NF Membranes Research Articles

Selective ion permeation enables reduced combined gypsum-organic fouling of loose nanofiltration membranes

During the long-term operation of NF membranes, the occurrence of combined gypsum-organic fouling is a significant challenge. While numerous studies have focused on enhancing the fouling resistance of NF through various methods (e.g., antiscalants, pretreatment), there has been limited exploration into the correlation between its structural looseness and fouling resistance. Herein, we conducted an experimental study to evaluate the correlation by employing three NF membranes with different looseness degrees: a custom-developed loosely structured NF membrane (CLNF), the moderately loose NF270, and the tightly structured NF90. Our findings indicated that NF membranes with loose polyamide structure exhibited superior fouling resistance to gypsum scaling and combined gypsum-organic fouling, induced by model organic matters like bovine serum albumin (BSA), humic acid (HA), and sodium alginate (SA). After applying SA-coating to calibrate the surface properties of the membranes to exclude the influence of surface roughness, hydrophilicity, and functional groups, our study attributed the difference in fouling resistance to variations in ionic selectivity stemming from membrane looseness. Specifically, the primary advantage of looser polyamide NF membranes lies in enhanced Ca2+ permeation, which not only reduces the “egg-box” effect and surface foulant accumulation but also diminishes cake-enhanced concentration polarization, effectively mitigating gypsum-organic fouling. In real water testing scenarios, the enhanced fouling resistance of loose NF membranes was further affirmed. This research underscored the unexpected benefit of loose NF membranes in terms of fouling resistance, providing a novel insight for future application.

Treatment of tomato paste wastewater by electrochemical and membrane processes: process optimization and cost calculation.

This study investigated the treatment of wastewater from tomato paste (TP) production using electrocoagulation (EC) and electrooxidation (EO). The effectiveness of water recovery from the pretreated water was then investigated using the membrane process. For this purpose, the effects of independent control variables, including electrode type (aluminum, iron, graphite, and stainless steel), current density (25-75 A/m2), and electrolysis time (15-120 min) on chemical oxygen demand (COD) and color removal were investigated. The results showed that 81.0% of COD and 100% of the color removal were achieved by EC at a current density of 75 A/m2, a pH of 6.84 and a reaction time of 120 min aluminum electrodes. In comparison, EO with graphite electrodes achieved 55.6% of COD and 100% of the color removal under similar conditions. The operating cost was calculated to be in the range of $0.56-30.62/m3. Overall, the results indicate that EO with graphite electrodes is a promising pretreatment process for the removal of various organics. In the membrane process, NP030, NP010, and NF90 membranes were used at a volume of 250 mL and 5 bar. A significant COD removal rate of 94% was achieved with the membrane. The combination of EC and the membrane process demonstrated the feasibility of water recovery from TP wastewater.

Improving the quality of liquid smoke by filtration using membranes

Liquid smoke (LS) is getting more attention in many applications, especially food preservation. However, there is still a big problem with the purity of LS. The objective of this study is to improve the quality of LS using membrane filtration. The filtrations were conducted using ultrafiltration or nanofiltration membrane at various pressures. The quality of LS before and after filtration was compared based on their appearance. During the filtration process, LS changed from a dark yellow fluid with a pungent odor to a pale colorless substance with a less smokey odor and a slightly sweet aroma. The color and fragrance parameters of LS before and after filtration using UF membranes were not significantly different. NF membrane filtering had the opposite effect on the appearance of LS. Chemical composition of volatile fraction was studied by GC/MS. Phenols were the predominant aromatic chemicals found in all samples, with LS containing up to 80.8%, 17.53% in treated LS by UF membrane (2 bars), and 48.31% in NF membrane (5 bars). The results proved that the membrane processing can eliminates potentially toxic compounds while still imparting the desired flavors and pleasent aromas of LS.

