Membranes

18 pages, 837 KB

Open AccessArticle

Comparative Assessment of Reverse Osmosis and Nanofiltration for Wine Partial Dealcoholization: Effects on Membrane Performance, Fouling, and Phenolic Compounds

by Josip Ćurko, Marin Matošić, Karin Kovačević Ganić, Marko Belavić, Vlado Crnek, Pierre-Louis Teissedre and Natka Ćurko

Membranes 2026, 16(1), 48; https://doi.org/10.3390/membranes16010048 - 22 Jan 2026

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Abstract

This study evaluates the partial dealcoholization of red wine using reverse osmosis (ACM3) and nanofiltration (TS80) membranes at 25 and 35 bar, targeting 2% and 4% ethanol reductions. Membrane performance was assessed through fouling analysis and ethanol partitioning, while wine phenolic (flavan-3-ols, anthocyanins) [...] Read more.

This study evaluates the partial dealcoholization of red wine using reverse osmosis (ACM3) and nanofiltration (TS80) membranes at 25 and 35 bar, targeting 2% and 4% ethanol reductions. Membrane performance was assessed through fouling analysis and ethanol partitioning, while wine phenolic (flavan-3-ols, anthocyanins) and color characteristics (CIELab parameters) were determined. The 2% reduction process with ACM3 at 25 bar resulted in minimal phenolic changes. The 4% reduction process revealed distinct performance profiles: ACM3 exhibited exceptional stability (3.35–5.30% permeability loss, linear flux decline with R² > 0.93) and ethanol rejection of 17.6–25.5%, while TS80 achieved processing rates three to six times faster with moderate fouling (16.3% loss, 7.7–13.3% rejection). Decreases in flavan-3-ols and anthocyanin concentrations correlated with fouling intensity rather than processing duration. Proanthocyanidin structure remained stable, and color shifts reflected changes in polymeric pigments rather than anthocyanin loss. Reverse osmosis at low transmembrane pressure proved most suitable for quality preservation. The operational trade-off is clear: TS80 offers three to six times faster processing but with greater phenolic loss, while ACM3 requires longer batch times with minimal fouling. Both processes demonstrate that membrane-based dealcoholization without fluid replacement is feasible, providing winemakers with a valuable method to reduce alcohol while preserving quality. Full article

(This article belongs to the Special Issue Membrane Technologies in Food Processing)

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18 pages, 2446 KB

Open AccessArticle

Preparation of Ester-Crosslinked PI Membranes with Enhanced Gas Selectivity and Plasticization Resistance

by Yu Li, Jiangzhou Luo, Honglei Ling and Song Xue

Membranes 2026, 16(1), 47; https://doi.org/10.3390/membranes16010047 - 20 Jan 2026

Viewed by 288

Abstract

Fabricating polyimide (PI) membranes with outstanding anti-plasticization ability and gas separation performance remains a challenge. In this study, two novel diamine monomers, DAMBO (methyl 3,5-diamino-4-methylbenzoate) and DAPGBO (3-hydroxypropyl 3,5-diamino-4-methylbenzoate), were synthesized through esterification reactions. Then, we copolymerized each of these two new monomers [...] Read more.

Fabricating polyimide (PI) membranes with outstanding anti-plasticization ability and gas separation performance remains a challenge. In this study, two novel diamine monomers, DAMBO (methyl 3,5-diamino-4-methylbenzoate) and DAPGBO (3-hydroxypropyl 3,5-diamino-4-methylbenzoate), were synthesized through esterification reactions. Then, we copolymerized each of these two new monomers with 4,4′-diaminodiphenylmethane (DAM) and 4,4′-(Hexafluoroisopropylidene) diphthalic anhydride (6FDA) separately to yield two monoesterified PIs. Following this, we further prepared the ester-crosslinked PIs by inducing a transesterification crosslinking reaction within the PI-PGBO membrane via thermal treatment. As expected, we found that the formation of cross-linked structures can effectively regulate the microporous structure, enhance its sieving performance, and thus improve the membrane’s gas selectivity. Furthermore, the resulting network structure endowed the thermally treated PI membrane with excellent anti-plasticization ability. Physical characterization results show that after heat treatment, both the d-spacing and BET surface area of the PI membrane decreased, but the solvent resistance of the thermally treated PIs was significantly improved. Gas separation experiments revealed that the representative membrane (PI-PGBO-300) exhibited the optimal CO₂/CH₄ separation performance, with a CO₂ permeability of 371.05 Barrer, a CO₂/CH₄ selectivity of 28.11, and a CO₂ plasticization pressure exceeding 30 bar. This study provides valuable insights into the design of cross-linked polyimides (PIs) via transesterification reactions, which are capable of enhancing the performance of membrane-based gas separation processes. Full article

(This article belongs to the Special Issue Membranes and Membrane Reactors for Gas Purification and Production: Towards More Sustainable Processes)

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3 pages, 147 KB

Open AccessEditorial

Application of Membrane Materials in Bioseparation and Downstream Processing

by Wei Zhang and Lingxue Kong

Membranes 2026, 16(1), 46; https://doi.org/10.3390/membranes16010046 - 19 Jan 2026

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Abstract

Membrane technologies have played an instrumental role in bioseparation and downstream processing [...] Full article

(This article belongs to the Special Issue Application of Membrane Materials in Bioseparation and Downstream Processing)

21 pages, 5659 KB

Open AccessArticle

Development of High-Performance Catalytic Ceramic Membrane Microchannel Reactor for Carbon Dioxide Conversion to Methanol

by Aubaid Ullah, Nur Awanis Hashim, Mohamad Fairus Rabuni, Mohd Usman Mohd Junaidi, Ammar Ahmed, Mustapha Grema Mohammed and Muhammed Sahal Siddique

Membranes 2026, 16(1), 45; https://doi.org/10.3390/membranes16010045 - 17 Jan 2026

Viewed by 378

Abstract

Conversion of carbon dioxide (CO₂) to methanol in a traditional reactor (TR) with catalytic packed bed faces the challenge of lower reactant conversion due to thermodynamic limitations. On the contrary, membrane reactors selectively remove reaction products, enhancing the conversion, but it [...] Read more.

Conversion of carbon dioxide (CO₂) to methanol in a traditional reactor (TR) with catalytic packed bed faces the challenge of lower reactant conversion due to thermodynamic limitations. On the contrary, membrane reactors selectively remove reaction products, enhancing the conversion, but it is still limited, and existing designs face challenges of structural integrity and scale-up complications. Therefore, for the first time, a ceramic membrane microchannel reactor (CMMR) system was developed with 500 µm deep microchannels, incorporated with catalytic membrane for CO₂ conversion to methanol. Computational fluid dynamic (CFD) simulations confirmed the uniform flow distribution among the microchannels. A catalytic LTA zeolite membrane was synthesized with thin layer (~45 µm) of Cu-ZnO-Al₂O₃ catalyst coating and tested at a temperature of 220 °C and 3.0 MPa pressure. The results showed a significantly higher CO₂ conversion of 82%, which is approximately 10 times higher than TR and 3 times higher than equilibrium conversion while 1.5 times higher than conventional tubular membrane reactor. Additionally, methanol selectivity and yield were achieved as 51.6% and 42.3%, respectively. The research outputs showed potential of replacing the current industrial process of methanol synthesis, addressing the Sustainable Development Goals of SDG-7, 9, and 13 for clean energy, industry innovation, and climate action, respectively. Full article

(This article belongs to the Special Issue Ceramic Membranes: Preparation, Modification and Multidisciplinary Applications)

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11 pages, 1305 KB

Open AccessProtocol

Protocol for Engineered Compositional Asymmetry Within Nanodiscs

by Christopher F. Carnahan, Wei He, Yaqing Wang, Matthew A. Coleman and Atul N. Parikh

Membranes 2026, 16(1), 44; https://doi.org/10.3390/membranes16010044 - 16 Jan 2026

Viewed by 336

Abstract

Membrane proteins remain the most challenging targets for structural characterization, yet their elucidation provides valuable insights into protein function, disease mechanisms, and drug specificity. Structural biology platforms have advanced rapidly in recent years, notably through the development and implementation of nanodiscs—discoidal lipid–protein complexes [...] Read more.

