Preparation Of MIL-101/PA Composites And Their Adsorption Properties For VOCs

It is of great significance to develop efficient and ordered volatile organic compounds（VOCs）adsorption materials.However,there is a general disadvantage of low adsorption performance for VOCs adsorption materials,and metal-organic frameworks（MOFs）are well known for their high adsorption performance.However,MOFs have not achieved industrial large-scale application due to the water stability problem and the reduced adsorption performance due to their compactness during processing.In this work,terephthalic acid（H₂BDC）was used as the organic ligand,Cr（NO₃）₃·9H₂O and Mg（NO₃）₂·6H₂O are MOFs synthesized from metal salts（MIL-101（Cr）,MIL-101（Cr,Mg））,in situ growth of MIL-101（Cr）/PA,MIL-101（Cr,Mg）/PA-NH₂on polyacrylate spherical particles（PA sup port）and functionalized polyacrylate spherical particles（PA-NH₂）,the benzene and toluene adsorption properties of the two composite materials were evaluated.The main research contents are as follows:（1）The PA carrier was prepared by emulsion polymerization and suspension polymerization,and the MIL-101（Cr）precursor solution was impregnated into the carrier with developed porosity and high hardness.By limiting the concentration of the precursor solution and changing the impregnation method,the diffusion of the precursor solution in the carrier is regulated,so as to effectively control the in-situ growth of MOFs grains and the pore structure of the composite material to form an efficient and ordered nanocomposite.The structure and morphology of MIL-101（Cr）/PA were characterized,and it was proved that MIL-101（Cr）was synthesized in the PA carrier;the properties of MIL-101（Cr）were chara cterized,and the results showed:compared with MIL-101（Cr）,the particle size of MIL-101（Cr）/PA is reduced by 60%,and the nanoscale dispersion of MOF grains is basically realized.;the mesoporous content of MI L-101（Cr）/PA increases,and the pores become more numerous,providing channels for guest molecules;the adsorption capacity of MIL-101（Cr）/P A for benzene is 1093.0 mg/g,and the adsorption capacity for toluene is as high as 1356.7 mg/g,which are 1.03 times and 1.13 times that of MIL-101（Cr）,respectively;the simulation results of the breakthrough curve of MIL-101（Cr）/PA for toluene are consistent with the PFO model.（2）The PA carrier was enlarged 250 times,the density was maintained at 0.11～0.13 g/mL stably,and it had good porosity.Further improvement of the amplified PA carrier to obtain PA-NH₂carrier with functionalized amine group.MIL-101（Cr）was modified by introducing Mg²⁺to enhance its hydrophobicity.The controllable growth of the composite MIL-101（Cr,Mg）/PA-NH₂crystal is realized by controlling the MIL-101（Cr,Mg）.By testing the structure and properties of the composite material,it can be confirmed that MIL-101（Cr,Mg）is synthesized inside the carrier.Its adsorption capacity for benzene is 1196.0 mg/g,which is 9.5%higher than that of single metal composites.;through the hydrophobic angle test and water destructive test of the composite material,it is proved that MIL-101（Cr,Mg）/PA-NH₂has strong hydrophobicity and remains stable after immersion in water for 21 days.In this study,the nanoscale and uniform dispersion of MOFs has been achieved,which provides a new idea for solving the problem of MOFs accumulation and degradation in industrial production,and provid es technical support for the industrial production of MOFs composites.