Membranes

16 pages, 1432 KB

Open AccessArticle

Bacterial Nanocellulose Functionalized with Graphite and Niobium Pentoxide: Limited Antimicrobial Effects and Preserved Cytocompatibility

by Juliana Silva Ribeiro de Andrade, Adriana Poli Castilho Dugaich, Andressa da Silva Barboza, Maurício Malheiros Badaró, Pedro Henrique Santaliestra e Silva, Tiago Moreira Bastos Campos, Karina Cesca, Debora de Oliveira, Sheila Cristina Stolf and Rafael Guerra Lund

Membranes 2026, 16(1), 16; https://doi.org/10.3390/membranes16010016 - 31 Dec 2025

Abstract

Chronic wounds remain locked in persistent inflammation with high microbial burden, demanding dressings that suppress infection without sacrificing biocompatibility. Bacterial nanocellulose (BNC) is an attractive matrix due to its biocompatibility, nanofibrillar architecture, and moisture retention, but it lacks antimicrobial activity. Here, we engineer [...] Read more.

Chronic wounds remain locked in persistent inflammation with high microbial burden, demanding dressings that suppress infection without sacrificing biocompatibility. Bacterial nanocellulose (BNC) is an attractive matrix due to its biocompatibility, nanofibrillar architecture, and moisture retention, but it lacks antimicrobial activity. Here, we engineer BNC membranes post-functionalized with functionalized graphite (f-Gr; predominantly graphitic with residual surface groups) and/or niobium pentoxide (Nb₂O₅), and evaluate four groups: BNC (matrix control), BNC/Nb₂O₅, BNC/f-Gr, and BNC/f-Gr/Nb₂O₅. Physicochemical analyses (Raman and Voigt fitting, FTIR-ATR, XRD, and SEM) confirm a graphitic carbon phase and physical incorporation of the modifiers into the BNC network, with a noticeable shift in the hydration/polarity profile—more evident in the presence of f-Gr. In standardized microbiological assays, BNC/f-Gr promoted a moderate, contact-dependent reduction in bacterial proliferation, particularly against Staphylococcus aureus, whereas BNC/Nb₂O₅ behaved similarly to pristine BNC under the tested conditions. The combined f-Gr/Nb₂O₅ formulation showed an intermediate antimicrobial response, with 再no clear synergy beyond f-Gr alone. Cytotoxicity assays indicated cytocompatibility for BNC, BNC/f-Gr, and BNC/Nb₂O₅; the combined group displayed a slight reduction that remained within acceptable limits. Overall, BNC/f-Gr emerges as the most promising antimicrobial dressing, while Nb₂O₅ did not significantly enhance antimicrobial performance under the tested conditions and warrants further optimization regarding loading and distribution. Full article

(This article belongs to the Special Issue Interfacial Interactions of Nanoparticles and Molecular Nanostructures with Model Membrane Systems)

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20 pages, 601 KB

Open AccessArticle

Ammonia Recovery from Animal Manure via Hollow Fibre Membrane Contactors: Impact of Filtration Pre-Treatment and Organic Foulants on Mass Transfer and Performance

by Niloufar Azizi, Shaun Connolly, Dominika Krol and Eoin Syron

Membranes 2026, 16(1), 15; https://doi.org/10.3390/membranes16010015 - 31 Dec 2025

Abstract

Ammonia (NH₃) recovery from animal manure offers both environmental and economic benefits by reducing nitrogen emissions and producing valuable fertilisers. Hollow fibre membrane contactors (HFMCs) are a promising technology for this purpose, yet their performance is strongly influenced by the complex [...] Read more.

Ammonia (NH₃) recovery from animal manure offers both environmental and economic benefits by reducing nitrogen emissions and producing valuable fertilisers. Hollow fibre membrane contactors (HFMCs) are a promising technology for this purpose, yet their performance is strongly influenced by the complex composition of manure. In this study, the effects of solids concentration and organic foulants concentration on the mass transfer coefficients governing NH₃ recovery were systematically investigated. Total suspended solids (TSS) were reduced through graded filtration, and protein concentrations in the ammonium solutions were quantified to assess their role in limiting mass transfer. Results showed that TSS concentration primarily affected the shell-side film resistance. After extensive filtration, residual proteins attached to the membrane surface induced partial wetting, thereby reducing the effective membrane mass transfer coefficient. Using a penalty function approach, it was possible to separately describe TSS- and protein-related resistances, enabling improved prediction of effective model coefficients under real world conditions. These findings highlight the dual importance of solid–liquid separation and protein management in optimising HFMC operation for NH₃ recovery and provide a framework for up-scaling the technology in agricultural nutrient management systems. Full article

