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Achieving precise selective separation of monovalent and divalent cations, as well as anions, is vital yet challenging in practical applications involving complex component treatments. Current membranes are typically effective for separating either cation pairs or anion pairs. To address this issue, a straightforward strategy for fabricating a nanofiltration (NF) membrane is developed that selectively permeates monovalent ions. This study focused on neutralizing the surface charge and tuning the pore size distribution of the polyamide membranes through a secondary interfacial polymerization using a zwitterionic copolymer consisting of 2‐methacryloyloxyethyl phosphorylcholine and 2‐aminoethyl methacrylate hydrochloride. The optimized NF membrane prepared in this study, with a near‐neutrally charged membrane surface and appropriate pore size distribution, demonstrates favorable performance in precisely separating monovalent and divalent ions, irrespective of the ion charge sign. The optimum NF membrane features high selectivity for both Cl−/SO42− (93) and Li+/Mg2+ (67) ion pairs, along with high water permeance of 8.5 L m−2 h−1 bar−1, making it competitive with many reported membranes. This study offers new insights into the ion‐selective mechanisms of polyamide membranes for monovalent/divalent ions and may guide the development of advanced membranes with single‐solute selectivity. [ABSTRACT FROM AUTHOR]

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AbstractNanodiamonds are unique spherical carbon nano-entities having the advantages of very high surface area and high optical, thermal, wear and strength characteristics. Like other carbonaceous nanoparticles (like fullerene, graphene or carbon nanotube), nanodiamond nano-reinforcements have been investigated for the significant types of polymeric matrices (such as thermosets, thermoplastics, rubbers) nanocomposites. Consequently, this overview was planned to systematically describe the current scientific status of the nanodiamonds reinforced thermoplastic nanomaterials. In this regard, polyamide/nanodiamonds, polyimide/nanodiamonds and polystyrene/nanodiamonds nanocomposites have been fabricated using the facile solution, in-situ and melt mixing techniques. We suggest that including nanodiamonds in polyamides and polyimides increased their engineering characteristics, like mechanical properties and thermal stability, of the resulting nanocomposites due to a distinct interface formation and their compatibilization effects toward these matrices. Correspondingly, including nanodiamonds in polystyrene has been observed to increase the intrinsically low strength/toughness features of this polymer. Predominantly, nano-reinforcement and miscibility effects of the nanodiamonds with the polystyrene and their mutual matrix-nanofiller synergies were responsible to improve the overall microstructural and physical properties of the resulting nanocomposites. As per our analysis, the research reports so far on the important categories of the nanodiamonds reinforced thermoplastic matrix nanocomposites have shown important technical applications in the fields of high-tech coatings, membranes and energy devices. [ABSTRACT FROM AUTHOR]

Polyethylene‐supported nanofiltration (NF) membranes have been reported for several cases in recent years. However, few have disclosed a NF membrane which achieves a high salt/water separation efficiency. Here, a novel polyamide NF membrane was prepared by conducting interfacial polymerization on poly(vinyl alcohol)‐decorated polyethylene separator. The polyethylene‐supported NF membranes were systematically investigated with respect to chemical structures, microscopic morphology, surface properties, as well as desalination performance. In particular, a distinctive morphology transformation occurred on the polyamide layers through regulating poly(vinyl alcohol) loading amounts. Performance testings demonstrated the optimal membrane reaches a water permeance over 17.4 L·m−2·h−1·bar−1 and Na2SO4 rejection above 98.7%, as well as favorable performance stability. This work may provide some consideration for fabricating NF membranes with new support layers and good desalination performance. [ABSTRACT FROM AUTHOR]

Membrane materials that resist nonspecific or specific adsorption are urgently required in widespread practical applications, such as water purification, food processing, and life sciences. In water purification, inevitable membrane fouling not only limits membrane separation performance, leading to a decline in both permeance and selectivity, but also remarkably increases operation requirements, and augments extra maintenance costs and higher energy consumption. In this work, we report a freestanding interfacial polymerization (IP) fabrication strategy for in situ creation of asymmetric block copolymer (BCP) nanofilms with antifouling properties, greatly outperforming the conventional surface post‐modification approaches. The resultant free‐standing asymmetric BCP nanofilms with highly‐dense, highly‐hydrophilic polyethylene glycol (PEG) brushes on one side, can be readily formed via a typical IP process of a well‐defined double‐hydrophilic BCP composed of a highly‐efficient antifouling PEG block and a membrane‐forming multiamine block. The asymmetric BCP nanofilms have been applied for efficient and sustainable natural water purification, demonstrating extraordinary antifouling capabilities accompanied with superior separation performance far beyond commercial polyamide nanofiltration membranes. The antifouling behaviors of asymmetric BCP nanofilms derived from the combined effect of the hydration layer, electrostatic repulsion and steric hindrance were further elucidated by water flux and fouling resistance in combination with all‐atom molecular dynamics (MD) simulation. This work opens up a new avenue for the large‐scale and low‐cost creation of broad‐spectrum, asymmetric membrane materials with diverse functional "defect‐free" surfaces in real‐world applications. [ABSTRACT FROM AUTHOR]

Four non-fluorinated sulfonimide polyamides (s-PAs) were successfully synthesized and a series of membranes were prepared by blending s-PA with polyvinylidene fluoride (PVDF) to achieve high-methanol-permeation resistivity for direct methanol fuel cell (DMFC) applications. Four membranes were fabricated by blending 50 wt% PVDF with s-PA, named BPD-101, BPD-102, BPD-111 and BPD-211, respectively. The s-PA/PVDF membranes exhibit high methanol resistivity, especially for the BPD-111 membrane with methanol resistivity of 8.13 × 10−7 cm2/s, which is one order of magnitude smaller than that of the Nafion 117 membrane. The tensile strength of the BPD-111 membrane is 15 MPa, comparable to that of the Nafion 117 membrane. Moreover, the four membranes also show good thermal stability up to 230 °C. The BPD-x membrane exhibits good oxidative stability, and the measured residual weights of the BPD-111 membrane are 97% and 93% after treating in Fenton's reagent (80 °C) for 1 h and 24 h, respectively. By considering the mechanical, thermal and dimensional properties, the polyamide proton-exchange membrane exhibits promising application potential for direct methanol fuel cells. [ABSTRACT FROM AUTHOR]

