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Membranes
Volume 15
Issue 6
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Membranes, Volume 15, Issue 6 (June 2025) – 31 articles

Cover Story (view full-size image): Nymphaeol A is a lipophilic molecule with two domains, a tetrahydroxyflavanone and a geranyl chain. It is a component of propolis, a complex mixture used since ancient times as a healthy drug. This bioactive complex exhibits significant antioxidant, antifungal, antibacterial, antiviral, anticancer and antimicrobial properties, and Nymphaeol A is one of its main components. Nymphaeol A is capable of inserting spontaneously into the membrane and can be found in a monomeric form, as well as forming aggregates, tending to remain in its most extended conformation. Nymphaeol A movement along the membrane z-axis is greater than that of lipids, and it inserts between the phospholipid hydrocarbon chains, slightly increasing membrane fluidity. Nymphaeol A location and movement within the membrane are well-suited to its potent bioactivity. View this pape
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12 pages, 3509 KiB  
Article
Binding and Activating of Analgesic Crotalphine with Human TRPA1
by Mingmin Kang, Yanming Zhang, Xiufang Ding, Jianfu Xu and Xiaoyun Pang
Membranes 2025, 15(6), 187; https://doi.org/10.3390/membranes15060187 - 19 Jun 2025
Abstract
TRPA1 (Transient Receptor Potential Ankyrin 1), a cation channel predominantly expressed in sensory neurons, plays a critical role in detecting noxious stimuli and mediating pain signal transmission. As a key player in nociceptive signaling pathways, TRPA1 has emerged as a promising therapeutic target [...] Read more.
TRPA1 (Transient Receptor Potential Ankyrin 1), a cation channel predominantly expressed in sensory neurons, plays a critical role in detecting noxious stimuli and mediating pain signal transmission. As a key player in nociceptive signaling pathways, TRPA1 has emerged as a promising therapeutic target for the development of novel analgesics. Crotalphine (CRP), a 14-amino acid peptide, has been demonstrated to specifically activate TRPA1 and elicit potent analgesic effects. Previous cryo-EM (cryo-electron microscopy) studies have elucidated the structural mechanisms of TRPA1 activation by small-molecule agonists, such as iodoacetamide (IA), through covalent modification of N-terminal cysteine residues. However, the molecular interactions between TRPA1 and peptide ligands, including crotalphine, remain unclear. Here, we present the cryo-EM structure of ligand-free human TRPA1 consistent with the literature, as well as TRPA1 complexed with crotalphine, with resolutions of 3.1 Å and 3.8 Å, respectively. Through a combination of single-particle cryo-EM studies, patch-clamp electrophysiology, and microscale thermophoresis (MST), we have identified the cysteine residue at position 621 (Cys621) within the TRPA1 ion channel as the primary binding site for crotalphine. Upon binding to the reactive pocket containing C621, crotalphine induces rotational and translational movements of the transmembrane domain. This allosteric modulation coordinately dilates both the upper and lower gates, facilitating ion permeation. Full article
(This article belongs to the Section Biological Membranes)
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11 pages, 1035 KiB  
Article
Electrodialysis Using Zero-Gap Electrodes Producing Concentrated Product Without Significant Solution Resistance Losses
by W. Henry Freer, Charles Perks, Charles Codner and Paul A. Kohl
Membranes 2025, 15(6), 186; https://doi.org/10.3390/membranes15060186 - 19 Jun 2025
Abstract
Electrochemical separations use an ionic current to drive the flow of ions across an ion exchange membrane to produce dilute and concentrated streams. The economics of these systems is challenging because passing an ionic current through a dilute solution often requires a small [...] Read more.
Electrochemical separations use an ionic current to drive the flow of ions across an ion exchange membrane to produce dilute and concentrated streams. The economics of these systems is challenging because passing an ionic current through a dilute solution often requires a small cell gap to lower the ionic resistance and the use of a low current density to minimize the volage drop across the dilute product stream. Lower salt concentration in the product stream improves the fraction of the salt recovered but increases the electricity cost due to high ohmic losses. The electricity cost is managed by lowering the current density which greatly increases the balance of the plant. The cell configuration demonstrated in this study eliminates the need to pass an ionic current through the diluted product stream. Ionic current passes only through the concentrated product stream, which allows use of high current density and smaller balance of the plant. The cell has three chambers with an anion and cation membrane separating the cathode and anode, respectively, from the concentrated product solution. The device uses a zero-gap membrane electrode assemblies to improve the cell voltage and system performance. As ions concentrate in the center compartment, the solution resistance decreases, and the product is recovered with a lower voltage penalty compared to traditional electrodialysis. This lower voltage drop allows for faster feed flow rates and higher current density. Additionally, the larger cell gap for the product provides opportunities for systems with solids suspended in solution. It was found that the ion collection efficiency increased with current due to enhanced convective mass transfer in the feed streams. Full article
(This article belongs to the Section Membrane Applications for Energy)
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14 pages, 1095 KiB  
Article
Experimental Investigation of Temperature Polarization near Membrane Surface During Air Gap Membrane Distillation Processes
by Lianqi Jing, Jiaqi Sun, Yaoling Zhang, Jiaming Chen and Fei Guo
Membranes 2025, 15(6), 185; https://doi.org/10.3390/membranes15060185 - 18 Jun 2025
Abstract
Temperature polarization is a critical factor influencing the performance of membrane distillation. The presence of temperature polarization causes the temperature of the fluid near the membrane surface to be different from that in the bulk region, reducing the effective temperature difference across the [...] Read more.