Grafting modification of thin-film composite membrane with quaternary ammonium polyelectrolyte for Mg2+/Li+ separation

The positively charged nanofiltration membrane (NF) has a strong repulsive effect on divalent magnesium ions, thus could be applied for the separation of Mg2+/Li+. Chemical grafting modification is an effective way to prepare positively charged membranes. However, it is difficult to achieve chemical modification on the surface of polyamide membrane as the chemical stability of polyamide. By introducing hydroxyl rich monomers (3-[n-tris(hydroxymethyl)methylamino]−2-hydroxypropanesulfonic, HMAH) as active sites in the interfacial polymerization process, the olefin monomers containing quaternary ammonium salt functional groups (acryloxyethyl trimethyl ammonium chloride, ATA) were reacted onto the surface of NF membrane through radical polymerization initiated by cerium ions to obtain positively charged NF membrane. The successful grafting reaction of quaternary ammonium salt monomer onto the surface of NF membrane was verified by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). The membrane with dense and smooth surface layer showed C-N+ characteristic peak in XPS N1s spectra and high isoelectric point. Meanwhile, the as-prepared membrane achieved high MgCl2 rejection of 95.74% and low LiCl rejection of 18.1%, with pure water permeance of 9.43 L·m−2·h−1·bar−1. After 60 hours of mixture filtration experiment, the membrane exhibited good long-term stability, maintaining the ionic separation selectivity over 30, which indicated that the positively charged membrane prepared by grafting method has potential application in the separation of Mg2+/Li+.

Structural and separation evaluation of polysulfone-based loose NF membrane modified with itaconic acid-choline chloride deep eutectic solvent as additive

In this research, a type of deep eutectic solvent (DES) based on itaconic acid-choline chloride (IA-CC) was used as an efficient additive to modify the structure of the polysulfone-based membrane. Structural investigation of the as-obtained loose nanofiltration (LNF) membrane was performed through various analyses. The results showed that the use of a very low amount of IA-CC DES in the structure of the polysulfone (PSF) membrane caused the formation of finger-like pores in the structure and increased the porosity. Consequently, a significant increase in the water flux was obtained compared to the membrane synthesized with polyvinylpyrrolidone (PVP) as a common pore former (from 18.22 to 257.14 LMH). The rejection for anionic and cationic dyes as well as the binary mixtures of dyes was evaluated. The rejection of divalent Mg and Ca ions was 16.5% and 15.0%, respectively, while that of monovalent sodium ions was less than 3%. Based on the best of our knowledge, the highest water flux at low pressure (2 bar) despite the high rejection for dyes among all the NF membranes has been reported in this work. Moreover, the antifouling properties of DES-modified membrane against bovine serum albumin (BSA) showed a slight increase in the antifouling index.

Preparation of high performance membrane via one-step polymerization and co-deposition of polydopamine/zwitterionic monomers/poly(ethylene glycol) diacrylate

Membrane separation is an effective method for water purification. However, conventional preparation processes for the membranes usually suffer from complicated production technology and lack versatility. Mussel-inspired chemistry has generated extensive interest in exploring a facile strategy for the preparation of polymeric membranes. In this work, a simple, green and time saving strategy is proposed for accomplishing the surface functionalization via one-step polymerization and co-deposition of dopamine/zwitterion/poly(ethylene glycol) diacrylate (PEGDA). The chain segment of the zwitterion can tightly bind water molecules upon the membrane surface, enhancing the hydrophilicity of the membrane. The chain segment of PEGDA can offer cross-linking sites during the co-deposition process, facilitating the formation of the network structure. The retention to dyes for the membranes prepared with PEGDA was higher than those membranes prepared without PEGDA. The optimized membrane exhibited high water permeance up to 25.9 L m−2 h−1 bar−1, with rejection of 99.7 % and 99.6 % for Methyl blue and Congo Red. Meanwhile, the anti-bacterial rate for the optimized membrane reaches 75.9 %, and the water flux recovery rate (FRR) is as high as 86.65 %. The results cast a light on the exploration of the PDA-based NF membranes, featuring simple production technology and versatile capabilities for the separation of various dyes.

Optimization Thickness of Photoanode Layer and Membrane as Electrolyte Trapping Medium for Improvement Dye-Sensitized Solar Cell Performance