(This article belongs to the Topic Separation Techniques and Circular Economy)

17 pages, 2049 KB

Open AccessArticle

Dewatering Hypersaline Na₂SO₄ and NaCl via Commercial Forward Osmosis Module

by Noel Devaere and Vladimiros G. Papangelakis

Membranes 2026, 16(1), 14; https://doi.org/10.3390/membranes16010014 - 31 Dec 2025

Abstract

Efficient water recycling in the hydrometallurgical industry requires the dewatering of hypersaline Na₂SO₄ or similar brines via non-evaporative methods. Unfortunately, many non-evaporative methods require the use of specific solutes and are not compatible with complex hydrometallurgical effluents. Forward Osmosis (FO) [...] Read more.

Efficient water recycling in the hydrometallurgical industry requires the dewatering of hypersaline Na₂SO₄ or similar brines via non-evaporative methods. Unfortunately, many non-evaporative methods require the use of specific solutes and are not compatible with complex hydrometallurgical effluents. Forward Osmosis (FO) uses a draw solution to link known non-evaporative water recycling methods with feed solutions that are otherwise incompatible. There is minimal experimental data on the dewatering performance of today’s available commercial FO membranes, especially with hypersaline concentrations (>70,000 mg/L total dissolved solids). This study tests the commercially available Aquaporin HFFO2 hollow fibre FO membrane module with hypersaline Na₂SO₄ or NaCl feed solutions versus a MgCl₂ draw solution. It identifies a key requirement to maintain water flux above a certain threshold to prevent a decrease in Na Rejection or an increase in Mg reverse flux. It also defines a minimum osmotic differential that can be used to parameterize water flux, similar to the temperature of approach in heat exchangers, but to determine the extent of water removal in FO. We demonstrate that even under mildly acidic conditions, existing FO membranes can concentrate Na₂SO₄ to saturation, paving the way for their use in the hydrometallurgical industry. Full article

(This article belongs to the Special Issue Polymeric Membranes Engineered for Different Separation Processes)

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25 pages, 2368 KB

Open AccessReview

Enhancing Nitrogen Removal in MBRs: From Theoretical Advances to Practical Applications

by Jiayi Xun, Lu Wang, Fengwei Jia, Ziwen Han, Haoran Ma, Yiping Feng, Ying Zhao, Wenjuan Zhang, Dan Song and Jun Ma

Membranes 2026, 16(1), 13; https://doi.org/10.3390/membranes16010013 - 31 Dec 2025

Abstract

Nitrogen, a prevalent water pollutant, is a major cause of eutrophication and the formation of black, odorous water bodies, posing significant threats to both ecological security and human health. Effectively controlling nitrogen pollution in wastewater is therefore essential for preserving aquatic ecosystems. The [...] Read more.

Nitrogen, a prevalent water pollutant, is a major cause of eutrophication and the formation of black, odorous water bodies, posing significant threats to both ecological security and human health. Effectively controlling nitrogen pollution in wastewater is therefore essential for preserving aquatic ecosystems. The membrane bioreactor (MBR), which integrates the advantages of biological and membrane technologies, has attracted considerable attention for its application potential in wastewater nitrogen removal. This article elucidates the mechanisms and characteristics of nitrogen removal in MBR systems based on the latest research advancements. It provides an in-depth analysis of the key environmental factors affecting nitrogen removal efficiency and comprehensively summarizes enhanced processes centered on MBR technology. Furthermore, the article addresses corresponding strategies for mitigating MBR membrane fouling and offers suggestions and prospects for future research directions. Full article

(This article belongs to the Special Issue Advanced Membranes and Membrane Technologies for Wastewater Treatment)

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25 pages, 6319 KB

Open AccessArticle

Uncovering Structure–Conductivity Relationships in Anion Exchange Membranes (AEMs) Using Interpretable Machine Learning

by Pegah Naghshnejad, Debojyoti Das, Jose A. Romagnoli, Revati Kumar and Jianhua Chen

Membranes 2026, 16(1), 12; https://doi.org/10.3390/membranes16010012 - 31 Dec 2025

Abstract

Anion exchange membranes (AEMs) play a vital role in the performance of water electrolyzers and fuel cells, yet their discovery and optimization remain challenging due to the complexity of structure–property relationships. In this study, we introduce a machine learning framework that leverages conditional [...] Read more.