Temperature polarization is a critical factor influencing the performance of membrane distillation. The presence of temperature polarization causes the temperature of the fluid near the membrane surface to be different from that in the bulk region, reducing the effective temperature difference across the membrane and thus diminishing the transmembrane mass transfer driving force. This study investigates the monitoring of temperature polarization and its effects on the transmembrane mass transfer performance in a typical air gap membrane distillation system. A set of thermocouples within a feed module were employed to monitor and capture the development of the temperature polarization profile. The test results reveal that temperature polarization reduces the effective temperature difference across the membrane, leading to a certain difference between the theoretical estimation and experimental values of the mass transfer coefficient across the porous membrane. To address this issue, the temperature polarization factor was further analyzed as a metric to quantify the impact of temperature polarization on the transmembrane flux in membrane distillation, with a detailed discussion of its range and implications. Full article
(This article belongs to the Special Issue Near-Membrane-Surface Effects During Membrane Distillation)
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35 pages, 16650 KiB  
Article
Membrane Charge Effects on Solute Transport in Nanofiltration: Experiments and Molecular Dynamics Simulations
by Suwei Liu, Zihao Foo, John H. Lienhard, Sinan Keten and Richard M. Lueptow
Membranes 2025, 15(6), 184; https://doi.org/10.3390/membranes15060184 - 18 Jun 2025
Abstract
Polyamide membranes, such as nanofiltration (NF) membranes, are widely used for water purification. However, the mechanisms of solute transport and solute rejection due to solute charge interactions with the membrane remain unclear at the molecular level. Here, we use molecular dynamics simulations to [...] Read more.
Polyamide membranes, such as nanofiltration (NF) membranes, are widely used for water purification. However, the mechanisms of solute transport and solute rejection due to solute charge interactions with the membrane remain unclear at the molecular level. Here, we use molecular dynamics simulations to examine the transport of single-solute feeds through charged nanofiltration membranes with different membrane charge concentrations of COO− and NH+2 resulting from the deprotonation or protonation of polymeric end groups according to the pH level that the membrane experiences. The results show that Na+ and Cl− solute ions are better rejected when the membrane has a higher concentration of negatively charged groups, corresponding to a higher pH, whereas CaCl2 is well rejected at all pH levels studied. These results are consistent with those of experiments performed at the same pH conditions as the simulation setup. Moreover, solute transport behavior depends on the membrane functional group distribution. When COO− functional groups are concentrated at membrane feed surface, ion permeation into the membrane is reduced. Counter-ions tend to associate with charged functional groups while co-ions seem to pass by the charged groups more easily. In addition, steric effects play a role when ions of opposite charge cluster in pores of the membrane. This study reveals solute transport and rejection mechanisms related to membrane charge and provides insights into how membranes might be designed to achieve specific desired solute rejection. Full article
(This article belongs to the Special Issue Nanofiltration Membranes: Preparation, Structure and Separation Performance)
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15 pages, 1776 KiB  
Article
Selection of Optimal Nanofiltration/Reverse Osmosis (NF/RO) Membranes for the Removal of Organic Micropollutants from Drinking Water
by E. Busra Tasdemir, Marie Pardon, Sareh Rezaei Hosseinabadi, Laurens A. J. Rutgeerts, Deirdre Cabooter and Ivo F. J. Vankelecom
Membranes 2025, 15(6), 183; https://doi.org/10.3390/membranes15060183 - 17 Jun 2025
Viewed by 8
Abstract
The growing presence of organic micropollutants (OMPs) in water sources is a major health concern. Successful removal of OMPs from water sources and ensuring the cleanliness of drinking water has become an important topic in recent years. In this study, 15 nanofiltration (NF) [...] Read more.
The growing presence of organic micropollutants (OMPs) in water sources is a major health concern. Successful removal of OMPs from water sources and ensuring the cleanliness of drinking water has become an important topic in recent years. In this study, 15 nanofiltration (NF) and reverse osmosis (RO) commercial membranes were selected and their potential to remove 10 frequently encountered OMPs in drinking water, with systematically different chemical characteristics, was evaluated. To quickly identify the most promising membranes, high throughput dead-end filtrations were initially conducted. Subsequently, the 4 best performing membranes were used in a more relevant high-throughput cross-flow filtration. Membrane performance was evaluated by analyzing OMP concentrations in the feed and retentates of the different membranes using ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS). This study identified NF 90 (Dow), NF 270 (Dow), NFX (Synder) and TS80 (Trisep) as membranes with superior performance, with a permeance between 3 and 7 L.m−2.h−1.bar−1 and retentions that were generally around 90%, except for NFX which showed slightly lower retentions. Full article
(This article belongs to the Special Issue Membrane Processes for Water Recovery in Food Processing Industries)
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17 pages, 698 KiB  
Article
A Generalized Helfrich Free Energy Framework for Multicomponent Fluid Membranes
by Hao Wu and Zhong-Can Ou-Yang
Membranes 2025, 15(6), 182; https://doi.org/10.3390/membranes15060182 - 17 Jun 2025
Viewed by 5
Abstract
Cell membranes contain a variety of biomolecules, especially various kinds of lipids and proteins, which constantly change with fluidity and environmental stimuli. Though Helfrich curvature elastic energy has successfully explained many phenomena for single-component membranes, a new theoretical framework for multicomponent membranes is [...] Read more.
