Organic solvent nanofiltration membrane with improved permeability by in-situ growth of metal-organic frameworks interlayer on the surface of polyimide substrate

Applications of Metal–Organic Frameworks‐Based Membranes in Separation

“…[43] In addition, Chen et al successfully grew HKUST-1 on a polyimide (PI) support membrane using in situ preparation and used it for organic solvent nanofiltration (NF). [44] The in situ growth method has the advantages of simple steps, mild reaction conditions, repeatability, uniform membrane growth, and high crystallinity, which are beneficial for industrial applications. However, the membranes of MOFs synthesized by the in situ growth method are not tightly bound to each other and are easily detached from the carrier.…”

An Evolving Insight into Metal Organic Framework-Functionalized Membranes for Water and Wastewater Treatment and Resource Recovery

“…Schematics of fabrication strategies of ultrathin MOF-based membranes for organic solvent nanofiltration: (A) in situ growth, , (B) vacuum-assisted assembly, (C) metal-based deposition, ,,, (D) contra-diffusion, ,, (E) blending method, ,,,,, and (F) layer-by-layer assembly . Reproduced with permission from ref .…”

“…Homogeneous nucleation is typically more uniform. However, heterogeneous nucleation, which relies heavily on the surface property of the porous substrate, tends to form MOF islands with intracrystalline cracks and intercrystalline cracks on the surface. , Hence, the key point for depositing a uniform continuous MOF layer on the surface of the porous substrate is to improve the heterogeneous nucleation process. , Several synthesis approaches, such as in situ growth, , vacuum-assisted assembly, metal-based deposition, ,,, contra-diffusion, ,, blending method, ,,,,, and layer-by-layer assembly, have been developed, and we summarize them as follows. in situ growth: , The substrate is pretreated with functional molecules to generate heterogeneous nucleation sites and then immersed into the mixed bulk MOF solution containing metal ions and organic ligands. vacuum-assisted assembly: The porous substrate is immersed into the mixture of bulk MOF solution and template suspension, and then vacuumed from the substrate side to deposit the MOF/template layer on the substrate surface. metal-based deposition: ,,, The metal-based precursor (metal ions, metal-oxo clusters, or metal-based gel coatings) for MOF is first anchored on the substrate surface, followed by injecting organic ligand vapor precursor. contra-diffusion: ,, The two precursors are separated by the porous substrate (barrier) and can only meet through the channels; once they meet each other, MOF starts to crystallize and eventually forms an ultrathin continuous defect-free MOF layer. blending method: ,,,,, The aqueous solution for TFC is first deposited on the substrate surface, followed by coating the MOF ink (MOF solutions in organic solution for TFC) to form a MOF/TFC layer on the substrate surface. layer-by-layer assembly: The target substrate is immersed into the precursor solutions in alternating sequence, followed by repeating the process for certain cycles, which would be able to precisely control the thickness of the synthesized film in nanoscale. …”

“…metal-based deposition: ,,, The metal-based precursor (metal ions, metal-oxo clusters, or metal-based gel coatings) for MOF is first anchored on the substrate surface, followed by injecting organic ligand vapor precursor.…”

2D Material Based Advanced Membranes for Separations in Organic Solvents

“…MOFs have been widely used as membrane materials for gas separation, [109][110][111] water treatment, [112,113] and OSN [114][115][116][117] due to their abundant porous structures, chemical versatility, and functionalities. [112,118] However, the application of 2D structured MOFs for membrane-based separation is much less compared with their 3D structured counterparts.…”