Anion exchange membranes (AEMs) play a vital role in the performance of water electrolyzers and fuel cells, yet their discovery and optimization remain challenging due to the complexity of structure–property relationships. In this study, we introduce a machine learning framework that leverages conditional graph neural networks (cGNNs) and descriptor-based models and a hybrid graph neural network (HGARE) to predict and interpret ionic conductivity. The descriptor-based pipeline employs principal component analysis (PCA), ablation, and SHAP analysis to identify factors governing anion conductivity, revealing electronic, topological, and compositional descriptors as key contributors. Beyond prediction, dimensionality reduction and clustering are performed by employing t-SNE and KMeans as well as SOM, which reveal distinct membranes clusters, some of which were enriched with high anion conductivity. Among graph-based approaches, the graph convolutional (GCN) achieved strong predictive performance, while the Hybrid Graph Autoencoder-Regressor Ensemble (HGARE) achieved the highest accuracy. Additionally, atom-level saliency maps from GCN provide spatial explanations for conductive behavior, revealing the importance of polarizable and flexible regions. This work contributes to the accelerated and data-driven design of high-performance AEMs. Full article

(This article belongs to the Special Issue Design, Synthesis and Applications of Ion Exchange Membranes)

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31 pages, 9749 KB

Open AccessArticle

On the Effect of Melittin on Surface Properties of Erythrocyte and Mitochondrial Membranes

by Virjinia Doltchinkova, Victoria Vitkova, Meglena Kitanova, Milena Shkodrova, Siya Lozanova, Avgust Ivanov and Chavdar Roumenin

Membranes 2026, 16(1), 11; https://doi.org/10.3390/membranes16010011 - 31 Dec 2025

Abstract

Many biomedical applications require a detailed understanding of the action of antimicrobial peptides on biological membranes. The cationic hemolytic peptide melittin, a major component of European honey bee (Apis mellifera) venom, is considered a model for elucidating lipid–protein interactions that are [...] Read more.

Many biomedical applications require a detailed understanding of the action of antimicrobial peptides on biological membranes. The cationic hemolytic peptide melittin, a major component of European honey bee (Apis mellifera) venom, is considered a model for elucidating lipid–protein interactions that are important for the function of biological systems. Here, we address the surface properties of human erythrocytes and rat liver mitochondrial membranes under in vitro melittin treatment. These membranes are negatively charged at neutral pH and represent primary targets of melittin’s effects in the onset of inflammatory diseases. The correlation between the functional activity of membrane systems and their surface electrical charge was assessed using microelectrophoresis, hemolysis assays, membrane transport measurements, lipid peroxidation analysis, and fluorescence microscopy. A mechanistic hypothesis for the divergent effects of sub-lytic, pre-pore doses of melittin on erythrocytes and mitochondria is discussed. At low concentrations, melittin interacts electrostatically with erythrocyte membranes, resulting in altered proton transport through the Band 3 protein. Melittin also induces changes in erythrocyte morphology and malondialdehyde content, as well as aggregation of mitochondrial vesicles. The electrokinetic mechanism of melittin action, associated with membrane stability, provides a novel perspective on its potential relevance to biomedical applications. Full article

(This article belongs to the Section Biological Membranes)

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20 pages, 21431 KB

Open AccessArticle

Computational Fluid Dynamics Analysis of a Venturi-Integrated Diffuser Design for Membrane Bioreactors

by Veli Batmaz and Necati Kayaalp

Membranes 2026, 16(1), 10; https://doi.org/10.3390/membranes16010010 - 30 Dec 2025

Abstract

In a standard diffuser system in a membrane bioreactor (MBR), uneven air distribution scouring the membrane surface causes transmembrane pressure to reach its ultimate value earlier, which requires membrane cleaning more frequently. In this study, a Venturi-integrated innovative diffuser design is proposed to [...] Read more.

In a standard diffuser system in a membrane bioreactor (MBR), uneven air distribution scouring the membrane surface causes transmembrane pressure to reach its ultimate value earlier, which requires membrane cleaning more frequently. In this study, a Venturi-integrated innovative diffuser design is proposed to improve membrane bioreactor (MBR) technology. The proposed design aims to increase filtration efficiency by creating a homogeneous scouring effect on the membrane surface. To compare the performance of the proposed diffuser configuration (V-MBR) with that of a conventional diffuser (S-MBR), computational fluid dynamics models were established for each of the two configurations. The results showed that the V-MBR model produced about 50% higher average shear stress on the membrane surfaces. Statistical analysis also showed that the V-MBR model generally produced low variance and non-zero shear stress values. Along with shear stress distribution, other parameters such as volume fraction, velocity, turbulent kinetic energy, and turbulent eddy distribution were evaluated to compare the performance of two diffuser system configurations. These parameters also supported the superior performance of the new V-MBR model over the conventional S-MBR. It is concluded that homogeneous shear stress distribution on the membrane surface is an important parameter that increases filtration efficiency by preventing the formation of dead zones. Full article