BACKGROUND: Nowadays, research focusing on natural compounds is getting more importance across the globe. Recently, natural bioactive compounds have gained the attention of researchers as a consequence of their exemplary physicochemical properties and exceptional utility in the food and pharma industries. However, separating and concentrating these bioactive compounds from their origin sources still poses a considerable challenge to their profitable commercial usage. The current study focuses on the application of a facile nanofiltration method for recovering betanin from model beetroot extract solutions using a polyamide nanofiltration membrane. Furthermore, the three‐parameter Spiegler–Kedem model was used to determine the transport parameters of the membrane and theoretically predict the performance of the membrane. Additionally, variance‐based sensitivity analysis methods were deployed to study the sensitivity of different operating and membrane transport parameters. RESULT: The results indicate that the membrane exhibited the highest rejection of 99% and permeate flux of 3.14 ⨯ 10−5 m3 m−2 s−1 at 0.6 MPa pressure and 600 mL min−1 flow rate. The data obtained through the Spiegler–Kedem model were coherent with the experimental observations. Simulations on sensitivity analysis revealed that specific hydraulic permeability and cross‐membrane pressure majorly influence permeate flux and rejection. CONCLUSION: This study showed that nanofiltration with 150 Da cut‐off membranes effectively concentrated betanin with 99% rejection. Higher cross‐membrane pressure and higher feed flow rates were preferable operating conditions for higher rejections. Variance‐based sensitivity analysis showed that cross‐membrane pressure and hydraulic permeability are the most influential parameters affecting permeate flux and rejection. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Membranes facilitate scalable and continuous lithium concentration from hypersaline salt lakes and battery leachates. Conventional nanofiltration (NF) membranes, however, exhibit poor monovalent selectivity in high‐salinity environments due to weakened exclusion mechanisms. This study examines polyamide NF membranes coated with polyelectrolytes enriched with ammonium groups to maintain high monovalent cation selectivity in hypersaline conditions. Over 8000 ion rejection measurements are recorded using salt lake brines and battery leachates. The experiments exemplify the coated membrane's ability to reduce magnesium concentrations to 0.14% from salt lakes and elevate lithium purity to 98% from battery leachates, in a single filtration stage. The membrane's selectivity is retained after 12 weeks in acidic conditions. Molecular dynamics analyses reveal that the ammonium groups create an electrostatic barrier at low pH, selectively hindering multivalent cation transport. This is corroborated by the Coulombic attraction between cations and carboxylate groups, along with a repulsive barrier from ammonium groups. Despite a 14.7% increase in specific energy, a two‐stage NF system using the coated membranes for lithium recovery significantly reduces permeate magnesium composition to 0.031% from Chilean salt lake brines. For NMC leachates, the coated membranes achieve permeate lithium purity exceeding 99.5%, yielding enhanced permeate quality with minor increases in energy demands. [ABSTRACT FROM AUTHOR]

This study aimed to improve the anti‐fouling properties of a thin‐film composite polyamide membrane by modifying it with chitosan and acrylic acid using UV‐induced and Redox‐initiated graft polymerization methods. The modified membrane's separation performance was evaluated by measuring the flux and retention of sodium ions in water during filtration. The anti‐fouling capacities of the modified membranes were determined by measuring the maintained flux ratios and irreversible fouling factors during the 8‐h filtration of aqueous solutions of sodium chloride at different concentrations (1000 and 10,000 ppm). In addition, by evaluating the membrane's surface properties using various methods, including field emission scanning electron microscopy, attenuated total reflection – Fourier transform infrared spectroscopy, and water contact angle measurements, we have demonstrated the validity of the experimental results. Our results showed that the grafted membranes under UV irradiation or redox initiators had enhanced anti‐fouling properties while maintaining salt retention. The modified membranes fabricated by UV‐induced or Redox‐initiated technique had superior anti‐fouling capabilities, with irreversible fouling factors and maintained flux ratios of around 8% and 43%, respectively, after 8 h of filtration, compared to only 12% and 36% for the unmodified membrane. These findings suggest that the modified membranes have the potential for use in filtration systems to prevent the fouling phenomenon. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The scarcity of freshwater resources, driven by rapid population growth and industrialization, underscores the urgent need for advanced desalination technologies. This research aims to meet this critical demand by enhancing the performance of polyamide membranes through innovative chemical tuning of the active layer. By strategically using Boc-protected ethylenediamine (EDA), we can precisely control the membrane's surface properties. One amino group in EDA is protected with a Boc group, allowing the other to participate in the interfacial polymerization (IP) reaction with meta-phenylenediamine (MPD) and trimesoyl chloride (TMC). This inclusion of Boc-protected EDA enables in situ tuning of the active layer chemistry during polymerization. Subsequent removal of the Boc protection generates hydrophilic ammonium groups on the membrane surface, enhancing its desalination capabilities. As a result, three distinct membranes were fabricated and thoroughly characterized: MPD-TMC (control), MPD-TMC-EDA-Boc, and MPD-TMC-EDA-Deboc. At 20 bar and 2000 ppm NaCl feed, the MPD-TMC-EDA-Deboc membrane demonstrated superior desalination performance with a salt rejection of 98 ± 0.5% and a permeate flux of 25 L m−2 h−1; an increase of 25% compared to the control membrane. For the seawater nanofiltration (NF) permeate with a TDS of 33,700 ppm, a salt rejection of 97% and a permeate flux of 23 L m−2 h−1 was recorded at 20 bar. The MPD-TMC-EDA-Deboc membrane showed enhanced antifouling performance (95 ± 1% flux recovery) compared to the control MPD-TMC membrane with 93 ± 1% flux recovery. The Boc-protection/deprotection strategy demonstrated the high potential of this approach to significantly enhance the performance of polyamide membranes for desalination applications. [ABSTRACT FROM AUTHOR]

Membranes are important in the pharmaceutical industry for the separation of antibiotics and salts. However, its widespread adoption has been hindered by limited control of the membrane microstructure (pore architecture and free‐volume elements), separation threshold, scalability, and operational stability. In this study, 4,4′,4′′,4′′′‐methanetetrayltetrakis(benzene‐1,2‐diamine) (MTLB) as prepared as a molecular building block for fabricating thin‐film composite membranes (TFCMs) via interfacial polymerization. The relatively large molecular size and rigid molecular structure of MTLB, along with its non‐coplanar and distorted conformation, produced thin and defect‐free selective layers (~27 nm) with ideal microporosities for antibiotic desalination. These structural advantages yielded an unprecedented high performance with a water permeance of 45.2 L m−2 h−1 bar−1 and efficient antibiotic desalination (NaCl/adriamycin selectivity of 422). We demonstrated the feasibility of the industrial scaling of the membrane into a spiral‐wound module (with an effective area of 2.0 m2). This module exhibited long‐term stability and performance that surpassed those of state‐of‐the‐art membranes used for antibiotic desalination. This study provides a scientific reference for the development of high‐performance TFCMs for water purification and desalination in the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • TFC NF membranes were fabricated by coating a loose network-like interlayer. • TA/PSS interlayer riches in –SO 3 H and –OH to form 36.3–63.9 nm PA layer. • TFC-2 presents 22.7 L m−2 h−1 bar−1 pure water flux and 97.1 % rejection Na 2 SO 4. The traditional polyamide composite nanofiltration membranes have high selectivity and low water permeance, so it is necessary to find strategies to raise the permeance. Herein, a novel polyamide nanofiltration membranes with high permeance were fabricated by coating a loose hydrophilic network-like interlayer, where tannic acid (TA) with pentapophenol arm structure binds to poly(4-styrenesulfonate) (PSS) polymer through hydrogen and ionic interactions. The effects of the network-like TA/PSS interlayer on surface morphology, surface hydrophobicity, and the interfacial polymerization mechanism were investigated. The outcomes demonstrated that the TA/PSS interlayer can offer a favorable environment for interfacial polymerization, enhance the hydrophilicity of the substrate membrane, and delay the release of piperazine (PIP). The optimized TFC-2 presents pure water flux of 22.7 ± 2.8 L m−2 h−1 bar−1, Na 2 SO 4 rejection of 97.1 ± 0.5 %, and PA layer thickness of about 38.9 ± 2.5 nm. This provides new strategies for seeking to prepare simple interlayers to obtain high-performance nanofiltration membranes. [ABSTRACT FROM AUTHOR]

