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The separation and removal of nutrient salts from wastewater can realize environmental remediation, and resource recycling and utilization. Electrodialysis (ED) membrane separation technology can offer an effective and low-energy consumption alternative but requires selective separation of nutrient salts with rapid anions permeation rate. We fabricated selective anion exchange membranes (PA-ATG) with the polyamide (PA) surface modification of commercial ATG anion exchange membrane by interfacial polymerization (IP) method. The dense PA thin-film layer with high hydrophilicity and electronegativity facilitates nitrate/phosphate anions selectively permeating through the PA-ATG membrane. The PA-ATG membrane exhibited a NO 3 − anion permeation rate of 1.1 mol m−2 h−1 and good NO 3 −/HxPO 4 (3−x)- permselectivity of 2.02, which is ∼2.0 times higher than that of the pristine ATG membrane. Owing to the rigid aromatic crosslinking structure, and electrostatic and hydrogen-bonding multiple interfacial interaction, the as-prepared membrane PA-ATG showed good stable and efficient separation performance during ED process for the nutrient wastewater treatment. [Display omitted] • Polyamide modified anion exchange membrane PA-ATG was prepared via interfacial polymerization. • The PA modification thin-layer had high hydrophilicity and electronegativity. • The PA-ATG membrane exhibited both high NO 3 − permeation rate and NO 3 −/H x PO4(x−3)- permselectivity. • The PA-ATG membrane had good reproducibility and process stability for nutrient wastewater treatment. [ABSTRACT FROM AUTHOR]

The separation of organic-organic azeotropic mixtures is important in the petrochemical, agrochemical, and pharmaceutical industries, which is energy-intensive by using the current distillation technology. Pervaporation process is energy-efficient for azeotropic separation, while lacks of high-performing membrane materials. In this work, to realize efficient separation of dimethyl carbonate/methanol azeotropic mixtures, a benchmarked membrane, polydimethylsiloxane (PDMS), was incorporated by zeolites with tunable pore chemistry. Specifically, MFI-type zeolite was grafted by alkyl chains with different carbon numbers (C 1 , C 4 , C 8), thereby providing tunable transport channels for organic molecules. Based on systematic characterizations (e.g., sorption and LF-NMR) and permeation test, we found that the organophilic alkyl chain can trap organic molecules into the zeolitic pores while may also hinder the organic diffusion through the zeolite due to the steric hindrance effect. The PDMS mixed-matrix membrane (MMM) with optimized C 1 -grafted MFI loading as high as 50 wt% exhibited separation factor of 3.6, and permeation flux of 11.5 kg m−2 h−1 for 30 wt% DMC-methanol azeotropic mixture at 40 °C. With slightly higher separation factor, the flux of PDMS MMM is 1.5-fold higher than that of the pure PDMS membrane. This work highlights the critical role of filler pore chemistry on the solution-diffusion transport and thus performance enhancement of MMM. [Display omitted] • Incorporating MFI zeolites with tunable pore chemistry into PDMS membrane. • Zeolite filler possesses tunable transport channels for organic molecules. • MTES-MFI/PDMS MMM exhibits significantly enhanced pervaporation flux. [ABSTRACT FROM AUTHOR]

The design of membrane networks to recover chemical components from liquid mixtures is intricate due to the large number of potential network configurations. Additionally, nonidealities present in liquid mixtures pose difficulties in describing membrane permeators. In this work, we present a framework for membrane network synthesis to recover valuable components from liquid mixtures using mixed-integer nonlinear programming (MINLP). First, to model membrane permeation, we develop a physics-based nonlinear surrogate model for crossflow membranes. Second, we construct a richly connected superstructure to account for all potential membrane network configurations. Third, we demonstrate how the two aforementioned elements can be integrated into a MINLP model to obtain the optimal membrane network configuration. Finally, through various applications, we illustrate how the proposed approach can achieve globally optimal solutions. [Display omitted] • Developed surrogate membrane model for multicomponent liquid mixture separation. • Generated rich-superstructure embedding various membrane network configurations. • Proposed novel MINLP model to obtain globally optimal membrane network. • Applied approach to demonstrate applications in liquid mixture separation problems. [ABSTRACT FROM AUTHOR]

Separation of azeotropic mixtures is a typical energy-intensive process in chemical industry, in which pervaporation membrane process shows great potential in energy efficiency. However, the performance of commercial membranes such as polydimethylsiloxane (PDMS) is unattractive for practical application. Henein, for the first time, we employed microporous MAF-6 as a new filler incorporating into PDMS membrane for pervaporation separation of DMC/methanol azeotropic mixture. The resulting MAF-6/PDMS mixed-matrix membrane with the optimal filler size of 300 nm and filler loading of 12 wt% exhibited highly DMC permeability (651–811.5 Barrer) and selectivity (10.1–10.4) during 31 days continuous separation process, which fairly exceeds the state-of-the-arts membrane performance. A pervaporation-distillation coupled process was further proposed for the purification of DMC/methanol mixtures, showing 55.7 % of energy-saving compared with conventional distillation process. [Display omitted] • MAF-6/PDMS MMMs for separation of DMC/methanol azeotropic mixture. • Both flux and separation factor are enhanced by incorporating MAF-6. • Distillation integrated with membrane process reduces energy consumption of 55.7 %. [ABSTRACT FROM AUTHOR]

Achieving strong interaction with the targeted composition and constructing abundant transport channels is crucial to obtain the pervaporation (PV) membrane with high selectivity and flux. Here, three ionic liquids (ILs) were screened out based on their relative selectivity and capacity targeting for bioethanol dehydration by COSMO-RS. The interaction energies analysis between ILs, EtOH, and H 2 O suggests that the ILs can form strong hydrogen bonds with water and disrupt the hydrogen bond in the EtOH–H 2 O azeotropic mixture, which is beneficial for improving the selectivity. Furthermore, driven by the multiple hydrogen bonds, electrostatic interactions, and van der Waals forces, ILs could self-assemble with polyvinyl alcohol (PVA) to fabricate the PV membrane with well-ordered micelle nanostructure, as its structure was revealed by MD simulations. The formation of the ILs-PVA micelle dramatically influenced membrane surface morphology, roughness, and water contact angle, providing an extra transport channel for the membrane. The optimal membrane (at the cmc point) exhibited a superior ethanol dehydration separation factor of 1627, along with a flux of 684 g/m2h at 50 °C. It can be expected that this novel self-assembled ILs-PVA micelle nanostructure strategy will find promising applications in other azeotropic mixture separation processes, like ethanol-ethyl acetate, water-butanol, etc. Herein, the formation of micelle nanostructure within the PVA-ILs dope solution was investigated using the Tyndall effect and transmission electron microscopy (TEM). Subsequently, free-standing PVA-ILs membrane with micelle nanostructure was fabricated and was employed for efficient bioethanol dehydration via pervaporation. [Display omitted] • The ILs disrupted the hydrogen bond in the EtOH–H 2 O azeotropic mixture, which is beneficial for the separation. • The ILs and PVA self-assembled to form the well-ordered micelle nanostructure and improved the performance of the membrane. • The optimal membrane exhibited a superior ethanol dehydration separation factor of 1627, along with flux of 684 g/m2h. [ABSTRACT FROM AUTHOR]

The rapid development of modern industrialization has put forward high demands on separation and purification technologies. To reduce energy consumption, improve efficiency, and enhance process flexibility, nanofiltration membranes for high temperature separation have become more and more important. Herein, we report the use of 3,3′-diaminobenzidine (DAB) as the aqueous phase monomer and trimesoyl chloride (TMC) as the organic phase monomer to engineer thermally resistant nanofiltration membranes via interfacial polymerization. The incorporation of DAB enhances the rigidity of the cross-linked polyamide network, reduces segmental thermal motion at high temperature, and improves the thermal stability of the composite membrane. The variations in fractional free volumes of the nanofiltration membranes were analyzed at different temperatures by molecular dynamics (MD) simulation, which have also been confirmed by experiments. The findings reveal that incorporating a rigid monomer into the polyamide layer can significantly enhance the thermal resistance. The resultant composite membrane exhibits outstanding resistance to high-temperature feed solutions, boasting a highly stable rejection rate (97.0 %) to Na 2 SO 4 between 25–85 °C. Remarkably, even under sustained operation at 85 °C for 12 h, the rejection rate is consistently stable. This work presents a novel system for the design of thermally stable nanofiltration membranes for high temperature separation. [Display omitted] • A rigid amine monomer improves the thermal stability of the nanofiltration membrane. • The fractional free volumes of the separation layers were analyzed by molecular dynamics simulation. • The nanofiltration membrane exhibits excellent thermal and operational stability. [ABSTRACT FROM AUTHOR]

Advancements in membrane separation technology play a pivotal role in separation processes closely associated with the environment and energy. However, presently available commercial polymeric membranes encounter the challenge of low permeability, impacting both separation efficiency and membrane module costs. Here, we propose a simple and effective in situ acid hydrolysis strategy to significantly enhance membrane permeability. Specifically, a tetrafluorinated monomer with hydrolyzable Schiff base groups (TFNAD) has been meticulously designed, synthesized, and copolymerized with commercial TFTPN and TTSBI, yielding a series of copolymers. Subsequently, in situ hydrolysis removes aniline from the membrane, freeing up the occupied free volume and creating additional channels for gas transport. This process substantially enhances gas permeability while preserving the desired selectivity. PIM-TFAD-30 showed a 68 % improvement in CO 2 permeability with virtually no compromise in CO 2 /N 2 selectivity compared to the pre-hydrolysis membrane. Meanwhile, PIM-TFAD-30 also displayed outstanding separation performance and plasticization resistance in simulated flue gas tests, demonstrating its potential for practical application. This facile and straightforward hydrolysis method opens up a new perspective for preparing and modifying polymeric separation membranes beyond gas separation. [Display omitted] • A simple and effective strategy for in situ acid hydrolysis is presented. • Hydrolysis significantly enhances the gas permeability of the membrane while maintaining almost identical selectivity. • In situ hydrolysis strategy offers a novel perspective on the design of superior gas separation membranes. [ABSTRACT FROM AUTHOR]