(This article belongs to the Special Issue Mathematical and Computational Modelling in Membrane Separations: From Preparation to Processes)

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19 pages, 4416 KB

Open AccessArticle

Fabrication of Microphase-Separated Tröger’s Base Polymer Membranes for Oxygen Enrichment

by Chaoyue Yang, Li Zhou, Qian Zhang, Ya Huang, Peixiao Zhang, Jingwen Xue, Qing Li, Weijie Sun and Jiayou Liao

Membranes 2026, 16(1), 9; https://doi.org/10.3390/membranes16010009 - 30 Dec 2025

Abstract

Tröger’s base (TB) polymers have received increasing attention as a novel class of polymers with intrinsic microporosity, particularly for applications in gas separation. In this study, TB was quaternized with hydrophobic long chains to create a microphase-separated structure to enhance gas separation performance. [...] Read more.

Tröger’s base (TB) polymers have received increasing attention as a novel class of polymers with intrinsic microporosity, particularly for applications in gas separation. In this study, TB was quaternized with hydrophobic long chains to create a microphase-separated structure to enhance gas separation performance. On one hand, the tertiary amine structure of TB enabled facile grafting modification through the Menshutkin reaction. On the other hand, microphase-separated channels were created in the quaternized Tröger’s base (QTB) membrane due to the polarity differences between the hydrophilicity of the quaternary ammonium groups and hydrophobicity of iodoalkanes, providing channels for gas transport within the membrane and thereby improving permeability selectivity. The successful synthesis of QTB membranes was confirmed by FTIR and ¹H NMR spectroscopy, while AFM and SAXS analyses validated the microphase-separated morphology. To investigate the impact of microphase separation on oxygen permeability and selectivity, different iodoalkanes and various concentrations of iodobutane were grafted onto the TB backbone. Among the prepared membranes, QTB-C₄-70% membrane exhibited the highest in O₂ permeability. Gas separation performance under different O₂ pressures and temperatures revealed that O₂ permeability decreased slightly with increasing pressure, indicating good pressure stability of the membrane. With increasing temperature, the permeability increased while the selectivity decreased. These findings demonstrated that microphase-separated QTB membranes offer a viable strategy for creating effective materials for gas separation. Full article

(This article belongs to the Topic Membrane Separation Technology Research, 2nd Edition)

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18 pages, 3319 KB

Open AccessArticle

Proton-Blocking Anion-Exchange Membranes for Efficient Lithium Hydroxide Recovery by Bipolar Membrane Electrodialysis

by Ji-Hyeon Lee and Moon-Sung Kang

Membranes 2026, 16(1), 8; https://doi.org/10.3390/membranes16010008 - 30 Dec 2025

Abstract

In bipolar membrane electrodialysis (BPED), proton transport through the anion-exchange membrane (AEM) is a major factor that reduces overall process efficiency. In this study, we propose a composite AEM incorporating a proton-blocking layer that combines strongly basic and weakly basic functional groups on [...] Read more.

In bipolar membrane electrodialysis (BPED), proton transport through the anion-exchange membrane (AEM) is a major factor that reduces overall process efficiency. In this study, we propose a composite AEM incorporating a proton-blocking layer that combines strongly basic and weakly basic functional groups on top of a strongly basic AEM, providing proton-blocking capability while minimizing degradation of membrane conductivity. The proton-blocking layer is prepared by reacting brominated poly(phenylene oxide) (BPPO) with diamines having different alkyl chain lengths, namely N,N,N′,N′-tetramethyl-1,6-hexanediamine (TMHDA), N,N,N′,N′-tetramethyl-1,3-propanediamine (TMPDA), and N,N,N′,N′-tetramethylethylenediamine (TMEDA). When TMHDA, which has the longest alkyl chain, is introduced into PPO, the resulting membrane exhibits high conductivity but low proton-blocking performance. In contrast, when TMEDA, which has the shortest alkyl chain, is introduced, the membrane shows low conductivity and high proton-blocking performance. Therefore, the balance between membrane conductivity and proton-blocking performance can be optimized by adjusting the molar ratio of the two diamines. The composite AEM prepared with the optimal composition simultaneously demonstrates superior conductivity and proton-blocking performance compared to the commercial proton-blocking membrane (ACM, Astom Corp., Tokyo, Japan). Furthermore, the application of this membrane has been shown to effectively improve both the energy efficiency and current efficiency of the BPED process for lithium hydroxide recovery. Full article

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

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17 pages, 1439 KB

Open AccessArticle

Characterization of the Regenerative Capacity of Membranes in the Presence of Fouling by Microalgae Using Detergents

by Volker Bächle, Marco Gleiß and Hermann Nirschl

Membranes 2026, 16(1), 7; https://doi.org/10.3390/membranes16010007 - 26 Dec 2025

Abstract

The filtration of microalgae generates fouling through algal matter and exopolymer particles with consequences for the flow rate. Therefore, regeneration that is as complete and continuous as possible is necessary. For this purpose, a commercial membrane with a pore size of 0.8 µm [...] Read more.