Dye-Sensitized Solar Cells (DSSC) are photovoltaic devices that contain a dye that acts as a solar light acceptor. The use of dyesensitized solar cells to solve increasing energy demand and environmental problems still results in low efficiency values. In this study, optimization of DSSC components was carried out to increase DSSC efficiency by varying the thickness of the titanium dioxide (TiO2) semiconductor photoanode layer, polyvinylidene fluoride (PVDF) trap electrolyte membrane, and polyvinylidene fluoride nanofiber (PVDF NF) to obtain the optimum thickness. Scanning Electron Microscope (SEM) results of membrane thickness variation and titanium dioxide (TiO2) semiconductor photoanode coating showed the formation of nanofiber fibers composed of three-dimensional, porous, and diameter networks connected to the PVDF NF membrane. The increase in density and decrease in pore size, along with an increase in thickness and cracking as the TiO2 photoanode semiconductor layer increases, affect the electron transport rate of the DSSC. The higher particle density level will inhibit the electron transport rate, so it can reduce the efficiency of DSSC. The optimum thickness of the TiO2 semiconductor layer and PVDF NF electrolyte membrane of 0.20 mm and 0.35 mm can produce values, voltage, fill factor current density, and electrical efficiency of 500 mV, 2.7 x 10−3 mA.cm−2, 1.80%, and 2.40%, respectively.

A membrane-assisted green strategy for purifying bioactive compounds from extracted white wine lees

This work was aimed at investigating the recovery of wine-derived bioactive compounds from white wine lees through a combination of hydroalcoholic extraction and membrane-based operations, as a potential alternative for winery wastewater treatment and valorisation.Hydroalcoholic extracts obtained in selected conditions of solid–liquid ratio, extraction time and working temperature (1:10, 25 % and 32 ± 2 °C, respectively) were previously clarified by ultrafiltration (UF) in order to produce a clarified solution free of suspended solids and colloidal substances. The concentration of bioactive compounds from the clarified extract was investigated by using three different spiral-wound NF membranes with molecular weight cut-off (MWCO) in the range of 200–1000 Da (TS40, XN45 and NP010, all from Microdyn-Nadir); their performance was analysed in terms of productivity, fouling index and retention towards target compounds (polyphenols, flavonoids, sugars) and antioxidant activity.Low molecular weight polyphenols (i.e. gallic acid, catechin, vanillic acid, epicatechin and caffeic acid) were highly rejected by the selected membranes despite their difference in MWCO; on the other hand, the rejection index for total phenolic content (TPC), flavonoids and glucose was in agreement with the MWCO. The TS40 membrane, with a lowest cut-off (200–300 Da), showed the highest rejection for flavonoids (100 %) and rejections for total phenolic compounds of 85 % resulting in concentrated fractions containing 1.7 g of gallic acid equivalents per liter (GAE/L); most of the components analysed in the retentate samples showed a concentration factor of approximately 3.5 in agreement with the weight reduction factor of the NF process. The analysis of fouling mechanisms according to the Hermia’s model revealed that the cake filtration mechanism was the predominant one for all selected NF membranes.

Per- and polyfluoroalkyl substance separation by NF and RO membranes: a critical evaluation of advances and future perspectives

Treating PFAS-contaminated water is challenging due to the recalcitrant nature of PFAS. This review discusses advances in NF/RO membranes for separating PFAS from water and introduces a total management plan for handling the concentrated PFAS stream.

Comprehensive analysis of permeation resistance changes of the TFC RO/NF membranes during heat curing

The TFC RO/NF membranes are the predominant membranes applied in desalination, and heat curing is an essential step in its industrial production, which increases the polyamide cross-linking degree and facilitate packing but leads permeability decrease. Nevertheless, the mechanism of heat curing on TFC membranes permeation resistance changes is still ambiguous. Figuring it out will aid in crafting a more effective optimization strategy in high flux membrane preparation. Herein, we prepared a range of TFC RO/NF membranes with various monomer concentrations on different substrates and quantified the permeation resistance changes by a resistance-in-series model. For nascent TFC RO/NF membranes, the PA layer provided almost all permeation resistance. After heat curing, the substrate exhibited a marked increase in permeation resistance. The change in the permeation resistance composition was further exacerbated by the decrease in monomer concentration. For TFC NF membranes with heat curing, the proportion of substrate permeation resistance increased significantly, rising from 31.62 % to 75.05 %. This study made a comprehensive analysis of the impact of the permeation resistance in TFC RO/NF membranes caused by heat curing, enriched the insight into the impact of heat curing on TFC membranes, and helped to prepare TFC membranes with better desalination performance.