The recovery of valuable chemicals, such as sinapic acid, from enzymatic hydrolysates is essential to enabling a sustainable biorefinery. In this study, we designed a system to recover sinapic acid produced chemo-enzymatically from waste mustard bran. The process involves sequential separation, beginning with size partitioning using ultrafiltration for enzyme removal and recovery, followed by charge-mediated size partitioning via nanofiltration to isolate sinapic acid from other extracts. Four polyethersulfone (PES) ultrafiltration membranes with molecular weight cut-offs (MWCOs) of 5000 and 10 000 Da and maximum allowable working pressures (MAWPs) of 3 and 10 bar were screened for their effectiveness in removing Bovine Serum Albumin (BSA) as a model compound. Subsequently, these membranes were applied to recover the feruloyl esterase enzyme. The membrane with an MWCO of 5000 Da and an MAWP of 10 bar achieved 97.93 % enzyme recovery with a permeate flow rate of 31.4 L/h/m2 at 6 bar. Next, we evaluated the effects of zeta potential interactions on the preferential rejection of sinapic acid using various nanofiltration membranes with potentially charged surfaces, including polyimide, silicon-based thin film composite, and polypiperazine amide membranes with MWCOs ranging from 150 to 600 Da. The polypiperazine amide membrane demonstrated the highest recovery of sinapic acid, achieving 86 % recovery from a model solution and 64 % recovery from mustard bran hydrolysate. Compositional analysis of the permeate confirmed that the rejection rate (R) is influenced primarily by the pKa rather than molecular size, following the trend: sinapic acid (pKa = 4.58; 224.2 Da; R = 64.0 %), acetic acid (pKa = 4.76; 60.1 Da; R = 23.8 %), xylose (pKa = 12.15; 150.1 Da; R = 13.7 %), glucose (pKa = 12.28; 180.2 Da; R = 8.7 %), and arabinose (pKa = 12.34; 150.1 Da; R = 8.5 %). The zeta potential interactions across nanofiltration membranes enhanced sinapic acid recovery from the mustard bran hydrolysate, hence, charge mediation significantly influenced the membrane separation of these complex mixtures with varying pKa values. [Display omitted] • Combining size and charge separation can enhance the separation of similarly sized compounds. • Membrane (5k Da cut-off) recovered 97.93 % of the enzyme from hydrolysate. • Electrostatic interaction improved separation, recovering up to 64 % of sinapic acid. • Negatively charged polypiperazine amide membranes and positive solutes boost separation. • The membranes are reusable with >8 % permeability loss after NaOH and water washing. [ABSTRACT FROM AUTHOR]

Nanofiltration (NF) is commonly recognized as one of the effective technologies for the separation of magnesium (Mg2+) and lithium (Li+) from salt-lake brines. Charge repulsion and size exclusion effects often play an important role, whose functions primarily occur at the top surface and the matrix, respectively, of the skin layer. In this study, a novel nanofiltration (NF) membrane is prepared that integrates both size exclusion and charge repulsion effects into the matrix of the skin layer for enhanced Mg2+/Li+ separation. With the surface-modified hydrophilic polyethylene (PE) membrane as the supporting layer, the prepared NF membrane successfully incorporated Fe3+ ions into the matrix of the skin layer during the interfacial polymerization (IP). Fe3+ ions which chelate with amine groups of PEI (aqueous-phase monomers during IP) ensure abundant positive charges within the matrix of the skin layer, providing good hydrophilicity and sustained electrostatic repulsive force against the transmembrane transport of Mg2+, and thus the enhanced rejection. Results exhibited a remarkable 92.6 % rejection rate for MgCl 2 and a higher water permeance of 22 LMH/bar, which is 1.57 times greater than that of the traditional PEI-TMC membranes. The nanofiltration process effectively reduced the Mg2+/Li+ ratio from 50 in the feed to 5.4 in the permeate solution. It is also interesting to find that although the pore size of the skin layer (0.53 nm in radius) exceeds both the hydrated radii of Mg2+ and Li+, the positive charges within the matrix of the skin layer still provide good selective separation performance, thus effectively breaking the trade-off of permeability and selectivity. This study offers a fresh perspective on the preparation of nanofiltration membranes by systematically exploring the potential of integration of charge repulsion and size exclusion effects into one location, i.e., the matrix of the skin layer for enhanced Mg2+/Li+ separation performance. [Display omitted] • Integration of size exclusion and charge repulsion into the skin layer matrix of NF membranes. • Continuous repulsive force offered by Fe3+ against the transmembrane transport of Mg2+. • High permeance (22 LMH/bar) with remarkable 92.6 % rejection despite of larger pore size. • Stable 72-h NF performance with Mg2+/Li+ ratio decreasing from 50 (feed) to 5.4 (permeate). • Break of trade-off between permeability and selectivity by the positive charges in skin layer matrix. [ABSTRACT FROM AUTHOR]

Membrane fouling during long-term usage severely restricts the practical application of membrane separation technology for oil-in-water emulsion treatment. Underwater superoleophobic/superhydrophilic membrane with superior self-cleaning and flux recovery performance is highly desirable, owing to its high anti-fouling ability in an oil-in-water emulsion. Herein, a polyglycidyl methacrylate-/iminodiacetic acid (IDA)/Fe(III) superhydrophilic layer was fabricated onto a polyvinylidene fluoride (PVDF) microfiltration membrane via radiation-induced graft polymerization, and subsequent adsorption of Fe(III) as the photo-Fenton activation site, labeled as Fe@PVDF, in which the loading capacity of Fe(III) was 18.31 wt%. The grafted layer acts as both, an underwater superoleophobic/superhydrophilic layer (OCA˃150o) for highly effective oil-in-water emulsion separation (99.4 %) and as a photo-Fenton activation layer for self-cleaning in 10 min under visible light irradiation with high flux (⁓2300 L m−2 h−1 bar−1). The mineralization of contaminants on the membrane surface was then systematically investigated using a series of experiments, X-ray absorption fine structure (XAFS) measurements, and density functional theory (DFT) calculations, demonstrating that the Fe/IDA site with an Fe(III) atom acts as the active site with an optimal energy gap for photo-Fenton self-cleaning activation and greatly accelerates the Fe (III) to Fe (II) cycle. Moreover, our work shows a pathway for photo-Fenton self-cleaning membranes combining excellent stability (15 cycles), and satisfactory oil-in-water emulsion separation with quick and reliable flux recovery performance, revealing their huge potential application in advanced sewage treatment. [Display omitted] • The Fe@PVDF was fabricated via RIGP in which the loading amount of Fe(III) was 18.31 wt%. • The grafted layer acts as an underwater superoleophobic/superhydrophilic layer and a photo-Fenton self-cleaning layer. • The high-loading Fe (III) membrane with maximum atom efficiency accelerates the photo-Fenton self-cleaning process in 10 min. • The Fe@PVDF shows satisfactory stability, oil/water emulsion separation, and fast and robust flux recovery performance. • The synergistic effect of active sites and activation mechanism were revealed via XAFS and DFT. [ABSTRACT FROM AUTHOR]

Due to the growing demand for lithium in the new energy industry, significant attention has been focused on developing lithium extraction technologies from salt-lake brine. However, the high Mg/Li ratio in salt-lake brine presents challenges for membrane separation technology. If a membrane can allow Mg2+ and water molecules to pass through while retaining Li+, the retained brine will have concentrated Li+ with a reduced Mg/Li ratio, creating the facilitation of further lithium extraction. In this study, we discovered through non-equilibrium molecular dynamics simulations that strongly hydrophilic covalent organic frameworks membranes capture Li+ in their pores, preventing additional Li+ from entering the nanopores. Meanwhile, Mg2+ can freely penetrate these nanopores along with water molecules. This adsorption of Li+ and the free permeation of Mg2+ with water molecules result in the effective separation of Li+ and Mg2+. Consequently, the retained brine becomes lithium-rich with reduced Mg/Li ratio. The findings of this work provide valuable guidance for designing nanofiltration membranes for extracting lithium from salt lakes with high Mg/Li ratio. [Display omitted] • The adjustment of membrane hydrophilicity influences the Mg/Li selectivity. • Enhanced membrane hydrophilicity promotes Li + retention, rather than Mg2+. • Strong hydrophilicity induces the adsorption of Li + onto the pore walls. • High concentration of Li + inside membranes hinders further entrance of Li+. • The penetration of Mg2+ is not influenced due to the large pore size of TpPa. [ABSTRACT FROM AUTHOR]

Traditional membrane separation technology for pharmaceutical tailwater purification has certain limitations, including inefficient removal of residual drugs and serious membrane fouling. This report describes a novel electro-Fenton membrane that was fabricated by coating an iron single-atom porous carbon layer (Fe-SA@PC/CM) and used to promote the in situ degradation of the antibiotic, amoxicillin, in pharmaceutical tailwater during electro-Fenton membrane filtration (EFMF). The Fe-SA@PC/CM membrane exhibited excellent electrocatalytic activity and conductivity for the oxygen reduction reaction. The designed flow-through mode remarkably outperformed the flow-by and conventional batch modes, with the corresponding mass transfer rate constant (k m) reaching 0.0044 cm/s. Active species identification and COMSOL simulations demonstrated that the enhanced convective diffusion of H 2 O 2 was crucial for supporting continuous •OH production. The Fe-SA@PC/CM membrane exhibited favorable durability and self-cleaning properties and could feasibly purify pharmaceutical tailwater. This study provides new insights regarding approaches to enhance EF oxidation via the convection-diffusion of oxygenated reactants for synergistic wastewater purification and membrane fouling mitigation. [Display omitted] • Electron transfer ability enhances O 2 reduction on the surface of Fe-SA@PC/CM. • High mass transfer efficiency of Fe-SA@PC/CM accelerates amoxicillin removal. • Convective diffusion of oxidants is essential for electro-Fenton membrane filtration. • Fe-SA@PC/CM showed favorable durability and feasibility in practical application. • In situ self-cleaning of Fe-SA@PC/CM effectively mitigates membrane fouling. [ABSTRACT FROM AUTHOR]