The filtration of microalgae generates fouling through algal matter and exopolymer particles with consequences for the flow rate. Therefore, regeneration that is as complete and continuous as possible is necessary. For this purpose, a commercial membrane with a pore size of 0.8 µm is contaminated with the microalgae mixture Haematoccocus Pluvialis and Tetradesmus obliquus, and then regenerated with mechanical (backwashing), chemical (HCl, NaOH, NaClO, P3-Ultrasil) and biological (dishwashing and laundry detergents) cleaning methods. The filtration time of the individual experiments is compared with a new membrane, and the increase is determined. Backwashing cleans the pores, but the biofilm sticks to the membrane surface and blocks the pores shortly after a new cycle. It was shown that the biofilm can only be removed chemically through oxidative effects or anionic surfactants. Hydrolysis does not remove the biofilm, and it can actually make the blockage worse. Bigger cellular residues can only be removed with enzymes. This improves cleaning performance by 61% compared to commercial cleaning agents for membranes and 42% compared to backwashing. Full article

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

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16 pages, 2948 KB

Open AccessArticle

Visualizing the Effect of Process Pause on Virus Entrapment During Constant Flux Virus Filtration

by Wenbo Xu, Xianghong Qian, Hironobu Shirataki, Daniel Straus and Sumith Ranil Wickramasinghe

Membranes 2026, 16(1), 6; https://doi.org/10.3390/membranes16010006 - 26 Dec 2025

Abstract

Virus filtration is an essential unit operation used to validate clearance of adventitious virus during the manufacture of biopharmaceutical products such as monoclonal antibodies. Obtaining at least a 10,000-fold reduction in virus particles in the permeate is challenging as monoclonal antibodies are about [...] Read more.

Virus filtration is an essential unit operation used to validate clearance of adventitious virus during the manufacture of biopharmaceutical products such as monoclonal antibodies. Obtaining at least a 10,000-fold reduction in virus particles in the permeate is challenging as monoclonal antibodies are about half the size of the virus particles. Minute virus of mice, FDA-recommended model adventitious virus, was labeled with a fluorescent dye. Laser scanning confocal microscopy was used to determine the location of virus entrapment within the virus filtration membrane. Three different hollow fiber membranes made of regenerated cellulose and polyvinylidene fluoride were tested. Feed streams consisted of MVM spiked in buffer and MVM spiked in 5 g L⁻¹ bovine serum albumin known to contain aggregates similar in size to the MVM. After filtering the feed, a buffer flush was used, with and without 30 min pause before the buffer flush. For all virus filters, a 30 min process pause led to broadening and movement of the virus entrapment zone deeper into the membrane. The presence of aggregates led to greater broadening of the entrapment zone. Both effects could lead to reduced virus clearance. Visualization of virus entrapment helps improve understanding of the behavior of virus filtration membranes. Full article

(This article belongs to the Special Issue Membrane Science and Engineering for a Sustainable Future: IMSTEC 2025)

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22 pages, 1663 KB

Open AccessReview

Toward Rational Design of Ion-Exchange Nanofiber Membranes: Meso-Scale Computational Approaches

by Inci Boztepe, Shuaifei Zhao, Xing Yang and Lingxue Kong

Membranes 2026, 16(1), 5; https://doi.org/10.3390/membranes16010005 - 23 Dec 2025

Abstract

This review highlights the growing relevance of ion-exchange nanofibrous membranes (IEX-NFMs) in membrane chromatography (MC) for protein purification, emphasising their structural advantages such as high porosity, tunable surface functionality, and low-pressure drops. While the adsorption of IEX-NFMs in MC is expanding due to [...] Read more.

