Nanofiltration (NF) membranes show superior ion selectivity, which, however, decreases with temperature owing to excessive pore expansion of the selective layers. Herein, an effective and feasible co-solvent strategy is proposed to improve the thermostability of polyamide NF membranes. The co-solvent systems with low interfacial tension accelerate the interfacial diffusion of aqueous monomers during the interfacial polymerization. Moreover, the enhanced compatibility between the organic phase and the nascent polyamide layer, which is assessed by the Hansen solubility parameters, facilitates the formation of selective layers with high cross-linking degree. The resultant compact selective layers possess enhanced thermostability. The optimized NF membrane exhibits a high permeance of 24.8 L center dot m- 2 center dot h- 1 center dot bar- 1 with 98.3% MgSO4 rejection at 85 degrees C. The present method shows great potential for preparing thermostable NF membranes.

Coordination-driven metal-organic membranes are promising for sustainable nanofiltration yet their synthesis is often limited by uncontrolled coordination kinetics, resulting in broad pore size distributions and low salt rejection, which remain a great challenge in nanofiltration field. Here, an all-aqueous solid-liquid interfacial coordination assembly strategy is developed by introducing a coordination polymer, polyethyleneimine (PEI), as a confinement platform to regulate metal ion distribution and coordination kinetics. The resulting phytic acid (PhA)-metal membrane exhibits a most probable pore size of 0.28 nm, a narrowed pore size distribution, a water contact angle of similar to 22 degrees, a surface potential of -32 mV at pH = 7, and a high Na2SO4 rejection of 97.8% with water permeance of 8.2 L m(-2) h(-1) bar(-1). The membrane also shows excellent stability and efficient antibiotic desalination, achieving over 99.1% rejection for multiple antibiotics and with a tetracycline/NaCl selectivity of 78.1. Compared with state-of-the-art metal-organophosphate membranes, our membrane exhibits a 56.2% reduction in pore size and a 79.9% higher selectivity for SO42-/Cl-. Importantly, the strategy is broadly applicable to diverse metal ions, guided by hard-soft acid-base theory, enabling tunable interfacial crosslinking and membrane properties. By confining and regulating coordination on the membrane surface, this work offers a green and sustainable route for fabricating high-performance PhA-based nanofiltration membranes with narrow pore size distribution and high salt rejection.

Salt-lake brine, with its vast lithium reserves, represents a crucial supply for the world. However, conventional lithium extraction technologies are often challenged by high energy consumption and/or poor environmental compatibility. Herein, we develop a solar-evaporation-driven, efficient, and green lithium extraction system. Its core is a multilayer evaporation-separation floating fiber-based composite membrane. The upper evaporation layer achieves a broad-spectrum absorption of 95% and an evaporation efficiency of 94.8% under 1 sun, whereas the underlying ion-separation layer consists of an ultra-thin (similar to 57 nm) polyamide film with a tunable pore size. The two layers are tightly coupled, and the negative pressure generated by solar evaporation provides the driving force for lithium ion (Li+) transport across the polyamide film. The system achieves a Li+ flux of 9.1 mg m(-2) h(-1) and a Li (+) selectivity of 5.2 at a high salinity of 1 g L-1, demonstrating excellent anti-fouling capability and operational durability. This work offers an innovative technological pathway for the green and low-carbon development of lithium resources from salt-lake.

Thermally stable thin-film composite (TFC) nanofiltration (NF) membranes are essential for high-temperature separation in various industrial applications. Herein, we present a rapid and scalable surface modification of polyvinylidene fluoride (PVDF) ultrafiltration membrane using tannic acid (TA) and 2-aminopropyltriethoxysilane (APTES), which can be used as the substrate membrane for the preparation of thermally stable NF membranes. The modified PVDF substrate shows enhanced mechanical strength and thermal stability, with tensile strength rising from 1.5 to 4.7 MPa, decomposition temperature increasing from 459 to 482 degrees C, and a coefficient of thermal expansion (CTE) reduced by 36.4%. These improvements ensure the structural integrity and strong adhesion between the substrate and polyamide layers, thereby further improving the reliability of the TFC NF membrane during long-term operation under high-pressure and high-temperature conditions. Consequently, the PVDF-based TFC NF membrane sustains >97.5% MgSO4 rejection and remarkable water permeance (42.1 LMH/bar) during 100-h operation at 70 degrees C. This rapid and scalable modification method provides a practical route toward the fabrication of robust PVDF-based TFC NF membranes for high-temperature separation.

