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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]

Inspired by biological membranes with charge-gated channels that allow the transport of water and ions but restrict the undesired substances, various regulated nanofiltration (NF) membranes containing charge-gated channels have been developed for water purification. However, most of these membranes are mono-charged (positively or negatively) that show high rejection only to the corresponding co-ions but low rejection to the counter-ions, which limits their wider applications. Herein, we report NF membranes with gas-tunable charge-gated channels and high rejection to different salts on demand. The membranes are prepared by assembling a CO 2 -responsive polymer, poly(N,N-dimethylaminoethyl methacrylate), on the surface of graphene oxide (GO). As a result of CO 2 -induced reversal of the charge sign, the membranes exhibit "self-regulation" of their surface charges. Upon bubbling CO 2 into water, the membranes are positively charged, which shows high rejection to MgCl 2. After bubbling Ar to remove CO 2 , the membranes gradually transform to negatively charged, and high rejection to Na 2 SO 4 is obtained. This study demonstrates the gas-tunable charge-gated ion transport behavior of the CO 2 -responsive NF membranes, and opens up new avenues for the design of on-demand NF membranes. New nanofiltration membranes exhibit on-demand switchable rejections toward cations and anions with the participation and departure of CO 2. Image 1 • New nanofiltration membrane was built with graphene oxide and CO 2 -responsive polymer. • The surface of nanopores can be reversibly switched between opposite charged state. • Charge sign can easily be reversed in a robust and contamination-free manner. • Ion transport behavior was dominated with the participation and departure of CO 2. [ABSTRACT FROM AUTHOR]

In this study, we focused on the effective disposal of radioactive wastewater through the development of nanofiltration membranes using biomass materials. We developed functionalized nanofilms using a bio-derived polymer for the decontamination of nuclear wastewater. The synthesis involved a straightforward interfacial polymerization (IP) process, followed by post-functionalization with polyethyleneimine (PEI). We investigated the impact of curdlan self-assembly on membrane separation performance, both pre- and post-IP reaction. Simultaneous self-assembly of curdlan and PEI grafting led to membranes exhibiting superior separation performance. By manipulating PEI molecular weights, we optimized the membranes' physicochemical properties, leading to superior separation efficiency. As a result, exceptional rejections of Co2+, Sr2+, and Cs+ ions were achieved, with rejection rates reaching 95.5 %, 93.7 %, and 92.54 %, respectively. Furthermore, long-term stability experiments validated the membrane's potential for purifying nuclear wastewater. These findings hold promise for the application of biomaterial-based membranes in the treatment of radioactive nuclear wastewater. [Display omitted] • Curdlan with self-assembly properties was applied as an aqueous phase to regulate the interfacial polymerization process. • Polyethyleneimine (PEI) post-functionalization were introduced to tune the surface charge and pore size of the TFC membranes. • The novel positively-charged TFC membranes exhibited excellent nuclear wastewater sieving ability. [ABSTRACT FROM AUTHOR]

Thin film nanocomposite (TFN) membranes synthesized by introducing nanofillers into a polyamide layer have attracted increasing attentions. However, due to the aggregation of the nanofillers, the fabricated TFN membranes inevitably suffer from a reduced stability. In this work, a novel nanofiltration (NF) selective layer with in-situ formed ZIF-8 was fabricated by an integrated vacuum filtration and interfacial polymerization (IP) method. The d -spacing of MXene nanosheets could be well tailored by controlling the content of in-situ formed ZIF-8 nanoparticles, thus optimizing the surface morphology and chemical composition of the as-prepared NF membrane. The highly hydrophilic MXene nanosheets and controllable ZIF-8 size enabled the molecular sieving ability of the selective layer. Compared with the pristine thin film composite membrane, the optimal membrane exhibited an excellent pure water permeability up to 40.8 L m−2 h−1 bar−1 while maintaining high rejections (>99.0 %) for Congo red, reactive blue 19, xylene brilliant cyaninG250 and methyl blue, respectively. Furthermore, the membranes preserved low salt rejections for Na 2 SO 4 , NaCl, MgSO 4 and MgCl 2. This novel fabrication strategy provides new insights to augment the interlayer distance of 2D nanosheets and broadens the prospects to employ nanofillers inside a membrane matrix for efficient dye/salt separation. [Display omitted] • 2D MXene nanosheets were supplied as nanofillers and blockers on membranes surface though a 0D/2D heterojunction structure. • The d-spacing of MXene were further turned by an in-situ growth of ZIF-8 nanoparticles. • The aggregation of ZIF-8 nanoparticles was avoided. • The membranes exhibit excellent separation performance for dye/salt mixtures. [ABSTRACT FROM AUTHOR]