IMPLEMENTATION OF METAL-ORGANIC FRAMEWORK ON MEMBRANE DEVELOPMENT FOR LIQUID SEPARATION : INVESTIGATION, CHARACTERIZATION AND APPLICATION

Abstract

The implementation of metal-organic frameworks (MOFs) in the development of MOF-membrane composites for liquid separation remains at nascent stage. As most of discovered MOFs suffer from poor water stabilities, it has severely limited these composites’ further applications and commercialization. In this thesis, a series of zirconium (IV)-carboxylate MOFs (Zr-MOFs), namely UiO-66 and its derivatives, have been employed in the fabrication of high-performance MOF-based membranes. Benefiting from the exceptional water stability of the UiO-66 nanoparticles, the resultant membranes have demonstrated long-term stability in water applications. In addition, the incorporation of UiO-66 into membranes have tailored the surface morphologies and chemistries, optimized the membrane structures, leading to a significantly improvement of separation performance compared to the pristine membranes. To further investigate the influence of MOF crystals on the separation performance, a continuous UiO-66-NH2 polycrystalline layer has been successfully intergrown on the top of polymeric substrates for the first time. As a result, the pure polycrystalline layer can function as permeation channels to allow the transportation of target solvent molecules while rejecting dye molecules via size-exclusion mechanism. These works will provide insights into the implementation of MOF nanoparticles on membrane development and stimulate further development of high-performance MOF-membrane composites in near future.