Cell membranes contain a variety of biomolecules, especially various kinds of lipids and proteins, which constantly change with fluidity and environmental stimuli. Though Helfrich curvature elastic energy has successfully explained many phenomena for single-component membranes, a new theoretical framework for multicomponent membranes is still a challenge. In this work, we propose a generalized Helfrich free-energy functional describe equilibrium shapes and phase behaviors related to membrane heterogeneity with via curvature-component coupling in a unified framework. For multicomponent membranes, a new but important Laplace–Beltrami operator is derived from the variational calculation on the integral of Gaussian curvature and applied to explain the spontaneous nanotube formation of an asymmetric glycolipid vesicle. Therefore, our general mathematical framework shows a predictive capabilities beyond the existing multicomponent membrane models. The set of new curvature-component coupling EL equations have been derived for global vesicle shapes associated with the composition redistribution of multicomponent membranes for the first time and specified into several typical geometric shape equations. The equilibrium radii of isotonic vesicles for both spherical and cylindrical geometries are calculated. The analytical solution for isotonic vesicles reveals that membrane stability requires distinct elastic moduli among components (kA≠kB, k¯A≠k¯B), which is consistent with experimental observations of coexisting lipid domains. Furthermore, we elucidate the biophysical implications of the derived shape equations, linking them to experimentally observed membrane remodeling processes. Our new free-energy framework provides a baseline for more detailed microscopic membrane models. Full article
(This article belongs to the Special Issue Design Principles and Biomedical Applications of Multifunctional Biological Membranes)
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18 pages, 3908 KiB  
Article
Impact of Additives on Poly(acrylonitrile-butadiene-styrene) Membrane Formation Process Using Non-Solvent-Induced Phase Separation
by Sulaiman Dhameri, Jason Stallings, Jr., Endras Fadhilah, Emily Ingram, Mara Leach, Anastasiia Aronova and Malgorzata Chwatko
Membranes 2025, 15(6), 181; https://doi.org/10.3390/membranes15060181 - 16 Jun 2025
Viewed by 90
Abstract
Poly(acrylonitrile-butadiene-styrene) (ABS) is a common polymer used in toys, automobile parts, and membranes. Membranes fabricated with this copolymer commonly employ toxic solvents and have a dense architecture, which may not work in all applications. This work investigates the synthesis of ABS membranes, using [...] Read more.
Poly(acrylonitrile-butadiene-styrene) (ABS) is a common polymer used in toys, automobile parts, and membranes. Membranes fabricated with this copolymer commonly employ toxic solvents and have a dense architecture, which may not work in all applications. This work investigates the synthesis of ABS membranes, using green solvents and the influence of additives on the phase inversion process during the non-solvent-induced phase separation. The addition of water-soluble additives, ethanol, and acetone is hypothesized to provide additional control over viscosity and volatility, and, consequently, impact the phase inversion process. Membranes were fabricated with PolarClean and with various additive concentrations and evaporation times. The resulting membranes were characterized using scanning electron microscopy (SEM) and a pycnometer to visualize the pore structure and obtain porosity information. Membrane performance, including water flux and bovine serum albumin rejection, was evaluated using dead-end cell filtration. Membranes fabricated using only PolarClean had fingerlike pore morphology and relatively low protein rejection. The addition of additives resulted in a change in pore architecture and rejection, which is hypothesized to be a result of additives’ volatility, humidity, and destabilization of liquid–liquid separation. This study provides a more detailed understanding of the impact of additives on the resulting ABS membrane structure and performance, with a focus on safer solvents. Full article
(This article belongs to the Section Membrane Fabrication and Characterization)
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12 pages, 2875 KiB  
Article
Inhibition of ISAV Membrane Fusion by a Peptide Derived from Its Fusion Protein
by María Elena Tarnok, Lucía Caravia-Merlo, Constanza Cárdenas, Fanny Guzmán and Luis F. Aguilar
Membranes 2025, 15(6), 180; https://doi.org/10.3390/membranes15060180 - 15 Jun 2025
Viewed by 189
Abstract
Peptides designed to interfere with specific steps of viral infection mechanisms have shown promising antiviral potential. In this study, we investigated the ability of a synthetic peptide (peptide 303), derived from the fusion protein sequence of the Infectious Salmon Anemia Virus (ISAV), to [...] Read more.
Peptides designed to interfere with specific steps of viral infection mechanisms have shown promising antiviral potential. In this study, we investigated the ability of a synthetic peptide (peptide 303), derived from the fusion protein sequence of the Infectious Salmon Anemia Virus (ISAV), to inhibit membrane fusion mediated by the ISAV fusion peptide (ISAV-FP1). To assess this, we employed a model membrane system consisting of large unilamellar vesicles (LUVs) composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), dipalmitoylphosphatidylcholine (DPPC), and cholesterol. Membrane fusion kinetics were monitored via R18 fluorescence dequenching. Additionally, the interaction of peptide 303 with lipid membranes was evaluated using fluorescence anisotropy measurements. The potential direct interaction between peptide 303 and ISAV-FP1 was further examined through Förster Resonance Energy Transfer (FRET) assays. Our results demonstrate that peptide 303 effectively inhibits ISAV-FP1-mediated membrane fusion. Furthermore, peptide 303 was shown to interact with lipid bilayers and with ISAV-FP1 itself. These findings suggest a dual inhibitory mechanism in which peptide 303 both prevents ISAV-FP1 binding to the membrane and directly interacts with the fusion peptide, thereby disrupting its fusogenic activity. Full article
(This article belongs to the Special Issue Membrane Systems: From Artificial Models to Cellular Applications)
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13 pages, 3292 KiB  
Article
The Charged Superhydrophilic Polyelectrolyte/TiO2 Nanofiltration Membrane for Self-Cleaning and Separation Performance
by Weiliang Gu, Lei Han, Ye Li, Jiayi Wang, Haihong Yan, Zhenping Qin and Hongxia Guo
Membranes 2025, 15(6), 179; https://doi.org/10.3390/membranes15060179 - 12 Jun 2025
Viewed by 253
Abstract
Nanofiltration (NF) technology has extensive application in the treatment of wastewater generated in the dyeing industry. However, NF membranes often encounter fouling issues during the operation process. In this work, the superhydrophilic and self-cleaning multilayer nanofiltration membrane was prepared by self-assembling polyelectrolyte incorporating [...] Read more.