Membrane proteins remain the most challenging targets for structural characterization, yet their elucidation provides valuable insights into protein function, disease mechanisms, and drug specificity. Structural biology platforms have advanced rapidly in recent years, notably through the development and implementation of nanodiscs—discoidal lipid–protein complexes that encapsulate and solubilize membrane proteins within a controlled, native-like environment. While nanodiscs have become powerful tools for studying membrane proteins, faithfully reconstituting the compositional asymmetry intrinsic to nearly all biological membranes has not yet been achieved. Proper membrane leaflet lipid distribution is critical for accurate protein folding, stability, and insertion. Here, we share a protocol for reconstituting tailored compositional asymmetry within nanodiscs through membrane extraction from giant unilamellar vesicles (GUVs) treated with a leaflet-specific methyl-β-cyclodextrin (mβCD) lipid exchange. Nanodisc asymmetry is verified through a geometric approach: biotin-DPPE-preloaded mβCD engages in lipid exchange with the outer leaflet of POPC GUVs solubilized by the lipid-free membrane scaffold protein (MSP) Δ49ApoA-I to form nanodisc structures. Once isolated, nanodiscs are introduced to the biotin-binding bacterial protein streptavidin. High-speed atomic force microscopy imaging depicts nanodisc–dimer complexes, indicating that biotin-DPPE was successfully reconstituted into a single leaflet of the nanodiscs. This finding outlines the first step toward engineering tailored nanodisc asymmetry and mimicking the native environment of integral proteins—a potentially powerful tool for accurately reconstituting and structurally analyzing integral membrane proteins whose functions are modulated by lipid asymmetry. Full article

(This article belongs to the Special Issue Membrane Proteins: New Insights into Structure, Dynamics and Functions)

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22 pages, 1803 KB

Open AccessArticle

Optimizing Al₂O₃ Ceramic Membrane Heat Exchangers for Enhanced Waste Heat Recovery in MEA-Based CO₂ Capture

by Qiufang Cui, Ziyan Ke, Jinman Zhu, Shuai Liu and Shuiping Yan

Membranes 2026, 16(1), 43; https://doi.org/10.3390/membranes16010043 - 16 Jan 2026

Viewed by 292

Abstract

High regeneration energy demand remains a critical barrier to the large-scale deployment of ethanolamine-based (MEA-based) CO₂ capture. This study adopts an Al₂O₃ ceramic-membrane heat exchanger (CMHE) to recover both sensible and latent heat from the stripped gas. Experiments confirm [...] Read more.

High regeneration energy demand remains a critical barrier to the large-scale deployment of ethanolamine-based (MEA-based) CO₂ capture. This study adopts an Al₂O₃ ceramic-membrane heat exchanger (CMHE) to recover both sensible and latent heat from the stripped gas. Experiments confirm that heat and mass transfer within the CMHE follow a coupled mechanism in which capillary condensation governs trans-membrane water transport, while heat conduction through the ceramic membrane dominates heat transfer, which accounts for more than 80%. Guided by this mechanism, systematic structural optimization was conducted. Alumina was identified as the optimal heat exchanger material due to its combined porosity, thermal conductivity, and corrosion resistance. Among the tested pore sizes, CMHE-4 produces the strongest capillary-condensation enhancement, yielding a heat recovery flux (q value) of up to 38.8 MJ/(m² h), which is 4.3% and 304% higher than those of the stainless steel heat exchanger and plastic heat exchanger, respectively. In addition, Length-dependent analyses reveal an inherent trade-off: shorter modules achieved higher q (e.g., 14–42% greater for 200-mm vs. 300-mm CMHE-4), whereas longer modules provide greater total recovered heat (Q). Scale-up experiments demonstrated pronounced non-linear performance amplification, with a 4 times area increase boosting q by only 1.26 times under constant pressure. The techno-economic assessment indicates a simple payback period of ~2.5 months and a significant reduction in net capture cost. Overall, this work establishes key design parameters, validates the governing transport mechanism, and provides a practical, economically grounded framework for implementing high-efficiency CMHEs in MEA-based CO₂ capture. Full article

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13 pages, 10056 KB

Open AccessArticle

An Electrical Equivalent Model of an Electromembrane Stack with Fouling Under Pulsed Operation

by Pablo Yáñez, Hector Ramirez and Alvaro Gonzalez-Vogel

Membranes 2026, 16(1), 42; https://doi.org/10.3390/membranes16010042 - 16 Jan 2026

Viewed by 291

Abstract

This study introduces a novel hybrid model for an electromembrane stack, unifying an equivalent electrical circuit model incorporating specific resistance (

R_{M}, R_{s}

) and capacitance (

C_{g s}, C_{d l}

) parameters with an empirical fouling [...] Read more.

This study introduces a novel hybrid model for an electromembrane stack, unifying an equivalent electrical circuit model incorporating specific resistance (

R_{M}, R_{s}

) and capacitance (

C_{g s}, C_{d l}

) parameters with an empirical fouling model in a single framework. The model simplifies the traditional approach by serially connecting N (

N = 10

) ion exchange membranes (anionic PC-SA and cationic PC-SK) and is validated using

N a C l

and

N a_{2} S O_{4}

solutions in comparison with laboratory tests using various voltage signals, including direct current and electrically pulsed reversal operations at frequencies of 2000 and 4000 Hz. The model specifically accounts for the chemical stratification of the cell unit into bulk solution, diffusion, and Stern layers. We also included a calibration method using correction factors (

α_{i}

) to fine-tune the electrical current signals induced by voltage stimulation. The empirical component of the model uses experimental data to simulate membrane fouling, ensuring consistency with laboratory-scale desalination processes performed under pulsed reversal operations and achieving a prediction error of less than 10%. In addition, a comparative analysis was used to assess the increase in electrical resistance due to fouling. By integrating electronic and empirical electrochemical data, this hybrid model opens the way to the construction of simple, practical, and reliable models that complement theoretical approaches, signifying an advance for a variety of electromembrane-based technologies. Full article

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20 pages, 1991 KB

Open AccessArticle

Application of Artificial Intelligence in Mathematical Modeling and Numerical Investigation of Transport Processes in Electromembrane Systems

by Ekaterina Kazakovtseva, Evgenia Kirillova, Anna Kovalenko and Mahamet Urtenov

Membranes 2026, 16(1), 41; https://doi.org/10.3390/membranes16010041 - 12 Jan 2026

Viewed by 352

Abstract

To enhance desalination efficiency and reduce experimental costs, the development of advanced mathematical models for EMS is essential. In this study, we propose a novel hybrid approach that integrates neural networks with high-accuracy numerical simulations of electroconvection. Based on dimensionless similarity criteria (Reynolds, [...] Read more.