The worldwide shortage of clean water is a well-recognized challenge, moreover, the water system is undergoing serious oil pollution. Due to the superior separation efficiency and cost-effectiveness, membrane separation technology has gained prominence for treating oily wastewater. Nevertheless, its wider adoption is largely hindered by the persistent issue of membrane fouling. Recently, hydrophilic modification offers a promising solution to mitigate this issue, and proven to be both simple and effective. In this study, MXene-MOF composite membranes with photocatalytic self-cleaning properties were constructed by using self-assembly techniques. The membrane flux is 2534.89 ± 13.63 L m⁻2 h⁻1 bar⁻1, with separation efficiency exceeding 99.7 %. Notably, the water contact angle drops below 5° within 5 s, attributed to the hydroquinone-functionalized coating on the BIC@MIL-101(Fe) surface, effectively preventing oil adhesion onto the membrane surface. The incorporation of functionalized BIC@MIL-101(Fe) nanoparticles further improves the membrane's photocatalytic self-cleaning performance, furtherly enhancing its anti-fouling capabilities. Following 10 cycles of water cleaning and photocatalytic self-cleaning experiments, high water flux and separation efficiency are maintained, with a flux recovery rate ≥90 %. The anti-fouling mechanism of the membrane is further elucidated using the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. The current findings highlight the considerable potential of MXene-MOF composite membranes for effectively treating oily wastewater. [Display omitted] • MXene-BIC@MIL-101(Fe) membrane with photocatalytic self-cleaning properties were fabricated using self-assembly techniques. • These membranes are utilized to achieve highly efficient oil-water separation capabilities (≥99.7 %). • Catechol modified BIC@MIL-101(Fe) improved the hydrophilicity of the composite membrane and enhanced its light absorption capacity. • The excellent photocatalytic self-cleaning ability enables the composite membrane to maintain a flux recovery rate of ≥90 % after multiple cycles. • Composite membrane maintains stable separation efficiency after multiple cycles. [ABSTRACT FROM AUTHOR]

Advanced CO 2 separation technology is one of the key technologies for reducing carbon emissions and can make significant contributions to reducing the negative impact of the greenhouse effect on human survival. Membrane separation technology is regarded as a new generation of carbon capture technology because of its great potential to reduce carbon capture energy consumption and improve net carbon capture efficiency. Mixed matrix membranes (MMMs) can break through the performance limit of traditional polymer membranes, but the influence of bridging agents for post-modifying nanofillers on membrane structure and properties needs further systematic investigation. In this work, four types of ligands were selected for synthesizing polymer-modified nanofillers and then incorporated into poly (vinylamine) (PVAm) to prepare MMMs. The comparative analysis results indicate that bridging ligands with superior flexibility are conducive to enhancing the gas permeability within the pores by diminishing the compactness of the polymer shell. The constructed phase interface transition area with uniformly enhanced mechanical strength demonstrates the improved interface compatibility between the matrix and nanofillers bridged via the flexible ligand. Techno-economic evaluation verifies the industrial application potential of the optimal MMMs targeting CO 2 capture from post-combustion gas. Diagram of Nanofillers Structure Post-modified Using Polymer Homologous to the Matrix via Different Bridging Ligands. [Display omitted] • The properties of the polymer shell were regulated by bridging ligands with different flexibility. • Post-modification of nanofillers by homologous polymer generated excellent interfacial compatibility. • Ligands with strong flexibility stretched outer polymer to promote nanofillers' gas permselectivity. • The Maxwell model was conducted to verify the superiority of UIO- DEB -PVAm nanofillers. [ABSTRACT FROM AUTHOR]

Successful pre-combustion CO 2 capture from synthetic gas for H 2 production requires effective membrane separation technology. While polymer-based membrane materials offer promising industrial scalability, they generally lack a sufficiently high H 2 /CO 2 selectivity to make this process energy-efficient. In this work, we have designed a scalable dual-polymer blend membrane consisting of sulfonated polyphenylsulfone (sPPSU) and polybenzimidazole (PBI), and then being infiltrated with amine-rich poly(ethyleneimine) (PEI) molecules as effective CO 2 retardants to substantially elevate the H 2 /CO 2 selectivity. PEI molecules were infiltrated into the dual-polymer matrix via solution-treatment to crosslink the polymer network and retard CO 2 transport using its amine-rich nature. The PEI infiltration dramatically increased the H 2 /CO 2 selectivity of the dual-polymer matrix from 4.6 to up to 59.3 while maintaining a minimum H 2 permeability of 2.49 Barrer at a low temperature of 35 °C, which not only surpasses the Robeson upper bound but also places the newly developed membrane among the best-performing polymer-based membranes. More importantly, the solution infiltration of PEI incurs no phase segregation, maintaining the polymer mechanical robustness, which is crucial for industrial scaling. This study offers promising opportunities to develop three-polymer membrane systems for H 2 /CO 2 separation using synergistic polymer blends and CO 2 -retarding molecules. [Display omitted] • A three-polymer membrane system was developed for H 2 /CO 2 separation at ambient temperature. • Synergistic scalable dual-polymer blends and CO 2 -retarding molecules were employed for better H 2 /CO 2 separation. • No phase segregation for the membrane system, it had mechanical robustness for industrial scaling. • The sPPSU-PBI-PEI membranes enabled H 2 /CO 2 separation performance surpassing the upper bound. [ABSTRACT FROM AUTHOR]

Emerging nanofiltration (NF) separation technology for precision ionic/molecular separation at the nanoscale, which has the advantages of energy conservation, excellent separation and a small footprint, is promising for obtaining sustainable water resources via efficient water treatment and recycling. However, traditional NF membranes are restricted to applications at approximately room temperature because of the sharp deterioration in stability induced by the fragility of the nanopore structure at higher temperatures. Herein, we synthesized an unparalleled nanofiltration (NF) membrane with superior thermal stability up to 90 °C and finely tailored nanopores with 0.3–1.1 nm, via de novo carbon skeleton-mediated polymerization (CSMP). Molecular thermodynamics simulations and experiments demonstrated that C–C skeletons can manipulate the stability of the intrinsic structure and intermolecular gap size, contributing to exceptionally thermostable and well-tailored nanopores. The synthesized membrane exhibited excellent long-term water permeance and high rejection of (sub)nanoscale contaminant molecules at high temperatures, which is far superior to the performance of currently available NF membranes. [Display omitted] • The designed VTEs-VP-GMA reactive monomer is successfully synthesized. • The thermostable and tailored nanofiltration membrane is successfully synthesized. • The rigidity of C–C skeletons from VP improves the stability of nanopores. • VP tailors sizes of nanopores through C–C skeleton bridging between reactive sites. • The nanofiltration membrane exhibits excellent operational and thermal stability. [ABSTRACT FROM AUTHOR]

The drive to decarbonize chemical processes necessitates exploring low-energy solutions for separating complex liquid mixtures ubiquitous in food, pharmaceuticals, petrochemical, and synthetic fuel production industries. This report comprehensively investigates conceptualizing and implementing two novel organic solvent separation processes: Organic Solvent Forward Osmosis (OSFO) and Organic Solvent Pressure Assisted Osmosis (OSPAO). The intrinsic molecular specificity of ultramicroporous carbon molecular sieve (CMS) membranes allowed the unprecedented separation of a complex mixture of short-chain alcohols (e.g. , methyl alcohol, ethyl alcohol, and isopropyl alcohol) at room temperature. A new hybridized membrane-based separation methodology, OSPAO, that combines the elements of organic solvent nanofiltration (OSN) and OSFO is introduced. CMS-based OSPAO demonstrated a marked enhancement in the flux of organic species permeate, considerably improving separation efficiencies. The separation modalities presented in this report underscore the essential role of osmosis in the differentiation of organic solvents, thereby contributing valuable insights to osmosis-based separation technologies. [Display omitted] • This study investigates OSFO and OSPAO separations of ternary alcohol mixtures using a CMS/alumina composite hollow fiber. • Optimizing the CMS structure through varying pyrolysis temperature yields outstanding size selectivity. • The hierarchical CMS pore structure enables mass transport combining solution-diffusion and pore flow in OSPAO mode. • OSPAO separation enhances the transport rate of alcohols while preserving molecular selectivity. [ABSTRACT FROM AUTHOR]

For antibiotics, the purification and separation in the synthesis process, as well as enrichment and recycling in the utilization process, has a profound impact on human health and environmental issues, which pose an unignorable challenge for selective molecular sieving of separation technology. Herein, we offered a convenient high-accuracy separation membrane construction by using three dimensional rigid triptycenes as building-blocks to fabricate porous triptycene networks polyarylate nanofilms (PTN-NFs) by interfacial polymerization. With permanent porous structure and excellent stability, the PTN-NF membrane exhibited remarkable separation precision around 90 g mol−1 scale for several mixture separation and significant selectivity as high as 39.3 for piperacillin/6-aminopenicillanic acid (6-APA) separation. The contorted rigid triptycene monomer 2,6,14-trihydroxyltriptycene (THT) was employed by one-step interfacial polymerization to fabricate a porous triptycene network (PTN) thin film membrane (PTN–NF– 1) for the first time. The PTN–NF– 1 manifested the high selective accuracy of ∼90 g mol−1, from which realized the precise separation in several mixed systems, including antibiotics separation of 6-APA/piperacillin, for which the selectivity was calculated to be 39.3. [Display omitted] • A new porous triptycene networks nanofilm was fabricated for the first time. • The membrane exhibited remarkable separation precision around 90 g mol−1 scale. • The membrane realized accurate molecular sieving in several mixtures. • The membrane reached 39.3 significant selectivity for piperacillin/6-APA separation. [ABSTRACT FROM AUTHOR]

Coupling photocatalysis with membrane separation technology becomes one pioneering method to solve the membrane fouling. In this study, Ag@SnS photocatalyst was synthesized and blended with polyvinylidene fluoride (PVDF) to fabricate Ag@SnS/PVDF composite membranes via non-solvent induce phase separation (NIPS) method. The results show that with the addition of Ag@SnS, water flux of Ag@SnS/PVDF hybrid membranes increases due to the enhanced membrane hydrophilicity and increased porosity. The optimal hybrid membrane (MAS-2) exhibits the rejection rate of 97.0 % and 95.4 % for BSA and HA accompanied with a water permeance of 578.5 L m−2 h−1 bar−1. Moreover, MAS-2 membrane reveals excellent self-cleaning ability by photodegradation of HA on membrane surface, and its flux recovery rate (FRR) can achieve 91.7 % after UV irradiation and 95.8 % after 3 h natural sunlight irradiation via photocatalysis regeneration. The heterostructure of Ag@SnS can assist separation of photoinduced electrons and holes by transferring photoinduced electrons to Ag nanoparticles with enhanced photocatalytic activity. After three cycles, the FRR can still reach around 90.0 %, revealing its outstanding cleaning ability. Therefore, the Ag@SnS/PVDF membranes have a foreseeable potential in the field of water treatment due to its high flux performance, self-cleaning ability via photocatalysis process. [Display omitted] • Ag@SnS/PVDF photocatalytic membranes were revealed for the first time. • The membrane shows a PWP of 578.5 L m−2 h−1 bar−1 and BSA rejection of 97.0 %. • The fouled Ag@SnS/PVDF membranes can be regenerated via UV or sunlight irradiation. • Heterostructure of Ag@SnS enhanced the photocatalytic activity of the membranes. [ABSTRACT FROM AUTHOR]

