Preparation Of Metal-Organic Framework Compositions And Their Application In Water Treatment

Metal-organic frameworks（MOFs）are new porous crystalline materials constructed by coordination bonds between metal cations（metal clusters）and polydentate organic connectors.MOFs materials have the characteristics of high specific surface area,abundant active sites,adjustable pore structure,good stability,and easy modification and functionalization.Based on the advantages of MOFs materials,MOFs materials are widely studied in the field of water treatment.However,the problems to be solved in the field of water treatment are complex and involve a wide range.A single MOFs material cannot be all-round.In order to improve the defects of MOFs and expand the scope of application of MOFs materials,MOFs composite materials came into being.MOFs composite materials not only retain the excellent properties of MOFs,but also give MOFs new functional characteristics,which are of great significance to promote the application of MOFs materials in the field of water treatment.In this work,based on UiO-66-NH₂ material,different functional composites are applied to it and applied to the removal of persistent organic pollutants in simulated wastewater.The main research contents and results of this paper are as follows:（1）Using UiO-66-NH₂ as a carrier,a series of UiO-66-NH₂/ZIF-8 composite materials with different ratios were synthesized,and the adsorption behavior of three common dye pollutants（MB、MO、Rh B）in water was studied.Multiphase adsorption experiments show that proper ZIF-8 loading can change the surface potential of UiO-66-NH₂ and effectively improve the selective adsorption of MB.The adsorption experiment results show that:UiO-66-NH₂/ZIF-8 composite material has better adsorption effect and regeneration performance;the adsorption isotherm conforms to Langmuir model;the adsorption process is self-heating physical adsorption.（2）In order to solve the problem that MOFs powder is not easy to recycle,this study designed and synthesized UiO-66-NH₂/PAN composite nanofibers by electrospinning method to remove dyes in water by means of adsorption and membrane separation.The optimal spinning conditions under different UiO-66-NH₂ loadings and the effect on dye removal effect were explored.The experiment showed that UiO-66-NH₂/PAN composite nanofibers had good water stability and adsorption effect.In the membrane separation experiment,the UiO-66-NH₂/PAN composite electrospinning membrane has a higher Rh B rejection rate than the pure PAN electrospinning membrane.The research shows that UiO-66-NH₂/PAN composite nanofibers have good application prospects in the field of water treatment.（3）The g-C₃N₄/UiO-66-NH₂/CdS composite photocatalyst（g US-X）was designed and synthesized,and its photocatalytic degradation ability to tetracycline was explored.The addition of CdS can broaden the light absorption range of the g-C₃N₄/UiO-66-NH₂composite material and improve the light utilization rate.At the same time,a heterostructure is formed between CdS and g-C₃N₄/UiO-66-NH₂,which can inhibit the recombination of photogenerated carriers and enhance the photocatalytic activity of the material.In addition,the g US-1 photocatalyst has good cycle regeneration.This study shows that the g-C₃N₄/UiO-66-NH₂/CdS composite has great potential for photocatalytic degradation of pollutants.