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The development of high flux and solvent-stable thin-film composite (TFC) organic solvent nanofiltration (OSN) membranes was reported. A novel cross-linked polyimide substrate, consisting of a thin skin layer with minimum solvent transport resistance and a sponge-like sublayer structure that could withstand membrane compaction under high-pressure was first fabricated. Then the solvent flux was significantly enhanced without compromising the solute rejection by the coupling effects of (1) the addition of triethylamine/camphorsulfonic acid into the monomer solution, and (2) the combined post-treatments of glycerol/sodium dodecyl sulphate immersion and dimethyl sulfoxide (DMSO) filtration. Finally, the long-term stability of the TFC membrane in aprotic solvents such as DMSO was improved by post-crosslink thermal annealing. The novel TFC OSN membrane developed was found to have superior rejection to tetracycline (MW: 444 g/mol) but was very permeable to alcohols such as methanol (5.12 lm−2h−1bar−1) and aprotic solvents such as dimethylformamide (3.92 lm−2h−1bar−1) and DMSO (3.34 lm−2h−1bar−1). © 2014 American Institute of Chemical Engineers AIChE J, 60: 3623-3633, 2014 [ABSTRACT FROM AUTHOR]

Abstract: We have molecularly designed positively charged nanofiltration (NF) membranes by chemical cross-linking modification of P84 porous hollow fiber substrates with hyperbranched polyethyleneimine (PEI) 60,000. Experimental results show that both the macroscopic and microscopic morphology of P84 substrates affect the NF performance of the PEI cross-linked membranes. To withstand high pressure operations, macrovoid-free hollow fiber substrates were developed by manipulating dope formulation and spinning conditions with the addition of methanol or ethanol in spinning dopes. To design NF membranes with a narrow pore size suitable for the PEI cross-linking modification, a critical mean effective pore radius (r p ) of 1.5nm was found for the substrates and the resultant PEI cross-linked membrane can be used effectively for heavy metal removal. The rejection data of MgCl2, Pb(NO3)2 and glucose indicate that Donnan exclusion is the dominant rejection mechanism when the pore radius of the cross-linked membrane is over 0.34nm while size exclusion plays a more important role if the pore size is less than 0.34nm. The rejections of MgCl2 and Pb(NO3)2 increase with an increase in transmembrane pressure. Upon optimizing the transmembrane pressure and solution pH, the optimal rejections of Pb(NO3)2 was achieved at 91.05%. [Copyright &y& Elsevier]

Traditional technologies for solvent/water separation such as distillation and chromatography remain energy intensive. State-of-the-art organic solvent nanofiltration (OSN) membranes exhibit high solvent-solute selectivity, but their ability to discriminate between solvents is limited. Graphene oxide (GO) with homogeneous and tunable 2D nanochannels is a promising solution for this purpose, benefiting from its exceptional transport properties. Here, a one-step pressure-assisted cross-linking strategy was applied to coat GO on the inner surface of hollow fiber membranes. The direction of the external driving force during the assembly of the GO selective layers displays an important influence on the microstructure of the nanochannel and the separation performance. The covalent bonding formed at the GO/polyimide (PI) interface and PI substrate endows the membrane with significantly improved stability in solvent environments. The tunable morphology and hydrophilicity characteristic of the GO layer leads to the rapid transport of acetonitrile while impeding the penetration of water molecules. What's more, the migration route of acetonitrile is shorter than that of water in the cross-linked GO nanochannels. In particular, the cross-linked GO hollow fiber (CGHF) membrane exhibits a high acetonitrile permeance of 145.3 L m−2h−1 bar−1, and the dilute acetonitrile solution could be concentrated from 10 wt% to 92.4 ± 3.0 wt%. This means that the elaborately designed nanochannels offer a high energy-efficient prospect for solvent dehydration and OSN. [Display omitted] • GO hollow fiber membrane was prepared by a one-step cross-linking strategy. • The selective GO layer and PI support were synergistically regulated. • GO nanochannel exhibits ultra-high diffusion rates for acetonitrile. • High solvent permeance endows significantly enhanced solvent dehydration ability. [ABSTRACT FROM AUTHOR]