Nanofiltration (NF) technology has extensive application in the treatment of wastewater generated in the dyeing industry. However, NF membranes often encounter fouling issues during the operation process. In this work, the superhydrophilic and self-cleaning multilayer nanofiltration membrane was prepared by self-assembling polyelectrolyte incorporating the anatase PSS-TiO2 nanoparticles. The negatively charged PSS-TiO2 nanoparticles were beneficial to the formation of the nanohybrid selective layers via electrostatic interforce. The prepared (PEI/PSS-TiO2)4.0 hybrid membrane showed favorable photoinduced superhydrophilicity. The water contact angle of the membrane decreased with the UV irradiation from 35.7° to 1.6°. The negatively charged (PEI/PSS-TiO2)4.0 membrane exhibited a 100% rejection rate to XO and EbT, with a permeance flux of 5.2 and 6.4 L/(m2·h·bar), respectively. After UV irradiation for 60 min, the permeance flux could be further increased to 13.4 and 14.0 L/(m2·h·bar), and the rejection remained at 97.8% and 96.7%. Owing to the low content of TiO2 NPs photocatalytic effect under UV irradiation, the fabricated hybrid membrane exhibited a compromised permeance recovery of about 80.6%. Full article
(This article belongs to the Special Issue Nanofiltration Membranes: Preparation, Structure and Separation Performance)
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18 pages, 2170 KiB  
Review
Machine Learning in the Design and Performance Prediction of Organic Framework Membranes: Methodologies, Applications, and Industrial Prospects
by Tong Wu, Jiawei Zhang, Qinghao Yan, Jingxiang Wang and Hao Yang
Membranes 2025, 15(6), 178; https://doi.org/10.3390/membranes15060178 - 11 Jun 2025
Viewed by 546
Abstract
Organic framework membranes (OFMs) have emerged as transformative materials for separation technologies due to their tunable porosity, structural diversity, and stability, yet their design and optimization face challenges in navigating vast chemical spaces and complex performance trade-offs. This review highlights the pivotal role [...] Read more.
Organic framework membranes (OFMs) have emerged as transformative materials for separation technologies due to their tunable porosity, structural diversity, and stability, yet their design and optimization face challenges in navigating vast chemical spaces and complex performance trade-offs. This review highlights the pivotal role of machine learning (ML) in overcoming these limitations by integrating multi-source data, constructing quantitative structure–property relationships, and enabling the cross-scale optimization of OFMs. Methodologically, ML workflows—spanning data construction, feature engineering, and model optimization—accelerate candidate screening, inverse design, and mechanistic interpretation, as demonstrated in gas separations and nascent liquid-phase applications. Key findings reveal that ML identifies critical structural descriptors and environmental parameters, guiding the development of high-performance membranes that surpass traditional selectivity–permeability limits. Challenges persist in liquid separations due to dynamic operational complexities and data scarcity, while emerging frameworks offer untapped potential. The integration of interpretable ML, in situ characterization, and industrial scalability strategies is essential to transition OFMs from laboratory innovations to sustainable, adaptive separation systems. This review underscores ML’s transformative capacity to bridge computational insights with experimental validation, fostering next-generation membranes for carbon neutrality, water security, and energy-efficient industrial processes. Full article
(This article belongs to the Special Issue Preparation, Characterization, and Application of Advanced Separation Membrane Materials)
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16 pages, 3318 KiB  
Article
Nanofibrous Membranes Based on Collagen and Conductive Polymers with Perspective for Biological Applications
by Tonantzi Pérez-Moreno, Claudia D’Urso, Gabriel Trejo, Maria V. Contreras-Martínez, Omar Lozano, Gerardo J. García-Rivas, Luis G. Arriaga, Gabriel Luna-Barcenas and Janet Ledesma-García
Membranes 2025, 15(6), 177; https://doi.org/10.3390/membranes15060177 - 11 Jun 2025
Viewed by 517
Abstract
In this study, membranes of collagen–chitosan (C-Ch) in combination with conductive polymers (CPs) such as polyaniline (Pani) and polypyrrole (Ppy) were obtained by electrospinning using non-toxic solvents such as PBS and ethanol. The change in the morphology after swelling was observed by SEM, [...] Read more.
In this study, membranes of collagen–chitosan (C-Ch) in combination with conductive polymers (CPs) such as polyaniline (Pani) and polypyrrole (Ppy) were obtained by electrospinning using non-toxic solvents such as PBS and ethanol. The change in the morphology after swelling was observed by SEM, while an FTIR analysis showed specific interactions between C-Ch and CP. Mechanical tests showed that C-Ch/Ppy exhibited more elastic behavior and a better stress distribution compared to C-Ch/Pani. The diffusion of Na+ and Ca2+ ions through the membranes was evaluated and showed a greater resistance for Ca2+ in both membrane types. Preliminary biocompatibility testing with H9C2 cells showed a successful cell adhesion to the membranes. These results emphasize the potential of C-Ch/Pani composites for electrically active scaffolds and of C-Ch/PPy composites for applications in mechanically dynamic tissue-specific regeneration. Full article
(This article belongs to the Section Membrane Applications for Other Areas)
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23 pages, 1533 KiB  
Article
Oil and Water Recovery from Palm Oil Mill Effluent: A Comparative Study of PVDF and α-Al2O3 Ultrafiltration Membranes
by Saqr A. A. Al-Muraisy, Jiamin Wu, Mingliang Chen, Begüm Tanis, Sebastiaan G. J. Heijman, Shahrul bin Ismail, Jules B. van Lier and Ralph E. F. Lindeboom
Membranes 2025, 15(6), 176; https://doi.org/10.3390/membranes15060176 - 10 Jun 2025
Viewed by 291
Abstract
Recovering oil and water from palm oil mill effluent reduces environmental pollution and promotes sustainable practices. An effective method to achieve this is ultrafiltration (UF), which uses semi-permeable membranes to separate oil, solids, and other contaminants from wastewater under pressure. To assess the [...] Read more.
