Nanoconfined Zeolitic Imidazolate Framework Membranes with Composite Layers of Nearly Zero Thickness

Abstract

The key to preparing dense composite membranes is reducing the thickness of the composite layer with stable separation performance. Herein, we report a nanoconfined composite membrane prepared by in situ growth of Zeolitic Imidazolate Framework (ZIF) nanocrystals in the nanoporous layer of the substrate via a fine-tuning contra-diffusion method. The thickness of the composite layer on the membrane surface was nearly zero. The formed ZIF nanoconfined composite membranes showed state-of-art flux and high stability in removing dyes from water. This new strategy is expected to offer great opportunities for the potential practical application of polymer-supported metal-organic framework (MOF) composite membranes.

Air–water interfacial synthesis of metal–organic framework hollow fiber membranes for water purification

“…The water permeance reached as high as 46.3 L m −2 h −1 bar −1 , averaged from the performance of three membranes, which was much greater than that of polymeric nanofiltration membranes with similar rejection (Table S1). As demonstrated in previous studies, 21,22,41,45 the high permeance was ascribed to the great porosity of ZIF-8 with large cages of 11.6 Å and small windows of 4.0 Å, which allowed the transports of water molecules but rejected the entrances of dye molecules. Theoretically, the completely continuous ZIF-8 membrane with small apertures should have dye rejection of 100% based on size exclusion.…”

A Review of Nanostructured Ion‐Exchange Membranes

“…Also, the selection of substrates with suitable pore-size, for example, ultrafiltration membrane of polyacrylonitrile, can successfully decrease the diffusion rate to delicately control the rate of contra-diffusion to achieve an ultrathin nanoconfined ZIF-8 composite membrane. [27] These research strategies enhance heterogeneous nucleation on the chosen surface of the porous substrate and also enabled the production of a defect-free ultrathin ZIF-8 surface layer of only 200 nm. [35] The rate of crystallization of the MOF materials on the porous substrate is also dependent on the available sites of metal ions, allowable for interaction with the organic ligands.…”

“…Several other methods, such as secondary growth and counter-diffusion surface layering methods, are possible alternatives to produce thinner functional surface films but still cannot resolve the reproducibility issue. [27] Recently, fast current-driven synthesis and chemical vapor deposition techniques are also adopted to resolve the reproducibility issues. [28,29] Such techniques enable thin-MOF-film formation on porous substrates, resulting in the fabrication of composite MOF membranes with good reproducibility and performance.…”

A novel antifouling ultrafiltration membranes prepared from percarboxylic acid functionalized SiO2 bound Fe3O4 nanoparticle (SCMNP‐COOOH)/polyethersulfone nanocomposite for BSA separation and dye removal

“…14 Polymeric materials used in the manufacture of membranes, such as polyethersulfone (PES), polyvinylidene fluoride (PVDF) and polysulfone (PSf ), are usually hydrophobic and hydrophilic nanoparticles could improve their hydrophilicity. [15][16][17][18][19] PES is one of the polymeric materials, and possesses excellent chemical, mechanical and thermal properties and is widely used in the preparation of industrial filtration membranes. 14 However, this material is intensely influenced by fouling, generally owing to their relatively hydrophobic properties.…”