[Display omitted] • The dispersant-PMAS was used to facilitate mild preparation of CQDs-NH 2 membrane. • The PMAS improved particles deposition behavior and interface compatibility. • High water permeance and salt/dye separation efficiency were obtained. Nanomaterial-based membranes are a research hot spot for their sub-nanometer structural precision that can realize selective separation within a molecular scale. However, their preparation needs complex processes (heat treatment, time-consuming, vacuum-assisted filtration, etc), restricting their development. For the first time, the dispersant-poly (maleic acid-co-acrylic acid) sodium salt (PMAS) was designed to promote the mild formation of amine-carbon quantum dots (CQDs-NH 2) membrane at room temperature via a facile interfacial polymerization. First, PMAS incorporation may form an electric double layer and strengthen the electrostatic force between CQDs-NH 2 and substrate, accelerating CQDs-NH 2 particle deposition. Second, the PMAS may be conjunct with the adjacent CQDs-NH 2 particles, lowing the long-range force, and improving CQDs-NH 2 particle deposition behavior. Third, its surfactant property may regulate the interface compatibility, improving the reactivity to promote the mild preparation of the separation layer. The prepared membrane possessed high water permeance (55 L/m2·h1·bar1) and high selective separation to the NaCl/reactive black 5 mixture, showing great potential for wastewater treatment and resource recovery. [ABSTRACT FROM AUTHOR]

[Display omitted] • CNTs-loaded core-shell nanofibers were obtained by coaxial electrospinning. • Tunable wettability of substrate enabled constructing defect-free selective layer. • Introducing CB6 endowed selective layer with enlarged pores and reduced thickness. • Membrane exhibits four times enhanced permeability without sacrificing selectivity. • Membrane shows excellent and stable organic solvent nanofiltration performance. Solvent resistance and high perm-selectivity have always been the pursuit in organic solvent nanofiltration field. Insoluble polyimide nanofibrous membranes feature superior solvent resistance. However, its high hydrophobicity usually limits the uniform spread of the aqueous amine monomers during the interfacial polymerization process, resulting in the non-uniform reaction with the acyl chloride and the defective selective layer. Herein, coaxial electrospinning was employed to construct the core–shell nanofibrous substrates, in which aminated multi-walled carbon nanotubes were added to the shell layer. This strategy endowed the nanofibrous substrates with tunable wettability without sacrificing stability, which guaranteed the one-step construction of defect-free thin-film nanofibrous composite membranes via interfacial polymerization (IP). Further, cucurbit[6]uril was embedded into the polyamide network by coupling host–guest chemistry and IP, providing the wider solvent transport channels and achieving the four times enhanced methanol permeance (22.34 L·m−2·h−1·bar−1) without sacrificing the selectivity. The membrane shows application prospects for solvent recovery in chemical, pharmaceutical, and other fields. This work provides new thoughts for the design and modification of novel nanofiltration membranes. [ABSTRACT FROM AUTHOR]

[Display omitted] • ANPI is covalently grafted on the membrane surface to ensure grafting stability. • Ethanol as grafting solvent can inhibit the hydrolysis of -COCl to bind more ANPI. • The easily protonated ANPI would increase positive charges of membrane surface. • There will be no excess PA layer due to miscibility between ethanol and n-hexane. • Ethanol would slightly swell the PA layer to improve the membrane permeability. • Grafted membrane shows high selectivity and good stability in acidic solution. To efficiently recycle metal ions from electroplating wastewater, a positively charged acid-resistant nanofiltration membrane was prepared by coupling interfacial polymerization and postgrafting modification with an ethanol grafting solution containing N-(3-aminopropyl)-imidazole (ANPI). Ethanol, as the grafting solvent, not only slightly swelled the original polyamide (PA) layer but also is mutually miscible with n-hexane, which prevented the formation of additional PA layers. ANPI, as the grafting monomer, was covalently bound to the -COCl groups of the PA layer to guarantee grafting stability. Due to the inhibited hydrolysis of the -COCl group by ethanol, more ANPI was grafted on the PA layer, which could be easily protonated under low pH. This resulted in a looser, thinner and positively charged selectivity layer. The membrane permeability was improved by 56.0 ± 0.55% with high interception performance (> 98% for Cu2+ and Ni2+ ions) in electroplating rinse wastewater. The formed positive protective layer prevented H+ ions from attacking the –CO-NH- bonds, resulting in strong stability after immersion in 10 wt% H 2 SO 4 and H 3 PO 4. Therefore, the obtained membrane shows promise for application in highly acidic wastewater. [ABSTRACT FROM AUTHOR]