Membrane-based separation is one of the most energy-efficient methods to meet the growing need for a significant amount of fresh water. It is also well-known for its applications in water treatment, desalination, solvent recycling, and environmental remediation. Most typical membranes used for separation-based applications are thin-film composite membranes created using polymers, featuring a top selective layer generated by employing the interfacial polymerization technique at an aqueous–organic interface. In the last decade, various manufacturing techniques have been developed in order to create high-specification membranes. Among them, the creation of ultrathin polyamide membranes has shown enormous potential for achieving a significant increase in the water permeation rate, translating into major energy savings in various applications. However, this great potential of ultrathin membranes is greatly hindered by undesired transport phenomena such as the geometry-induced "funnel effect" arising from the substrate membrane, severely limiting the actual permeation rate. As a result, the separation capability of ultrathin membranes is still not fully unleashed or understood, and a critical assessment of their limitations and potential solutions for future studies is still lacking. Here, we provide a summary of the latest developments in the design of ultrathin polyamide membranes, which have been achieved by controlling the interfacial polymerization process and utilizing a number of novel manufacturing processes for ionic and molecular separations. Next, an overview of the in-depth assessment of their limitations resulting from the substrate membrane, along with potential solutions and future perspectives will be covered in this review. [ABSTRACT FROM AUTHOR]

The separation of chiral drugs continues to pose a significant challenge. However, in recent years, the emergence of membrane‐based chiral separation has shown promising effectiveness due to its environmentally friendly, energy‐efficient, and cost‐effective characteristics. In this study, we prepared chiral composite membrane via interfacial polymerization (IP), utilizing β‐cyclodextrin (β‐CD) and piperazine (PIP) as mixed monomers in the aqueous phase. The chiral separation process was facilitated by β‐CD, serving as a chiral selective agent. The resulting membrane were characterized using SEM, FT‐IR, and XPS. Subsequently, the chiral separation performance of the membrane for DL‐tryptophan (Trp) was investigated. Lastly, the water flux, dye rejection, and stability of the membrane were also examined. The results showed that the optimized chiral PIP0.5β‐CD0.5 membrane achieved an enantiomeric excess percentage (ee%) of 43.0% for D‐Trp, with a solute flux of 66.18 nmol·cm−2·h−1, and maintained a good chiral separation stability. Additionally, the membrane demonstrated positive performance in the selective separation of mixed dyes, allowing for steady operation over a long period of time. This study offers fresh insights into membrane‐based chiral separations. [ABSTRACT FROM AUTHOR]

Thin-film composite reverse osmosis membranes have remained the gold standard technology for desalination and water purification for nearly half a century. Polyamide films offer excellent water permeability and salt rejection but also suffer from poor chlorine resistance, high fouling propensity, and low boron rejection. We addressed these issues by molecularly designing a polyester thin-film composite reverse osmosis membrane using co-solvent-assisted interfacial polymerization to react 3,5-dihydroxy-4-methylbenzoic acid with trimesoyl chloride. This polyester membrane exhibits substantial water permeability, high rejection for sodium chloride and boron, and complete resistance toward chlorine. The ultrasmooth, low-energy surface of the membrane also prevents fouling and mineral scaling compared with polyamide membranes. These membranes could increasingly challenge polyamide membranes by further optimizing water-salt selectivity, offering a path to considerably reducing pretreatment steps in desalination. [ABSTRACT FROM AUTHOR]

This paper presents the study results of formation features of composite hydrogel/polyamide membranes obtained by modification of hydrogel films based on 2-hydroxyethylmethacrylate (HEMA) and polyvinylpyrrolidone (PVP) copolymers. The formation process of composite two-layer membranes was carried out in two stages: obtaining hydrogel membrane substrates followed by their modification with an ultra-thin layer based on a mixture of polyamide (PA) with PVP. The main task of the work was to investigate the possibility of forming a modifying PA/PVP coating on the surface of hydrogel films and to obtain composite hydrogel membranes with the required strength and osmotic permeability based on them. For the formation of composite two-layer membranes, PVP with MM = 12 × 103 g/mol and MM = 360 × 103 g/mol were used. Additional use of PVP in the modifying solution contributes to the process of its penetration into the hydrogel substrate. Together with the formation of a reinforcing layer, this ensures the obtainment of hydrogel films of increased strength, with the possibility of directional regulation of their diffusion permeability. It was found that the main factors affecting the nature of the interaction between the layers of the obtained composite films, as well as their physico-mechanical and sorption–diffusion properties, are the HEMA:PVP ratio in the original polymer–monomer composition (PMC), the formulation of the reinforcing layer, the duration of the modification process and the molecular weight of PVP in PMC and in the modifying solution. The strength and water content of two-layer composite hydrogel/polyamide membranes, as well as their salt and water permeability coefficients, are the highest in the case of using high-molecular weight PVP (MMPVP = 360 × 103 g/mol) and low-molecular weight (MMPVP = 12 × 103 g/mol) during the synthesis of the hydrogel substrate to obtain a PA-6/PVP solution for forming a reinforcing layer. [ABSTRACT FROM AUTHOR]

An imidazolium‐type room‐temperature ionic liquid containing silsesquioxane frameworks is successfully prepared. The polar ionic liquid products are grafted onto the surface of prepared aromatic polyamide (PA) membranes to improve water flux of PA membranes. Membranes grafted with an ionic liquid exhibit a water flux of 1.89 L m−2 h−1 bar−1), 48% higher than that of pure PA membranes while the salt rejection still remains at 96%. This improvement can be attributed to the enhanced hydrophilicity of the membrane surface, as evidenced by the reduced water contact angle. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Tiangong University is the property of Journal of Tianjin Polytechnic University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Considering growing efforts to understand and improve the solute-specific selectivity of nanofiltration (NF) membranes, we explored the ion-specific effects that govern the charge and performance of a loose polyamide NF membrane that is commonly used for solute-solute separations. Specifically, we systematically evaluated the zeta potential of the membrane under different conditions of pH, salinity, and ionic composition, and correlated the obtained data with membrane performance tested under similar conditions. Our results identify the pKa of both carboxylic and amine groups bonded to the membrane surface and suggest that the highly polarizable chloride anions in the solution adsorb to the polyamide, increasing its negative charge. We also show that monovalent cations of different "stickiness" can neutralize the negative membrane charge to different extents due to their varying tendency to sorb to the polymer matrix or screen the fixed carboxyl groups on the membrane surface. Notably, our correlation between zeta potential measurements and permeability experiments indicates the substantial contribution of solution ions to Donnan exclusion in NF membranes. [ABSTRACT FROM AUTHOR]