The separation of oil from oily water is a critical endeavor owing to the escalating global oil pollution. Membrane separation technology has gained widespread adoption for oily water treatment. Inspired by the vertical segregation phenomenon in drying multi-component suspensions, this study proposed an evaporation-induced stratification coupled with sacrificial template method to prepare superhydrophobic polychlorotrifluoroethylene (PCTFE) membrane for fast gravity-driven oil/water separation. The precursor of PCTFE microporous membranes, PCTFE/fluoroelastomer/hydrophobic silica nanoparticles (PCTFE/FR/SiO 2) composite films, were fabricated via a solvent-assisted method. Induced by solvent evaporation, the pre-fabricated composite films exhibited a stratified structure, where SiO 2 nanoparticles enriched near the top surfaces, making it easily tailor the surficial wettability. For the matrix, PCTFE-rich domains and FR-rich domains intersected, forming a bicontinuous structure. After sacrificing FR, PCTFE porous membranes were obtained. Meanwhile, the PCTFE-based porous skeletons combining with surface enriched SiO 2 nanoparticles constructed a multi-level roughness, thus achieving superhydrophobicity. The optimized membrane possessed an average pore size of ∼1.84 μm, a porosity of ∼60 %, and a WCA above 155°, owning excellent self-cleaning properties and efficient oil/water separation ability. The membrane exhibited remarkable capability in various oil/water mixtures, including emulsified water-in-oil. The separation flux and oil recovery purity for water-in-dichloromethane emulsion were up to 2843 ± 84 L/(m2·h) and 99.95 wt%, respectively. Furthermore, though being immersed into various organic solvents for 7 days or experiencing 15 separation cycles, the performances of the membranes hardly changed. Accordingly, this work provides a practical approach for tailoring surficial wettability and fabricating PCTFE-based membranes suitable for oil/water separation fields. [Display omitted] • Novel strategy to fabricate superhydrophobic PCTFE membrane. • An evaporation-induced stratification coupled with sacrificial template. • Evaporation-induced stratification was adopted to tailor surface wettability. • Remarkable capability in segregating various oil/water mixtures and emulsion. • Excellent self-cleaning property, reusability, and organic solvent resistance. [ABSTRACT FROM AUTHOR]

Chitosan, as the second most abundant biopolymer on earth, is constantly increasing attention from different fileds such as biomedicals, food, energy, and the environment. However, its application in membrane technology such as pervaporation is lacking of an effective membrane manufacture strategy to improve its separation efficiency. Herein, we use a chitosan-based membrane subjected to neutralization and crosslinking procedures in contrasting solvents—specifically, water and ethanol—to explore the impact of polymer-solvent interactions on the effective nanogaps between polymer nanofibers. Under identical conditions, the procedures conducted in water yield hydrated membranes, while those in ethanol resulted in anhydrous membranes. In hydrated membranes, strong hydrogen bonds formed between water and amine groups block nanogaps amongst polymer nanofibers, significantly impeding molecular transport. Conversely, the absence of such strong hydrogen bonds in anhydrous membrane avoided this effect. This study highlights the potential of controlling the transport of organic molecules by tuning the nanogaps within the membrane matrix. This was achieved through a novel strategy involving washing the chitosan-based membranes with pure ethanol to remove free acids, followed by direct crosslinking in a glutaraldehyde ethanol solution. This strategy was able to double the membrane selectivity despite a 25 % reduction in methanol permeance. [Display omitted] • A fabrication strategy boosts organic mixture separation with CS-based membranes. • CS-solvent effects on the CS nanogap in the membrane fabrication are studied. • Water-produced membranes show strong hydrogen bonds, slowing molecular transport. • Ethanol-produced membranes lack strong hydrogen bonds, avoiding the effect. [ABSTRACT FROM AUTHOR]

Achieving highly selective separation of organic mixtures is crucial to modern fine chemicals and pharmaceutical industries. The membrane-based organic solvent reverse osmosis (OSRO) technology is expected to break through this barrier. The key to achieving the separation of organic mixed liquids is to design the OSRO membrane as needed based on the physical and chemical properties of the target separation solvent. However, this poses a huge challenge to traditional OSRO membranes. In this work, we report composite polyamide (PA) OSRO membranes with ultrahigh polar/non-polar organic mixture selectivity. The surface polarity of the composite PA membrane is increased by coating a layer of Fe3+/tannic acid (Fe3+/TA) layer on the surface of the PA membrane. The enhanced surface polarity increases the interaction difference between polar and non-polar solvents and the membrane. And a polarization layer is formed on the membrane surface, which weakens the concentration polarization effect on the membrane surface. Under high-concentration feed liquid (the mass ratio of methanol/hexane is 7:3), the separation factor of the prepared membrane reaches 218, which is the highest value of all OSRO membranes reported so far. For the first time, we establish a partial flux analysis for the OSRO process. This analysis unravels the pressure, concentration dependence, and sensitivity of separation performance. It provides novel insights into the design of high-performance OSRO membranes. [Display omitted] • High-performance OSRO PA membrane prepared by Fe3+/TA surface modification. • Fe3+/TA coating enhances the surface polarity of PA membrane. • Enhanced surface polarity affects membrane-solvent interactions. • PA-Fe3+/TA membranes show ultrahigh separation factor for methanol/hexane mixture. • Established partial flux analysis to gain in-depth understanding of OSRO process. [ABSTRACT FROM AUTHOR]

The development of analytical models for predicting the transport properties of membranes in the separation of multicomponent mixtures is highly relevant because (1) measurements of permeability and sorption of gas mixtures in membrane materials are laborious and time-consuming, and (2) estimation of transport properties based on pure gas measurements is desirable, however, rather unreliable and can lead to serious errors. In this paper, within the framework of the well-known frictional-coefficient formalism, we present nonlinear equations for the fluxes of gas mixture components through the membrane, which take into account the diffusional coupling of the fluxes compared to independent gas transport. As a result, an analytical equation for the mixed-gas selectivity was obtained. This equation has an implicit form, which is not quite convenient for practical application, since it has to be solved numerically. A simple explicit expression for mixed gas selectivity was derived using the so-called linear transport model, which is a linearized version of the original nonlinear flux equations. It is important to emphasize that a comparison of the linear model with the formally more rigorous nonlinear model showed only minor quantitative differences. The input parameters for the model are the single gas transport parameters. Testing the linear model using experimental data for the separation of hydrocarbons (n -butane/methane, n -butane/ i -butane, propylene/propane) revealed an acceptable fit. A comparison of the model with recent experimental data on the separation of CO 2 -containing mixtures using microporous polymers is also presented. It is found that the calculated CO 2 /N 2 mixed gas selectivity is in good agreement with the experimental data, while only a semi-quantitative agreement is observed for the CO 2 /CH 4 separation. Besides, it is shown that the model developed for binary gas separation can be extended to ternary gas mixtures. [Display omitted] • Analytical model of binary gas permeation through membrane. • Explicit expression for mixed-gas selectivity of membrane. • Input parameters are single gas transport parameters. • Model extension to ternary gas permeation. [ABSTRACT FROM AUTHOR]

Conventional techniques for the removal of silicone oils from small siloxane molecules (either cyclic species, such as D4 or linear siloxanes, known as L2-L6) include stripping and adsorption. Membrane separations could serve as low-energy alternatives or complements to these industrial separation techniques to reduce the overall process energy demand since they do not involve a phase change. This paper presents polymeric membranes as materials for purifying D4 (octamethylcyclotetrasiloxane) rich feed of 90 % D4 from a silicone fluid mixture. The transport properties (diffusion, sorption, and permeation) are studied experimentally to understand the driving force and mechanism for the separation related to the properties of the penetrant molecules, such as molecular size. These parameters are utilized in the solution-diffusion model to predict the permeation rates and separation performance of PDMS membranes for the siloxane-silicone fluid mixtures that are rich in the small siloxane. The results presented here suggest that PDMS membranes may serve as an industrially scalable low-cost alternative to small siloxane purification. [Display omitted] • OSRO separation of cyclic siloxane/silicone oil mixture studied for the first time. • Siloxanes and silicone oil sorption in PDMS obeys near-Fickian transport. • Transport of siloxanes follows the solution-diffusion model. • Separation of the siloxane-oil mixture is mostly driven by sorptive selectivity. • PDMS membrane is feasible for siloxane cleansing to achieve commercial grade of D4. [ABSTRACT FROM AUTHOR]

Ammonia (NH 3) produced by Haber-Bosch process is separated through the condensation process, which needs a large amount of energy consumption. Membrane separation technology is compelling for achieving energy-saving and efficient NH 3 separation. Therefore, 3-(trihydroxysilyl)-1-propanesulfonic acid (TPS) was applied, for the first time, to fabricate sulfonic silica-based membranes and evaluated for NH 3 selective permeation. The amorphous siloxane network can be formed by simple condensation of silanol (Si–OH) under sulfonic acid (-SO 3 H) self-catalysis, as confirmed by the results of Fourier transform infrared spectroscopy and X-Ray diffractometry. Moreover, TPS xerogel powders dried from TPS sols showed excellent thermal stability and dense structure via thermogravimetric and N 2 adsorption analyses. Importantly, an intensive NH 3 adsorption amount of ∼3.0 mmol g−1 for TPS xerogels from NH 3 adsorption and temperature-programmed desorption was twice higher than the reported oxidized (3-mercaptopropyl)trimethoxysilane xerogels (∼1.41 mmol g−1), which was ascribed to the inherently stronger proton-acidic -SO 3 H groups in TPS. Finally, TPS membranes prepared using TPS solutions diluted with ethanol expressed superior NH 3 -selective permeation based on favorable molecular sieving and NH 3 adsorption-diffusion via single and binary gas permeation, especially remarkable NH 3 permeance of ∼2.6 × 10−7 mol m−2 s−1 Pa−1 and excellent NH 3 /N 2 selectivity of 266 at 300 °C. [Display omitted] • Siloxane was obtained from condensation of Si–OH by self-catalysis of -SO 3 H groups. • TPS gel has high NH 3 adsorption amount of 3.0 mmol g−1 due to inherent -SO 3 H groups. • TPS membrane was simply fabricated via coating TPS solutions on intermediate layer. • TPS membrane can be used for a wide range of 50–300 °C with an excellent performance. [ABSTRACT FROM AUTHOR]