Recovering oil and water from palm oil mill effluent reduces environmental pollution and promotes sustainable practices. An effective method to achieve this is ultrafiltration (UF), which uses semi-permeable membranes to separate oil, solids, and other contaminants from wastewater under pressure. To assess the most effective recovery method, an experimental comparison was conducted between PVDF and α-Al2O3 UF membranes at constant permeate of 20–50 LMH for PVDF and 20–70 LMH for α-Al2O3 membranes. Both membranes achieved 99.8% chemical oxygen demand (COD) rejection, with oil concentration factor (Fo) of 186.8% and 253.0%, and water recovery (Rw) of 46.6% and 60.5%, respectively. The permeate water quality was superior to the Malaysian discharge standards, and the fat, oil, and grease (FOG) content was suitable for phase separation processes. The optimal permeate fluxes, with stable transmembrane pressures (TMP), were observed at 40 LMH (PVDF) and 60 LMH (α-Al2O3). Total resistance (Rt) values were 1.30 × 1012 m−1 (PVDF) and 1.59 × 1012 m−1 (α-Al2O3). The ratio of irreversible to total resistances (Rir/Rt) was 0.02 (PVDF) and 0.06 (α-Al2O3), indicating minimal irreversible fouling. Overall, the α-Al2O3 membrane demonstrated superior performance in oil and water recovery with more stable operation compared to the PVDF membrane. UF membrane technology emerges as an efficient technique for recovering oil and water compared to conventional methods. Full article
(This article belongs to the Special Issue Membrane Distillation and Other Membrane-Related Applications for Water Cleaning and Desalination)
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13 pages, 4682 KiB  
Communication
Seven-Channel Polyethersulfone Hollow-Fiber Membrane Preparation with Vapor-Induced Phase Separation
by Xiaoyao Wang, Zhiyuan Hao, Rui Huang, Yajing Huang, Huiqun Zhang and Xiujuan Hao
Membranes 2025, 15(6), 175; https://doi.org/10.3390/membranes15060175 - 10 Jun 2025
Viewed by 428
Abstract
Polyethersulfone (PES) has been widely used to fabricate hollow-fiber ultrafiltration membranes due to its good oxidative, thermal, and hydrolytic stability. Typical PES hollow-fiber membranes with a single bore have limited strength and may break under uneven pressure and vibration during membrane backwashing. Multi-channel [...] Read more.
Polyethersulfone (PES) has been widely used to fabricate hollow-fiber ultrafiltration membranes due to its good oxidative, thermal, and hydrolytic stability. Typical PES hollow-fiber membranes with a single bore have limited strength and may break under uneven pressure and vibration during membrane backwashing. Multi-channel hollow-fiber membranes have stronger breaking force due to their larger cross-sectional area, but fabricating them remains challenging due to the difficulty in controlling the phase inversion process. This study uses the vapor-induced phase separation (VIPS) method to fabricate a seven-channel PES hollow-fiber membrane, and the air gap and air relative humidity can help in membrane morphology control. Moreover, carboxylic graphene quantum dots (CGQDs) are first used in ultrafiltration membranes to increase membrane porosity and hydrophilicity. We found that the membrane prepared with a 7.5% CGQD mass fraction, a 10 cm air gap, and 99% relative humidity had the highest flux and porosity; the membrane pore size distribution was concentrated at 72 nm, and the pure water flux could reach 464 L·m−2 h−1·bar−1. In the long-term filtration performance test, the membrane can reject more than about 15% TOC and 84% turbidity at 50 L·m−2 h−1 flux, confirming its stability for water purification applications. Full article
(This article belongs to the Special Issue Membrane Technologies for Water Purification)
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12 pages, 7533 KiB  
Article
Determining Accurate Pore Structures of Polypropylene Membrane for ECMO Using FE-SEM Under Optimized Conditions
by Makoto Fukuda, Yoshiaki Nishite, Eri Murata, Koki Namekawa, Tomohiro Mori, Tsutomu Tanaka and Kiyotaka Sakai
Membranes 2025, 15(6), 174; https://doi.org/10.3390/membranes15060174 - 9 Jun 2025
Viewed by 339
Abstract
Long-term ECMOs are expected to be put into practical use in order to prepare for the next emerging severe infectious diseases after the novel coronavirus pandemic in 2019–2023. While polypropylene (PP) and polymethylpentene (PMP) are currently the mainstream materials for the hollow fiber [...] Read more.