To enhance desalination efficiency and reduce experimental costs, the development of advanced mathematical models for EMS is essential. In this study, we propose a novel hybrid approach that integrates neural networks with high-accuracy numerical simulations of electroconvection. Based on dimensionless similarity criteria (Reynolds, Péclet numbers, etc.), we establish functional relationships between critical parameters, such as the dimensionless electroconvective vortex diameter and the plateau length of current–voltage curves. Training datasets were generated through extensive numerical experiments using our in-house developed mathematical model, while multilayer feedforward neural networks with backpropagation optimization were employed for regression tasks. The resulting AI (artificial intelligence)-driven hybrid models enable rapid prediction and optimization of EMS design and operating parameters, reducing computational and experimental costs. This research is situated at the intersection of membrane science, artificial intelligence, and computational modeling, forming part of a broader foresight agenda aimed at developing next-generation intelligent membranes and adaptive control strategies for sustainable water treatment. The methodology provides a scalable framework for integrating physically based modeling and machine learning into the design of high-performance electromembrane systems. Full article

(This article belongs to the Special Issue Artificial Intelligence and Machine Learning for Membrane Process Optimization and Membrane Design)

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17 pages, 1683 KB

Open AccessArticle

Optimization of a 100% Product Utilization Process for LPG Separation Based on Distillation-Membrane Technology

by Peigen Zhou, Tong Jing, Jianlong Dai, Jinzhi Li, Zhuan Yi, Wentao Yan and Yong Zhou

Membranes 2026, 16(1), 40; https://doi.org/10.3390/membranes16010040 - 10 Jan 2026

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Abstract

This study presents the techno-economic optimization of a hybrid distillation-membrane process for the complete fractionation of liquefied petroleum gas (LPG), targeting high-purity propane, n-butane, and isobutane recovery. The process employs an initial distillation column to separate propane (99% purity) from a propane-enriched stream, [...] Read more.

This study presents the techno-economic optimization of a hybrid distillation-membrane process for the complete fractionation of liquefied petroleum gas (LPG), targeting high-purity propane, n-butane, and isobutane recovery. The process employs an initial distillation column to separate propane (99% purity) from a propane-enriched stream, which is subsequently fed to a two-stage membrane system using an MFI zeolite hollow-fiber membrane for n-butane/isobutane separation. Through systematic simulation and sensitivity analysis, different membrane configurations were evaluated. The two-stage process with a partial residue-side reflux configuration demonstrated superior economic performance, achieving a total operating cost of 31.58 USD/h. Key membrane parameters—area, permeance, and separation factor—were optimized to balance separation efficiency with energy consumption and cost. The analysis identified an optimal configuration: a membrane area of 800 m², an n-butane permeance of 0.9 kg·m⁻²·h⁻¹, and a separation factor of 40. This setup ensured high n-alkane recovery while effectively minimizing energy use and capital investment. The study concludes that the optimized distillation-membrane hybrid process offers a highly efficient and economically viable strategy for the full utilization of LPG components. Full article

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21 pages, 2946 KB

Open AccessArticle

Antiparasitic Veterinary Drugs—In Silico Studies of Membrane Permeability, Distribution in the Environment, Human Oral Absorption and Transport Across the Blood–Brain Barrier

by Anna W. Sobańska, Andrzej M. Sobański and Elżbieta Brzezińska

Membranes 2026, 16(1), 39; https://doi.org/10.3390/membranes16010039 - 10 Jan 2026

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Abstract

The present study examined the safety of 86 veterinary antiparasitic drugs in mammals based on their mobility in the soil–water compartment, bioconcentration factor in fish, and blood–brain barrier permeability. An in silico analysis was performed based on biomembrane permeability descriptors, using novel multiple [...] Read more.

The present study examined the safety of 86 veterinary antiparasitic drugs in mammals based on their mobility in the soil–water compartment, bioconcentration factor in fish, and blood–brain barrier permeability. An in silico analysis was performed based on biomembrane permeability descriptors, using novel multiple linear regression, boosted tree, and artificial neural network models. Additionally, intestinal absorption in humans was predicted quantitatively using pkCSM software and qualitatively using SwissADME. It was established that the majority of studied drugs are at least slightly mobile in soil, are unlikely to bioaccumulate in fish, and may be absorbed from the human gastro-intestinal tract; in addition, some of them have high potential to enter the mammalian brain. Full article

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16 pages, 3094 KB

Open AccessArticle

Effects of Lipopolysaccharides from Hafnia alvei PCM1200, Proteus penneri 12, and Proteus vulgaris 9/57 on Liposomal Membranes Composed of Natural Egg Yolk Lecithin (EYL) and Synthetic DPPC: An EPR Study and Computer Simulations

by Dariusz Man, Barbara Pytel and Izabella Pisarek

Membranes 2026, 16(1), 38; https://doi.org/10.3390/membranes16010038 - 8 Jan 2026

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Abstract

The aim of this study was to investigate the effects of three lipopolysaccharides (LPS), obtained from Hafnia alvei PCM 1200, Proteus penneri 12, and Proteus vulgaris 9/57, on the fluidity of liposomal lipid membranes. The experiments were performed on liposomes composed of egg [...] Read more.

The aim of this study was to investigate the effects of three lipopolysaccharides (LPS), obtained from Hafnia alvei PCM 1200, Proteus penneri 12, and Proteus vulgaris 9/57, on the fluidity of liposomal lipid membranes. The experiments were performed on liposomes composed of egg yolk lecithin (EYL) in the liquid-crystalline phase and synthetic lecithin (DPPC) in the gel phase. The experimental results were compared with data obtained from a computational model of the membrane surface layer. Membrane fluidity was assessed using EPR spectroscopy with the spin probes TEMPO (surface layer; changes in the F parameter) and 16-DOXYL (hydrophobic core; changes in the τ parameter). In EYL liposomes, all LPS samples induced a reduction in surface-layer fluidity (decrease in the F/F₀ ratio). In contrast, effects on the hydrophobic core (τ/τ₀) were observed only at low dopant concentrations (<0.2%), above which membrane fluidity plateaued. In DPPC membranes, the response was more complex: local minima in F/F₀ and maxima in τ/τ₀ were detected, indicating transient alterations in membrane stiffening and plasticization that depended on the specific LPS applied. Computational simulations of the membrane surface further confirmed the greater susceptibility of low-mobility systems (corresponding to the gel phase) to dopant-induced perturbations. In the model, the best agreement with the EPR data was obtained when an effective dopant charge of q = 3 was assumed. Full article

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20 pages, 4094 KB

Open AccessArticle

Theoretical and Experimental Studies of Permeate Fluxes in Double-Flow Direct-Contact Membrane Distillation (DCMD) Modules with Internal Recycle

by Chii-Dong Ho, Ching-Yu Li, Thiam Leng Chew and Yi-Ting Lin

Membranes 2026, 16(1), 37; https://doi.org/10.3390/membranes16010037 - 6 Jan 2026

Viewed by 369

Abstract

A new DCMD module design that introduces an insulation barrier of negligible thickness to divide the open duct of the hot-saline feed into two subchannels for dual-flow operation was investigated. This configuration enables one subchannel to operate in a cocurrent-flow mode and the [...] Read more.