• All-in-one integration of nanofiltration and ion exchange membranes. • The high removal rate of heavy metal oxyanions and heavy metal cations. • Sustainable recycling and regeneration by the electro-deionization process. The composition of wastewater containing heavy metal mixtures is often complex and poses a serious threat to human and environmental health. Effective removal of a variety of heavy metal ions with a single technology is challenging, and the conventional split integrated technologies require multi-step processing and a massive footprint. For the first time, we achieve hierarchically integrating ion exchange and nanofiltration into all-in-one "iNF" membranes. The iNF membrane has a hierarchical structure with an interfacial polymerization layer and an ion exchange layer, which can achieve highly efficient indiscriminate heavy metal ion removal, overcoming the defect that traditional nanofiltration membranes can only remove single metal cations or oxyanions. The ion exchange layer can remove heavy metal ions through sulfonic acid groups and quaternary amine groups. In addition, the ion exchange layer can be regenerated by electro-deionization, which is meaningful for sustainable membrane usage. This facile, scalable, and compact integrated process shows outstanding potential and universal applicability in complex wastewater treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A photocatalytic membrane was constructed by sol-gel assisted IP technique. • Customized pore size and enhanced electronegativity conduce to precise separation. • TiO 2 -based membranes own superior property of self-cleaning and durability. • Diafiltration model was utilized to examine the durability of membrane. Nanofiltration (NF) membranes with fast and precise separation performance and self-cleaning capabilities are desired for the treatment of textile wastewater. However, a decline in performance caused by membrane fouling severely limits the applications of NF membranes. Meanwhile, the dense selective layer fabricated by traditional interfacial polymerization (IP) weakens the ability of precise molecular separation. In this work, we report a novel sol–gel assisted interfacial polymerization (SGIP) technique involving an interfacial polymerization reaction and simultaneous generation of titanium dioxide (TiO 2). This approach can tune the performance and morphology of the NF membranes and endow membranes with self-cleaning properties. The synthesized membrane achieved a high water permeability (18.76 L m−2 h−1 bar−1) without sacrificial rejection of Na 2 SO 4. The membrane also has good photocatalytic properties and is stable during eight fouling-irradiation cycles. This work provides distinctive insights into the preparation of a self-cleaning thin-film nanocomposite (TFN) membrane for selective separation in the field of wastewater treatment and resource recovery. [ABSTRACT FROM AUTHOR]

Large amounts of lignin, hemicellulose, organic matter and inorganic salts are present in pulping and papermaking wastewater. Therefore, the treatment and discharge of pulping wastewater are important issues. We have designed and developed the world's first zero liquid discharge (ZLD) system for it based on pretreatment-membrane-evaporative crystallization integrated technologies. However, for the treatment of high salt reverse osmosis (RO) brine, there are still challenges that need to be addressed. In this work, the feasibility of using a membrane distillation crystallization (MDC) process to treat high saline RO brine was investigated. Two different coating materials, Hyflon AD 40H and perfluoropolyether (PFPE), were applied to improve the membrane surface hydrophobicity for stable and efficient performance. After modification, the water contact angle was up to 138.4o and 157.7o for Hyflon/polyvinylidene fluoride (PVDF) and PFPE/PVDF composite membranes, respectively. Moreover, the PFPE/PVDF membrane showed a higher repellency toward RO brine, which is better for the following MDC treatment. During the MDC progress using composite PFPE/PVDF membranes, the salt crystals precipitated and gradually accumulated. More importantly, the final NaCl purity can be up to 94%. Therefore, it is hopeful to improve of the existing ZLD system by MDC operation. [Display omitted] • Membrane crystallizer was proposed to achieve zero liquid discharge in the papermaking industry. • (Super)hydrophobic composite membrane was prepared by coating PFPE and Hyflon. • Composite PFPE/PVDF membrane showed the best anti-fouling and anti-wetting properties. • The PFPE/PVDF membrane showed the potential to extract salts and pure water from real pulping brine. [ABSTRACT FROM AUTHOR]