Novel polymers of intrinsic microporosity (PIMs) exhibit rigidity and non-planar structures, which make them promising for constructing high-permeability separation materials. However, the intrinsic hydrophobicity of PIMs limits their application in separation membranes for aqueous systems. Herein, we report an in situ interfacial polymerization strategy utilizing a catechol-functionalized PIM monomer in conjunction with dopamine (DA) to fabricate a thin-film composite (TFC) nanofiltration membrane with intrinsic microporosity. In this process, the aqueous-phase monomer, 5,5 ',6,6 '-tetrahydroxy-3,3,3 ',3 '-tetramethyl-1,1 ' spirobiindan (TTSBI), modulated the pore size distribution, which facilitated water transport and enhanced permeance, while DA improved hydrophilicity and adhesion. Furthermore, the steric hindrance imparted by the contorted structure of TTSBI interfered with the self-polymerization and assembly behavior of DA, inhibiting the formation of larger aggregates and consequently reducing structural defects within the composite layer. The resulting composite membrane exhibits a narrow pore size distribution (0.3-0.4 nm), high Vitamin B12 (VB12) rejection rate (92.5%), and outstanding permeance (4.6 L m-2 h-1 bar-1). Moreover, long-term testing demonstrated excellent stability, with only a 4.4% decline in rejection after 96 h. This work provides valuable insights for the fabrication of high-performance nanofiltration membranes for water treatment.

Separating monovalent ions from divalent ions remains a central challenge in resource recovery. While the classic poly(piperazine-amide) nanofiltration membrane exhibits superior rejection of divalent anion, the application in cation separation is constrained by the strongly negatively charged surface and limited size-sieving precision. To address this limitation, we propose a solvent treatment-induced optimization strategy for surfactant-tailored polyamide networks. The surfactant-assisted interfacial polymerization yields a dense and uniform nascent polyamide network that can withstand solvent treatment while preserving its cross-linked structure. Subsequent solvent treatment selectively removes oligomers trapped within the network, thereby refining the polyamide network architecture. This strategy facilitates the formation of a thinner polyamide selective layer that exhibits an attenuated negative surface charge and a more uniform pore size distribution. The optimized membrane achieves a dual enhancement in performance, exhibiting high mono-/divalent ion selectivity (Li+/Mg2+ selectivity of 96.1 and Cl-/SO42- selectivity of 1351) coupled with a high water permeance of 14.9 L m-2 h-1 bar-1. This work provides a straightforward and effective method to refine surface properties and internal architecture of polyamide networks for efficient mono-/divalent ion separation.

Traditional thin-film composite (TFC) polymer membranes suffer performance deterioration in high-temperature liquid separation due to insufficient thermal stability. Herein, a facile and effective strategy was proposed to fabricate TFC nanofiltration membranes with enhanced thermal stability by using mono-n-dodecyl phosphate (MDP) as an oil-soluble surfactant to regulate the interfacial polymerization. MDP molecules markedly reduce the water/hexane interfacial tension and act as transport carriers to promote the diffusion of amine monomers, as validated by density functional theory (DFT) calculations. By adjusting the concentration of MDP in the organic phase, the polyamide thickness and compactness, surface properties, and the separation performance of the TFC membranes at high temperature can be effectively modulated. The optimal TFC membrane exhibits exceptional thermal stability, maintaining rejection to MgSO4 > 98.5% and water permeance >35 L m(-2) h(-1) bar(-1) during a continuous operation at 85 degrees C for 100 h. Temperature-dependent pore size analysis further confirms the enhanced structural integrity of the MDP-regulated TFC membranes under high temperature. This research establishes a novel paradigm for developing nanofiltration membranes with high thermal stability.