A new DCMD module design that introduces an insulation barrier of negligible thickness to divide the open duct of the hot-saline feed into two subchannels for dual-flow operation was investigated. This configuration enables one subchannel to operate in a cocurrent-flow mode and the other in a countercurrent-flow recycling mode, thereby significantly enhancing the permeate flux. Theoretical and experimental investigations were conducted to develop modeling equations capable of predicting the permeate flux in DCMD modules. These studies demonstrated the technical feasibility of minimizing temperature polarization effects while improving flow characteristics to boost permeate flux. Results indicated that increasing both convective heat-transfer coefficients and residence time generally improved device performance. The dual-flow operation increased fluid velocity and extended residence time, leading to reduced heat-transfer resistance and enhanced heat-transfer efficiency. Theoretical predictions and experimental results consistently showed that the absorption flux improved by up to 40.77% under the double-flow operation with internal recycling configuration compared to a single-pass device of identical dimensions. The effects of inserting the insulation barrier on permeate flux enhancement, power consumption, and overall economic feasibility were also discussed. Full article

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1 pages, 162 KB

Open AccessCorrection

Correction: Rosentreter et al. Partial Desalination of Saline Groundwater: Comparison of Nanofiltration, Reverse Osmosis and Membrane Capacitive Deionisation. Membranes 2021, 11, 126

by Hanna Rosentreter, Marc Walther and André Lerch

Membranes 2026, 16(1), 36; https://doi.org/10.3390/membranes16010036 - 6 Jan 2026

Viewed by 254

Abstract

There was an error in the original publication [...] Full article

(This article belongs to the Special Issue Selected Papers from the MELPRO 2020)

17 pages, 1279 KB

Open AccessReview

Polysulfone Membranes: Here, There and Everywhere

by Pere Verdugo, Iwona Gulaczyk, Magdalena Olkiewicz, Josep M. Montornes, Marta Woźniak-Budych, Filip F. Pniewski, Iga Hołyńska-Iwan and Bartosz Tylkowski

Membranes 2026, 16(1), 35; https://doi.org/10.3390/membranes16010035 - 5 Jan 2026

Viewed by 678

Abstract

Polysulfone (PSU) membranes are widely recognized for their thermal stability, mechanical strength, and chemical resistance, making them suitable for diverse separation applications. This review highlights recent advances in PSU membrane development, focusing on fabrication techniques, structural modifications, and emerging applications. Phase inversion remains [...] Read more.

Polysulfone (PSU) membranes are widely recognized for their thermal stability, mechanical strength, and chemical resistance, making them suitable for diverse separation applications. This review highlights recent advances in PSU membrane development, focusing on fabrication techniques, structural modifications, and emerging applications. Phase inversion remains the predominant method for membrane synthesis, allowing precise control over morphology and performance. Functional enhancements through blending, chemical grafting, and incorporation of nanomaterials—such as metal–organic frameworks (MOFs), carbon nanotubes, and zwitterionic polymers—have significantly improved gas separation, and water purification., In gas separation, PSU-based mixed matrix membranes demonstrate enhanced CO₂/CH₄ selectivity, particularly when integrated with MOFs like ZIF-7 and ZIF-8. In water treatment, PSU membranes effectively remove algal toxins and heavy metals, with surface modifications improving hydrophilicity and antifouling properties. Despite these advancements, challenges remain in optimizing cross-linking strategies and understanding structure–property relationships. This review provides a comprehensive overview of PSU membrane technologies and outlines future directions for their development in sustainable and high-performance separation systems. Full article

(This article belongs to the Special Issue Advanced Membrane Technologies for Gas Capture and Clean Energy: Multiscale Insights and Applications)

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15 pages, 2433 KB

Open AccessArticle

Investigation of Biogas Dry Reforming over Ru/CeO₂ Catalysts and Pd/YSZ Membrane Reactor

by Omid Jazani and Simona Liguori

Membranes 2026, 16(1), 34; https://doi.org/10.3390/membranes16010034 - 5 Jan 2026

Viewed by 456

Abstract

The biogas dry reforming reaction offers a promising route for syngas production while simultaneously mitigating greenhouse gas emissions. Membrane reactors have proven to be an excellent option for hydrogen production and separation in a single unit, where conversion and yield can be enhanced [...] Read more.

The biogas dry reforming reaction offers a promising route for syngas production while simultaneously mitigating greenhouse gas emissions. Membrane reactors have proven to be an excellent option for hydrogen production and separation in a single unit, where conversion and yield can be enhanced over conventional processes. In this study, a Pd/YSZ membrane integrated with a Ru/CeO₂ catalyst was evaluated for biogas reaction under varying operating conditions. The selective removal of hydrogen through the palladium membrane improved reactant conversion and suppressed side reactions such as methanation and the reverse water–gas shift. Experiments were performed at temperatures ranging from 500 to 600 °C, pressures of 1–6 bar, and a gas hourly space velocity (GHSV) of 800 h⁻¹. Maximum conversions of CH₄ (43%) and CO₂ (46.7%) were achieved at 600 °C and 2 bar, while the maximum hydrogen recovery of 78% was reached at 6 bar. The membrane reactor outperformed a conventional reactor, offering up to 10% higher CH₄ conversion and improved hydrogen production and yield. Also, a comparative analysis between Ru/CeO₂ and Ni/Al₂O₃ catalysts revealed that while the Ni-based catalyst provided higher CH₄ conversion, it also promoted methane decomposition reaction and coke formation. In contrast, the Ru/CeO₂ catalyst exhibited excellent resistance to coke formation, attributable to ceria’s redox properties and oxygen storage capacity. The combined system of Ru/CeO₂ catalyst and Pd/YSZ membrane offers an effective and sustainable approach for hydrogen-rich syngas production from biogas, with improved performance and long-term stability. Full article

(This article belongs to the Special Issue Advanced Membrane Design for Hydrogen Technologies)

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17 pages, 7229 KB

Open AccessArticle

Impact of Lipid Composition on Membrane Partitioning and Permeability of Gas Molecules

by Paween Mahinthichaichan, Ahmad Raeisi Najafi, Fraser J. Moss, Ardeschir Vahedi-Faridi, Walter F. Boron and Emad Tajkhorshid

Membranes 2026, 16(1), 33; https://doi.org/10.3390/membranes16010033 - 4 Jan 2026

Viewed by 569

Abstract

The permeation of different chemical substances across the membrane is of utmost importance to the life and health of a living cell. Depending on the nature of the permeant, the process is mediated by either the protein (e.g., membrane channels) or lipid phases [...] Read more.

The permeation of different chemical substances across the membrane is of utmost importance to the life and health of a living cell. Depending on the nature of the permeant, the process is mediated by either the protein (e.g., membrane channels) or lipid phases of the membrane, or both. In the case of small and physiologically important gas molecules, namely O₂ and CO₂, the literature supports the involvement of both pathways in their transport. The extent of involvement of the lipid phase, however, is directly dependent on the nature of the lipid constituents of the membrane that determine its various structural and physicochemical properties. In this study, we use molecular dynamics simulation, as a method with sufficient spatial and temporal resolutions, to analyze these properties in heterogeneous lipid bilayers, composed of phospholipids with varied tails, sphingomyelin, and cholesterol, to different degrees. Together with the calculation of the free energy profiles, diffusion constants, and gas diffusivity, the results shed light on the importance of the lipid phase of membranes in gas transport rate and how they can be modulated by their lipid composition. Full article

(This article belongs to the Special Issue Biomolecular Interactions with Cell and Model Membranes: Integrating Biophysical Experiments and Computational Simulations)

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14 pages, 3081 KB

Open AccessArticle

Silicalite Nanosheet Laminated Membranes: Effects of Layered Structure on the Performance in Pervaporation Desalination

by Xinhui Sun, Yukta Sharma, Landysh Iskhakova, Zishu Cao and Junhang Dong

Membranes 2026, 16(1), 32; https://doi.org/10.3390/membranes16010032 - 4 Jan 2026

Viewed by 383

Abstract

Silicalite nanosheet (SN) laminated membranes are promising for pervaporation (PV) desalination of concentrated brines for water purification and critical material concentration and recovery. However, scaling up the SN-based membranes is limited by inefficient synthesis of monodispersed open-pore SN single crystals (SNS). Here, we [...] Read more.

