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Covalent organic frameworks (COFs) have emerged as promising candidate for the construction of advanced separation membranes due to their well-defined pore structure and highly ordered porous channels. Nevertheless, the implementation of high-efficient COFs-incorporated membranes still suffers from harsh synthetic conditions and possible agglomeration of COFs. Herein, a kind of sandwich-like thin film composite reverse osmosis (RO) membranes was fabricated to overcome such challenges via interfacial assembly of a COFs interlayer on polysulfone substrate, then followed by the formation of a polyamide skin layer via traditional interfacial polymerization (IP) process. The COFs interlayer not only tailored the pore structure and interfacial properties of the substrate, but also manipulated the uptake and release of the amine monomer during the IP process, which would contribute to forming a more ordered polyamide separation layer. The resultant COFs-interlayered RO membrane exhibited a nearly 33.8% higher water permeance (16.78 L m−2 h−1 MPa−1) along with a slightly increased NaCl rejection (99.2%) compared with the pristine RO membrane. More importantly, the emerging RO membrane presented a superior chemical (critic acid and NaOH) resistance and desirable long-term filtration stability, which paved a new pathway to construct high-performance RO membranes for desalination. Image 1 • The RO membranes were prepared on interfacial assembled COFs interlayer. • COFs interlayer optimized physicochemical and interfacial properties of substrate. • The COFs-modulated IP procedure enabled a thinner, denser and smoother PA layer. • The PA/COFs/PSf membrane enhanced the optimal water permeance by up to 33.8%. • The COFs-interlayered RO membrane exhibited a satisfying long-term stability. [ABSTRACT FROM AUTHOR]

This study describes the preparation and characterisation of MIL-53(Fe) and its effect on the performance of forward osmosis (FO) membranes. The cellulose acetate (CA)/MIL-53(Fe) hybrid membranes were fabricated using the method of phase inversion by dispersing MIL-53(Fe) in a CA casting solution. To improve the selectivity and permeability performance of FO membranes, the effects of MIL-53(Fe) content, casting solution temperature, coagulation bath temperature, and annealing temperature were studied. Results from scanning electron microscopy, membrane porosity, atomic force microscopy, and water contact angle tests of all the membranes show that the structural properties of the CA/MIL-53(Fe) hybrid membranes were optimised. The results of the FO performance tests, including the values of water flux and reverse salt flux, indicate improvement in the selectivity and permeability properties of the CA/MIL-53(Fe) hybrid membranes. Under the conditions of deionised water as the feed solution and 1 M NaCl solution as the draw solution, the water flux and reverse salt flux of the CA/MIL-53(Fe) hybrid membranes reached 34.9 L/(m2·h) and 2.02 g/(m2·h), respectively, in comparison with CA membranes. This study demonstrates that MIL-53(Fe) can improve the desalination performance and structural properties of FO membranes. • MIL-53(Fe) with high porosity was used to fabricate cellulose acetate (CA)/MIL-53(Fe) hybrid membranes for the first time. • Optimal experimental conditions of CA/MIL-53(Fe) hybrid membranes were conducted. • The water flux and reverse salt flux of CA/MIL-53(Fe) hybrid membranes were improved compared to CA membranes. • Effect of MIL-53(Fe) on structural properties of CA membranes was widely discussed. [ABSTRACT FROM AUTHOR]

Solvent resistant nanofiltration (SRNF) membranes are highly demanded in processing organic solutions especially those contain large molecules with molecular weight between 200 to 2000 Da, yet they have some drawbacks such as relatively poor solvent resistance and low solvent permeance. The current work presented an innovative class of amino-functionalized graphene quantum dots (aGQDs) embedded thin film nanocomposites (TFN) for SRNF membranes which were prepared via interfacial polymerization (IP) and subsequent steps (chemical imidization, crosslinking, and solvent activation). The prepared membranes enabled covalent interactions not only between the IP skin layer and the substrate, but also between the IP layer and the embedded aGQDs. The ethanol permeance and surface porosity increased by 44% and 69%, respectively, with the embedment of aGQDs under the optimal conditions, while the Rhodamine B (RDB, 479 Da) rejection maintained essentially stable above 99%. Furthermore, our novel membranes exhibited excellent long-term stability, with a rejection of over 99% for Rose Bengal (RB, 1017 Da) during the continuous filtration of 100 mg L−1 RB/ N , N -dimethyl formamide (DMF) solution at room temperature for more than 768 h. They also exhibited good organic solvent resistance and high-temperature tolerance in both DMF and NMP solvents, with a RDB rejection of over 99% and an ethanol permeance of about 38 L m−2 h−1 MPa−1 after being immersed in DMF at 80 oC for 248 h, and a RDB rejection of over 99% and an ethanol permeance of about 41 L m−2 h−1 MPa−1 after being immersed in NMP at 80 oC for 232 h. The results demonstrated that the aGQDs-embedded TFN OSN membrane has vast potential in SRNF applications. Image 1 • (PI-aGQDs/PI) XA membrane was prepared via IP, imidization, crosslinking, activation. • The (PI-aGQDs/PI) XA SRNF membrane owns a wholly covalent bonding chemical structure. • aGQDs improve greatly the surface morphology and performance of the SRNF membrane. • The SRNF membranes kept >99% RB rejection in filtration of DMF at 25 oC for 30 days. • The SRNF membranes kept good solvent resistance in DMF and NMP at 80 oC for 10 days. [ABSTRACT FROM AUTHOR]