Preparation And Performance Of Metal-organic Frameworks/Polyamide Composite Membrane

Population explosion and industrial activities have been responsible for the large consumption of water resource,and water shortage is one of the most serious issues in the world today.In order to solve the above problem,membrane separation process with the advantages of high efficiency,easy operation,environmental protection and low energy consumption,has been explored in the field of desalination.The polyamide?PA?membranes have been used on the desalination.However,because of the limited balance between the water flux and salt rejection,the development of high-flux polyamide?PA?membranes with high rejection rate becomes a hot research topic.To meet the above aim,various porous materials such as zeolites,carbon nanotubes,metal-organic frameworks and graphene were incorporated into the polyamide layer to fabricate different polyamide composite membranes with specific structures.Metal-organic frameworks?MOFs?possessed the advantages of large surface area and tunable pore sizes.In this study,due to the strong coordination interactions between inserted metal ions and ligands and/or carboxylate groups in PA dense layer,metal ion impregenation as forequarter site was first employed to in situ assembly continuous and well-intergrown MOF/polyamide?PA?composite membrane for desalination.Compared with the conventional method,the coordination driving method eliminated the preparation and mix process of MOF nanoparticles.this strategy was proved to be feasible in the production of high-quality hybrid membranes with uniform dispersion and good compatibility between MOFs and polymers,thus providing outstanding desalination ability.Moreover,we also prepared the MOF nanoparticles by conventional methods and mixed them into the polyamide film to prepare MOF/polyamide composite membrane.Comparison of traditional methods and new Metal ion-directed method,the latter have more advantages,and the synthesized Fe?BTC?/PA composite membrane exhibited extremely high flux(?5.11L m^-2 h^-1 bar^-1),which was about four times higher than the PA membrane,and excellent multivalent ion rejection?e.g.,99%for MgSO₄,98%for CaCl₂,and 99%for Na₂SO₄?.