Silicalite nanosheet (SN) laminated membranes are promising for pervaporation (PV) desalination of concentrated brines for water purification and critical material concentration and recovery. However, scaling up the SN-based membranes is limited by inefficient synthesis of monodispersed open-pore SN single crystals (SNS). Here, we report a scalable approach to fabricate multilayered silicalite nanosheet plate (SNP) laminated membranes on porous alumina and PVDF substrates and demonstrate their excellent PV desalination performance for simulated brines containing lithium and high total dissolved salts (TDS). At 73 ± 3 °C, the SNP laminated membrane on alumina support achieved a remarkable water flux (

J_{w}

) of nearly 20 L/m²·h, significantly outperforming the alumina-supported SNS laminated membrane (

J_{w}

= 9.56 L/m²·h), while both provided near-complete salt rejection (

r_{i}

~99.9%) when operating with vacuum pressure on the permeate side. The PVDF-supported SNS and SNP laminated membranes exhibited excellent

J_{w}

(14.0 L/m²·h) and near-complete

r_{i}

(>99.9%), surpassing the alumina-support SNP laminated membranes when operating by air sweep on the permeate side. However, the

r_{i}

of the PVDF-supported membranes was found to decline when operating with vacuum pressure on the permeate side that was apparently caused by minimal liquid permeation through the inter-SNP spaces driven by the transmembrane pressure. With scalable SNP production, SNP-A membranes show potential for PV desalination of high-TDS solutions, especially in harsh environments unsuitable for polymer membranes. Full article

(This article belongs to the Special Issue Advanced Membrane Technologies for the Treatment of Industrial Wastewater and Emerging Contaminants: Challenges and Innovations)

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19 pages, 3824 KB

Open AccessArticle

Development of Chitosan Polymer Membranes with Potential Use in Filtration Processes

by Ana Luisa Aguilar-Ruiz, Tomás Jesús Madera-Santana, Reyna G. Sánchez-Duarte, Yedidia Villegas-Peralta, Ana Alejandra Aguilar-Ruiz and Víctor Manuel Orozco-Carmona

Membranes 2026, 16(1), 31; https://doi.org/10.3390/membranes16010031 - 4 Jan 2026

Viewed by 550

Abstract

Polymeric membranes based on chitosan (Cs) were extracted from shrimp shells and evaluated. These membranes were modified using polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and glycerol (Gly) and crosslinked with glutaraldehyde (GA) to examine their suitability for water filtration processes. The Cs exhibited high [...] Read more.

Polymeric membranes based on chitosan (Cs) were extracted from shrimp shells and evaluated. These membranes were modified using polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and glycerol (Gly) and crosslinked with glutaraldehyde (GA) to examine their suitability for water filtration processes. The Cs exhibited high purity, a total nitrogen content of 6.49%, and an average molecular weight of 456 kDa, all of which are suitable for membrane formation. Four membranes (Cs-GA, B2: Cs-PEG, B5: Cs-PEG-PVP, and B7: Cs-Gly) were characterized by means of FTIR, SEM, AFM, thickness, contact angle, tensile testing, TGA, DSC, and filtration with distilled water at 4.83 bar. B2 and B5 showed thicknesses of 207 and 190 μm and contact angles of 56.7° and 58.9°, lower than that of Cs-GA (89.4°). In filtration, B2 achieved a flux of 2222.70 LMH, a permeance of 460.19 LMH·bar⁻¹, and a hydraulic resistance of 8.79 × 10¹¹ m⁻¹, while Cs-GA, B5, and B7 exhibited fluxes of 24.10, 40.43, and 24.77 LMH, respectively, permeances of 9.75, 8.37, and 5.13 LMH·bar⁻¹, and hydraulic resistances of 4.15 × 10¹³, 4.83 × 10¹³, and 7.89 × 10¹³ m⁻¹, in the same order. Overall, membranes B2 and B5 are recognized as the most promising for water filtration under pressured operating conditions. Full article

(This article belongs to the Special Issue Recent Advances in Polymeric Membranes—Preparation and Applications (2nd Edition))

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17 pages, 6443 KB

Open AccessArticle

Lattice Boltzmann Simulation of Mass Transfer Characteristics in Catalyst Layer of High-Temperature Proton Exchange Membrane Fuel Cells

by Shengzheng Ji, Guogang Yang and Hao Wang

Membranes 2026, 16(1), 30; https://doi.org/10.3390/membranes16010030 - 4 Jan 2026

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Abstract

As a critical component of high-temperature proton exchange membrane fuel cells (HT-PEMFCs), the catalytic layer (CL) significantly influences the overall performance of these systems. In this study, a pore-scale lattice Boltzmann (LB) model was established to simulate the multi-component mass transport in the [...] Read more.

As a critical component of high-temperature proton exchange membrane fuel cells (HT-PEMFCs), the catalytic layer (CL) significantly influences the overall performance of these systems. In this study, a pore-scale lattice Boltzmann (LB) model was established to simulate the multi-component mass transport in the HT-PEMFC catalyst layer. Based on the reconstruction of CL, the transport behavior of phosphoric acid was simulated. The effects of different carbon carrier diameters, porosity values, and Pt/C mass ratios on the transport of phosphoric acid in CL were studied. The distribution of phosphoric acid and air concentration, as well as the electrochemical surface area, was qualitatively and quantitatively analyzed. Finally, the optimal design parameters of CL structure were determined. The results show that, with increases in carbon carrier diameter, porosity, and Pt/C mass ratio, the distribution of phosphoric acid concentration shows an upward trend, and the distribution of air concentration shows a downward trend. The optimal ranges of carbon carrier diameter, porosity, and Pt/C mass ratio are 50–80 nm, 60–70%, and 40–50%, respectively. This study provides a new idea for further understanding the mass transport mechanism in the HT-PEMFC catalyst layer and provides effective suggestions for the optimization design of the HT-PEMFC catalyst layer structure. Full article

(This article belongs to the Special Issue Simulation and Artificial Intelligence Method Development for Complex Membrane Transport)

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14 pages, 6318 KB

Open AccessArticle

Reverse Osmosis Membrane Cleaning Optimization from Textile Dyeing Wastewater Reuse Applications

by Zhengwei Wang, Rulu Ouyang, Guorui Zhang, Chunhai Wei, Shiming Ji, Qixuan Li, Chunyang Tao and Hongwei Rong

Membranes 2026, 16(1), 29; https://doi.org/10.3390/membranes16010029 - 4 Jan 2026

Viewed by 398

Abstract

Reverse osmosis (RO) is the key process for textile dyeing wastewater reuse applications. Membrane fouling reduces both permeability and rejection capability, negatively affecting the technological economy of RO process. Membrane cleaning is critical to recovery of the permeability of fouled RO membranes. Based [...] Read more.