Gas transport properties of two sets of polynorbornenes bearing carbocyclic substituents of different nature (cyclohexyl, norbornyl, phenyl groups, and framed oligocyclic moieties) were systematically studied. The influence of side chain carbocyclic substituents on gas permeability and separation selectivity for CO 2 -containing gas pairs and gaseous hydrocarbons was evaluated. It was found that the presence of carbocyclic moieties in side chains of polynorbornenes promotes the increase in gas permeability similarly to that of SiMe 3 groups, with this effect being enhanced by the increase in the number of cycles in the substituents. As a result, P (CO 2) of the metathesis polymer with pentacene-based substituents is equal to 1200 Barrer. Studied polynorbornenes with carbocyclic substituents displayed promising gas separation selectivities: CO 2 /N 2 separation selectivity up to 41 (above the 2008 upper bound in the Robeson diagram) and solubility-controlled hydrocarbon separation selectivity up to 16 for the n -butane/methane gas pair. For the polymer with pentacene-based substituents, the separation of the mixture of hydrocarbons and aging were studied. The studies revealed that the mixed gas C 4 /C 1 separation selectivity of this polymer reaches 4, and a two-time reduction of permeability occurs in 8.5 months. Therefore, the incorporation of carbocyclic groups in the side chains of polynorbornenes can be considered as an efficient strategy for the design of polymeric gas separation membrane materials. [Display omitted] • Structure-property study of polynorbornenes with carbocycles in side chains. • Carbocyclic moieties improve both CO 2 permeability and CO 2 /gas selectivity. • Polymeric membranes for CO 2 /N 2 and hydrocarbons separation. • Framed carbocyclic structures are Si-free alternatives to SiMe 3 substituents. • The characteristics of AP-NBNBa for CO 2 /N 2 are above 2008 Robeson upper bound. [ABSTRACT FROM AUTHOR]

The integration of membrane separation and electrospinning technologies has significantly advanced oil-water separation processes. However, enhancing the mechanical robustness, corrosion resistance, and durability of oil-water separation membranes remains a challenge. In this paper, we utilized the electrospinning technique to fabricate a micro-nanostructured nanofibrous (NFs) membrane by blending benzophenone monomer (BPAF-an) with thermoplastic polyurethane elastomer (TPU). By optimizing the solid content, the mass ratio of compounds to polymers, and the solvent composition in the spinning precursor solution, we determined the optimal electrospinning parameters for fabricating the TPU/BPAF-an NFs membrane. The incorporation of BPAF-an, known for its low surface energy, significantly enhanced the hydrophobicity of the nanofiber membrane. The TPU/BPAF-an NFs membrane demonstrated excellent mechanical properties, exhibiting a tensile strength of 7.38 MPa and an elongation at break of 292 %. The membrane had good hydrophobicity and its water contact Angle is up to 145.2°. It also displayed exceptional separation efficiency, exceeding 99 % for oil-in-water emulsions and various oil-water mixtures. Even in harsh environments such as strong acids, alkalis and salts, they have prominent hydrophobicity, lipophilicity and chemical stability. In addition, the membrane maintained a high flux rate of 1995.37 L m−2 h−1 and a separation efficiency of 96 % even after 100 cycles of oil-water separation. Consequently, the TPU/BPAF-an NFs membrane, with its superior mechanical properties and cycle stability, holds substantial promise for application in oil-water separation. [Display omitted] • Benzoxazine/elastic polyurethane nanofibrous membrane fabricated via electrospinning. • The membranes demonstrate excellent mechanical properties. • The membrane exhibits high efficiency in the separation of oil-water and emulsions. • The membranes have good corrosion resistance and durability. [ABSTRACT FROM AUTHOR]

Traditional thin film composite polyamide nanofiltration (NF) membranes are difficult to simultaneously achieve high rejection for salts that are divalent anionic and cationic, and their separation selectivity for mono-/di-valent salt separation is usually poor. Herein, novel polyesteramide NF membranes were developed by interfacial polymerization on modified poly(vinylidene fluoride) (PVDF) substrates containing tannic acid (TA) self-assembled coating (TC@PVDF). TC@PVDF substrates were firstly fabricated via non-solvent induced phase separation technology using amphiphilic hyperbranched poly(methyl methacrylate- co -N-methylacrylamide) (HPMH) copolymers as in situ modifiers and TA aqueous solution as coagulation bath. The self-assembly behavior between TA and HPMH results in the increase of substrate surface hydrophilicity, electronegativity and pore size, which would facilitate the storage and uniform distribution of aqueous monomer piperazine on the substrate surface. For these reasons, TA coating interlayered NF (TCi-NF) membrane exhibits a thick polyesteramide layer with crisscrossing ridge surface morphology, a low molecular weight and a small pore size. The TCi-NF membrane not only demonstrates high rejection toward Na 2 SO 4 (99.3 %) and MgCl 2 (95.7 %), but also displays exceptional separation selectivity for both mono-/di-valent anions [α(Cl−/SO 4 2−) = 49] and mono-/di-valent cations [α(Na+/Mg2+) = 52]. Since the surface charge property of TCi-NF membrane is close to weak negativity, electrostatic effect between charged ions and membrane surface would be weakened, so the separation mechanism mainly depends on the size exclusion effect. Specifically, the TCi-NF membrane displays stable long-term separation performance and high salt concentration resistance. Therefore, this research provides a new preparation strategy for improving the precise desalination performance of thin film composite NF membranes. [Display omitted] • Tannic acid (TA) aqueous solution as coagulation bath adjusts structure of substrates by surface self-assembly. • TA coating interlayer (TCi) plays multiple roles in interfacial polymerization process. • Weakly negative TCi-NF membrane with low MWCO and small pore size. • Outstanding separation selectivity for both Cl−/SO 4 2− and Na+/Mg2+. • Excellent long-term stability and high salt concentration resistance. [ABSTRACT FROM AUTHOR]

The sulfur removal from crude oil is important for economic, energetic, and environmental reasons. Membranes are competitive for a variety of industrial separations and could be integrated in oil fractionation process. The key challenge lies in designing materials that are easily processable for membrane production while delivering high performance under the demanding conditions of industrial operation for the separation of intricate mixtures. We report the synthesis of polytriazole membranes with chemically stable hydrophilic and hydrophobic segments. These membranes were evaluated for the fractionation of crude oil, demonstrating the capability to separate lighter oil fractions, and remove asphaltene. Simultaneously, they exhibit an impressive capability to eliminate up to 50% of the sulfur compounds. Their superior performance has the potential to expedite the shift toward a more sustainable petrochemical industry. [Display omitted] • Copolytriazole with hydrophobic/hydrophylic units for complex separations. • Copolytriazole membranes for asphaltine separation. • Membranes able to eliminate up to 50% of the sulfur compounds. • Fractionation of crude oil. [ABSTRACT FROM AUTHOR]

The increasing release of oily wastewater from both household and industrial activities has led to a significant environmental challenge. Among the various methods for treating oil-water mixtures, membranes with specialized wettability characteristics have emerged as one of the most effective and cost-efficient approaches. In this field, reducing the thickness of membranes is a key strategy to lessen resistance to mass transfer. This paper describes the creation of a super-hydrophobic, submicron-thin (945 nm) and even transparent (79.99% relative transparency at 600 nm wavelength) composite membrane for oil/water separation. This was achieved by depositing polydivinylbenzene (PDVB) onto ∼170 nm ultrathin freestanding polyethylene (PE) membranes to form hierarchical rough textures. Based on the super-hydrophobicity and high roughness, PE/PDVB composite membrane is enabled to separate oil from water in both mixtures and emulsions of immiscible oil/water. Moreover, PE/PDVB demonstrated a separation efficiency exceeding 99.91% for various water-in-oil emulsions. Impressively, this efficiency could be sustained above 99.87% even after 30 cycles of separation involving surfactant-stabilized isooctane/water emulsions. This performance robustness persisted against various chemical environments such as acidic, alkaline, and saline conditions over prolonged periods. To our knowledge, PE/PDVB is currently the thinnest oil/water purification membrane available, combining both an active layer and support. This work also highlights the practicality of using an ultra-thin support layer for efficient oil/water separation. This work may be at use for membrane scientists who are developing ultra-thin membrane materials and processes for future applications. TOC graphic: The first submicron ultrathin oil/water purification membrane. [Display omitted] • The whole oil/water purification membrane has been thinned down less than 1 micron-thin, for the first time. • High efficiencies of separating immiscible mixtures and emulsions were both reported. • The cyclic stability, chemical resistance and mechanical integrity have been verified. [ABSTRACT FROM AUTHOR]

Membrane-based pervaporation (PV) is an energy-efficient separation technology for liquid molecular mixtures, which is an increasingly important function in chemical industries. This work accomplished the first synthesis of high-performance FAU (NaX type) zeolite membranes on α-alumina tubular supports via the secondary growth method using 50 nm nanoseeds. The effects that the synthesis parameters exerted on the crystal structures, morphologies, and PV performance of FAU membranes were systematically investigated. The nanosized seeds showed high levels of activity that promoted the rapid growth of the zeolite layer. In addition, either extending the crystallization time or raising the temperature readily caused trans -crystallization to form NaP impurity zeolites, which decreased the membrane flux and separation factor. When synthesis conditions were optimized, a high-quality and pure-phase FAU membrane was obtained and tested for the permeation of single gases and for the PV dehydration of various organic solvents (methanol, ethanol, n-propanol, iso-propanol, and tert-butanol). The relationships between the single-gas permeance, PV permeance, and polarity index were investigated using a similar size range of permeate molecules (0.289–0.5061 nm). The results show that gas permeance exhibits Knudsen selectivity. The PV permeance, however, correlated well with the polarity index of the permeate, which indicates that PV dehydration through the FAU membrane is controlled by an adsorption-diffusion mechanism. Moreover, the correlation provides a new tool for predicting PV performance. Compared with studies using FAU membranes, the as-synthesized FAU membrane features good reproducibility, excellent stability, and high PV performance, which suggests the great potential of FAU membranes for use in industrial organic solvent dehydration. Schematic illustrations of the hydrothermal synthesis of FAU membranes derived from nanoseeds for pervaporation dehydration, as well as a PV performance prediction via the polarity index. [Display omitted] • Synthesis parameters are optimized to form a high-performance FAU membrane. • Nanoseeds are highly active and promote the growth of the zeolite layer. • PV dehydration is controlled by the adsorption-diffusion mechanism. • PV performance correlated well with the polarity index of solvents. • Polarity index is used to predict PV performance. [ABSTRACT FROM AUTHOR]