Reclamation of impacted urban phreatic water through nanofiltration technology: Insight on natural organic matter removal by fluorescence spectroscopy

Nanofiltration (NF) is a promising technology called to play a relevant role in water reclamation, which lies in the core of circular economy in the water sector. The aim of this study was to assess two aromatic polyamide-based NF membranes (the looser NF270 and the tighter NF90 ones) for the treatment of urban impacted phreatic water. The focus was centred on the removal of dissolved inorganic and organic solutes and on the differences observed between solutes. Membrane ions rejection was modelled by the Solution-Electro-Diffusion Film Model (SEDFM). DOC was tracked by Fluorescence Excitation-Emission Matrices (FEEM) coupled to Parallel Factor Analysis (PARAFAC) to get insight into the character of DOC rejected by or permeated through the membranes. Results showed that the NF90 membrane systematically achieved upper values in the rejection of ions than the looser NF270 one. Variations between ions could be interpreted by the mechanisms ruling their rejection, i.e. Donnan and dielectric exclusion phenomena. Experimental rejections were also satisfactorily fit by the SEDFM, indicating that that the presence of DOC in the phreatic water did affect modelling of ions transport through the membranes. DOC was rejected at very high percentages (>90%) by both membranes, but FEEM-PARAFAC analysis revealed that humic- and tryptophan- like components were more rejected (>90% for both membranes) than tyrosine-like compounds (45% for NF270 and 57% for NF90). The finding is of relevance from a point of view of disinfection practices, as it has been observed that humic-like substances are strongly correlated with DBPs formation.

Effects of acid acceptor and pH on the structure and filtration performance of nanofiltration membrane

The thin film composite nanofiltration (TFC-NF) membranes with various properties were prepared by changing type and concentration of acid acceptors in the piperazine (PIP) solution. The influences of acid acceptors on interfacial polymerization (IP) process depend on the pH of PIP solution and the properties of acid acceptors. Na2CO3 and TEA provide positive effects at a pH range of 11.2–12.0. Especially for Na2CO3, water permeability and ion selectivity of the membrane simultaneously enhanced. The pH values reached above 12.8 with NaOH, and negative effects on permeance and selectivity were detected. The pH values ranged 10–11 after adding Na3PO4 and NaHCO3. The rejections of both Cl− and SO42− were high, especially for Cl− rejection increasing to above 73%. The pH values got to around 7 with NaH2PO4. The IP reaction was retarded and defects were detected on the membrane with quite low SO42− rejection. Protonation of PIP happens at low pH, while hydrolysis of acyl chloride of trimesoyl chloride happens at high pH. These changes will slow down the deprotonated PIP diffusion and the IP reaction. It is a feasible way to fabricate tailored NF membranes by changing acid acceptors and adjusting pH value of the PIP solution.

C3N4-interlayer-mediated interfacial polymerization of homopolymer nanofiltration membranes for efficient water purification

Interlayered thin film composite (TFNi) membranes have been shown to achieve high-quality polyamide (PA) skin layers with enhanced permeability and selectivity. Herein, we demonstrate the construction of a hydrophilic interlayer by polymeric graphitic carbon nitride (g-C3N4) for optimizing the interfacial polymerization of the nanofiltration membrane. Due to the effective enrichment and the slowed diffuse rate of amine monomer solutions, g-C3N4 modification decreases the thickness of the PA skin layer and increases the electronegativity of membranes. The best TFNi membrane exhibits a high water permeance of 31.82 L m−2 h−1 bar−1, nearly twice as high as that of the membrane without g-C3N4 interlayer, while maintaining a comparably Na2SO4 rejection efficiency. The stronger hydrophilicity and more negatively charged surface of the TFNi membrane effectively retarded membrane fouling, contributing to the high-efficiency removal of harmful drugs from actual surface water, with more than two times higher water flux that of commercialized NF270 membrane. This work provides a facile strategy to synthesize TFNi membranes with great application potential for high-performance nanofiltration.