Reverse osmosis (RO) is the key process for textile dyeing wastewater reuse applications. Membrane fouling reduces both permeability and rejection capability, negatively affecting the technological economy of RO process. Membrane cleaning is critical to recovery of the permeability of fouled RO membranes. Based on multi-batch filtration and cleaning experiments, this study systematically evaluated the RO membrane fouling potential of pre-treated textile dyeing wastewater by a membrane bioreactor and the recovery performance of fouled RO membranes after different cleaning methods. A significant decline (more than 15%) in RO membrane permeability occurred after RO membrane permeate production of 625 L/m² at a water recovery ratio of 60%. Protein-like substances and soluble microbial products were identified as the primary organic foulants via three-dimensional fluorescence excitation-emission matrix spectrometry (3D-FEEM). The single forward flushing with either pure water, acid, alkaline, or sodium hypochlorite solutions with a low active chlorine concentration showed very limited recovery of fouled RO membrane permeability. The combined forward flushing with acid followed by alkaline solutions restored fouled membrane permeability by up to 87% of a new RO membrane. The addition of pure water backwashing at a transmembrane pressure (TMP) of 0.5 MPa after both acid and alkaline solutions combined forward flushing restored fouled membrane permeability by up to 97% of a new RO membrane but deteriorated the rejection capability of the RO membrane. The backwashing parameters were further optimized at a TMP of 0.125 MPa and crossflow velocity (CFV) of 0.5 m/s, achieving fouled RO membrane permeability by up to 96% of a new RO membrane, and there were no negative effects on the rejection capability of the RO membrane. Alkaline forward flushing followed by pure water backwashing was the dominant contributor for fouled RO membrane permeability recovery. A preliminary economic analysis showed that the total chemical cost per RO production was 0.763 CNY/m³ and could be further reduced via removing acid cleaning and replacing combined alkaline flushing and pure water backwashing with alkaline backwashing. Full article

(This article belongs to the Section Membrane Applications for Water Treatment)

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19 pages, 8676 KB

Open AccessArticle

Towards a Circular Economy in Electroless Pore-Plated Pd/PSS Composite Membranes: Pd Recovery and Porous Support Reuse

by Alejandro J. Santos-Carballes, David Alique, Raúl Sanz, Arturo J. Vizcaíno and José A. Calles

Membranes 2026, 16(1), 28; https://doi.org/10.3390/membranes16010028 - 4 Jan 2026

Viewed by 438

Abstract

The recycling of a planar composite Pd membrane over a porous stainless-steel support modified with a CeO₂ interlayer (Pd/CeO₂/PSS) was investigated using a leaching-based recycling strategy to recover palladium while maintaining the support’s structural integrity. The membrane was prepared by [...] Read more.

The recycling of a planar composite Pd membrane over a porous stainless-steel support modified with a CeO₂ interlayer (Pd/CeO₂/PSS) was investigated using a leaching-based recycling strategy to recover palladium while maintaining the support’s structural integrity. The membrane was prepared by a continuous flowing electroless pore-plating method (cf-ELP-PP) previously developed by our group. A series of experiments was conducted to evaluate the effect of leaching conditions—temperature, acid concentration, and duration—on Pd extraction and support preservation. Nitric acid (HNO₃) was used as the leaching agent, and the condition of 30 vol.% HNO₃ at 35 °C for 24 h was found to enable complete Pd recovery with limited dissolution of metals from the support. The regenerated supports exhibited an Fe-Cr oxide layer and part of the CeO₂ interface, allowing the elimination of cleaning and calcination steps in the membrane reprocessing workflow. A new Pd-CeO₂ interfacial layer was applied, followed by Pd redeposition via cf-ELP-PP. The resulting recycled membrane exhibited a homogeneous and defect-free Pd layer, with hydrogen permeation performance comparable to that of membranes fabricated on fresh supports. These results demonstrate that Pd membranes can be successfully fabricated on recycled 316L stainless-steel substrates, supporting the viability of this approach for material reuse in membrane technology. Full article

(This article belongs to the Special Issue Membrane Technologies in Hydrogen Separation and Purification)

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21 pages, 7172 KB

Open AccessReview

A Critical Review on Desalination Technologies for High-Salinity Wastewater: Development and Challenges

by Xiao Wang, Xinyi Cheng, Ao Shuai, Xiyu Xu, Xinran Guo, Dan Song, Caihong Liu and Wenjuan Zhang

Membranes 2026, 16(1), 27; https://doi.org/10.3390/membranes16010027 - 3 Jan 2026

Viewed by 726

Abstract

The ongoing expansion of industrial operations has resulted in the generation of a large amount of high-salinity wastewater with complex compositions. The direct discharge of this wastewater poses significant threats to ecosystems and leads to the loss of valuable salt resources, for example, [...] Read more.

The ongoing expansion of industrial operations has resulted in the generation of a large amount of high-salinity wastewater with complex compositions. The direct discharge of this wastewater poses significant threats to ecosystems and leads to the loss of valuable salt resources, for example, triggering freshwater salinization syndrome and mobilizing heavy metals to form toxic “chemical cocktails”, leading to the loss of valuable salt resources. Desalination of high-salinity wastewater primarily involves two key processes: concentration and crystallization, whereby a concentrated brine is first obtained through membrane-based or thermal methods, followed by salt recovery via crystallization. This review begins by employing a bibliometric analysis to map the knowledge structure and trace the evolution of research trends, revealing that “membrane-thermal integration” has become a dominant research hotspot since 2020. It then provides a systematic examination of advanced treatment technologies, chronicling the progression from early biological methods to contemporary membrane-based and thermal desalination approaches. A specific analysis of the influence of salinity on membrane scaling is also included. Consequently, this paper critically assesses the prospects and challenges of several alternative desalination technologies and proposes that integrated processes, combining membrane-based and thermal desalination, represent a highly promising pathway for achieving zero liquid discharge (ZLD). Finally, we suggest that future research should prioritize the development of key functional materials, explore efficient hybrid physiochemical–biochemical processes, and advance emerging technologies, aimed at enhancing treatment efficiency and reducing operational costs. Full article

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17 pages, 6853 KB

Open AccessArticle

Experimental Performances of Titanium Redox Electrodes as the Substitutes for the Ruthenium–Iridium Coated Electrodes Used in the Reverse Electrodialysis Cells for Hydrogen Production

by Zhaozhe Han, Xi Wu, Lin Xu and Ping He

Membranes 2026, 16(1), 26; https://doi.org/10.3390/membranes16010026 - 3 Jan 2026

Viewed by 411

Abstract

Reverse electrodialysis (RED) enables the efficient conversion of the chemical potential difference between seawater and freshwater into electricity while simultaneously facilitating hydrogen production for integrated energy utilization. Nevertheless, the widespread deployment of RED remains constrained by the reliance on ruthenium–iridium-coated electrodes, which are [...] Read more.

Reverse electrodialysis (RED) enables the efficient conversion of the chemical potential difference between seawater and freshwater into electricity while simultaneously facilitating hydrogen production for integrated energy utilization. Nevertheless, the widespread deployment of RED remains constrained by the reliance on ruthenium–iridium-coated electrodes, which are expensive and resource-limited. This study proposes the adoption of titanium-based redox electrodes as a replacement for traditional precious metal electrodes and employs a novel spike structure to accelerate hydrogen bubble detachment. The electrochemical performance of titanium electrodes in an RED hydrogen production system was systematically evaluated experimentally. The influences of several parameters on the RED system performance were systematically examined under these operating conditions, including the ruthenium–iridium catalytic layer, operating temperature (15 to 45 °C), electrode rinse solution (ERS) concentration (0.1 to 0.7 M), and flow rate (50 to 130 mL·min⁻¹). Experimental results demonstrate that optimized titanium redox electrodes maintain high electrocatalytic activity while significantly reducing system costs. Under optimal conditions, the hydrogen yield of the Ti redox electrode reached 89.7% of that achieved with the mesh titanium plate coated oxide iridium and oxide ruthenium as electrodes, while the electrode cost was reduced by more than 60%. This is also one of the cost-cutting solutions adopted by RED for its development. Full article

(This article belongs to the Special Issue Innovative Membrane Materials and Systems for Electrodialysis and Electro-Driven Separations)

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23 pages, 1823 KB

Open AccessArticle

Experimental and Modeling Study of a Semi-Continuous Slurry Reactor–Pervaporator System for Isoamyl Acetate Production Using a Commercial Pervaporation Membrane

by Miguel-Ángel Gómez-García, Izabela Dobrosz-Gómez and Wilmar Osorio Viana

Membranes 2026, 16(1), 25; https://doi.org/10.3390/membranes16010025 - 3 Jan 2026

Viewed by 367

Abstract

Building on our previous study on batch pervaporation membrane reactors for isoamyl acetate synthesis, this work evaluates a two-step continuous process integrating a slurry reactor and a commercial pervaporator module based on a hybrid silica membrane. The system combines catalytic esterification of acetic [...] Read more.

