Polymer-Assisted Enhanced Metal-Organic Framework Materials For Dye Adsorption And Catalysis

Metal organic framework materials?as MOFs?are crystals of a porous network structure formed by the ordered assembly of inorganic metal ions and organic ligands.It has an adjustable pore size,high stability,large specific surface area and open metal active sites.This series of properties allows MOFs to be widely used in catalysis,gas adsorption and separation,energy storage,dye adsorption,biopharmaceuticals,and so on.However,MOFs are confronted with many difficulties in application,such as dispersion,recycling,etc.Therefore,researchers are committed to improving the practical application value of MOFs through the strategy of heterogeneous material compounding.In this paper,through the strategy of polymer compounding,the dispersibility of MOFs in non-polar is increased,and the processability and recyclability of MOFs are improved.The main research work is as follows:?1?By using the modifiability of MOFs,different polystyrene-modified metal organic frameworks?UiO-66@PS and Cr-MIL-101@PS?were prepared by"click reaction".Water contact experiments show that polystyrene modification may significantly enhance the hydrophobicity of MOFs.Dispersibility experiments show that the obtained materials have enhanced dispersion in non-polar solvents.The specific surface area and pore size distribution analysis showed that although the polymer modification reduced the specific surface area of MOFs,the specific surface area of UiO-66@PS decreased from 1000 m² g^-11 before modification to 806 m² g^-1.The specific surface area of Cr-MIL-101@PS decreased from 1346 m²g^-1to 1055m² g^-11 before modification,but still showed high porosity and no significant change in pore size distribution,indicating that the polymer entered the MOFs.The specific surface area is reduced inside the pores,but due to the large diffusion resistance,the polymer can only modify a part of the pores of the outer layer.?2?The polystyrene modified metal orgainc framework composites UiO-66@PS and Cr-MIL-101@PS,have a remarkable effect in adsorbing the organic dye methylene blue?MB?.Cr-MIL-101@PS was close to saturation in 5 min,and the maximum saturated adsorption amount reached 328.9 mg/g.Compared with Cr-MIL-101 without macromolecule modification,thecomposites adsorption performance was improved about 3 times than Cr-MIL-101,which may be attributed to the polystyrene modification to enhance its?-?stacking effect.The composite Langmuir adsorption and Freundlich adsorption are linear.And it follows pseudo-second-order kinetics.The composite material also has good recycling property after 5 cycles.?3?Design and synthesis of magnetic macroporous metal-organic frameworks?MOFs?have been of significant interest,in order to improve the catalytic efficiency and reusability.In this work,we prepared magnetic macroporous MOF composites based on as-prepared magnetic macroporous polyacrylamides?MMPam?.Different MOFs with or without unsaturated coordinative metal sites,including HKUST-1,MOF-2,UiO-66,and Fe-MIL-101?-NH₂?were grown on and within the MMPam matrices.The composites showed hierarchical porosity with both micro-and macropores,which facilitated substrate diffusion to increase the conversion for isomerization of?-pinene oxide from 62%in the case of pure HKUST-1microparticles to 90%in the case of HKUST-1@MMPam.The magnetic property also endowed the composites with easy recovery and reasonable reusability.