Preparation Of MOFs Mats Supported By Electrospinning And Study On Removal Of Chloramphenicol In Water

Water is the source of life,and the quality of water directly affects human life and health.In recent years,As the population growth and economic development,Pharmaceutical and Personal Care Products（PPCPs）are widely used,its residues are discharged into environmental water bodies,causing potential impacts on human health and the environment.Chloramphenicol（CAP）,as a type of PPCPs,belong to a new type of persistent organic pollutants,Conventional wastewater treatment methods usually cannot completely remove it,and it often accumulate in the environment.The adsorption and the photocatalytic have the advantages of good treatment effect,low cost,simple operation,and will not cause secondary pollution.They are very popular in water treatment and become effective methods for the advanced treatment of CAP wastewater.At the same time,the adsorbent and photocatalyst can be recycled,so as to realize the recovery of CAP and the utilization of waste resources.Therefore,from the perspective of environmental governance and resource utilization,the above two methods have broad application prospects.The performance of the adsorbent and photocatalyst is the key condition to determine the effectiveness of this method.The development of new and efficient adsorbent and photocatalyst has always been a hot spot for domestic and foreign scholars to study the treatment of CAP wastewater.Metal-organic frameworks（MOFs）have demonstrated potential application value in many fields due to their unique advantages.However,in practical water treatment applications,powdered MOFs have the disadvantages of being difficult to separate and recycle from aqueous solutions,and easy to agglomerate.In this study,a new composite material was successfully prepared by combining MOFs with electrospun nanofibers;A variety of characterization methods were used to analysis and research the crystal phase,morphology,element composition and reusability of the four adsorbents and three photocatalysts;They were applied to the adsorption separation and photocatalytic degradation of CAP in the aqueous phase,respectively.and the mechanism of their adsorption and degradation is discussed.The specific work is as follows:（1）Preparation and adsorption properties of PVA/SiO₂@MOFs composites materials based on polyvinyl alcohol（PVA）/SiO₂.PVA/SiO₂ electrospun nanofiber membrane as the substrate,functionalized modification using dopamine（PDA）,and then loading various MOFs crystals on the surface by in-situ growth method,a PVA/SiO₂@MOFs composite mats was synthesized.The results show that the surface of PVA/SiO₂ electrospun nanofibers modified by PDA are rich in-OH and-NH₂functional groups,which can provide nucleation sites for the growth of MOFs crystals,thereby increasing the loading rate of the crystals and obtaining uniform and dense MOFs mats.Four prepared PVA/SiO₂@MOFs mats（MIL-53（Al）,ZIF-8,Ui O-66-NH₂ and NH₂-MIL-125（Ti））were used for CAP adsorption,and the adsorption kinetic model and the isothermal adsorption model explores the inherent mechanism of adsorption.Each PVA/SiO₂@MOFs composite exhibits good adsorption performance for CAP in solution.At room temperature,the adsorption capacity of MIL-53（Al）,NH₂-MIL-125（Ti）,ZIF-8,and Ui O-66-NH₂ for CAP reached 79.5mg·g^-1,49.5 mg·g^-1,25.1 mg·g^-1 and 13.9 mg·g^-1,respectively.Among them,the PVA/SiO₂@MIL-53（Al）mats have the best adsorption effect,quickly and efficiently remove CAP.（2）Preparation of TiO₂ electrospun nanofiber-loaded MOFs composite material and its photocatalytic performance.PVP/TiO₂ electrospun nanofiber mats was prepared by electrospinning technology.The high temperature calcination removes the polymer PVP and promotes the conversion of TiO₂to anatase,and then deposits three MOFs crystals（ZIF-8,Ui O-66-NH₂ and NH₂-MIL-125（Ti））on the surface by in-situ growth,TiO₂@MOFs composite material was synthesized.The results show that the pores left on the surface of the TiO₂ fibers after calcination are conducive to the growth and nucleation of MOFs crystals,resulting in the MOFs mats.The prepared samples tested the photocatalytic degradation performance of CAP and the reutilization rate of MOFs mats under ultraviolet and visible light irradiation,respectively.The photocatalytic degradation mechanism was analyzed by the kinetic model.Compared with pure MOFs crystals and TiO₂,the photocatalytic performance of the TiO₂@MOFs composite material has been improved.Among them,the TiO₂@Ui O-66-NH₂ composite material has the highest photocatalytic activity,and has a high photocatalytic degradation efficiency for CAP under ultraviolet and visible radiation.After light exposure for 120 minutes.It can reache 96.73%and 84.32%,respectively.Moreover,the photocatalytic reaction of the TiO₂@MOFs composite material conforms to the first-order reaction kinetic model,and the regeneration experiment proves that the material still maintains a high degradation rate after repeated use for three times.The research work of this study shows that PVA/SiO₂ and PVP/TiO₂ electrospun nanofibers produced by high-voltage electrospinning technology are used as the supporting substrate for the growth of MOFs crystals,and the MOFs crystals are modified with PDA by in-situ growth method.The PVA/SiO₂ and calcined TiO₂ electrospun nanofibers were combined to prepare PVA/SiO₂@MOFs and TiO₂@MOFs composite materials.Throughout the preparation process,the synthetic route is simple,operable,and has good application prospects.Moreover,the prepared two kinds of MOFs composite mats have higher adsorption capacity and photocatalytic degradation rate,respectively,and can effectively remove CAP.It has outstanding practical significance for the treatment of environmental pollution caused by CAP.