Building on our previous study on batch pervaporation membrane reactors for isoamyl acetate synthesis, this work evaluates a two-step continuous process integrating a slurry reactor and a commercial pervaporator module based on a hybrid silica membrane. The system combines catalytic esterification of acetic acid with isoamyl alcohol with simultaneous water removal to enhance conversion and product selectivity. Operating conditions were defined using experimentally validated thermodynamic, kinetic, and mass-transport models. A hydrodynamic assessment confirmed turbulent flow within the membrane module, and model predictions were compared with experimental data for validation. The results confirmed the occurrence of reactive pervaporation and demonstrated that both the membrane area-to-reactor volume ratio and catalyst loading significantly influence the equilibrium shift. Although conversion remained limited by the available membrane area, the commercial pervaporation unit exhibited stable operation, consistent flux behavior, and effective water selectivity. These findings demonstrate the technical feasibility of the continuous slurry reactor–pervaporator configuration and establish a framework for further optimization and scale-up of isoamyl acetate production via reactive pervaporation. Full article

(This article belongs to the Section Membrane Applications for Other Areas)

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16 pages, 5762 KB

Open AccessArticle

Evaluation of Flat Sheet UF PES Membranes Modified with a Polymerized Coating of Bicontinuous Microemulsion for Wastewater Treatment: Insights from Laboratory MBR Experiments

by Sneha De, Tran Ly Quynh, Francesco Galiano, Raffaella Mancuso, Bartolo Gabriele, Jan Hoinkis and Alberto Figoli

Membranes 2026, 16(1), 24; https://doi.org/10.3390/membranes16010024 - 2 Jan 2026

Viewed by 479

Abstract

The study investigates the performance of polyethersulfone (PES) ultrafiltration (UF) membranes modified with a coating of polymerizable bicontinuous microemulsion (PBM) for membrane bioreactor (MBR) applications. Two types of PBM-modified PES membranes—casting-coated and spray-coated—were compared with a commercial PES membrane. A laboratory side-stream MBR [...] Read more.

The study investigates the performance of polyethersulfone (PES) ultrafiltration (UF) membranes modified with a coating of polymerizable bicontinuous microemulsion (PBM) for membrane bioreactor (MBR) applications. Two types of PBM-modified PES membranes—casting-coated and spray-coated—were compared with a commercial PES membrane. A laboratory side-stream MBR (ssMBR) was employed to treat model wastewater (MW) with activated sludge under aerobic conditions. The fouling propensity of the membranes in ssMBR was evaluated through the implementation of two protocols: (i) flux-step test to treat low-strength domestic model wastewater (DMW) and (ii) constant flux test to treat high-strength olive mill model wastewater (OMW). The findings indicated that both the commercial PES and PBM spray-coated PES membranes started to critically foul at 36 L m⁻² h⁻¹. The PBM spray-coated membranes showed enhanced fouling resistance in comparison to the PBM casting-coated membranes. The deposition of the biofouling layer was the thinnest on PBM spray-coated membranes, which can be attributed to the low surface charge and high hydrophilicity of the modified membrane surface. In contrast, deposition of a thicker fouling layer was found on the commercial PES membrane, which can be attributed to the relatively higher surface charge promoting organic adsorption. A comparison of the fouling trends exhibited by commercial PES and PBM spray-coated membranes in OMW treatment revealed that they have similar fouling tendencies. However, a notable distinction emerged when the PBM spray-coated membrane was observed to demonstrate a lower fouling propensity accompanied by comparatively thinner fouling layers. The results demonstrate that the PBM spray-coated membranes have enhanced fouling resistance and filtration efficacy in MBRs treating wastewater with diverse strengths, thereby affirming their potential for application in wastewater treatment systems. Full article

(This article belongs to the Special Issue Advanced Membrane Technologies for the Treatment of Industrial Wastewater and Emerging Contaminants: Challenges and Innovations)

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19 pages, 4926 KB

Open AccessArticle

A Bipolar Membrane Containing Core–Shell Structured Fe₃O₄-Chitosan Nanoparticles for Direct Seawater Electrolysis

by Hyeon-Bee Song, Eun-Hye Jang and Moon-Sung Kang

Membranes 2026, 16(1), 23; https://doi.org/10.3390/membranes16010023 - 2 Jan 2026

Viewed by 581

Abstract

Seawater has attracted increasing attention as a promising resource for hydrogen production via electrolysis. However, multivalent ions present in seawater can reduce the efficiency of direct seawater electrolysis (DSWE) by forming inorganic precipitates at the cathode. Bipolar membranes (BPMs) can mitigate precipitate formation [...] Read more.

Seawater has attracted increasing attention as a promising resource for hydrogen production via electrolysis. However, multivalent ions present in seawater can reduce the efficiency of direct seawater electrolysis (DSWE) by forming inorganic precipitates at the cathode. Bipolar membranes (BPMs) can mitigate precipitate formation by regulating local pH, thereby enhancing DSWE efficiency. Accordingly, this study focuses on the fabrication of a high-performance BPM for DSWE applications. The water-splitting performance of BPMs is strongly dependent on the properties of the catalyst at the bipolar junction. Herein, iron oxide (Fe₃O₄) nanoparticles were coated with cross-linked chitosan to improve solvent dispersibility and catalytic activity. The resulting core–shell catalyst exhibited excellent dispersibility, facilitating uniform incorporation into the BPM. Water-splitting flux measurements identified an optimal catalyst loading of approximately 3 μg cm⁻². The BPM containing Fe₃O₄–chitosan nanoparticles achieved a water-splitting flux of 26.2 μmol cm⁻² min⁻¹, which is 18.6% higher than that of a commercial BPM (BP-1E, Astom Corp., Tokyo, Japan). DSWE tests using artificial seawater as the catholyte and NaOH as the anolyte demonstrated lower cell voltage and stable catholyte acidification over 100 h compared to the commercial membrane. Full article

(This article belongs to the Special Issue Advanced Membrane Design for Hydrogen Technologies)

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15 pages, 3289 KB

Open AccessArticle

Decoupling Solvent Effects: Perfluorinated Sulfonic Acid Structure and Catalyst Layer Stability in PEM Water Electrolysis

by Jong-Hyeok Park and Jin-Soo Park

Membranes 2026, 16(1), 22; https://doi.org/10.3390/membranes16010022 - 1 Jan 2026

Viewed by 487

Abstract

Solvent differences in perfluorinated sulfonic acid ionomer (PFSI) dispersions confound comparisons of catalyst-layer (CL) binders for PEM water electrolysis. We use a propylene-glycol (PG) single-solvent platform to isolate effects of ionomer structure, i.e., side-chain architecture and equivalent weight (EW), across five PFSIs (Nafion [...] Read more.