Phytic acid and ferric chloride compound additives-regulated interfacial polymerization for high-performance nanofiltration membrane

To balance the permeability-selectivity trade-off effect of the polyamide nanofiltration membrane, interfacial polymerization regulation strategy is widely used to optimize the physicochemical structure of the polyamide film. In the present work, the compound additives of phytic acid and ferric chloride were added into the aqueous phase to regulate the interfacial polymerization process. On the one hand, a lot of piperazine monomers will be adsorbed around the phytic acid molecules due to the electrostatic interaction between phosphoric acid groups and amino groups. Meanwhile, the phytic acid molecules and ferric ions can form a complex in the piperazine solution, which results in a low diffusion rate of the other piperazine monomers without adsorbed on the phytic acid and ferric chloride complex due to steric hindrance. The synergistic effect of electrostatic interaction and steric hindrance leads to the optimized nanofiltration membrane with a thinner and looser polyamide structure. The best-performing nanofiltration membrane exhibits an approximately four-fold water permeance (28.4 L m−2 h−1 bar−1) compared with the controlled M0 nanofiltration membrane (6.5 L m−2 h−1 bar−1) without obviously sacrificing the Na2SO4 rejection (96.9 %). This simple interfacial polymerization regulation strategy provides a novel insight for the preparation of high-performance NF membrane.

The Removal of Potassium Phosphate using Ceramic Nanofiltration

In the current study, the separation and rejection behavior of potassium phosphate salt using NF membrane was studied theoretically and experimentally. The extended Nernst Planck equation was used to describe the NF separation behavior by using silver frost programming language using the version FTN95 model. Besides the modeling; an experimental work was done by preparing K3PO4 solution at concentration of 0.1 and 0.4 M. Where the rejections of K1+ and PO43- ions were obtain at different TMP values ranging between 1 to 5 bars. From theoretical results, it was noticed that the best rejection of K1+ and PO43- ions where at a volumetric fluxes ranging between was 2.5E-06 to 5E-07 m³/m².sec. Experimental results should that the rejection value for of PO43- ions increased as the concentration decreased and TMP increased; which is supported by the theoretical results. In the case of K1+ ion; the higher rejection values as the concentration increased and TMP increased

Lithium recovery from the spent lithium-ion batteries by commercial acid-resistant nanofiltration membranes: A comparative study

Given the critical requirements of environmental preservation and resource reutilization, the recovery of lithium from spent lithium-ion (LIBs) batteries holds immense significance. This study investigates the viability of nanofiltration (NF) membranes for selectively separating lithium from spent LIBs leaching solution. A membrane-based approach uniquely sidesteps the significant metal losses often encountered in traditional methods that necessitate initial pH adjustments. The NF270 and DK membranes were characterized and evaluated. DK demonstrated superior rejection capabilities for high-valence metal ions with over 99.0 % rejection, while allowing a notable 40.1 % lithium passage rate. Furthermore, DK showcased enhanced acid resistance compared to NF270. The findings underscore the characteristics essential for NF membranes in this application, and the study affirms the feasibility of membrane-based lithium recovery, marking a stride in battery recycling research.

Ionic liquid-functionalized antibiofouling nanofiltration membranes

Nanofiltration membranes hold great potential for water treatment applications, but are susceptible to fouling issues. In this study, we demonstrate the fabrication of NF membranes with high permeability, high rejection, antibiofouling and scaling resistance. The membrane was prepared through interfacial polymerization by doping the aqueous phase with 1-aminoethyl-3-methylimidazolium tetrafluoroborate ionic liquid. The TFC-0.2 membrane exhibited a more open nanoporous structure, resulting in an increased permeability from 5 ± 0.5 L·m−2·h−1·bar−1 (LMH/Bar) to 11.1 ± 0.4 LMH/Bar, while maintaining a comparable salt rejection performance to the original TFC membrane. Additionally, the TFC-0.2 membrane demonstrated excellent retention performance, with a removal efficiency exceeding 90 % for emerging contaminants such as antibiotics and PFOA. Notably, the TFC-0.2 membrane exhibited significant differences in the rejection of Na2SO4 and CaCl2, indicating its strong resistance to gypsum fouling. Furthermore, it is worth highlighting that the TFC-0.2 membrane displayed remarkable antibiofouling performance due to the bactericidal properties of AMIT. This capability allowed for the sterilization of bacteria at the early stage of attachment to the membrane surface, effectively mitigating biofouling. The findings of this study offer a simple yet effective strategy for fabricating high-performance nanofiltration membranes with exceptional antifouling properties.

Membrane Cascade Fractionation of Tomato Leaf Extracts-Towards Bio-Based Crop Protection.