Long-term ECMOs are expected to be put into practical use in order to prepare for the next emerging severe infectious diseases after the novel coronavirus pandemic in 2019–2023. While polypropylene (PP) and polymethylpentene (PMP) are currently the mainstream materials for the hollow fiber membranes of ECMO, the PP membrane coated with a silicone layer on the outer surface has also been commercialized. In this study, we sought a method to accurately observe the detailed pore morphologies of the PP membrane by suppressing irreversible changes in the morphology in SEM observation, which is a general-purpose observation with higher resolution. As a result, the convex surface morphologies of the PP membrane, which was a non-conductive porous structure, were confirmed in detail by utilizing the lower secondary electron image (LEI) mode (FE-SEM, JSM-7610F, JEOL Ltd., Tokyo, Japan) at low acceleration voltage, low magnification, and long working distance, to minimize morphological alterations caused by osmium (Os) sputtering. On the other hand, although the sputter-coating on non-conductive samples is mandatory for imaging morphologies with SEM, the non-sputtering method is also worthwhile for porous and fragile structures such as this sample to minimize morphological alterations. Furthermore, we propose a method to confirm the morphology of the deep part of the sample by utilizing the secondary electron image (SEI) mode at an appropriate acceleration voltage and high magnification with higher resolution. Full article
(This article belongs to the Special Issue Recent Advances in Polymeric Membranes—Preparation and Applications)
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26 pages, 9435 KiB  
Review
Comprehensive Insights into the Cholesterol-Mediated Modulation of Membrane Function Through Molecular Dynamics Simulations
by Ehsaneh Khodadadi, Ehsan Khodadadi, Parth Chaturvedi and Mahmoud Moradi
Membranes 2025, 15(6), 173; https://doi.org/10.3390/membranes15060173 - 8 Jun 2025
Viewed by 731
Abstract
Cholesterol plays an essential role in biological membranes and is crucial for maintaining their stability and functionality. In addition to biological membranes, cholesterol is also used in various synthetic lipid-based structures such as liposomes, proteoliposomes, and nanodiscs. Cholesterol regulates membrane properties by influencing [...] Read more.
Cholesterol plays an essential role in biological membranes and is crucial for maintaining their stability and functionality. In addition to biological membranes, cholesterol is also used in various synthetic lipid-based structures such as liposomes, proteoliposomes, and nanodiscs. Cholesterol regulates membrane properties by influencing the density of lipids, phase separation into liquid-ordered (Lo) and liquid-disordered (Ld) areas, and stability of protein–membrane interactions. For planar bilayers, cholesterol thickens the membrane, decreases permeability, and brings lipids into well-ordered domains, thereby increasing membrane rigidity by condensing lipid packing, while maintaining lateral lipid mobility in disordered regions to preserve overall membrane fluidity. It modulates membrane curvature in curved bilayers and vesicles, and stabilizes low-curvature regions, which are important for structural integrity. In liposomes, cholesterol facilitates drug encapsulation and release by controlling bilayer flexibility and stability. In nanodiscs, cholesterol enhances structural integrity and protein compatibility, which enables the investigation of protein–lipid interactions under physiological conditions. In proteoliposomes, cholesterol regulates the conformational stability of embedded proteins that have implications for protein–lipid interaction. Developments in molecular dynamics (MD) techniques, from coarse-grained to all-atom simulations, have shown how cholesterol modulates lipid tail ordering, membrane curvature, and flip-flop behavior in response to concentration. Such simulations provide insights into the mechanisms underlying membrane-associated diseases, aiding in the design of efficient drug delivery systems. In this review, we combine results from MD simulations to provide a synoptic explanation of cholesterol’s complex function in regulating membrane behavior. This synthesis combines fundamental biophysical information with practical membrane engineering, underscoring cholesterol’s important role in membrane structure, dynamics, and performance, and paving the way for rational design of stable and functional lipid-based systems to be used in medicine. In this review, we gather evidence from MD simulations to provide an overview of cholesterol’s complex function regulating membrane behavior. This synthesis connects the fundamental biophysical science with practical membrane engineering, which highlights cholesterol’s important role in membrane structure, dynamics, and function and helps us rationally design stable and functional lipid-based systems for therapeutic purposes. Full article
(This article belongs to the Section Biological Membranes)
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19 pages, 13134 KiB  
Article
Improving PFAS Rejection by Ultrafiltration Membranes via Polyelectrolyte Multilayer Coating
by Oruc Kaan Turk, Mehmet Cakmakci, Ismail Hakki Zengin, Dogan Karadag and Ebubekir Yuksel
Membranes 2025, 15(6), 172; https://doi.org/10.3390/membranes15060172 - 7 Jun 2025
Viewed by 542
Abstract
Per- and polyfluoroalkyl substances (PFASs), used since the 1940s, are persistent and carcinogenic pollutants. Water is a major exposure route; effective removal is essential. While nanofiltration (NF) and reverse osmosis (RO) are effective but costly, ultrafiltration (UF) membranes offer advantages such as lower [...] Read more.
Per- and polyfluoroalkyl substances (PFASs), used since the 1940s, are persistent and carcinogenic pollutants. Water is a major exposure route; effective removal is essential. While nanofiltration (NF) and reverse osmosis (RO) are effective but costly, ultrafiltration (UF) membranes offer advantages such as lower cost and higher flux, but their relatively large pore size makes them ineffective for PFAS compounds like perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). Since PFAS removal depends on both pore size and surface properties, this study investigates the effect of polyelectrolyte multilayer coatings using poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) on the zeta potential of UF membranes. Pristine UF membranes showed limited performance (UP150: ~2% for both PFOS and PFOA; UP020: 34.4% PFOS, 24.1% PFOA), while coating significantly enhanced removal (coated UP150: 45.3% PFOS, 43.4% PFOA; coated UP020: 77.8% PFOS, 73.3% PFOA). The modified UF membranes achieved PFAS removal efficiencies significantly closer to NF membranes, though still below those of RO (e.g., BW30XLE: up to 91.0% PFOS, 88.3% PFOA; NP030: up to 81.0% PFOS, 79.3% PFOA). Findings emphasize the importance of membrane surface charge and suggest that modified UF membranes offer a promising, low-cost alternative for PFAS removal under low-pressure conditions. Full article
(This article belongs to the Section Membrane Applications for Water Treatment)
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14 pages, 2703 KiB  
Article
Energy Efficient Forward Osmosis to Maximize Dewatering Rates
by Jongmin Jeon, Dongkeon Kim and Suhan Kim
Membranes 2025, 15(6), 171; https://doi.org/10.3390/membranes15060171 - 7 Jun 2025
Viewed by 313
Abstract
Forward osmosis (FO) is a membrane separation process driven by the osmotic pressure difference between a high-salinity draw solution (DS) and a low-salinity feed solution (FS). This pressure-free dewatering method is highly energy efficient, making it suitable for concentration and resource recovery. However, [...] Read more.