[Display omitted] • Intrinsic solvent-resistant nylon 6 was electrospun into nanofibrous substrates. • Solvent-assisted remelting was proposed to optimize PA6 nanofibrous substrates. • Pore size, roughness, and crystal form of substrates were optimized by remelting. • Defect-free active layers were constructed on optimized substrates via IP process. • Composite membranes show excellent stability and selectivity in multiple solvents. Organic solvent nanofiltration (OSN) as a new paradigm technology could satisfy the rapidly growing demand for small-molecular separation and purification in organic solvent systems. Aiming at two main bottlenecks of weak solvent resistance of traditional polymers and high transfer resistance of traditional phase inverted membrane structures, intrinsic solvent-resistant nylon 6 (PA6) was electrospun into nanofibrous substrates to avoid complex cross-linking and lower the transport resistance. A novel solvent-assisted remelting method was proposed to optimize PA6 nanofibrous substrates: pore size and roughness of substrates were reduced, which would provide an ideal substrate for constructing defect-free selective layer; (2) crystal form of PA6 was transferred from semi-stable γ state to stable α state, leading to 2.5 times enhancement of mechanical strength of membranes. Based on the optimized substrate, a high-performance composite membrane was constructed successfully via interfacial polymerization, displaying high methanol permeability of 9.6 L m−2 h−1 bar−1 and high rejections for different water-soluble and alcohol-soluble dyes, which indicates a succinct and efficient strategy for designing novel OSN membranes. [ABSTRACT FROM AUTHOR]

Although covalent organic frameworks (COFs) demonstrate notable potential for developing advanced separation membranes, contemporary COF membranes still lack controlled stacking and highly efficient sieving. Here, Turing-architecture COF membranes were constructed by engineering a reaction-diffusion assembly process via heterogeneous nucleation synthesis with tannic acid (TA). TA covalently binds with amine monomers to form a composite precursor with increased reactivity and decreased diffusivity. This altered the pathway of Schiff base reactions with aldehyde monomers, fulfilling suitable reaction-diffusion conditions, and ultimately formed the labyrinthine stripe or spot-patterned Turing COF film with controlled stacking and uniform pore structure. This endows our COF membrane with highly efficient molecule sieving ability for organic solvent nanofiltration while exhibiting a flux that is 621% greater than that of commercial membranes. Thus, this study provides a paradigm for the in situ synthesis of highly efficient COF membranes for diversely sustainable separations.

Membranes tailored for selective ion transport represent a promising avenue toward enhancing sustainability across various fields including water treatment, resource recovery, and energy conversion and storage. While nanochannels formed by polymers of intrinsic microporosity (PIM) offer a compelling solution with their uniform and durable nanometer-sized pores, their effectiveness is hindered by limited interactions between ions and nanochannel. Herein, we introduce the randomly twisted V-shaped structure of Tröger's Base unit and quaternary ammonium groups to construct ionized sub-nanochannel with a window size of 5.89-6.54 Å between anion hydration and Stokes diameter, which enhanced the dehydrated monovalent ion transport. Combining the size sieving and electrostatic interaction effects, sub-nanochannel membranes achieved exceptional ion selectivity of 106 for Cl - /CO 3 2- and 82 for Cl - /SO 4 2- , significantly surpassing the state-of-the-art membranes. This work provides an efficient template for creating functionalized sub-nanometer channels in PIM membranes, and paves the way for the development of precise ion separation applications., (© 2024. The Author(s).)

Nanofiltration (NF) membranes play a pivotal role in water treatment; however, the persistent challenge of membrane fouling hampers their stable application. This study introduces a novel approach to address this issue through the creation of a poly(3,4-ethylenedioxythiophene) (PEDOT)-based conductive membrane, achieved by synergistically coupling interfacial polymerization (IP) with in situ self-polymerization of EDOT. During the IP reaction, the concurrent generation of HCl triggers the protonation of EDOT, activating its self-polymerization into PEDOT. This interwoven structure integrates with the polyamide network to establish a stable selective layer, yielding a remarkable 90 % increase in permeability to 20.4 L m -2 h -1 bar -1 . Leveraging the conductivity conferred by PEDOT doping, an electro-assisted cleaning strategy is devised, rapidly restoring the flux to 98.3 % within 5 min, outperforming the 30-minute pure water cleaning approach. Through simulations in an 8040 spiral-wound module and the utilization of the permeated salt solution for cleaning, the electro-assisted cleaning strategy emerges as an eco-friendly solution, significantly reducing water consumption and incurring only a marginal electricity cost of 0.055 $ per day. This work presents an innovative avenue for constructing conductive membranes and introduces an efficient and cost-effective electro-assisted cleaning strategy to effectively combat membrane fouling., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The nanofiltration (NF) membranes with the specific separation accuracy for molecules with the size of 0.5-2 nm have been applied in various industries. However, the traditional polymeric NF membranes still face problems like the trade-off effect, organic solvent consumption, and weak durability in harsh conditions. The participation of coordination action or metal-organic coordination compounds (MOCs) brings the membrane with uniform pores, better antifouling properties, and high hydrophilicity. Some of the aqueous-phase reactions also help to introduce a green fabrication process to NF membranes. This review critically summarizes the recent research progress in coordination chemistry relevant NF membranes. The participation of coordination chemistry was classified by the various functions in NF membranes like additives, interlayers, selective layers, coating layers, and cross-linkers. Then, the effect and mechanism of the coordination chemistry on the performance of NF membranes are discussed in depth. Perspectives are given for the further promotion that coordination chemistry can make in NF processes. This review also provides comprehensive insight and constructive guidance on high-performance NF membranes with coordination chemistry., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Smart voltage-gated nanofiltration membranes have enormous potential for on-demand and precise separation of similar molecules, which is an essential element of sustainable water purification and resource recovery. However, the existing voltage-gated membranes are hampered by limited selectivity, stability, and scalability due to electroactive monomer dimerization. Here, for the first time, the host-guest recognition properties of cucurbit[7]uril (CB[7]) are used to protect the viologen derivatives and promote their assembly into the membrane by interfacial polymerization. Viologen functions as a voltage switch, whereas CB[7] complexation prevents its dimerization and improves its redox stability. The inhibited diffusion of the CB[7]-viologen complex enables the precise patterning of the surface structure. The resultant voltage-gated membrane displays 80% improved rejection performance, excellent recovery accuracy for similar molecules, and anti-fouling properties. This work not only provides an innovative strategy for the preparation of voltage-gated smart nanofiltration membranes but also opens up new avenues for ion-selective transmission in water treatment, bionic ion channels, and energy conversion.