Fine design of surface charge properties of polyamide membranes is crucial for selective ionic and molecular sieving. Traditional membranes face limitations due to their inherent negative charge and limited charge modification range. Herein, we report a facile ionic liquid-decoupled bulk/interfacial diffusion strategy to elaborate the double charge flips of polyamide membranes, enabling on-demand transformation from inherently negative to highly positive and near-neutral charges. The key to these flips lies in the meticulous utilization of ionic liquid that decouples intertwined bulk/interfacial diffusion, enhancing interfacial while inhibiting bulk diffusion. These charge-tunable polyamide membranes can be customized for impressive separation performance, for example, profound Cl−/SO42− selectivity above 470 in sulfate recovery, ultrahigh Li+/Mg2+ selectivity up to 68 in lithium extraction, and effective divalent ion removal in pharmaceutical purification, surpassing many reported polyamide nanofiltration membranes. This advancement adds a new dimension to in the design of advanced polymer membranes via interfacial polymerization. Currently polyamide membranes fabricated by interfacial polymerization are limited by inherently negative charge as well as narrow charge tailoring window restricting the application of these membranes. Here, the authors report a facile ionic liquid-decoupled bulk/interfacial diffusion strategy to fabricate polyamide membranes which can transform on-demand from inherently negative to highly positive and near-neutral charge. [ABSTRACT FROM AUTHOR]

It is particularly essential to analyze the complex crosslinked networks within polyamide membranes and their correlation with separation efficiency for the insightful tailoring of desalination membranes. However, using the degree of network crosslinking as a descriptor yields abnormal analytical outcomes and limited correlation with desalination performance due to imperfections in segmentation and calculation methods. Herein, we introduce a more rational parameter, denoted as harmonic amide bond density (HABD), to unravel the relationship between the crosslinked networks of polyamide membranes and their desalination performance. HABD quantifies the number of distinct amide bonds per unit mass of polyamide, based on a comprehensive segmentation of polyamide structure and consistent computational protocols derived from X-ray photoelectron spectroscopy data. Compared to its counterpart, HABD overcomes the limitations and offers a more accurate depiction of the crosslinked networks. Empirical data validate that HABD exhibits the expected correlation with the salt rejection and water permeance of reverse osmosis and nanofiltration polyamide membranes. Notably, HABD is applicable for analyzing complex crosslinked polyamide networks formed by highly functional monomers. By offering a powerful toolbox for systematic analysis of crosslinked polyamide networks, HABD facilitates the development of permselective membranes with enhanced performance in desalination applications. Relating the degree of network crosslinking as a descriptor to the desalination performance of crosslinked polymer membranes remains challenging. Here, the authors introduce a parameter based on distinct amide bonds per unit mass of polyamide, to unravel the relationship between the crosslinked networks of polyamide membranes and their desalination performance. [ABSTRACT FROM AUTHOR]

[Display omitted] Vacuum assistance is used for filtering solid substances onto porous substrates to create composite membranes typically. However, the potential of this approach has rarely been assessed in facilitating the distribution of liquids within those porous substrates to fabricate composite membranes in typical interfacial polymerization. In this work, we demonstrate the advantages of vacuum-assisted interfacial polymerization (VAIP) in terms of substrate universality, monomer concentration range, and performance reproducibility in the fabrication of polyimide nanofiltration membranes. Aqueous solutions of PIP can be homogeneously distributed by vacuum filtration on diverse microfiltration substrates of polyether sulfone (PES), Nylon-66, polyvinylidene fluoride (PVDF), cellulose acetate (CA), and mixed cellulose esters (MCE), respectively. Interfacial polymerization is then performed on these substrates using different concentrations of piperazine (PIP, 0.0075–0.1000 wt%) and trimoyl chloride (TMC, 0.0112–0.1500 wt%). Remarkably, a uniform and ultra-thin polyamide layer with a thickness of 15 nm can be achieved at an exceptionally low PIP concentration of 0.0250 wt%, exhibits a rejection rate of over 98.8 % for Na 2 SO 4 and a water permeance of 25.8 L·m−2·h−1·bar−1. The membranes with a diameter of 30 cm demonstrate reproducibility in nanofiltration performance and satisfactory long-term stability. This method offers a simple yet effective strategy for regulating the liquid distribution and optimizing interfacial polymerization in fabricating polyamide composite membranes. [ABSTRACT FROM AUTHOR]

The modification of conventional polyamide reverse osmosis (RO) membranes with grafted methacrylic acid in the presence of nanomaterial is disclosed. To decrease fouling, this study shows the effectiveness of grafting a hydrophilic methacrylic acid (PMAA) and graphene oxide (GO) nanosheet. The change in membrane surface after coating method with different layers was obvious. The results of the ATR‐FTIR, SEM, AFM, contact angle investigations from side and enhanced rejection and permeability from other side proved that the grafting and modification processes had been successful. In comparison between different modifications based on grafting for thin film and blend RO membranes (RO T, RO P, and RO PG), it was found that the modified membrane nominated RO TG membranes showed less biofouling. The modified membrane with 1.25 weight percent PMAA concentration and 0.4 weight percent distributed GO had the lowest contact angle, the least fouling, the highest chlorine resistance, and improved desalination performance. Highlights: Biofouling study for modified RO membranesChlorine resistance membranes for water desalinationEnhanced surface hydrophilicity through grafting of polyamide membranes [ABSTRACT FROM AUTHOR]

In this study, the semi‐aromatic polyamide membranes were synthesized by the interfacial polymerization between piperazine (PIP) monomers in the water phase and Benzene‐1,3,5‐tricarbonyl chloride in the organic phase. To further modify the semi‐aromatic pervaporation membrane, the two amino acids, glycine, and l‐lysine, were mixed with PIP monomers for interfacial polymerization. The morphology and physicochemical properties of the synthesized membranes were analyzed using Fourier transform infrared (FTIR), field emission scanning electron microscope (FE‐SEM), atomic force microscope (AFM), and contact angle measurements. The results show that the semi‐aromatic polyamide membranes modified by the two amino acids possess a higher hydrophilic surface and lower thickness compared to the unmodified membrane. Additionally, the permeation flux of the semi‐aromatic polyamide membranes was improved by 18.6% and 38.5% as modified with glycine and l‐lysine, respectively, at the operating temperature of 70°C when the rejection of both NaCl and arsenic are higher than 99.8%. Furthermore, the operating temperature significantly influenced the permeation flux, while the salt rejections were insignificantly affected. The permeation flux increases by 3.2‐ and 4.0‐folds for glycine and lysine‐modified membranes, respectively, when elevating the feed temperature from 40°C to 70°C. The highest permeation flux of 29.5 kg m−2 h−1 with a 5 wt% NaCl rejection of 99.8% was obtained at 70°C by using 0.3 wt% l‐lysine modified polyamide (PA) membrane. For elimination of 1.5 mg L−1 As solution at the feed temperature of 70°C, such l‐lysine modified PA membrane exhibited the permeation flux of 30.5 kg m−2 h−1 and As rejection of 99.6%, respectively. This work provides a cost‐saving, facile, and eco‐friendly preparation method for effectively improving the permeation flux while not sacrificing the high rejection of salts of the modified membranes. [ABSTRACT FROM AUTHOR]