Solvent differences in perfluorinated sulfonic acid ionomer (PFSI) dispersions confound comparisons of catalyst-layer (CL) binders for PEM water electrolysis. We use a propylene-glycol (PG) single-solvent platform to isolate effects of ionomer structure, i.e., side-chain architecture and equivalent weight (EW), across five PFSIs (Nafion D2021, Nafion D2020, Aquivion D98-25BS, Aquivion D72-25BS, and 3M E-22397B) as hydrogen evolution reaction-CL binders. PG collapses ionomer aggregates from microns to sub-100 nm and reduces catalyst–ionomer agglomerates without a systematic EW trend, indicating that performance differences originate during film formation. PG makes CLs more hydrophobic (higher θ_R), yet aerophobicity (θ_Air) still increases with decreasing EW, consistent with higher sulfonic-acid density. Under PG, current density at 1.9 V rises with decreasing EW, with thicker short-side chain/mid-side chain (SSC/MSC) films (≥140 nm) and lower ohmic overpotentials than long-side-chain (LSC) Nafion. Durability under Accelerated Stress Test-2 (AST-2; 0.3/3.0 A cm⁻², 48 h) splits by class: LSC Nafion shows the largest degradation slopes, whereas SSC/MSC are lower; transmission electron microscope images show Pt growth with Nafion D2020-PG but minimal growth with Aquivion D98-25BS-PG. With solvent effects removed, ionomer structure governs CL performance and stability; SSC (EW ≈ 980) is recommended, and MSC maximizes current with moderate stability. Full article

(This article belongs to the Section Membrane Applications for Energy)

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18 pages, 4905 KB

Open AccessArticle

Antifouling and Antibacterial Activity of Laser-Induced Graphene Ultrafiltration Membrane

by Amit K. Thakur, Hasib Mahbub, Imtiaz Qavi, Masoud Nateqi, George Tan and Mahdi Malmali

Membranes 2026, 16(1), 21; https://doi.org/10.3390/membranes16010021 - 1 Jan 2026

Viewed by 488

Abstract

Fouling is a major challenge in membrane-based filtration processes, leading to higher operating and capital costs. Developing new membranes with better fouling resistance has always been a research focus in the membrane field. In particular, designing functional surfaces which mitigate fouling is an [...] Read more.

Fouling is a major challenge in membrane-based filtration processes, leading to higher operating and capital costs. Developing new membranes with better fouling resistance has always been a research focus in the membrane field. In particular, designing functional surfaces which mitigate fouling is an effective approach. We successfully fabricated membranes with a graphene functional layer using a single-step laser irradiation known as laser-induced graphene (LIG) on the membrane surface. The LIG ultrafiltration (UF) membranes were prepared by directly lasing poly(ether sulfone) (PES) membrane substrates. Scanning electron microscopy demonstrated the successful ablation of the PES membranes with controlled thickness. Water filtration tests confirmed that the permeance increased by 240% as the laser power increased from 2.4 to 3.2 W; the membrane lased with the highest ablation power (LIG-P8) displayed a high water permeance of ~400 L m⁻² h⁻¹ bar⁻¹ and a corresponding bovine serum albumin (BSA) rejection of 92.5%. Fouling experiments using BSA, humic acid (HA), and sodium alginate showed better permeance recovery ratios (78–90%) with LIG membranes compared to the neat PES membrane (65–68%). LIG membranes were also evaluated for antibioufouling filtration tests, which showed exceptional biofilm resistance and potent antibacterial killing effects when treated with Staphylococcus aureus. Applied external voltage and contact time were the key variables to optimize the antibiofouling properties of the LIG UF membranes. Full article

(This article belongs to the Section Membrane Applications for Water Treatment)

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14 pages, 1612 KB

Open AccessArticle

Nanotube Alignment and Surface Chemistry in Altering Water and Salt Permeabilities for Imogolite-Polyamide Membranes

by Savannah Bachmann and Jonathan Brant

Membranes 2026, 16(1), 20; https://doi.org/10.3390/membranes16010020 - 1 Jan 2026

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Abstract

Reducing the specific energy consumption of reverse osmosis (RO) processes motivates the development of new membrane materials that have enhanced water permeability while maintaining low salt permeability (high rejection). Nanocomposite membranes have shown great promise in achieving these goals, particularly those using nanotubes [...] Read more.

Reducing the specific energy consumption of reverse osmosis (RO) processes motivates the development of new membrane materials that have enhanced water permeability while maintaining low salt permeability (high rejection). Nanocomposite membranes have shown great promise in achieving these goals, particularly those using nanotubes as fillers. Here, we report on the relationships between the orientations and surface functionalities of imogolite nanotubes (INTs) with water and salt permeabilities for polyamide nanocomposite membranes. An external electric field was used to manipulate the INT orientation within the polyamide active layer. The INT interior and exterior chemistries, respectively, were made hydrophobic using methyl triethoxysilane as a precursor during INT synthesis and post-synthesis modification with alkali-phosphate groups. Irrespective of nanotube orientation or surface chemistry, membrane permeance increased from 0.3 to ≥1.0 L m⁻² h⁻¹ bar⁻¹. A salt permeability comparable to the conventional polyamide membrane was maintained by making the INT pore throat hydrophobic. These findings indicated that salt rejection could be tailored by manipulating the INT interior surface chemistry without sacrificing water permeability. Full article

(This article belongs to the Section Membrane Fabrication and Characterization)

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19 pages, 4005 KB

Open AccessReview

Efficient Separation of Per- and Polyfluoroalkyl Substances (PFAS) by Organic Framework Membranes: Advances, Mechanisms, and Challenges

by Jiawei Zhang, Baosheng Zhao and Hao Yang

Membranes 2026, 16(1), 19; https://doi.org/10.3390/membranes16010019 - 1 Jan 2026

Viewed by 548

Abstract

Per- and polyfluoroalkyl substances (PFAS) represent a class of highly persistent environmental contaminants with exceptional chemical stability. Efficient removal of PFAS from water poses a significant challenge for the chemical industry and constitutes a critical requirement for sustainable environmental development. Membrane technology has [...] Read more.

Per- and polyfluoroalkyl substances (PFAS) represent a class of highly persistent environmental contaminants with exceptional chemical stability. Efficient removal of PFAS from water poses a significant challenge for the chemical industry and constitutes a critical requirement for sustainable environmental development. Membrane technology has demonstrated considerable potential in water treatment due to its low energy consumption and environmentally friendly characteristics. This review comprehensively summarizes recent advances in emerging metal–organic framework (MOF)-, covalent organic framework (COF)-, and hydrogen-bonded organic framework (HOF)-based membranes for highly efficient separation and catalytic degradation of PFAS. We provide a detailed analysis of design strategies for various organic framework membranes (OFMs) and their synergistic separation mechanisms, including size exclusion, electrostatic interactions, adsorption, as well as catalytic degradation based on advanced oxidation processes. Furthermore, we systematically evaluate the performance and applicability of these membranes in practical aquatic environments. Finally, this review outlines future directions toward developing integrated “separation-degradation” membrane processes for practical applications by discussing current challenges concerning material stability, manufacturing costs, and long-term operational efficiency. This review aims to provide theoretical guidance and technical insights for developing next-generation high-performance membranes for PFAS removal. Full article

(This article belongs to the Special Issue Preparation, Characterization, and Application of Advanced Separation Membrane Materials)

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Membranes, Volume 16, Issue 1 (January 2026) – 48 articles

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