Forward osmosis (FO) is a membrane separation process driven by the osmotic pressure difference between a high-salinity draw solution (DS) and a low-salinity feed solution (FS). This pressure-free dewatering method is highly energy efficient, making it suitable for concentration and resource recovery. However, conventional FO systems using series-connected modules suffer from progressive DS dilution and FS concentration, leading to a reduction in the osmotic driving force and thereby limiting the overall performance. To address this issue, we propose a novel hybrid FO module configuration in which the FS flows in series while the DS is split and distributed in parallel across moules. This configuration was evaluated using an experimentally validated FO module model and RO simulation tools. Under seawater (600 mM NaCl) as DS and brackish water (10 mM NaCl) as FS, a conventional three-stage FO module achieved an enrichment ratio of 2.5 with an energy consumption of 0.151 kWh/m3. In contrast, the proposed draw solution split distribution (DSSD) achieved an enrichment ratio of 12.5 at a reduced energy consumption of 0.137 kWh/m3. In comparison, a reverse osmosis system consuming 0.58 kWh/m3 achieved a similar enrichment ratio of 12.3. These results demonstrate the high energy efficiency and dewatering capacity of the proposed FO configuration, highlighting its potential for industrial applications in food processing, beverage production, pharmaceuticals and agriculture. Full article
(This article belongs to the Special Issue Green Membrane Technologies: Advancements in Materials and Energy Efficiency for Water Treatment)
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20 pages, 2022 KiB  
Article
Prediction of Expected Fouling Time During Transmembrane Transition in Reverse Osmosis Systems
by Jozsef Lakner and Gabor Lakner
Membranes 2025, 15(6), 170; https://doi.org/10.3390/membranes15060170 - 6 Jun 2025
Viewed by 474
Abstract
Membrane filtration, including reverse osmosis filtration, is widely applied in water treatment worldwide, offering solutions to a broad range of separation challenges. However, due to the porous structure of membranes, they are prone to fouling, which reduces their efficiency and can eventually render [...] Read more.
Membrane filtration, including reverse osmosis filtration, is widely applied in water treatment worldwide, offering solutions to a broad range of separation challenges. However, due to the porous structure of membranes, they are prone to fouling, which reduces their efficiency and can eventually render the membranes incapable of functioning. In such cases, a systemic intervention becomes necessary, highlighting the importance of accurately predicting the expected fouling time. Various approaches for estimating fouling processes and times are well documented in the literature. However, a common limitation of these methods is that they typically assume constant and well-defined operating parameters over time. Under such stable conditions, the process can be described deterministically, and the fouling time can be predicted using straightforward extrapolation techniques. However, in industrial practice, process conditions often fluctuate due to multiple influencing factors, making fouling time a variable quantity. Therefore, it can be more appropriately treated as a random variable characterized by a mean value and standard deviation. Rather than predicting a precise fouling time, it is more relevant to define a probabilistic interval within which the fouling is expected to occur with a specified confidence level (e.g., 95%). The associated maintenance scheduling can then be optimized based on economic criteria. The probability-based model presented herein defines this interval based on operational measurements, thereby providing users with a time window during which maintenance should be planned. From this point forward, the exact timing of interventions becomes a matter of technical feasibility and economic optimization. Full article
(This article belongs to the Special Issue New Advances in Membrane Separation Technology for Water Pollution Control and Membrane Fouling Mitigation)
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17 pages, 3754 KiB  
Article
Calcium Ion Mixing Modes Govern Membrane Fouling Mitigation During Membrane-Based Recovery of Extracellular Polymeric Substances
by Da-Qi Cao, Yi-Xuan Song, Yun-Feng Wu, Guri Yihuo and Jing-Yi Jin
Membranes 2025, 15(6), 169; https://doi.org/10.3390/membranes15060169 - 5 Jun 2025
Viewed by 632
Abstract
Recycling extracellular polymeric substances (EPSs) from excess sludge in wastewater treatment plants has garnered significant research attention. Membrane separation offers a promising approach for EPS concentration; however, membrane fouling remains a critical challenge. Previous studies demonstrate that Ca2+ addition effectively mitigates membrane [...] Read more.