Amidst the ongoing advancements in membrane technology, a leading method has come to the forefront. Recent research has emphasized the substantial influence of surface attributes in augmenting the effectiveness of thin-film membranes in water treatments. These studies reveal how surface properties play a crucial role in optimizing the performance of these membranes, further establishing their prominence in the field of membrane technology. This recognition stems from the precise engineering of surfaces, ensuring they meet the demanding requirements of advanced separation processes. This study utilizes polyamide as a discerning layer, applied atop a polysulfone support sheet through interfacial polymerization (IP) for membrane fabrication. The amounts in the various membranes were created to vary. The membrane's permeability to water with significant salt rejection was enhanced, which improved its effectiveness. The polyamide (PA) membrane comprising graphene oxide (rGO, 0.015%) had a water permeability of 48.90 L/m2 h at 22 bar, which was much higher than the mean permeability of polyamide membranes (25.0 L/m2 h at 22 bar). On the other hand, the PA–rGO/CHIT membranes exhibited the lowest water permeability due to their decreased surface roughness. However, the membranes' effectiveness in rejecting salts ranged from 80% to 95% for PA–rGO and PA–rGO/CHIT membranes. [ABSTRACT FROM AUTHOR]

High performance polyamide nanofiltration membranes play important roles in Mg2+/Li+ separation and Li+ extraction, but they are prepared via multiple time‐/labor demanding steps. Both the scalability of these membranes and the engineering of membrane modules remain an elusive challenge. Here the design of a Gemini‐electrolyte monomer (GEM) featuring bidentate amine groups, quaternary ammonia, and endocyclic contorted conformation is reported. The monomer's low interfacial diffusivity is balanced by high condensational reactivity during its interfacial polymerization with trimesoyl chloride (TMC), leading to the straightforward formation of defect‐free, ≈14 nm thick membranes. The membrane shows the highest permeance (≈19.2 L m−2 h−1 bar−1) among Mg2+/Li+ nanofiltration membranes prepared via straightforward interfacial polymerization without post‐modification, combined with good Mg2+/Li+ selectivity (≈15.4) and stability. The validity of GEM design is verified by control monomers. Large‐area (1 × 2 m2) GEM‐TMC membranes and spiral‐wound modules (effective area: 0.5 m2) are prepared, both of which show reproducible and high performance. [ABSTRACT FROM AUTHOR]

The study illustrates the use of polyelectrolyte multilayer (PEM) membranes prepared with weak/strong polyelectrolyte combination of poly(ethyleneimine)/chondroitin sulfate A (PEI/CS) for the removal of metolachlor (MTR) from water samples. The proposed PEM membranes were characterized by chemical, physical, thermal, and morphological properties. The removal of MTR herbicide by PEI/CS multilayer deposited on a microfiltration polyamide membrane was found to be efficient with a retention rate of about 96.46% for 8 bilayers sat an excellent permeate flux of 6.27 m3/m2 day. The photodegradation of metolachlor which got trapped in PEMs in the presence of riboflavin (Rb) sensitizer was investigated at various concentrations. A comparative study on photo-elimination of MTR without the presence of Rb was also done. The degradation time was greatly shortened from more than 1 h for direct photolysis to 5–15 min depending on the initial concentration of the sensitizer. The degradation of metolachlor in the presence of Rb as well as direct photolysis was also experimentally studied. [ABSTRACT FROM AUTHOR]

Reverse osmosis desalination is a common technique to obtain fresh water from saltwater. Conventional membranes suffer from a trade‐off between salt rejection and water permeability, raising a need for developing new classes of membranes. C‐based membranes with porous graphene and carbon nanotubes offer high salt rejection, water permeability, and fouling resistance. However, controlling the pore size of these membranes is challenging. Therefore, a carbon honeycomb membrane is studied using classical molecular dynamics simulations. It is reported that functionalization with −COO– groups provides 100% salt rejection with around 1000 times higher water permeability than conventional polyamide membranes. Atomic‐level understanding of the effect of the functional groups' location on salt rejection and water permeability is developed. [ABSTRACT FROM AUTHOR]

Existing polyamide (PA) membrane synthesis protocols are underpinned by controlling diffusion-dominant liquid-phase reactions that yield subpar spatial architectures and ionization behavior. We report an ice-confined interfacial polymerization strategy to enable the effective kinetic control of the interfacial reaction and thermodynamic manipulation of the hexagonal polytype (Ih) ice phase containing monomers to rationally synthesize a three-dimensional quasilayered PA membrane for nanofiltration. Experiments and molecular simulations confirmed the underlying membrane formation mechanism. Our ice-confined PA nanofiltration membrane features high-density ionized structure and exceptional transport channels, realizing superior water permeance and excellent ion selectivity. [ABSTRACT FROM AUTHOR]

This study endeavors to augment the antibacterial and anti‐biofouling properties of thin‐film composite polyamide membranes by subjecting them to modification with antibacterial chitosan and silver nanoparticle materials through the UV‐induced graft polymerization technique. Various surface assessment methods were employed, and the efficiency of the membrane performance was demonstrated through the flux and the retention of the filtration process, which used calcium chloride as the foulant. Antibacterial, antifouling, and anti‐biofouling capabilities were assessed through several tests. The findings revealed that the chitosan/silver nanoparticles‐grafted membranes exhibited superior antibacterial and anti‐biofouling abilities with consistent flux and enhanced retention, underscoring the prospective implementation of this approach in filtration systems to curtail biofouling and bolster overall efficacy. [ABSTRACT FROM AUTHOR]