Fractionation of dyes and salts is a great challenge in high salinity wastewater from the textile industry. In this work, a high performance loose nanofiltration membrane (LNM) was fabricated to fractionate the dyes and salts in the solution via green rapid coating (GRC) process on polyethersulfone (PES) substrate. The organic solvent-free GRC process was achieved within 10 min based on the crosslinking between polyethylenimine (PEI) and tannic acid (TA). The resultant LNM performance was optimized by altering the coating parameters including the TA concentration and the coating time. The microstructure, surface properties and dye/salt separation performance of the LNM were demonstrated by characterizations and filtration experiments, respectively. With the co-existence of dye and salt, the optimized LNM exhibited desirable permeability (40.6 LMH·bar−1) and dye rejection (99.8% for 0.1 g/L Congo Red) as well as low salt rejection (6.1% for NaCl and 2.2% for Na 2 SO 4). Furthermore, it was observed that even under 60 g/L of salt content, the satisfying rejection of CR (99.3% in Na 2 SO 4 and 97.6% in NaCl) and high permeation of salts (98.9% for Na 2 SO 4 and 97.9% for NaCl) can still be maintained. Moreover, the LNM showed incredible stability during the filtration process (10 h) towards dye/salt aqueous mixture. The PEI-TA/PES LNM exhibited promising application potential in dye/salt separation. Image 1 • A green rapid coating process to high performance loose nanofiltration membrane is reported. • This method based on the aqueous crosslinking between polyethylenimine and tannic acid. • The optimized membrane exhibited high permeability and rejection to dye solution. • The membrane recovered over 90% of salt while rejected 99.4% of CR in mixture feed. [ABSTRACT FROM AUTHOR]

Abstract N 2 /SF 6 mixtures have been widely used in gas-insulated equipment. Highly efficient separation approaches are urgently required to recycle SF 6 from the mixtures during equipment maintenance. Gas separation with glassy polymeric membranes is regarded as a promising approach due to the great size difference between SF 6 and N 2 molecules. However, the common membranes are quite low permeable for N 2 /SF 6 mixtures. In this research, the dry-wet phase inversion was customized with sectionalized air gap, i.e., dried air at upper section and humidified air at lower section, to manufacture Matrimid® asymmetric membranes in bulk with an ultrathin and defect-free selective layer. After optimization, the defect-free selective layer could be thinned to 80 nm. The pure gas test at 25 °C revealed that J N2 was increased to 2.58 GPU, and α N2/SF6 was approximately 41, very close to the value in the literature [J. Membr. Sci., 2014, 452, 311]. Without the restriction from the usual PDMS coating layer for defect-blocking, the elevated temperature operation was able to be employed to further enhance gas permeation. At 128 °C, the selectivity α N2/SF6 was maximized to 115, and the relevant J N2 is 9.0 GPU. At 200 °C, the temperature close to the allowable upper limit, J N2 was increased to 15.9 GPU, and the relevant α N2/SF6 was 97. Furthermore, the mixed-gas test demonstrated the favorable long-term stability of the customized membranes, even under the extreme running condition with pressure up to 2.0 MPaG and temperature up to 200 °C. With high efficiency and throughput under elevated temperature operation mode, the Matrimid® asymmetric membrane with ultrathin and defect-free selective layer is a promising approach for the separation and recycle of SF 6 from the N 2 /SF 6 mixtures. Graphical abstract fx1 Highlights • Phase inversion is retrofitted to fabricate high-flux defect-free membrane in bulk. • Defect-free dense layer is thinned to 80 nm by modified dry-wet phase inversion. • Customized membrane behaved excellent with α N2/SF6 = 115 & J N2 = 9.0 GPU at 128 °C. • Customized membrane has favorable long-term stability under 2.0 MPaG and 200 °C. • Customized membrane with high temperature mode is promising for N 2 /SF 6 separation. [ABSTRACT FROM AUTHOR]

Abstract Networked hybrid materials containing various types of organic imides covalently bonded with polyhedral oligomeric silsesquioxanes (POSS) have recently been developed. One of their possible applications is for gas-separation under extreme conditions of pressure and/or temperature. Experimental results indicate that their permeation properties depend on the specific organic dianhydride precursor used in the synthesis. In this work, atomistic models of 6FDA-based and PMDA-based poly(POSS-imide) crosslinked networks have been used to investigate the sorption, desorption, relaxation and permeation properties of such materials at the molecular level and their dependence on the nature of the imide linker. Results have been compared to available experimental data. A highly-efficient parallelised version of the excluded volume map sampling test particle insertion (EVMS-TPI) method was used to obtain the infinite dilution solubilities of a number of small penetrants (N 2 , O 2 , CH 4 and CO 2) in these model networks. Analyses of the Boltzmann-weighted probability densities for the distribution of the insertion energies showed that very reliable estimates of solubilities could be obtained. Extensive molecular dynamics simulations were then performed to obtain the complete model sorption isotherms for CO 2 and CH 4 at 35 °C up to pressures of over 60 bar using an iterative technique which matches the chemical potential of the penetrant in the poly(POSS-imide) phase to that in the corresponding gas phase. The sorption-induced changes in volume, the significant space available to penetrants, the mean insertion energies and their distributions were characterized. Comparisons were not only made between both types of poly(POSS-imide) to characterize the effect of the linker, but also with (hypothetical) uncrosslinked mixtures of the POSS and dianhydride molecules in order to elucidate the effects of crosslinking. Given the known conditioning properties of CO 2 , desorption isotherms were also obtained for this penetrant. These showed significant hysteresis. Prolonged exposure to high concentrations of CO 2 was also found to lead to slow relaxations that have significant effects on the solubility. Permeabilities were obtained for methane and carbon dioxide at 100 °C, 200 °C and 300 °C at a pressure of ~ 2 bar. Differences in permeabilities were largely diffusion dependent. Graphical abstract fx1 Highlights • MD simulations of gas sorption and permeation in poly(POSS-imide) inorganic-organic network hybrid materials. • Full sorption isotherms for CO2 and CH4 at 35 °C up to pressures of over 60 bar were obtained using an iterative technique. • Prolonged exposure to high concentrations of CO2 leads to slow relaxations that have significant effects on the solubility. [ABSTRACT FROM AUTHOR]

Abstract Hydrophobic and highly porous poly(vinylidene fluoride) (PVDF) membranes with isotropic cross section as well as tunable and narrow barrier pore size distribution in the range from ~0.1 to ~1 µm have been prepared using the non-solvent vapor induced phase separation (VIPS) technique. The process conditions have been tuned to suit an industrial scale up, using a short production time and dimethyl sulfoxide (DMSO) as solvent for PVDF, instead of commonly used hazardous chemicals. Factors like kind of solvent, the relative humidity of air, the exposure time to humid air and the mass fraction of PVDF in the casting solutions have been used to tune membrane characteristics. Interestingly, it was revealed that DMSO as a less common solvent for PVDF shows better qualities regarding upscaling than other more frequently used polar aprotic solvents (e.g. dimethylacetamide) when using VIPS under suited conditions. The phenomenon was explained through investigations of the membrane formation step, in particular by water uptake and cloud point measurements, as well as structure and performance analyses, e.g. by scanning electron microscopy, gas flow/liquid dewetting permpometry, gas and water vapor permeability analyses and liquid water entry pressure measurements. Lab-scale manufactured membranes showed pore characteristics and performance desired for membrane contactor applications. Furthermore, fabrication on a roll-to-roll machine using a nonwoven support and the established VIPS conditions was realized in a short manufacturing time; resulting membranes structure and characteristics were found to be similar to the ones for the lab-scale membranes. Overall, the combination of PVDF with DMSO gives promising opportunities for a more eco-friendly industrial fabrication of porous membranes with advanced properties via VIPS. Highlights • DMSO established as alternative solvent for fast and tunable preparation of porous PVDF membranes via VIPS. • Role of crucial VIPS parameters for tuning PVDF pore structure identified. • Scalability of membrane fabrication demonstrated by transfer from batch lab to semi-continuous pilot scale. [ABSTRACT FROM AUTHOR]

Abstract Well-intergrown hydrophilic CAU-10-H membranes were successfully prepared by microwave-assisted secondary growth. The as-synthesized CAU-10-H membranes exhibited high and reproducible performance for ethanol dehydration. For a 90 wt% ethanol feed, the CAU-10-H membrane had a total flux of 493 g m-2 h-1 and water/ethanol separation factor of 148 at 65 °C. Along with the increasing temperature or water feed concentration, the total flux increased while the water/ethanol separation factor decreased. The ideal water/ethanol selectivities of the CAU-10-H membranes were found to be significantly lower than its membrane selectivities, demonstrating that the preferential adsorption of water on hydrophilic CAU-10-H membrane to hinder ethanol transport played a prominent part in the ethanol-water separation. The CAU-10-H membranes are capable of being used in acidic conditions, and therefore showing great prospects for industrial applications. Highlights • Hydrophilic CAU-10-H is stable in water at 80 °C around 190 h. • A dense CAU-10-H membrane was synthesized by microwave-assisted secondary growth. • CAU-10-H membranes showed high pervaporation performance for ethanol dehydration. • The performance of CAU-10-H membranes remained unchanged under acidic conditions. [ABSTRACT FROM AUTHOR]

Abstract The development of organic solvent nanofiltration (OSN) membranes has been a continuous effort during the past decade. Several groups generated and published experimental results and simulations with either tailor-made membranes or industrial products. The published data space is diverse, with a single publication often focusing on a certain membrane only, a group of specific solutes only, on the effect of solvent only. A comprehensive comparison of all of these is still lacking. An analysis on the reliability of quantified transport parameters is missing, in particular when different analysis methods and different membrane systems are used. The technology is in its incubation phase with a need for reliable data and measurement standards to ground the process design on reliable membrane transport properties. This study uses an unprecedented extensive standard experimental procedure to measure separation characteristics of polymer membranes for the separation of organic solutes from organic solvents. For a variety of different solvents, solutes and membranes, flux and retention measurements are rigorously characterized by round robin tests at different labs using different analytical systems. This extensive collaborative study evaluates for the first time which fluctuations in results occur under comparable conditions of lab-scale experiments at different locations and which influence these have on the design of OSN processes. Utilizing the variance in the membrane transport data, a process design study and optimization is presented. For the first time ever, we report how variance in membrane transport properties can influence the process design ranging from a simple single stage system for values for the upper transport limits, to a two stage system with a permeate recirculation for mean values, to a complex three stage system for the lower limits. Graphical abstract fx1 Highlights • Standard experimental procedure to characterize OSN membranes. • High-quality rejection and flux data of membrane-solvent-solute systems. • Best case approximations of comparability from experimental data. • Statistical analysis and evaluation of results from five research groups. • Effect of uncertainties of flux and retention measurement on process design. [ABSTRACT FROM AUTHOR]