Low concentration alcohols produced by state-of-the-art biological fermentation restrict subsequent purification processes for chemical, pharmaceutical, biofuel, and other applications. Herein, a rarely reported cucurbituril[ n ] ( n = 6, 8) is employed to pattern the thin-film composite membranes with controllable and quantifiable nanostrand structures through a host-guest strategy. The resulting nanofiltration membrane with such morphology is the first report that exhibits excellent separation performance for isopropyl alcohol (IPA) and water, condensing the initial 0.5 wt % IPA aqueous solution to 9.0 wt %. This not only provides a novel strategy for patterning nanostructural morphology but also makes nanofiltration membranes promising for alcohol condensation in the biological fermentation industry that may reduce energy consumption and postprocessing costs.

This study aims to develop a positively charged nanofiltration (NF) hollow fiber membrane for effective removal of ciprofloxacin from water. A novel NF membrane was fabricated by hyperbranched polyethyleneimine (PEI) induced cross-linking on a polyamide-imide hollow fiber support. The spongy-like, fully porous membrane support provides minimal transport resistance and sufficient mechanical strengths for water permeation under high pressures. It is found that the PEI modification significantly influences NF performance through the mechanisms of size exclusion, charge repulsion, and solute-membrane affinity. Specifically, after PEI induced cross-linking, the membrane pore size is significantly reduced. The membrane surface becomes more hydrophilic and positively charged. As a result of these synergic effects, the rejection of ciprofloxacin is substantially enhanced. Furthermore, experimental results show that the molecular weight of PEI has tremendous effect on NF performance of the as-modified membrane. The NF membrane modified by a high molecular weight PEI_60K exhibits the highest rejection, the lowest fouling tendency, and keeps a constant flux over the whole pH range. This study may have great potential for developing high-performance antifouling NF hollow fiber membranes for various industrial applications.

The nucleolar protein PinX1 has been proposed to be a putative tumor suppressor due to its binding to and inhibition of the catalytic activity of telomerase, an enzyme that is highly expressed in most human cancers in which it counteracts telomere shortening-induced senescence to confer cancer cell immortalization. However, the role of PinX1 in telomere regulation, as well as in cancer, is still poorly understood. In this study, we showed that the PinX1 protein is constitutively expressed in various human cells regardless of their telomerase activity and malignant status. Most interestingly, we found that silencing PinX1 expression by a potent short hairpin RNA construct led to a robust telomere length shortening and growth inhibition in telomerase-positive but not in telomerase-negative human cancer cells. We further showed that silencing PinX1 significantly reduced the endogenous association of telomerase with the Pot1-containing telomeric protein complex, and therefore, could account for the phenotypic telomere shortening in the affected telomerase-positive cancer cells. Our results thus reveal a novel positive role for PinX1 in telomerase/telomere regulations and suggest that the constitutive expression of PinX1 attributes to telomere maintenance by telomerase and tumorigenicity in cancer cells.