Separation under high temperature is a crucial challenge for polymer nanofiltration (NF) membranes. Polyamide NF membranes with favorable compactness and pore size distribution are promising for boosting their thermal stability and high-temperature separation performance. Despite recent strategies to improve thermal stability, the effect of polyamide membrane compactness on structural changes and separation performance at high temperatures remains insufficiently explored. Herein, we propose a straightforward and effective concentration regulation strategy to address this challenge in the classic piperazine-trimesoyl chloride (PIP-TMC) interfacial polymerization system, focusing on the precise tuning of the polyamide network structure and the high-temperature NF performance through the controlled adjustment of monomer concentration and the relative ratios. Polyamide layer fabricated with a PIP/TMC ratio of 30:1.5 exhibits higher cross-linking degree than that with a PIP/TMC ratio of 2:1.5, and the NF membrane exhibits exceptional thermal stability, with MgSO4 rejection remaining >98.5% at 85 °C. Molecular dynamics simulations reveal that denser polyamide network possesses significantly weaker segmental motion, along with smaller changes in pore size distribution and fractional free volume at elevated temperatures. This concentration regulation strategy effectively enhances the intrinsic thermal stability without complex modifications and provides critical insights into polyamide segment evolution at high temperature.

The low Li + concentration and the abundance of competing ions limit the efficiency of lithium extraction from seawater. In this work, we report a solar-powered seesaw extractor (SPSE) to boost Li + adsorption while minimizing scaling caused by competing ions during photothermal evaporation. The SPSE features a sandwich architecture, with a hydrophilic adsorbent layer placed between two hydrophobic photothermal layers. The seesaw configuration enables Li + to be elevated and concentrated through evaporation to overcome sluggish adsorption kinetics, while the associated salt scaling is removed by the seesawing motion. As a demonstration, we assembled 60 SPSEs into a 3 & times; 20 array that achieved a 15.5-fold increase in local Li + concentration and a 69.1% improvement in Li + uptake over 120 h, with a Li + /Na+ separation factor exceeding 370,000.

High-temperature nanofiltration (NF) technology is essential in various industrial applications. However, the thermal instability of thin-film composite (TFC) membranes remains inadequately addressed. As a crucial constituent of TFC NF membranes, substrate membrane is highly important to the thermal stability of TFC membranes. Herein, four commercial ultrafiltration membranes were used as substrates to fabricate TFC NF membranes via support-free interfacial polymerization, which generates polyamide selective layers with high crosslinking degree. Combining experimental characterizations and COMSOL Multiphysics (R) thermal-stress simulations, we decoupled the decisive roles of substrate glass transition temperature (Tg) and coefficient of thermal expansion (CTE) in determining membrane integrity at high temperature. Results show that TFC membranes supported by substrates with low Tg or high CTE exhibit a significant decline in MgSO4 rejection at high temperature. In contrast, substrates with high Tg and suitable CTE induce TFC membranes with a superior water permeance (33.4 L m-2 h-1 bar-1), a desirable MgSO4 rejection (96.4 %), and good operation stability at 85 degrees C. This work reveals the roles of substrate membranes and demonstrates the design of thermally stable TFC NF membranes for high temperature separation.

Polymer membranes are essential in separation processes such as desalination and organic solvent nanofiltration. However, simultaneously manipulating subnanometer pore size, homogeneity, and chemistry remains challenging due to the coupled diffusion-reaction of building blocks in membrane formation, resulting in the trade-off between permeance and selectivity. Here, we report a versatile enzyme-mediated strategy that kinetically decouples diffusion and reaction, enabling multidimensional pore engineering with tunable pore sizes (0.43-0.84 nm), improved homogeneity, and modular surface chemistry across eight polyamine-phenolic combinations. Phenolics with desired moieties diffuse uniformly into polyamine branch voids and create enzyme-regulated pores, forming highly homogenized and chemically tailored selective layers with ultraselectivity of ∼30 toward solutes with molecular weights below 350 Da, outperforming state-of-the-art membranes (selectivity <10). In high-value pharmaceutical separation, these membranes further achieve 1 order of magnitude higher selectivity, a 7.3-fold increase in solvent permeance, and a 6.8-fold improvement in enrichment efficiency compared to commercial membranes. By highlighting the importance of multidimensional pore engineering in improving membrane selectivity and permeability, our work suggests a pathway for unlocking the potential of polymer nanofiltration membranes for accurate molecular sieving applications.

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 Na2SO4 between 25-85 degrees C. Remarkably, even under sustained operation at 85 degrees 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.

