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Crystalline porous materials (CPMs), including covalent organic frameworks (COFs) and metal–organic frameworks (MOFs), are promising materials for advanced separation technologies. However, the challenge of transforming nanoscale CPMs into large‐area functional membranes hinders their application in the membrane separation process. Herein, a self‐standing pure COF (TpPa‐1) nanofiber membrane with high crystallinity, good flexibility, excellent mechanical properties, and scalability is prepared using an electrospinning process and polymer sacrificial template strategy. Subsequently, the COF nanofiber membrane is innovatively used to replace traditional inorganic discs, metal meshes, and polymer membranes as porous supports, and the COF–MOF composite CPM membrane is prepared through the tailorable and confined growth of zeolite imidazolium salt frame‐8 (ZIF‐8) on the surface of the COF membrane and in the gaps of the COF nanofibers. The COF–MOF composite membrane exhibits excellent permeability and significantly enhances separation selectivity for organic dyes. Moreover, MOF and COF form an interpenetrating network structure, and their similar chemical properties improve the interfacial stability between the two phases, giving the COF–MOF composite membrane good long‐term separation performance. This is the first self‐standing composite CPM membrane with excellent molecular sieving performance, which provides new insights into the design of high‐performance and robust composite membranes. [ABSTRACT FROM AUTHOR]

The development of carbon dioxide (CO2) separation technology is crucial for mitigating global climate change and promoting sustainable development. In this study, we successfully synthesized an array of cross‐linked poly(vinyl alcohol) (PVA) membranes, xALD‐PEG‐ALD‐c‐PVA, with enhanced CO2/N2 separation performance by employing dialdehyde polyethylene glycol (ALD‐PEG‐ALD) as a cross‐linker. The formation of the cross‐linked network structure not only inhibits the crystallization of PVA but also disrupts hydrogen bonding and thus increases fractional free volume of PVA chains. Under the synergistic effect of these multiple factors, the cross‐linked PVA membranes exhibit a significantly improved CO2 permeability. Moreover, they maintain high CO2/N2 selectivity, attributing to the CO2‐philic characteristic of ethylene oxide groups in the cross‐linked structure. At the ALD‐PEG‐ALD content of 1.6 mmol g−1, the xALD‐PEG‐ALD‐c‐PVA membrane demonstrates a CO2 permeability of 41.4 barrer and a CO2/N2 selectivity of 57.4 at 2 bar and 25°C. Furthermore, compared with the pristine PVA membrane, xALD‐PEG‐ALD‐c‐PVA membranes manifest superior mechanical properties and outstanding separation performance for a CO2/N2 (15/85, vol%) gas mixture. The excellent combination of permeability and selectivity makes xALD‐PEG‐ALD‐c‐PVA membranes highly promising for various CO2 separation applications. [ABSTRACT FROM AUTHOR]

ZIF-8-filled polydimethylsiloxane (PDMS) membranes, PDMS/ZIF-8, were prepared by a two-step polymerization process and were used to recovern-butanol from an aqueous solution by pervaporation (PV). Compared with pure PDMS membrane, PDMS/ZIF-8 membranes demonstrated an obviously highern-butanol permselectivity. As an increase of ZIF-8 content,n-butanol/water selectivity increased initially and then decreased, while then-butanol and water permeability decreased monotonously. PDMS/ZIF-8 membrane containing 2 wt% ZIF-8, that is, PDMS/ZIF-8-2 showed the highest selectivity. On the other hand, selectivity and permeability forn-butanol and water of PDMS/ZIF-8-2 membrane decreased with the increase of operating temperature. The selectivity and permeability forn-butanol reached 7.1 and 3.28 × 105barrer, respectively, at 30°C when the feed concentration ofn-butanol was 0.96 wt%. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO)-based nanofiltration membranes, featuring well-ordered microscopic structure, well-defined 2D nanochannels and superior molecular sieving ability, have attracted sustained research interest in molecular and ionic separation. However, most of current GO laminar membrane have a poor water flux and high rejection of both dyes and salts, which is not suitable for the dye/salt mixture separation. Herein, we report a vacuum filtration strategy to fabricate GO/NH 2 -Fe 3 O 4 nanofiltration membranes with high water flux and excellent separation performance for dye/salts mixture by introducing NH 2 -Fe 3 O 4. The NH 2 -Fe 3 O 4 is not only worked as the rigid spherical nanospacer to tune GO interlayer spacing but also as crosslinkers to improve the stability of GO membrane in water. FTIR, XRD, SEM, zeta potential and contact angle were applied to analyze the chemical composition and morphology of as-prepared membranes. The effect of intercalated NH 2 -Fe 3 O 4 nanoparticles on overall performance of the GO/NH 2 -Fe 3 O 4 membranes was systematically investigated. The resulted membrane with 8 wt% of NH 2 -Fe 3 O 4 loading has high water flux of up to 78 Lm−2 h−1, which is 4.8 times higher than that of pure GO membrane. Moreover, such membrane also displays high congo red rejection (94%) and low NaCl rejection (~15%), rendering the membranes promising for dye/salt mixtures separation. Intercalated NH 2 -Fe 3 O 4 can simultaneously tune the GO interlayer spacing and improve the stability of GO membrane in water. Unlabelled Image • GO/NH 2 -Fe 3 O 4 membranes were prepared for dye/salt mixture separation. • NH 2 -Fe 3 O 4 can simultaneously tune interlayer spacing and improve membrane stability. • GO/NH 2 -Fe 3 O 4 -8 membrane has high water flux and CR rejection but low NaCl rejection. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermal crosslinked alkynyl-based polyimide membrane (EBPA-TB-TC) showed high thermal stability and increased microporosity. • EBPA-TB-TC membrane exhibited He permeability (61.14 Barrer) and He/N 2 selectivity (72.78). • EBPA-TB-TC membrane demonstrated excellent anti-aging performance. Membrane separation technology plays a critical role in the utilization of helium (He) resources. Yet, the performance of current polymer membranes is hindered by a trade-off between permeability and selectivity, as well as by physical aging. Solving these problems is vitally crucial for the industrial application of He separation. This study reported controllable thermal crosslinking of alkynyl-based polyimide membrane (EBPA-TB-TC) to improve He permeability and anti-aging performance. The resulting covalently crosslinked structures conferred thermal and chemical stability to the membranes, as well as increased microporosity. It led to a notable 'anti-trade-off' effect and improved anti-aging characteristics. An optimized EBPA-TB-TC membrane exhibited a superior combination with a He permeability of 61.14 Barrer and an He/N 2 selectivity of 72.78. Crucially, mixed-gas He/N 2 (1:1, 50/50) separation results over 50 days revealed minimal reductions in He permeability (1.34 %) and He/N 2 selectivity (2.95 %), indicating fantastic anti-aging performance. These findings demonstrated the significant potential of thermally cross-linked EBPA-TB-TC membrane in long-term stable helium separation. [ABSTRACT FROM AUTHOR]