High efficiency of the polyamide membranes can be achieved by rationally tailoring the active layer, which empowers the membrane with better anti-fouling characteristics, high flux, and separation efficiencies. Herein, a next-generation anti-fouling positively charged copolymer of diallyldimethylammonium chloride (DADMAC) and N1, N1-diallyldodecane-1,12-diammonium chloride (DADAC) was synthesized and thoroughly characterized by TGA, FTIR, proton (1H) and the carbon (13C) NMR. The synthesized poly(DADMAC-co-DADAC), after conversion to poly(DADMAC-co-DADA) having free NH 2 group, was in-Situ grafted while forming the active layer due to its rationally designed anchoring points of NH 2 group. The in-Situ grafting resulted in a cross-linked polyamide active layer containing positively charged brushes of poly (DADMAC-co-DADA) at regular intervals. The AFM analysis has shown that the polyamide layer's surface roughness increased with the poly-(DADMAC-co-DADA) grafting concentration, which positively impacts the membranes' flux. When exposed to the water, the grafted poly-(DADMAC-co-DADA) expanded and spread a positively quaternary ammonium network on the membrane surface, effectively repelling the cations. The introduced membrane has shown high performance compared to the pristine polyamide membrane. The functionalized membranes have displayed a 3.5 times flux for 2000 ppm of NaCl while maintaining a good rejection at 93.1%. The anti-fouling behavior of the membranes was evaluated against the model positively charged CTAB (cetyltrimethylammonium bromide) foulants (2000 ppm). Poly- (DADMAC-co-DADA) grafted membranes have shown a high anti-fouling tendency. After 600 min (10 h) of continuous operation, the flux declined less than 15%, whereas the pristine polyamide membrane lost 99%. The poly-(DADMAC-co-DADA) grafted membranes recovered more than 93% of their maximum flux. Thus, the in-Situ grafting of positively charged polymer is a possible opportunity to develop the next generation of high-performance polyamide membranes. [Display omitted] [ABSTRACT FROM AUTHOR]

The current work was aimed at the development of a topical drug delivery system for azelaic acid (AzA) for acne treatment. The systems tested for this purpose were deep eutectic systems (DESs) prepared from choline chloride (CC), malonic acid (MA), and PEG 400. Three CC to MA and eight different MA: CC: PEG400 ratios were tested. The physical appearance of the tested formulations ranged from solid and liquid to semisolid. Only those that showed liquid formulations of suitable viscosity were considered for further investigations. A eutectic mixture made from MA: CC: PEG400 1:1:6 (MCP 116) showed the best characteristics in terms of viscosity, contact angle, spreadability, partition coefficient, and in vitro diffusion. Moreover, the MCP116 showed close rheological properties to the commercially available market lead acne treatment product (Skinorin®). In addition, the formula showed synergistic antibacterial activity between the MA moiety of the DES and the AzA. In vitro diffusion studies using polyamide membranes demonstrated superior diffusion of MCP116 over the pure drug and the commercial product. No signs of skin irritation and edema were observed when MCP116 was applied to rabbit skin. Additionally, the MCP116 was found to be, physically and chemically, highly stable at 4, 25, and 40 °C for a one-month stability study. [ABSTRACT FROM AUTHOR]

Membranes with molecular-sized, high-density nanopores, which are stable under industrially relevant conditions, are needed to decrease energy consumption for separations. Interfacial polymerization has demonstrated its potential for large-scale production of organic membranes, such as polyamide desalination membranes. We report an analogous ultrafast interfacial process to generate inorganic, nanoporous carbon-doped metal oxide (CDTO) nanofilms for precise molecular separation. For a given pore size, these nanofilms have 2 to 10 times higher pore density (assuming the same tortuosity) than reported and commercial organic solvent nanofiltration membranes, yielding ultra-high solvent permeance, even if they are thicker. Owing to exceptional mechanical, chemical, and thermal stabilities, CDTO nanofilms with designable, rigid nanopores exhibited long-term stable and efficient organic separation under harsh conditions. [ABSTRACT FROM AUTHOR]

A broad application of polar dimethylacetamide (DMAc) in the chemical industry leads to environmental pollution and a big recycling problem. Pervaporation is a membrane separation technology suitable for organic solvent dehydration. Herein, thin polyamide (PA) pervaporation membranes with different structures were prepared by interfacial polymerization method, in which trimesoyl chloride (TMC) as the organic phase, and either m-phenylenediamine (MPDA), propylene diamine (DAPE), or tetraethylene pentamine (TEPA) as the aqueous phase. It proved that the PA pervaporation membrane derived from TEPA as the aqueous monomer exhibited a high degree of crosslinking, resulting in regular packing of polymer chains. The permeation flux and water content of the 10 wt% DMAc/H2O system were 17.8 L m−2 h−1 and 98.4 wt% at 500 Pa and 70° C, respectively. Therefore, the TEPA-PA membrane has a good separation performance even when dealing with a low-concentration DMAc/H2O system. [ABSTRACT FROM AUTHOR]

Polyethyleneimine (PEI) based positive charge nanofiltration (NF) membranes have unique advantages in the removal of heavy metals. The regulation mechanism of the interlayer when PEI was used as monomer was still not clear. In this study, a PVA-based interlayer was constructed on the origin PES sublayer to tailor the interfacial polymerization in PEI systems. It was proved that the PVA interlayer can further elevate the PWP and rejections of heavy metals. Moreover, the absorption effect of interlayers could contribute to better removal of heavy metals. More negative charges of interlayer could result in a more enough and uniform absorption of PEI monomer as well as a slower diffusion rate of PEI monomer during the interfacial polymerization reaction, thus forming a loose top surface but dense sub-separating layer. This study provides new insight into the effect of interlayer on the performance of PEI-based nanofiltration membrane. [ABSTRACT FROM AUTHOR]

Tailored design of high‐performance nanofiltration membranes that can be used in a variety of applications such as water desalination, resource recovery, and sewage treatment is desirable. Herein, we describe the use of layered double hydroxides (LDH) intermediate layer to control the interfacial polymerization between trimesoyl chloride (TMC) and piperazine (PIP) for the preparation of polyamide (PA) membrane. The dense surface of LDH layer and its unique mass transfer behavior influence the diffusion of PIP, and the supporting role of the LDH layer allows the formation of ultrathin PA membranes. By only changing the concentration of PIP, a series of membranes with controllable thickness from 10 to 50 nm and tunable crosslinking‐degree can be prepared. The membrane prepared with a higher concentration of PIP shows excellent performance for divalent salt retention with water permeance of 28 Lm−2 h−1 bar−1, high rejection of 95.1 % for MgCl2 and 97.1 % for Na2SO4. While the membrane obtained with a lower concentration of PIP can sieve dye molecules of different sizes with a flux of up to 70 Lm−2 h−1 bar−1. This work demonstrates a novel strategy for the controllable preparation of high‐performance nanofiltration membranes and provides new insights into how the intermediate layer affects the IP reaction and the final separation performance. [ABSTRACT FROM AUTHOR]

High concentrations of fluoride in drinking water can lead to fluorosis of teeth and bones and other serious diseases, while nanofiltration is an attractive technique for fluoride removal. Interfacial temperature can determine the monomer diffusion rate in interfacial polymerization (IP) process, thereby tuning the structure of membrane such as thickness, pore size and surface charge. Herein, a fully‐aromatic polyamide nanofiltration membrane with desirable separation performance was customized by interface temperature. The resulting membrane exhibits a flux of 6 L m−2 h−1 bar−1 and the molecular weight cut‐off is 211 Da, most importantly, a 90.3% F− rejection to underground water, indicating that the membrane has application potential in underground water treatment. This work helps to better understand the effects of interface temperature on the IP process and provides a new strategy to address the drinking water problem. [ABSTRACT FROM AUTHOR]