Achieving rapid evaporation and durable scaling resistance simultaneously remains a major challenge for solar-driven interfacial evaporation, particularly when treating hypersaline brines. Inspired by the hollow, water-conducting structure of bamboo, we report a Janus tubular evaporator (JTE) that integrates the interfacial engineering of materials for confining water layer and reducing evaporation enthalpy with seesaw configuration for dynamic self-descaling. The JTE features a hydrophobic, photothermal polypyrrole-coated outer surface and a superhydrophilic silica-coated lumen, forming an ultra-thin confined water layer of 22-75 mu m that enhances heat localization and reduces vaporization enthalpy by 34.2 %. Under one-sun illumination, the JTE achieves evaporation rates of 3.43 kg & sdot;m-2 & sdot;h-1 and 3.21 kg & sdot;m-2 & sdot;h-1 for 7 wt% NaCl and 20 wt% NaCl, respectively. A salt-triggered seesaw configuration enables autonomous rocking and periodic self-descaling, effectively decoupling heat management from scaling control and sustaining stable operation over 120 h. The JTEs are parallelly assembled into an array with an optimized spacing of 1 cm for outdoor testing, yielding 4.75 kg & sdot;m-2 & sdot;day-1 of freshwater while concentrating 7 wt% brine to near saturation. This design offers an efficient and robust strategy for hyposaline brine desalination under real-world conditions.

The increasing demand for separation and purification at high temperature emphasizes the importance of thermostable thin-film composite (TFC) nanofiltration (NF) membranes. The performance of selective layers is profoundly influenced by the molecular structure, and thus the optimization of interfacial polymerization monomers can substantially enhance the thermal stability of NF membranes. Although some new amine monomers have been reported for the preparation of TFC membranes, piperazine (PIP) and m-phenylenediamine (MPD) are still the most widely used monomers. In this work, a co-monomer strategy integrating PIP with MPD as the aqueous monomers was employed to improve the rigidity of the polyamide selective layer, thereby fabricating thermostable TFC NF membranes. Precise modulation of PIP/MPD ratios enables effective control over the diffusion rate of aromatic monomers, and hence achieves tunable chemical composition and physical properties. Temperature-dependent pore size analysis and molecular dynamics simulations demonstrate that the incorporation of MPD significantly enhances the thermal stability of the polyamide selective layer. Remarkably, the TFC NF membrane maintains exceptional MgSO4 rejection (>98.5%) across a broad temperature range from 25 degrees C to 85 degrees C. This research not only provides fundamental insights into the design of co-monomer systems but also establishes a robust strategy for fabricating thermostable NF membranes.

Thin-film composite (TFC) nanofiltration (NF) membranes have been widely used for ionic/molecular separation. However, traditional NF membranes are limited by the unstable structure under high temperature, which leads to deteriorated separation performance. Herein, we report a secondary interfacial polymerization strategy to fabricate NF membranes with superior thermal stability from the conventional monomers. NF membranes after secondary polymerization possessed thicker and negatively charged polyamide layers. The secondary polymerization consumed partial residual acyl chloride groups and improved the compactness and structural stability of the polyamide layer. Molecular dynamics simulations further proved less polymer chain mobility of the polyamide segments after the secondary polymerization. The dense and thermostable NF membranes showed high rejections to MgSO4 and Na2SO4 at 85 °C. The membranes also maintained excellent stability during temperature cycling and long-term high-temperature operations. The proposed method is promising for the fabrication of thermostable NF membranes by simultaneously adjusting the chemical and physical structure via secondary interfacial polymerization.

Polymer nanofiltration membrane has been widely used in various fields. However, it generally suffers from pore expansion at high operating temperature, leading to deterioration in separation performance. It is important to develop thermally resistant membranes to meet high temperature separation requirement for energy conservation and improving economic benefit. Herein, three kinds of anionic dodecyl surfactants were used to assist the interfacial polymerization process to form polyamide layers with high crosslinking degree for high-temperature separation. Results show that the thickness of the polyamide layer increases dramatically with the addition of surfactant, and the surface wettability and surface charges change little. The appropriate addition of surfactants can increase the harmonic amide bond density of the polyamide layer. The optimal membrane exhibits excellent pore size stability as well as high-temperature separation performance with water permeance of 31.3 L m- 2 h- 1 bar- 1 and MgSO4 rejection of 98.0 % at 85 degrees C. The membrane also shows stable separation performance during cycling variations between 25 and 85 degrees C and a 100-h long-term operation at 85 degrees C. This work demonstrates a feasible and scalable method for fabricating nanofiltration membranes for high-temperature separation.

