Synthesis Of Photocatalysts Based On Zeolitic Imidazolate Framework Materials And Application Of Tetracycline Degradation

Tetracycline(TC)is widely used in human therapy and as a feed additive in agriculture.Due to its large dosage,good stability and strong adsorption capacity,it accumulates in land(soil)and aquatic environment,causing ecological and environmental pollution.Degradation method.Among various methods for degrading tetracycline,catalytic degradation of TC by photocatalyst has the advantages of high efficiency,low cost,and low secondary pollution,and has great development potential.At present,tetracycline photocatalysts are mainly metal oxides,metal sulfides,carbon materials and their heterostructures.However,due to their low light utilization,band gap mismatch,and photo-etching,they cannot meet the practical application requirements.The development of high-efficiency and low-cost photocatalysts is the key to the application of photocatalytic degradation technology by developing various carriers or precursors,and has become a research hotspot in recent years.Zeolitic imidazolate frameworks(ZIFs),as a common metal-organic framework material(MOF),have stable high porosity,chemical stability and thermal stability,and can be used for crystal structures.Organic transformation,the topology,crystallinity and porosity of ZIFs can be maintained throughout the process.The preparation of photocatalysts for degrading tetracycline by using ZIFs as a carrier or precursor is extremely attractive,but no related research has been conducted so far.In this paper,the advantages of ZIFs are convenient to prepare,active sites,easy loading and subsequent treatment.ZIF-8,ZIF-67 and ZIF-90 zeolite imidazole ester framework materials are used as carriers to support precious metals,high temperature reduction and in situ reduction.A series of visible light-responsive photocatalytic composites were prepared by other methods,and their structures were explored by various characterization methods and techniques to analyze their microstructure and physicochemical properties.These photocatalytic materials are then used to remove the tetracycline(TC)from water,and the photocatalytic degradation of pollutants is explored.Finally,the removal process and mechanism are discussed,and the stability of the photocatalytic performance and material recovery are Sex test.The main research work of this paper includes the following three parts:(1)Gold nanoparticle-loaded nano zinc oxide(Au@Zn0)was prepared by adsorbing ZIF-8 with chloroauric acid and reducing at high temperature,and the composite was used for photocatalytic degradation of tetracycline.Appropriate catalytic degradation conditions were found by adjusting the concentration of tetracycline(TC)and the amount of photocatalyst.The kinetic analysis of the process of catalytic degradation is carried out.At high concentration,the degradation is related to the surface concentration of the catalyst.Under low concentration conditions,the degradation rate is controlled by diffusion.Nano-ZnO supported by gold nanoparticles(Au@ZnO)has a removal rate of 85.6%for TC,and can still maintain 96.9%of initial degradation efficiency after 5 cycles of degradation.(2)A series of ZIFs materials were constructed,and three different metal oxide semiconductor photocatalysts were prepared by introducing silver ions to form Ag@ZIF-8,Ag@ZIF-67,Ag@ZIF-90 and calcining at high temperature.Ag@ZnO-8,Ag@Co203,Ag@ZnO-90,these materials were applied to the catalytic degradation of tetracycline under visible light.The introduction of silver nanoparticles improves the photocatalytic properties of ZIFs.Since Ag@ZIFs itself has low catalytic activity,high temperature calcination can greatly improve the catalytic performance.Among them,the removal rate of TC by Ag@ZnO-8 can reach 87.6%.(3)The process of high temperature calcination of ZIFs is complicated and the energy consumption is high.However,the degradation of pure ZIFs under visible light is not ideal.Therefore,Cl-is introduced through the halogenation solution on the base of(2)Ag@ZIF-8.The Ag/AgCl@ZIF-8 composite was prepared and enhanced by Ag/AgCl surface plasmon resonance to generate more electron-hole recombination centers to improve the optical activity under visible light.The removal rate of TC is improved by adjusting the ratio of Ag/AgCl.This experiment demonstrates the feasibility of using ZIFs series materials as carriers to prepare metal/metal halide series photocatalysts.In short,the high-efficiency degradation of tetracycline can be achieved by using ZIFs as precursors for doping noble metals,high-temperature calcination,redox and other means,which provides an idea for the application of ZIFs in the field of photocatalysis.In short,high-performance photocatalysts for degrading tetracycline can be realized by decorating precious metal nanoparticles on ZIFs followed by high temperature reduction and solution treatment.This work provides ideas for the application of ZIFs in the field of photocatalysis.