The paper aimed to produce four different types of sheep meat products with heterogeneous structures in the meat processing workshop of the University of Life Sciences Iasi, which presented as variation factors the type of membrane and the type of product (salami/sausage, imprinted by the membrane used). Two varieties of salami (in collagen and polyamide membrane) and two varieties of sausages (in natural pork and sheep membrane) served as the four samples. The four samples obtained were subjected to sensory analysis, carried out in two stages: the first stage consisted of assessing the products based on the main sensory attributes (appearance, aroma, taste, texture, overall acceptability), and the second stage aimed at describing the products using specific sensory terms included in the CATA (Check-All-That-Apply) test from the perspective of consumer perception. The results obtained revealed sensory attributes characteristic of membrane products with heterogeneous structure, with the CATA test describing the products through positive attributes (colour, aroma, texture), with the differentiation of a firmer, harder texture in the case of natural membrane products, superior juiciness in the case of the S3MC sample, and a slightly brittle texture in the S4MP sample. In terms of the results of the hedonic scale, the sausage samples received a higher score for section appearance (7.91 ± 0.831 for C1MP and 8.00 ± 0.775 for C2MO), compared to the salami samples (7.73 ± 1.104 for S3MC and 7.18 ± 1.168 for S4MP). The overall acceptability was highest for C1MP, which received 8.36 ± 0.674 points, being followed in descending order by C2MO (8.55 ± 0.688), S3MC (8.18 ± 0.751) and S4MP (7.45 ± 0.522). [ABSTRACT FROM AUTHOR]

Ti 3 C 2 T x -based modified separation materials are widely used in the field of wastewater separation, but most of them have poor fluxes. Here, grafting of l -cysteine and l -histidine onto polydopamine-pretreated Ti 3 C 2 T x surface was used to obtain amino acid-modified Ti 3 C 2 T x (L-CPT and L-HPT), respectively, by covalent and non-covalent bonds under mild conditions, enriching variety and number of hydrophilic groups on the Ti 3 C 2 T x surface. Polyurethane sponge (PU) coated with L-CPT and L-HPT (L-CPTPU and L-HPTPU) exhibit excellent underwater oleophobicity and show impressive separation efficiency (>99.4%) for various oil-water mixtures. Especially, L-CPTPU and L-HPTPU achieved high-throughput separation for cyclohexane-water mixtures with maximum permeation fluxes of 220,319 and 222,197 L m-2 h-1, respectively, and had excellent resistance to corrosive media. Besides, polyamide membranes modified with L-CPT and L-HPT (L-CPTPA and L-HPTPA) form abundant permeation channels, achieving high-efficiency separation for toluene in water emulsion with separation efficiency greater than 99.1%. In addition, L-CPTPA and L-HPTPA exhibited remarkable rejection (>99.1%) and high permeability (>1100 L m-2 h-1 bar-1) for 20 mg L-1 malachite green solution. Therefore, the amino acid-modified Ti 3 C 2 T x can functionally modify PU and PA substrates toseparate oily wastewater and dye wastewater, respectively. [ABSTRACT FROM AUTHOR]

In this study, thin-film nanocomposite nanofiltration (TFN) membranes were fabricated using interfacial polymerisation by incorporating modified cellulose nanoparticles (mNCs). In the first place, cellulose nanoparticles were modified by AAPTES, and were then dispersed in an organic solvent with the aim of reaction with the polyamide layer of TFC membrane. The resulting membranes were then tested for the removal of Cr(III) and Pb(II) heavy metals ions from wastewater. Modified nanoparticles and nanocomposite membranes were characterised by FTIR, TEM, AFM, SEM, and zeta potential. FTIR results showed the proper mNCs deposition on the surface of membranes. Also, SEM analyses demonstrated that the incorporation of mNCs to TFC membranes led to higher surface roughness. The performance results indicated that the water flux of TFN membranes increased from 42 L·m−2 h−1 to 125 L.m−2 h−1, which might have been due to the higher surface hydrophilicity of TFN membranes, while the rejection rates of Cr(NO3)3 and Pb(NO3)2 were over 99% at and 88%, respectively, showing a competitive and efficient removal of toxic heavy metal ions Pb(II) and Cr(III). Besides, regarding pH of the membranes, rejection performance of the membrane increased with increased pH so that at pH 8.5, the removal rates of Pb(II) and Cr(III) were 93% and 100%, respectively. [ABSTRACT FROM AUTHOR]

Commercial microporous polyamide (PA) membranes were smoothly coated with different aliquots of graphene oxide (GO) water solution and crosslinked with polyvinyl alcohol (PVA)/citric acid (CA). The functionalized membrane was attached to a low-cost and easy-to-assemble portable filtration unit for the removal of mono- and bivalent salt from brackish water. The structure and morphology of GO, which was synthesized via a modified Hummers method, and the as-prepared membranes, were characterized through X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). FTIR revealed the same bands for GO and the modified membranes, typical of oxygenated groups vibrations. XRD of crosslinked membranes exhibited traces of crystalline phases probably induced by GO-PVA interactions. SEM images revealed that the PA membranes exhibited an irregular porous geometry and that the GO sheets were uniformly deposited on them, forming a multilayer coat ranging from ∼0.3 to ∼0.5 µm thickness, depending on the amount of GO deposited. Tests using ultrasonic bath showed that the PVA/CA reticulation enhanced the mechanical stability of the membranes, by promoting esterification crosslinking reactions of the carboxyl groups, from the citric acid, with the hydroxyl groups, from the PVA and GO. The membranes were evaluated through salt rejection capacity for magnesium sulfate (MgSO 4) and sodium chloride (NaCl) ions in aqueous solutions. Polyamide membranes modified with GO aliquots of 0.75 mg exhibited the best performance, with rejection of 55 % and permeability of 1.42 L/m².h.bar for Mg+2, and rejection of 37 % and permeability of 2.08 L/m².h.bar for Na+. Furthermore, they can guarantee> 29 % retention for Mg+2 ions on the third reuse. These results indicate the potential for desalination of solutions with divalent and monovalent ions. The advances achieved during this work showed practical potentialities to be applied in portable desalination systems. [Display omitted] • PA membranes were functionalized with graphene oxide and PVA/citric acid. • A low-cost and portable filtration unit was built to treat brackish water. • Most divalent ions, and a part of the monovalent ions, could be separated. • The results showed practical potentialities to be applied in desalination systems. [ABSTRACT FROM AUTHOR]

