min of visible light irradiation,the photocatalytic removal rate of MC80（10 mg）for tetracycline hydrochloride（30 mg/L）was 92.5%.Under the same experimental conditions,the corresponding photocatalytic reaction rate is 2.26 times and 1.87 times of MIL-53（Fe）and CeO₂.At the same time,the dosage of photocatalyst and the pH of initial solution have influence on the final efficiency of mc80 photocatalytic degradation of tetracycline hydrochloride.The results of active substance capture experiment and ESR test showed that the degradation of tetracycline was affected by ·O₂^-and·OH,and the photocatalytic mechanism was explored.After four rounds of cycle experiment,MC80 still showed excellent degradation effect.