Adsorption And Photocatalysis Removal Of Typical Organic Pollutants In Water By Functionalized Metal Organic Framework Composites

The pollution caused by organic pollutants has become a non-negligible environmental issue recently.Organic pollutants such as dye and antibiotics can persist in the environment and eventually accumulate through the food chain,causing serious harm to human health and ecological environment system.Therefore,it is of great practical significance to study the control technique of organic pollutants.Metal organic frameworks?MOFs?,as emerging organic-inorganic hybrid materials,have attracted wide attention because of their high surface area,open metal sites,diverse structures and easily customized topological properties.MOFs have great application prospects in the fields of catalysis,gas separation,gas storage and pollutant purification.Nowadays,a series of MOFs and their composites have been used as adsorbents or photocatalysts for the removal of organic pollution in the water environment.Among them,the MIL-100?Fe?of MILs series composed with different transition metals and organic ligands,which have excellent chemical stability,can be used to absorb and remove water pollutants.However,MIL-100?Fe?still has limitation of low absorption capacity for certain antibiotic contaminants and needs further modification to improve its adsorption performance.Meanwhile UIO-66-NH₂ has good physical and chemical properties,but due to its structural limitations,the photocatalytic activity is constrained by the rapid recombination of carriers and light absorption capabilities.Therefore,it is necessary to functionally modify MIL-100?Fe?and UIO-66-NH₂ to improve their adsorbtion and photocatalytic efficiency.In this paper,functional MOFs were synthesized and applied in the field of environmental purification.The research contents are as follows.1.The zinc oxide doped MIL-100?Fe?composite was synthesized by one-pot synthesis method to enhance the adsorption and removal of cefixime?CFX?in water.X-ray diffraction spectroscopy?XRD?,scanning electron microscope?SEM?,fourier transform infrared spectrometer?FTIR?and X-ray photoelectron energy?XPS?were used to characterize the material.It found that the ZnO@MIL-100?Fe?contained the crystal structure of zinc oxide while retaining the crystal structure of MIL-100?Fe?.Using CFX as a model pollutant to evaluate the adsorption capacity of ZnO@MIL-100?Fe?.The results showed that compared with the MIL-100?Fe?,ZnO@MIL-100?Fe?has doubled the adsorption capacity of cefixime to 95.93 mg g^-1.The adsorption kinetics and thermodynamics of the ZnO@MIL-100?Fe?composite were further investigated,ZnO@MIL-100?Fe?could reach adsorption equilibrium within 180 min,and the adsorption process was consistent with pseudo-second-order kinetic and the monolayer of langmuir isotherm adsorption model which belongs to the spontaneous endothermic process of entropy reduction.The experiment further investigated the effect of solution p H on adsorption.ZnO@MIL-100?Fe?adsorbed CFX on the surface through hydrogen bond and electrostatic adsorption.Finally,the composite has good specificity and good cyclicity.It expected to adsorb and remove the cefixime in actual water environment.2.Exploring the adsorption capacity and photocatalytic activity of transition metal manganese modified amine functionalized zirconium MOFs,and investigating the removal efficiency of dye rhodamine B?Rh B?.Zirconium tetrachloride?Zr Cl₄?,2-amino-terephthalic acid?NH₂-H₂BTC?and manganese tetrahydrate?Mn Cl₂.4H₂O?were dissolved in N,N-dimethylformamide?DMF?to prepare manganese modified Mn UIO-X.Mn UIO-X was characterized by XRD,SEM,XPS,ICP-MS.It found that the Mn UIO-X not only retained the crystal structure of UIO-66-NH₂,but also has excellent structural.Rh B was selected as the model pollutant to evaluate the adsorption capacity and photocatalytic activity of Mn UIO-X.Mn UIO-X significantly improved the removal efficiency of Rh B,and the removal efficiency of Mn UIO-3 towards Rh B was about 93%.Compared with the UIO-66-NH₂,Mn UIO-X has larger pore size,which can reduce the blocking of the adsorption pores of Mn UIO-X by Rh B molecule,improving the adsorption capacity.At the same time,with the addition of manganese,Mn UIO-X obtains extra light absorption,broadens the material's light absorption band,and suppresses the recombination of photogenerated electron/hole pairs,which resulted in the increase the photocatalytic activity.Finally,the structural of Mn UIO-X is stable and Mn UIO-X has potential application in the field of environmental purification.