Endocrine-disrupting chemicals (EDCs) present in aquatic environment have been regarded as detrimental organic pollutants that pose significant adverse impacts on human health and the aquatic ecosystem. The removal of EDCs is highly desired to mitigate their harmful effects. Physical treatment through membrane-based separation processes is an attractive approach, as it can effectively remove a wide range of recalcitrant organic and nonorganic EDCs. In particular, the reverse osmosis (RO) process has shown promise in removing EDCs of various concentrations and from different sources. Recently, the development of innovative asymmetric RO membranes has become the forefront in this field. Various membrane modification strategies have been commenced to address the limitations of commercial membranes. This review provides an overview of the recent advances in asymmetric RO membranes for EDC removal from water and wastewater system. The potential areas of improvement for RO processes and RO membranes are also highlighted. Based on the existing literature using RO for EDC removal from water, the most investigated EDCs are bisphenol A (BPA) and caffeine in the concentration range of 200 ppb to 100 ppm. Polyamide RO membranes have been shown to remove EDCs from water bodies with a removal efficiency of ~30 to 99%, largely depending on the type and concentration of the treated EDCs, as well as the properties of the RO membranes. It has been demonstrated that the performance can be further heightened by tailoring the properties of RO membranes and optimizing the operating conditions of the RO process. [ABSTRACT FROM AUTHOR]

Nanoscale thin-film composite (TFC) polyamide membranes are highly desirable for desalination owing to their excellent separation performance. It is a permanent pursuit to further improve the water flux of membrane without deteriorating the salt rejection. Herein, we fabricated a high-performance polyamide membrane with nanoscale structures through introducing multifunctional crown ether interlayer on the porous substrate impregnated with m-phenylenediamine. The crown ether interlayer can reduce the diffusion of amine monomers to reaction interface influenced by its interaction with m-phenylenediamine and the spatial shielding effect, leading to a controlled interfacial polymerization (IP) reaction. Besides, crown ether with intrinsic cavity is also favorable to adjust the IP process and the microstructure of polyamide layer. Since the outer surface of the nanocavity is lipophilic, crown ether has good solvency with the organic phase, thus attracting more trimesoyl chloride molecules to the interlayer and promoting the IP reaction in the confined space. As a result, a nanoscale polyamide membrane with an ultrathin selective layer of around 50 nm is obtained. The optimal TFC polyamide membrane at crown ether concentration of 0.25 wt.% exhibits a water flux of 61.2 L·m−2·h−1, which is 364% of the pristine TFC membrane, while maintaining a rejection of above 97% to NaCl. The development of the tailor-made nanoscale polyamide membrane via constructing multifunctional crown ether interlayer provides a straightforward route to fabricate competitive membranes for highly efficient desalination. [ABSTRACT FROM AUTHOR]

Polymer membranes have been used extensively for Angstrom-scale separation of solutes and molecules. However, the pore size of most polymer membranes has been considered an intrinsic membrane property that cannot be adjusted in operation by applied stimuli. In this work, we show that the pore size of an electrically conductive polyamide membrane can be modulated by an applied voltage in the presence of electrolyte via a mechanism called electrically induced osmotic swelling. Under applied voltage, the highly charged polyamide layer concentrates counter ions in the polymer network via Donnan equilibrium and creates a sizeable osmotic pressure to enlarge the free volume and the effective pore size. The relation between membrane potential and pore size can be quantitatively described using the extended Flory-Rehner theory with Donnan equilibrium. The ability to regulate pore size via applied voltage enables operando modulation of precise molecular separation in-situ. This study demonstrates the amazing capability of electro-regulation of membrane pore size at the Angstrom scale and unveils an important but previously overlooked mechanism of membrane-water-solute interactions. The ability to regulate membrane pore size as needed has been a topic of active research for developing next-generation stimuli-responsive smart membranes. Herein, the authors report the observation of operando regulation of the pore size of A membrane based on electro-osmotic swelling. [ABSTRACT FROM AUTHOR]

Fabrication of high-dye/salt-separation-performances and chlorine-resistant nanofiltration (NF) membranes are crucial for dye desalination. In this study, a thin-film composite NF membrane (PES–DPS) was prepared through the interfacial polymerization of 3,3′-diaminodiphenyl sulfone (DPS) and trimesoyl chloride. Because of the low reactivity and the presence of the sulfone group (O=S=O) of DPS, the prepared PES–DPS membrane provided a relatively loose polyamide layer and exhibited excellent chlorine resistance, enhancing the membrane water flux and dye/salt separation performances. Furthermore, the influence of DPS concentration was systematically investigated. The optimal membrane PES–DPS–1 exhibited high direct Blue 71 rejection (99.1%) and low NaCl rejection (8.7%). Meanwhile, the PES–DPS–1 membrane displayed highly pure water flux (49.4 L·m−2·h−1·bar−1) even at a low-operating pressure (2 bar). Moreover, no significant difference in dye rejection was observed when the membrane was immersed in NaClO solution (pH = 4.0, 2000 ppm) for 12 h, thereby demonstrating its outstanding chlorine stability. In summary, this work provided a new monomer for the preparation of novel polyamide membranes to achieve excellent separation performances and chlorine resistances. [ABSTRACT FROM AUTHOR]

Reverse osmosis desalination is one of the most important and increasingly popular technologies to augment available water resources. Central to the technology is a thin-film-composite polyamide membrane capable of separating pure water from seawater or brine. Since its conception and initiation, the membrane industry has followed a linear life-cycle scheme. However, increasing production costs of fossil-based materials and more stringent environmental regulations drive the initiatives to adapt to a circular economy of membrane materials. In this perspective, we briefly summarize the pressing issues in the state-of-the-art membrane industry, then discuss the opportunities in future technology innovations with a focus on sustainable membrane manufacturing and recycling, and lastly provided an outlook for future membrane design and fabrication towards a circular economy. [ABSTRACT FROM AUTHOR]

For the treatment of wastewater and water resources, membrane technologies are rapidly developing. Also, water pollution by heavy metals, dyes, oil, medicinal, and salts leads to lower water quality and water shortages. In this research, thin-film nanocomposite nanofiltration (TFN) membranes were produced via the interfacial polymerization (IP) method between trimesoyl chloride (TMC) and m-phenylenediamine (MPD) monomers at the top surface of PES/(UF) membrane and modified by graphene oxide (GO) and aluminum fumarate (AlFu) metal-organic framework (MOF) nanostructures to remove heavy metal and (divalent and monovalent) salts. The FTIR, NMR, SEM, XRD, and zeta potential analyses investigated the modified thin-film nanocomposite membrane properties. Also, the hydrophilicity of the membrane was determined via contact angle analysis. Compared to the polyamide (PA) and PA/AlFu membranes, the as-synthesized TFN membrane contains 0.3 wt% GO had the highest water flux, 110.86 l/m2·h, rejection of Na2SO4 salt and Cr2+ about 98.94% and 97.5%, respectively. Generally, using nanostructures like GO and AlFu (MOF) opens a novel path to improve hydrophilicity, negative charge, water flux, and rejection of polyamide nanocomposite membrane. [ABSTRACT FROM AUTHOR]