This review highlights the growing relevance of ion-exchange nanofibrous membranes (IEX-NFMs) in membrane chromatography (MC) for protein purification, emphasising their structural advantages such as high porosity, tunable surface functionality, and low-pressure drops. While the adsorption of IEX-NFMs in MC is expanding due to their potential for high throughput and rapid mass transfer, a critical limitation remains: the precise binding capacity of these membranes is not well understood. Traditional experimental methods to evaluate protein–membrane interactions and optimise binding capacities are labour-intensive, time-consuming, and costly. Therefore, this review underscores the importance of computational modelling as a viable predictive approach to guide membrane design and performance prediction. Yet major obstacles persist, including the challenge of accurate representation of the complex and often irregular pore structures, as well as limited and/or oversimplified adsorption models. Along with molecular-scale simulations such as molecular dynamics (MD) simulations and quantum simulations, meso-scale simulations can provide insight into protein–fibre and protein–protein interactions under varying physicochemical conditions for larger time scales and lower computational burden. These tools can help identify key parameters such as binding accessibility, ionic strength effects, and surface charge density, which are essential for the rational design and performance prediction of IEX-NFMs. Moreover, integrating simulations with experimental validation can accelerate optimisation process while reducing cost. This technical review sets the foundation for a computationally driven design framework for multifunctional IEX-NFMs, supporting their use in next-generation chromatographic separations and broadening their applications in bioprocessing and analytical biotechnology. Full article

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

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20 pages, 5873 KB

Open AccessArticle

A Deep Reinforcement Learning-Optimized Blood Flow Profile for Enhanced Oxygenation Efficiency in Membrane Oxygenators

by Junwen Yu, Yuan Liu, Huaiyuan Guo, Qingyang Cheng, Junlong Meng and Ming Yang

Membranes 2026, 16(1), 4; https://doi.org/10.3390/membranes16010004 - 23 Dec 2025

Abstract

The membrane oxygenator serves as the core component of extracorporeal life support systems, and its gas exchange efficiency critically influences clinical outcomes. However, gas transfer is predominantly limited by the diffusion barrier within the blood-side boundary layer, where saturated red blood cells accumulate. [...] Read more.

The membrane oxygenator serves as the core component of extracorporeal life support systems, and its gas exchange efficiency critically influences clinical outcomes. However, gas transfer is predominantly limited by the diffusion barrier within the blood-side boundary layer, where saturated red blood cells accumulate. Current research focuses mainly on static approaches such as optimizing fiber bundle configuration to promote passive blood mixing or modifying material properties, which are fixed after fabrication. In contrast, dynamic blood flow control remains an underexplored avenue for enhancing oxygenator performance. This study proposes an active pulsatile flow control method that disrupts the boundary layer barrier by optimizing periodic flow profiles, thereby directly improving gas exchange. A deep reinforcement learning framework integrating proximal policy optimization and long short-term memory networks was developed to autonomously search for optimal flow waveforms under constant flow conditions. A simplified stacked-plate membrane oxygenator was specially designed as the experimental platform to minimize flow path interference. Experimental results demonstrate that the optimized pulsatile profile increases the oxygen transfer rate by

20.64 %

without compromising hemocompatibility. Full article

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4 pages, 170 KB

Open AccessEditorial

Recent Advances in Polymeric Membranes—Preparation and Applications

by Maria Ortencia González-Díaz and Manuel Aguilar-Vega

Membranes 2026, 16(1), 3; https://doi.org/10.3390/membranes16010003 - 22 Dec 2025

Abstract

Polymeric membranes have gained increasing importance due to their low energy consumption, ease of operation, and favorable chemical, mechanical, and thermal stability [...] Full article

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

21 pages, 4678 KB

Open AccessArticle

Performance of a Novel Worm-Assisted Membrane Bioelectrochemical System: Electricity Recovery, Sludge Reduction, and Membrane Fouling Mitigation

by Chenyu Ding, Xin Guo, Weiye Bian, Zhipeng Li, Yang Li, Hongjie Wang and Hui Li

Membranes 2026, 16(1), 2; https://doi.org/10.3390/membranes16010002 - 22 Dec 2025

Abstract

This study developed a novel worm-assisted membrane bioelectrochemical reactor (W-MBER) that integrates aquatic worms and a single-chamber sediment microbial fuel cell into a membrane bioreactor (MBR) to address challenges in energy recovery, sludge reduction, and membrane fouling. The system achieved a stable output [...] Read more.

This study developed a novel worm-assisted membrane bioelectrochemical reactor (W-MBER) that integrates aquatic worms and a single-chamber sediment microbial fuel cell into a membrane bioreactor (MBR) to address challenges in energy recovery, sludge reduction, and membrane fouling. The system achieved a stable output of 290 mV at an external resistance of 250 Ω and a maximum power density of 0.013 W/m² while maintaining high removal efficiencies for chemical oxygen demand (93.57%) and ammonia nitrogen (98.61%). Furthermore, the TN removal efficiency was 12.93% higher than that in the conventional MBR (C-MBR), attributed to the anodic anoxic microenvironment. The synergy of worm predation and the bioelectrochemical process reduced sludge production by 28.51% and extended the filtration cycle by 43.75%, indicating significant sludge reduction and membrane fouling mitigation. Mechanistic analysis revealed that the W-MBER system decreased protein content and protein/polysaccharide ratios in soluble microbial products (SMPs) and extracellular polymeric substances (EPSs), and the hydrophobicity of SMPs, EPSs, and sludge flocs was reduced, resulting in a lower free energy for their interaction with membrane. The foulants in the W-MBER encountered higher energy barriers and lower secondary energy minimums when approaching the membrane, indicating a lower membrane fouling propensity. These results demonstrate the promise of W-MBER for sustainable wastewater treatment. Full article