Abstract An oxygen transport membrane module capable of total 596 Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) membranes was constructed and tested under various capacities. The module is designed to operate with up to 20 bar feed pressure and a vacuum on the permeate side. The separation performance was tested with of up to 96 membranes tubes. A maximum oxygen purity of 98.9% was obtained and a maximum oxygen flux of 2.8 ml cm−2 min−1 was measured under a feed pressure of 10 bar. The maximum permeate oxygen flow rate achieved was 22 l min−1. The performance is lower than expected, for which an inhomogeneous module temperature and suboptimal flow distribution can be accounted for, as CFD simulations show. A lot of membrane breakages occurred during operation. Some reasons for that could be identified and the module could be optimized throughout the 2 years of testing. Within that time, three long term tests were performed and a maximum continuous operational time of 1800 h was achieved. Highlights • A pilot scale module operation for tubular, dead-end membranes in three-end operation is introduced. • Permeation rate, leakage rate and process control parameters of three long-term tests up to 1800 h are discussed. • Significant improvement regarding the reliability of the module was obtained by simple module design and process adaptions. [ABSTRACT FROM AUTHOR]

Nanofiber membrane separation technologies are promising for separation of emulsions, but it is still limited by membrane fouling. Herein, a new low-pressure driving Co 3 O 4 /polyacrylonitrile (PAN) nanofiber membrane (CPNFM) with peroxymonosulfate (PMS) activation self-cleaning ability was developed by simple electrospinning technology. The effects of Co 3 O 4 dosage on the properties and structures of resulting nanofiber membranes were investigated. The results revealed excellent superhydrophilic/underwater superoleophobic properties of the optimized CPNFM even under harsh conditions, such as acid, alkali and salt. Under sole gravity-driven, the optimized CPNFM efficiently separated multiple surfactant-stabilized emulsions with high separation efficiency (>99%) and superior flux (>300 L m−2 h−1). The optimized CPNFM also displayed a good catalytic effect toward the degradation of organic dyes through PMS activation. The effective synergy of the optimized CPNFM can also efficiently separate mixed wastewater composed of emulsion and organic dyes with high efficiency (99% for emulsion and 98% for methylene blue) and superior flux (>300 L m−2 h−1). Additionally, CPNFM displayed excellent self-cleaning ability, with restored separation performance after cycling through simple PMS activation. Overall, the high separation efficiency, good stability, and self-cleaning capability of the proposed CPNFM make it a potential candidate for long-term wastewater purification. [Display omitted] • CPNFM exhibited excellent separation performance under sole gravity-driven. • CPNFM were remarkably effective in separating mixed emulsion and MB. • CPNFM possessed outstanding superwettability even under harsh conditions. • CPNFM shows excellent anti-fouling and self-cleaning ability after PMS activation. [ABSTRACT FROM AUTHOR]

Organic solvent nanofiltration (OSN) membranes have become a powerful separation platform in a myriad of chemical and pharmaceutical fields owing to their superior merits in high separation efficiency and low energy consuming. Despite extensive progress in exploiting polyamide thin film composite (TFC) membranes for OSN, they are heavily limited by inferior solvent permeability, especially when using conventional low-porous polyimide as TFC substrate. Herein, we report a facile substrate engineering strategy to leverage macro-porous Nylon66 microfiltration membrane to replace the conventional low-porous polyimide substrates for fabricating TFC membranes by interfacial polymerization, enabling high and robust solvent permeability during OSN. Distinct from conventional polyimide, Nylon66 substrates take advantage of their high porosity, macro-porous size and excellent hydrophilicity to realize more monomers storage and uniform monomers distribution, allowing to create crumpled and defect-free polyamide layers. With this method, the polyamide TFC membranes show a 2.1-fold increase in ethanol permeance (up to 16.0 L h−1 m−2 bar−1) meanwhile possessing 98 % rejection of dye, surpassing the most reported TFC membranes. We also demonstrate that the TFC membranes exhibit excellent long-term stability in both polar and non-polar solvent, as well as hold huge promise in the precise separation of dye mixture, pharmaceutical ingredient, and catalyst. [Display omitted] • Nylon 66 substrate is first used to prepare TFC-based organic solvent nanofiltration membranes. • TFC membranes using Nylon 66 substrate feature crumpled and defect-free polyamide layer. • TFC membranes show an ultrahigh ethanol permeance of 16.0 L h−1 m−2 bar−1 and 98 % dye rejection. • TFC membranes deliver stable precise screening ability in both polar and non-polar solvent. [ABSTRACT FROM AUTHOR]

Positively charged composite membranes with polyethylene-based antimicrobial separation layers are conveniently developed herein for precise molecular sieving. Quaternization cross-linking between hyperbranched polyethylene- graft -poly(diethylaminoethyl methacrylate) and 1,2-dibromoethane constructs porous networks with abundant quaternary ammonium groups. Modified membranes exhibit different interception capabilities for anions, cations, and neutral molecules. We explain the possible sieving mechanisms with respect to size exclusion, the Donnan effect, and the intrapore energy barrier. A strongly positively charged separation layer introduces the electrostatic interaction which has different effects on cationic, anionic, and neutral molecules during filtration. Membranes prepared by the simple quaternization cross-linking strategy can efficiently separate molecular mixtures with different dimensions or charges. Moreover, the plentiful quaternary ammonium groups endow the membranes with favorable antimicrobial activity against Gram-positive E. coli and Gram-negative S. aureus. [Display omitted] • The graft copolymer HBPE- g -PDEAEMA was successfully synthesized by ATRP. • Hyperbranched polyethylene was used to moidify membranes for the first time. • Quaternization cross-linking was used to prepare molecular sieving membranes. • The membranes can precisely distinguish molecules with different charges or sizes. • The polyethylene-based separation layer showed favorable antimicrobial activity. [ABSTRACT FROM AUTHOR]

Membrane-based separation technology for carbon capture has received increasing attention in the world due to low energy consumption, investment and operating cost. However, the simultaneous improvement in selectivity and permeance has faced large challenge for mixed matrix membranes owing to limited affinity sites and transport channels. Herein, the nano-scale MIP-202 (SM-202) was first prepared by inhibited Ostwald ripening strategy during crystal growth, and then nano-scale amorphous MIP-202 (ASM-202) was prepared by thermal chemical reaction. Subsequently, mixed matrix composite membranes (MMCMs) were developed by using ASM-202 as a filler and polyether-block-amide (Pebax) as a polymer matrix, and the hydrophilicity-modified polysulfone ultrafiltration membrane (mPSf) was utilized as a porous support. It is observed that ASM-202 possessed good miscibility with Pebax polymer chains as a result of hydrogen bonds between two phases. Thus, the as-obtained MMCMs showed outstanding CO 2 separation performance (CO 2 permeance: 936 GPU; CO 2 /N 2 selectivity: 52), which were enhanced by 138 % and 108 % over that of the pristine Pebax membrane, as well as 15.3 % and 13.0 % over that of MMCMs incorporating with SM-202, respectively. The improvement in gas separation performance can be explained by the reason that the nano-scale ASM-202 with large specific surface area afforded more unsaturated metal sites and nitrogen-doped structure, thus improving the CO 2 affinity in membranes. Moreover, the loose amorphous structure of ASM-202 provides more transport passageways, which enhanced the diffusion rate of gas molecules through the membranes. Besides, resultant MMCMs maintained great stability for over 360 h using the CO 2 /N 2 mixed gas as feed gas, whose average CO 2 permeance and CO 2 /N 2 selectivity fluctuated at 880 GPU and 47. [Display omitted] • Nano-amorphous MIP-202 was prepared by combining inhibited Ostwald ripening strategy with thermal chemical reaction. • The nano-amorphous MIP-202 enhanced CO 2 permeance and CO 2 /N 2 selectivity of MMCMs concurrently. • The nano-scale amorphous MIP-202 had good compatibility with Pebax matrix. • MMCMs revealed a CO 2 permeance of 936 GPU with a CO 2 /N 2 selectivity of 52 which was superior to that loaded with MIP-202. [ABSTRACT FROM AUTHOR]

Poly(oxymethylene) dimethyl ethers of chain lengths n = 3 to 5 (OME 3 − 5) are clean-burning synthetic diesel fuels capable of utilizing biomass and captured carbon dioxide as raw materials. In water-tolerant OME 3 − 5 production processes, separating water from mixtures containing methanol, formaldehyde, water, and short-chain OME 1 − 2 is a critical and challenging task. This work focuses on the screening of membranes for water separation from such mixtures, particularly emphasizing their selectivity towards water and stability. Among the materials investigated, a ceramic SiO 2 membrane was identified as promising. Fourteen pervaporation experiments were conducted on a continuous setup at a mini-plant scale. No deterioration in flux or permeate quality was observed across the repeated experiments. The membrane exhibited significant separation factors for all components, demonstrating its selectivity for water. However, the selectivity towards water decreased for the mini-plant experiments compared to the screening experiments. A model describing the water flux as a function of the water concentration in the feed was developed, demonstrating accurate characterization of the operation dynamics. These outcomes establish the fundamental feasibility of water separation via pervaporation using SiO 2 membranes in water-tolerant OME 3 − 5 production processes. [Display omitted] • Membrane screening for drying systems containing poly(oxymethylene) dimethyl ethers. • Mini-plant scale pervaporation experiments on a SiO 2 membrane. • Development of a model to describe the water flux. • Assessment of the SiO 2 membrane stability and water selectivity. [ABSTRACT FROM AUTHOR]