Traditional polyamide nanofiltration (NF) membranes are not applicable to high-temperature separation because of insufficient thermal stability. Modulation of the interfacial polymerization process is effective in improving the high-temperature separation performance of NF membranes. Herein, we introduce an interfacial polymerization strategy modulated with acid acceptors to prevent HCl, a byproduct in interfacial polymerization, from protonating amine monomers, and hence increase the compactness and thermal stability of the polyamide selective layers. The thickness, water contact angles, and charge properties were investigated. The optimized NF membranes show high-temperature separation performance with 97.7 % rejection to MgSO4 and 24.4 L & sdot;m-2 & sdot;h-1 & sdot;bar-1 of permeance at 85 degrees C. The membranes also exhibit thermally stable separation performance at different salt concentrations, applied pressure, cycling temperature variations, and 100-h long-term operations. This study presents an inspiring method for preparing thermostable polyamide membranes.

Thermally stable polymer nanofiltration membranes are urgently demanded in high temperature separation. However, thin-film composite (TFC) nanofiltration membranes fabricated by conventional interfacial polymerization suffer from pore size expansion and thermal instability under high temperature. Herein, we report the fabrication of MoS2 nanosheet confined thin-film nanocomposite (TFN) membranes with enhanced thermal stability. The structural stability of the nanofiltration membranes were investigated by in-situ FTIR and in-situ AFM at different temperatures. The MoS2 nanosheets significantly improve the thermal stability of the nanofiltration membranes by stabilizing the pores and surface strength under high temperature. Molecular dynamic (MD) simulation further confirms the confinement effect of the MoS2 nanosheets on the thermal mobility of the polyamide chains. The TFN membrane presents a prominent permeance of over 30.0 L & sdot;m- 2 & sdot;h- 1 & sdot;bar- 1 and high rejections to Na2SO4 (99.8 %) and MgSO4 (98.1 %) at 80 degrees C. It also shows long-term stability and desirable selectivity of SO42- /Cl- at 80 degrees C. This work provides a feasible strategy for designing thermally stable nanofiltration membranes with excellent performance.

Nanofiltration (NF) membranes have aroused great attention in recent years. The most commonly used NF membranes are polyamide (PA) thin-film composite (TFC) membranes based on ultrafiltration membranes. Owing to the high porosity and interconnected pores, electrospun nanofibrous membranes are promising substrates for the fabrication of high-flux nanofiltration membranes, i.e., thin-film nanofibrous composite (TFNC) nanofiltration membranes. In this work, poly(l-lactic acid) (PLLA) nanofibrous membranes with adjustable hydrophilicity were successfully fabricated, and then, a PA layer was synthesized on the surface via the interfacial polymerization between piperazine (PIP) and trimesoyl chloride (TMC). The hydrophilicity of PLLA nanofibrous membranes influences the distribution and adsorption weight of PIP, which further affects the formation and morphology of the PA layer. Results indicate that, as the hydrophilicity of PLLA nanofibrous membranes increases, the adsorption amount of PIP increases, the thickness of the PA layer decreases, and the cross-linking degree increases, which ensures both high permeance and high rejection to Na2SO4. The TFNC membranes exhibit a water permeance of 17.0 Lm(-2)h(-1)bar(-1) and a Na2SO4 rejection of 98.0%. This work achieves the control of substrate hydrophilicity by introducing hydrophilic additives and provides new insights for the fabrication of high-performance nanofiltration membranes.

Loose nanofiltration (LNF) membranes show applications in various fields such as the separation of dyes and salts. The development of LNF membranes with high permeability and high dye/salt selectivity has received great attention in recent years. In this study, inorganic graphitic carbon nitride (g-C3N4) nanofibers modified with polyethyleneimine (PEI) were cross-linked by glutaraldehyde to fabricate a novel LNF membrane on polyethersulfone (PES) microfiltration membrane. Owing to the great hydrophilicity, electro-positivity, and unique structure, the composite membrane exhibits excellent Congo red (CR)/NaCl selectivity of 301.8 with water permeance as high as 162.7 L m(-2) h(-1) bar(-1). Moreover, the cross-linked inorganic separation layer enables the membranes with excellent alkali and temperature resistance. After being immersed in an acidic solution (pH = 1) or an alkaline solution (pH = 13) for 48 h, the rejection to CR does not significantly decrease. Furthermore, the nanofiltration membrane maintains structural stability without obvious decline in CR rejections over the temperature range of 25 similar to 95 degrees C, demonstrating the potential in high temperature separation. The present work will open up an avenue for designing and fabricating high-performance nanofiltration membranes.