(This article belongs to the Special Issue Application of Membrane-Based Modern Solutions in Separation Techniques for the Recovery of Metal Ions and Critical Resources)

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26 pages, 1556 KB

Open AccessReview

From Environmental Threat to Control: A Review of Technologies for Removal of Quaternary Ammonium Compounds from Wastewater

by Aleksandra Klimonda and Izabela Kowalska

Membranes 2026, 16(1), 1; https://doi.org/10.3390/membranes16010001 - 19 Dec 2025

Abstract

Cationic surfactants from the group of quaternary ammonium compounds (QACs) are widely used in disinfectants, cosmetics, and household and industrial products. Their strong antimicrobial activity and chemical stability make them valuable in applications but also highly persistent and toxic when released into aquatic [...] Read more.

Cationic surfactants from the group of quaternary ammonium compounds (QACs) are widely used in disinfectants, cosmetics, and household and industrial products. Their strong antimicrobial activity and chemical stability make them valuable in applications but also highly persistent and toxic when released into aquatic environments. This problem has become increasingly relevant during and after the COVID-19 pandemic, when global use of QAC-based disinfectants increased drastically, resulting in their frequent detection in municipal, hospital, and industrial effluents. The concentrations of QACs reported in wastewater range from trace levels to several mg/L, often reaching inhibitory thresholds for biological treatment processes. Although surfactants are not listed in any current European directive, the revised Directive (EU) 2024/1440 classifies micropollutants as a priority group, imposing stricter environmental quality standards and mandatory monitoring requirements. Within this regulatory framework, QACs are recognized as compounds of emerging concern, and their effective removal from wastewater has become a critical challenge. This review summarizes the current knowledge on conventional treatment technologies (coagulation, adsorption, ion exchange, advanced oxidation, and biological processes) and membrane-based methods (ultrafiltration, nanofiltration, reverse osmosis, forward osmosis, and hybrid systems) for the removal of cationic surfactants from water and wastewater. Mechanisms of separation, performance, and operational limitations are discussed. Full article

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18 pages, 11223 KB

Open AccessArticle

Water Purification Efficiency and Membrane Fouling Behavior of Ceramic Membrane-Nanofiltration in Treating Water Treatment Plant Production Wastewater

by Yawei Xie, Zewei Liu, Jiayi Yu, Zizhang Shan, Hongyuan Liu and Yan Zhang

Membranes 2025, 15(12), 387; https://doi.org/10.3390/membranes15120387 - 18 Dec 2025

Abstract

To mitigate the risks associated with production wastewater from water treatment plants, this study evaluated the effectiveness of nanofiltration (NF) and a hybrid ceramic membrane–nanofiltration (CM–NF) process in removing natural organic matter (NOM) and Ca²⁺. A comprehensive analysis of changes in [...] Read more.

To mitigate the risks associated with production wastewater from water treatment plants, this study evaluated the effectiveness of nanofiltration (NF) and a hybrid ceramic membrane–nanofiltration (CM–NF) process in removing natural organic matter (NOM) and Ca²⁺. A comprehensive analysis of changes in specific flux and fouling resistance of the NF membrane, combined with scanning electron microscopy (SEM) observations, provided deeper insight into membrane fouling behavior. The results show that the CM–NF process achieved average removal rates of 95.60% for DOC, 98.55% for UV₂₅₄, 34.50% for conductivity, and 50.71% for Ca²⁺. These values represent improvements of 4.70%, 1.40%, 16.37%, and 10.36%, respectively, compared to the standalone NF process. Furthermore, CM pretreatment consistently optimized the performance of the nanofiltration system. After continuous operation, the average specific membrane flux of the CM–NF system reached 0.715, 0.67, and 0.61 under varying pollutant concentrations—increases of 10.9%, 19.6%, and 17.3% over the standalone NF system—confirming a significant improvement in permeate flux. Under continuous operation, the average degree of irreversible fouling was markedly reduced across different pollutant concentrations—decreasing from 9.2%, 17.6%, and 23.6% for the standalone NF system to 8.9%, 15.6%, and 10.9% for the CM–NF system, which clearly demonstrates the efficacy of CM pretreatment in controlling irreversible fouling. SEM observations further corroborated that CM pretreatment effectively alleviated fouling on the NF membrane surface. Additionally, higher Ca²⁺ concentrations were found to contribute to reduced membrane fouling and enhance flux performance. Full article