The organic solvent reverse osmosis (OSRO) separation of alcohol-hydrocarbon mixtures with Matrimid membranes is studied via experiment as well as modelling with dry glass reference perturbation theory (DGRPT). It is shown that the separation of these mixtures is highly non-ideal, with strong maxima of the separation factors as a function of feed composition. The DGRPT model was fit to pure vapor sorption data, while the Fickian diffusivities were fit from pure liquid permeation data. From this pure component parameterization, the model successfully predicted the highly non-ideal separation behavior observed for mixtures of alcohols and hydrocarbons. Successful application of the model was crucial in the interpretation of the experimental data, conclusively showing that the non-ideal behavior observed in the separations was a result of thermodynamic phenomena. Observed OSRO separation of ethanol/hydrocarbon mixtures is predictable based on bulk liquid thermodynamics, pure solvent sorption, and pure solvent permeation experiments. [Display omitted] • OSRO separations of alcohol/hydrocarbon mixtures using Matrimid membranes are studied via experiment and theory. • Alcohol/hydrocarbon binaries are studied over the full composition range at trans -membrane pressures of 20 and 40 bar. • The non-ideal phase behavior observed in bulk systems translates to the OSRO separation. • Fickian diffusion employing DGRPT to evaluate membrane solubilities accurately predicts this non-ideal behavior. • It is demonstrated that the non-ideality in the OSRO separation is a result of thermodynamic considerations. [ABSTRACT FROM AUTHOR]

Organic solvent nanofiltration (OSN) is a new type of organic fluid separation technology that can greatly reduce energy consumption compared with traditional distillation techniques. However, the development and application of OSN are restricted by the high manufacturing cost of solvent resistant membranes, including expensive materials and complex post-treatment process. In this paper, a low-cost polyaryletherketone bearing amino group synthesized from industrial raw material phenolphthalein was proposed, and then the crosslinked polyaryletherketone membrane with remarkable stability in polar aprotic solvent was prepared by green, mild and simple crosslinking method. The separation accuracy of the membrane can be easily adjusted from ultrafiltration to nanofiltration by altering the composition of the cast solution. In addition, the prepared membrane can be operated in DMF for 120 h, which indicated the excellent stability of the membrane, even for hash polar aprotic solvents. Therefore, this work demonstrates a novel low-cost solvent resistant membrane material that is promising for OSN applications. Schematic diagram of the preparation process of crosslinked PEK-NH 2 membranes. [Display omitted] • A novel low-cost polymer membrane material with good comprehensive performance. • Crosslinking occurs in aqueous solutions, which is a green, mild, and simple process. • The separation accuracy of the membrane can be easily adjusted from ultrafiltration to nanofiltration. • The crosslinked membranes exhibited excellent stability in common organic solvents including DMF. [ABSTRACT FROM AUTHOR]

Carbon molecular sieve membranes (CMSMs) have exhibited significant potential in gas separation applications, particularly in the realm of hydrogen and carbon dioxide separation. Poly(furfuryl alcohol) (PFA) represents a cost-efficient and sustainable precursor utilized in the synthesis of CMSMs. Nonetheless, PFA-based CMSMs have exhibited suboptimal performance and frequently necessitate supplementary supporting layers. In the present investigation, we have explored various acids as catalysts for the in-situ self-polymerization of PFA. Our findings reveal that PFA membrane catalyzed by sulfuric acid exhibits the most favorable performance, yielding a hydrogen permeability of 1394.4 Barrer and a H 2 /CH 4 selectivity of 404.1. These values exceed the Robeson upper limits established in 2019. The enhanced gas separation performance of the sulfuric acid catalyzed PFA-based CMSM could be attributed to the increased furan ring opening and higher polymerization degree achieved through this catalytic process. Furthermore, our investigation delved into the addition of poly(styrene-co-acrylonitrile) (SAN) into the PFA membrane, yielding a CMSM featuring both dense and porous layers. With the addition of 6 wt% SAN in PFA membrane, the resulting CMSM exhibited a hydrogen permeability of 3126.4 Barrer, underscoring the potential for high-performance CMSMs made from the economical PFA precursor. The optimization of the PFA polymerization process and the incorporation of SAN, hold the promise of further elevating the performance of PFA-based CMSMs, and these advancements will substantially contribute to the advancement of sustainable and efficient gas separation technologies. [Display omitted] • Self-supported CMSMs are made from a bio-derived low-cost precursor, poly(furfuryl alcohol). • The furan ring opening in PFA affects the structures and gas separation performances of the resulting CMSMs. • The addition of SAN leads to phase separation and improves the gas permeability of CMSM. [ABSTRACT FROM AUTHOR]

Grafting of oligomers into the mesopores of ceramic membranes (e.g. γ-alumina) represents an attractive strategy for deploying durable, resistant, and efficient hybrid membranes for the industrial treatment of wastewater containing organic solvents and divers solutes. In general, to control the membrane/solute/solvent interactions, homogeneous surface modification and high grafting yields are required. However, reaching this goal is rather challenging with the current grafting approaches where the active diffusion of the oligomers to the membrane pore surface may be hampered. To mitigate such diffusion limitation, we present here a novel synthesis method consisting of an infiltration of concentrated PEG organophosphonic acid oligomer solution in ceramic ultrafiltration membranes before initiating the solid-state grafting reaction to form a PEG-brush-grafted nanofiltration ceramic membrane. The infiltration step was found to be decisive for the formation of weak bonds between the oligomer linking functions and the ceramic membrane ensuring the final synthesis of robust PEG-based membranes by a grafting reaction. The influence of the solvent polarity (water vs. cyclohexane) on the conformation of the grafted PEG brush inside the γ-alumina mesopores was observed as a key parameter in the analysis of the pore size and permeability results. In addition to this, it was studied here for the first time by molecular dynamic simulations. The as-prepared PEG-brush/ceramic membranes were found very efficient in the separation of small organic dyes such as Rhodamine B (479 g mol−1) up to 85%. As a result, the present synthesis method represents a sustainable and simple alternative way for the preparation of hybrid nanofiltration membranes with controlled surface properties and attractive separation performance. Moreover, the vacuum impregnation and solid-state grafting approach requires a minimal amount of functional oligomers and solvent (0.5 mmol for 2–3 mL of solvent) and can be applied to other porous materials used in separation technologies. [Display omitted] • Nanofiltration ceramic membranes made through impregnation of organo-phosphonic acidsfollowed by solid-state reaction. • A preferential binding configuration of the linking functions is induced prior to the grafting reaction. • Diffusion limitation of polymer brushes in ceramic membranes is overcome with the controlled impregnation-grafting method. • Mechanical and thermal stable PEG-brushes grafted ceramic membranes were obtained with MWCO of around 600 Da. • The end-group of the PEG polymer brush can influence solute rejection. [ABSTRACT FROM AUTHOR]

Membrane-based separation technology offers notable advantages in terms of its compact size and energy efficiency. However, single-stage membrane processes encounter limitations in achieving high levels of purity for target gases, particularly when dealing with low feed concentrations, due to the constrained separation performance of polymeric membranes. Herein, we report on the optimization of dual-stage membrane processes for diverse gas separation applications, including CO 2 /N 2 , CO 2 /CH 4 , H 2 /N 2 , and H 2 /CH 4 separation. The optimization process involves the utilization of various membrane combinations, which are carefully selected using a user-friendly apparent selectivity model. In particular, our evaluation includes an assessment of the separation performance of the proposed membrane combinations for different molar fractions in the feed while maintaining a fixed target purity. Additionally, we determine their practical feasibility by estimating other process parameters such as the required membrane area, energy demand, and material cost. Through process analysis, it is observed that a combination of more selective membranes in the first stage and more permeable membranes in the second stage can yield economic benefits for various gas separation applications. The present study provides a practical approach to enhancing the process efficiency of a dual-stage membrane process for various gas separation applications. [Display omitted] • A practical membrane combination is proposed to enhance dual-stage process efficiency. • The dual-stage membrane process is optimized for diverse industrial gas separations. • The use of dual-stage highly selective and permeable membranes yields economic benefits. [ABSTRACT FROM AUTHOR]

Abstract TiO 2 nanowires (NWs) membranes with varied wettability ranging from superhydrophilic to superhydrophobic have been facile fabricated via dip-coating for oil/water separation. Incorporating TiO 2 NWs results in the increase of roughness and the formed hierarchical structure from TiO 2 NWs micro-aggregations enlarges the wettability. Separation efficiency and permission flux of the as-prepared membranes increase first and decrease with the increment of TiO 2 NWs. These superhydrophilic/hydrophilic membranes eliminate water from oil/water mixtures and the separation efficiency declines with the increasing water contact angle until the membrane lose the oil/water separation property at around 90°. Membranes with water contact angle of 90–100° cannot separate oil/water mixtures while membranes with water contact angle larger than 120° become oil-remove type with separation efficiency around ~ 99% and high permission flux. The study illustrates that relatively large pore size (~ 15 µm) attributes to the high separation efficiency and permission flux. The synergetic effects of wettability and pore size indicate that surface wettability is critical for efficient oil/water separation. Both hydrophilic and superhydrophilic membranes show high separation efficiency and outstanding anti-fouling performances after long term oil/water separation. Graphical abstract fx1 Highlights • Membrane with varying wettability has been fabricated via coating small amount of TiO 2 nanowires; • Micro/nano hierarchical structure is formed via coating TiO 2 nanowires; • Synergetic effects of wettability and pore size on oil/water separation has been investigated; • As-prepared membrane shows outstanding anti-fouling performance after long term operation. [ABSTRACT FROM AUTHOR]

Abstract Hollow fillers with tailored nanostructures and functionalities have become promising candidates for advanced mixed matrix membranes (MMMs). Herein, polydopamine/poly (ethylene glycol) (PEG) composite microcapsules are synthesized by hard template method and embedded into the Pebax matrix to fabricate MMMs for CO 2 capture. As a well-known biomimetic adhesive, polydopamine in the capsule wall renders adequate polymer-filler interfacial adhesion. The template removal process produces through-wall mesopores, which allow rapid gas diffusion into the lumen, further significantly reducing the trans-membrane mass transfer resistance. The remaining PEG in the capsule wall not only increases CO 2 affinity, but also avoids excessive chain rigidification at polymer-filler interface. In this way, the composite capsules, compared with those without PEG, confer significantly enhanced separation performance on membranes. The optimal gas transport property of the resultant membranes is obtained with a CO 2 permeability of 510 Barrer and an ideal selectivity of 84.6 for CO 2 /N 2 at humidified state, i.e., 108%, 98% higher than those of neat Pebax membrane, respectively. In addition, owing to dopamine-enabled strong adhesion, the MMMs exhibit better stability than Pebax membrane in the long-term test at 85 °C. Graphical abstract fx1 Highlights • Hollow polydopamine/PEG composite nanoparticles (HDGs) are prepared as MMMs fillers. • Both CO 2 permeability and selectivity of the MMMs are doubled compared to Pebax. • The roles of the lumen and PEG moieties in gas transport are separately discussed. • Membrane stability at 85 °C is improved due to the strong adhesion of Pebax to HDGs. [ABSTRACT FROM AUTHOR]