Promising initial results from the use of membrane-fractionated extracts of tomato leaf as crop protection agents have recently been reported. This paper provides additional evidence from larger scale experiments that identify an efficient pipeline for the separation of tomato leaf extracts to generate a fraction with significant defence elicitor activity. A UF tubular membrane 150 kDa, with an internal diameter of 5 mm, proved appropriate for initial extract clarification, whereas afterwards a UF 10 kDa and three NF membranes (200-800 Da) in sequence were evaluated for the subsequent fractionation of this tomato extract. The compositions of sugars, proteins and total biophenols were changed in these fractions with respect to the initial extract. The initial extract ratio of sugars: proteins: biophenols was 1:0.047:0.052, whereas for the retentate of the 800 Da NF membrane, which has the higher crop protection activity, this ratio was 1:0.06:0.1. In this regard, it appears that the main crop protection effect in this fraction was due to the sugars isolated. It was found that with the appropriate membrane cascade selection (UF 150 kDa, UF 10 kDa and NF 800 Da) it was possible to produce (easily and without the need of additional chemicals) a fraction that has significant activity as an elicitor of disease resistance in tomato, whereas the remaining fractions could be used for other purposes in a biorefinery. This is very promising for the wider application of the proposed approach for the relatively easy formulation of bio-based aqueous streams with bio-pesticide activities.

Ternary deep eutectic solvent enhanced the diffusion control of amine monomer for highly permeable and anti-fouling polyamide nanofiltration membranes

Thin-film composite nanofiltration (TFC NF) membranes have been widely used in water treatment, while the common active polyamide (PA) separation layer suffers the problems of excessive mass transfer resistance and fouling. In this work, a novel ternary deep eutectic solvent (DES) of citric acid/choline chloride/glycol as an additive in the aqueous phase was focused on regulating the formation of PA layer. The ternary DES can interact with piperazine (PIP) via hydrogen bonding and electrostatic interaction, synergistically enhancing the diffusion control of PIP with viscosity modulation during interfacial polymerization. Notably, a thinner and rougher separation layer with a cellular-like structure was obtained by optimizing the ratio of citric acid in ternary DES. Accordingly, the optimized TFC10%-3 membrane maintained an excellent Na2SO4 rejection (98.8 %) and a 104.7 % increase in pure water permeance (39.5 L·m−2·h−1·bar−1) compared to the original membrane, outperforming commercial membranes and the most NF membranes reported in the literature. Besides, the introduction of citric acid in PA layer increased the surface hydrophilicity and electronegativity of TFC10%-3 membrane, resulting in a higher flux recovery rate (FRR = 93.2 %) of TFC10%-3 membrane than that of TFC10%-0 membrane (FRR = 83.9 %). This study provides a feasible design strategy for the preparation of highly permeable and anti-fouling TFC NF membranes and enrichs the application of ternary DES in water treatment.

Supramolecular chemistry assisted construction of ultra-permselective polyamide nanofilm with asymmetric structure for ion sieving

Highly-permselective NF membranes are critical to energy-efficient ionic separation. Herein, an ultra-permselective polyamide (PA) nanofilm with asymmetric two-layered structure is achieved by supramolecular chemistry modulated interfacial polymerization (IP) process. Such nearly-40-nm asymmetric PA nanofilm consists of a PA dense layer with nanoscale homogeneity and a polydopamine-β-cyclodextrin (PDA-β-CD) porous layer induced by mussel-inspired surface chemistry, with crosslinking. Experimental characterizations reveal that the exceptionally-hydrophilic and highly-porous PDA-β-CD coating imparts the spatial enrichment and temporal retardation of amine monomers via H-bonding and host-guest interactions, conducing to form the diffusion-difference-enabled striped PA nanofilm with nanoscale ordered structures and enhanced cross-linking degree. Meanwhile, the PDA-β-CD porous coating not only can finely tune the microstructure of PA nanofilm, but also highly prefers for surmounting funnel effect and shortening water transport path. As a result, the resultant asymmetric PA nanofilm attains a noticeable water permeance of 38.59 ± 2.42 L m−2 h−1 bar−1, competitive retention of Na2SO4 (99.4 ± 0.2 %) and unprecedented Cl−/SO42− selectivity of 202.1, far outperforming the state-of-the-art commercial and lab-made NF membranes. Moreover, it evinces an outstanding ion-sieving performance under the high-salinity solutions, suggesting that our approach for tuning microstructure enables the development of ultra-permeability and excellent selectivity for application in brine refinement and salt reclamation.