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17 pages, 2683 KB

Open AccessArticle

Polysulfone/Graphene Oxide Mixed Matrix Membranes for Improved CO₂/CH₄ Separation

by Mustafa Alsaady, Sharjeel Waqas, Mohammed A. Almarshoud, Khuram Maqsood, Aymn Abdulrahman and Yuying Yan

Membranes 2025, 15(12), 386; https://doi.org/10.3390/membranes15120386 - 18 Dec 2025

Abstract

This research focuses on developing and optimizing mixed matrix membranes (MMMs) by incorporating graphene oxide (GO) into a polysulfone (PSF) matrix to enhance the separation performance of CO₂ and CH₄. The morphology and gas separation performance of the MMMs were [...] Read more.

This research focuses on developing and optimizing mixed matrix membranes (MMMs) by incorporating graphene oxide (GO) into a polysulfone (PSF) matrix to enhance the separation performance of CO₂ and CH₄. The morphology and gas separation performance of the MMMs were systematically characterized. The incorporation of GO enhanced gas permeation and CO₂/CH₄ selectivity, as evaluated using a gas permeation setup. Notably, the PSF/GO-0.3 wt.% membrane exhibited superior performance, achieving a CO₂ permeability of 21.63 Barrer, among the highest reported for PSF-based MMMs. Additionally, the membrane demonstrated a CO₂/CH₄ selectivity of 14.32, highlighting its effectiveness in distinguishing between the two gases, which is essential for carbon capture and natural gas decontamination applications. The uniform distribution of GO within the polymer matrix contributed to the membrane’s enhanced performance. Furthermore, the MMMs exhibited outstanding resistance to CO₂ plasticization, with the PSF/GO-0.3 wt.% membrane maintaining its performance at pressures up to 10 bar, a significant improvement over the pristine PSF membrane, which failed at 4 bar. The improved plasticization resistance is ascribed to the reinforcing effect of GO, which stabilizes the polymer matrix, minimizing CO₂-induced swelling. The PSF/GO-0.3 wt.% membrane exhibited exceptional CO₂ permeability, selectivity, and plasticization resistance, making it a viable alternative for industrial gas separation applications and outperforming previously reported PSF-based MMMs. Full article

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

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16 pages, 3034 KB

Open AccessArticle

Synthesis and CO₂/N₂ Separation Performance Analysis of Mixed Matrix Membrane (MMM) Based on Different Bimetallic Metal–Organic Frameworks (Ni-Cu-MOF-74, Ni-Co-MOF-74, and Ni-Zn-MOF-74)

by Shoaib Ahsan, Muhammad Ahsan, Tayyaba Noor, Sarah Farrukh and Humais Roafi

Membranes 2025, 15(12), 385; https://doi.org/10.3390/membranes15120385 - 18 Dec 2025

Abstract

Polydimethylsiloxane (PDMS) is commonly used in gas-separation studies because of its high CO₂ permeability and stable mechanical properties. In this work, mixed matrix membranes (MMMs) were prepared by incorporating the bimetallic MOFs Ni-Cu-MOF-74, Ni-Co-MOF-74, and Ni-Zn-MOF-74 into a PDMS matrix. The membranes [...] Read more.

Polydimethylsiloxane (PDMS) is commonly used in gas-separation studies because of its high CO₂ permeability and stable mechanical properties. In this work, mixed matrix membranes (MMMs) were prepared by incorporating the bimetallic MOFs Ni-Cu-MOF-74, Ni-Co-MOF-74, and Ni-Zn-MOF-74 into a PDMS matrix. The membranes were fabricated by solution casting and characterized by SEM, XRD, FT-IR, and BET analyses, which confirmed uniform filler dispersion and the successful incorporation of the MOF-74 structures. Single-gas permeation tests showed clear performance improvements with MOF loading. The best results were obtained for the membrane containing 1 wt.% Ni-Cu-MOF-74, which reached a CO₂ permeability of 3188.25 Barrer and a CO₂/N₂ selectivity of 35.10. The improvement is attributed to the accessible metal sites and high surface area provided by the MOF-74 framework, which enhanced adsorption–diffusion pathways for CO₂ transport. These results show that PDMS/MOF-74 mixed-matrix membranes are effective for CO₂/N₂ separation, with Ni-Cu-MOF-74 achieving the highest performance. Full article

(This article belongs to the Special Issue Composite Membranes for Gas and Vapor Separation)

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