Recycling extracellular polymeric substances (EPSs) from excess sludge in wastewater treatment plants has garnered significant research attention. Membrane separation offers a promising approach for EPS concentration; however, membrane fouling remains a critical challenge. Previous studies demonstrate that Ca2+ addition effectively mitigates membrane fouling. This study reveals that Ca2+ mixing modes govern membrane fouling in the dead-end ultrafiltration of both the practical EPS and model EPS [sodium algiante (SA)]. The interaction mechanisms between Ca2+ and the EPS under varied mixing conditions and their impact on filtration performance were systematically investigated. At a low Ca2+ concentration, the addition sequence critically influenced colloidal particle sizes formed via Ca2+-EPS interactions, altering the cake layer structure governing filtration resistance; these effects diminished at higher Ca2+ concentrations. In suspensions prepared by adding EPS to Ca2+ solution (EPS-Ca), a portion of the EPS became encapsulated within an EPS-Ca layer formed through Ca2+ EPS binding, reducing free EPS concentration and enlarging colloidal aggregates. This encapsulation reduced EPS-mediated membrane fouling, thereby lowering filtration resistance. Conversely, in suspensions prepared by adding Ca2+ to EPS solution (Ca-EPS), more complete Ca2+ EPS interactions formed a dense crosslinked structure with smaller colloids on membrane surfaces, intensifying fouling and resistance. Additionally, EPS-Ca exhibited higher compressibility than Ca-EPS, though both exhibited comparable filtration resistance under high-pressure conditions. These results offer critical insights into optimizing EPS ultrafiltration concentration to mitigate membrane fouling through Ca2+ addition strategies. Full article
(This article belongs to the Section Membrane Applications for Water Treatment)
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13 pages, 1147 KiB  
Article
Exploring Nanofiltration for Transport of Small Molecular Species for Application in Artificial Kidney Devices to Treat End-Stage Kidney Disease
by Haley Duncan, Christopher Newton, Jamie Hestekin, Christa Hestekin and Ira Kurtz
Membranes 2025, 15(6), 168; https://doi.org/10.3390/membranes15060168 - 2 Jun 2025
Viewed by 575
Abstract
End-stage renal disease occurs when there is permanent loss of the kidney’s ability to filter toxins from the blood. Due to the limited number of transplants, dialysis is currently the most common treatment, but it significantly limits a patient’s lifestyle and has significant [...] Read more.
End-stage renal disease occurs when there is permanent loss of the kidney’s ability to filter toxins from the blood. Due to the limited number of transplants, dialysis is currently the most common treatment, but it significantly limits a patient’s lifestyle and has significant side effects. One solution is an artificial kidney, but significant challenges remain in its development. One challenge is the separation of glucose from urea. Nanofiltration is ideal for this separation; however, there is little understanding of the important parameters for this separation under physiological conditions. In this study, operating parameters (pressure and temperature) as well as feed conditions (increased glucose/salt) were explored for their effects on the separation of glucose from urea in six commercial membranes. The rejection of monovalent and divalent ions was also characterized. While increasing pressure increased flux, it had little effect on metabolite rejection, except for glucose, which increased above 20 psi. Increasing temperature led to a slight increase in flux and a slight decrease in the rejection of divalent ions. Glucose rejection was sensitive to feed conditions, while urea rejection was less affected. Divalent ions were rejected more strongly than monovalent ions and were also more affected by feed conditions. Full article
(This article belongs to the Section Membrane Applications for Other Areas)
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26 pages, 1134 KiB  
Review
Nanomembranes as Eco-Friendly Instruments for Modern Food Processing, from Filtration to Packaging
by Simona Gavrilaș
Membranes 2025, 15(6), 167; https://doi.org/10.3390/membranes15060167 - 2 Jun 2025
Viewed by 977
Abstract
With the increasing demand for safe, high-quality, and sustainable food, nanomembranes have attracted significant interest as innovative solutions in food processing. They are extremely thin structures created from special materials that allow for the selective filtration of very small particles. In the food [...] Read more.
With the increasing demand for safe, high-quality, and sustainable food, nanomembranes have attracted significant interest as innovative solutions in food processing. They are extremely thin structures created from special materials that allow for the selective filtration of very small particles. In the food industry, such approaches are increasingly used for packaging and processing, as they can slow down food degradation and thus extend its shelf life. This article examines the potential of utilizing nanomembranes as ecological tools at various stages of the food chain, ranging from advanced filtration of food liquids to the development of smart and active packaging. This study reviews the recent research in the field, highlighting the applications developed and presenting targeted advantages and disadvantages. The developed applications primarily focus on extending the shelf life of products while also discussing their antioxidant and antibacterial attributes. By highlighting the latest applications and emerging research directions, this article underscores the pivotal role of nanomembranes in facilitating the transition to a modern, sustainable, and environmentally responsible food industry. However, current research faces several challenges. Most products are less biodegradable and, consequently, could harm the environment. Additionally, data on the long-term effects of these materials on human health, particularly when used in packaging that comes into direct contact with food, remain insufficient. Therefore, more sustainable solutions are needed, such as nanomembranes based on natural biopolymers. Further studies are required to assess their safety and real-world effectiveness under industrial conditions. Full article
(This article belongs to the Section Membrane Applications for Other Areas)
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9 pages, 1752 KiB  
Communication
A Fiberglass-Cloth-Reinforced Perfluorosulfonic Acid Membrane
by Zhutao Zhang, Yiru Dou, Wen Zhang, Li Xu and Yuxin Wang
Membranes 2025, 15(6), 166; https://doi.org/10.3390/membranes15060166 - 2 Jun 2025
Viewed by 468
Abstract
Perfluorosulfonic acid (PFSA) membranes have found broad-ranging applications, owing to their high ionic conductivity and excellent chemical stability. However, membranes with higher mechanical strength, lower area-specific resistance, reduced swelling, less gas crossover and more affordable costs are desirable. Herein, we report on the [...] Read more.
Perfluorosulfonic acid (PFSA) membranes have found broad-ranging applications, owing to their high ionic conductivity and excellent chemical stability. However, membranes with higher mechanical strength, lower area-specific resistance, reduced swelling, less gas crossover and more affordable costs are desirable. Herein, we report on the fabrication of a fiberglass-cloth-reinforced PFSA membrane using a simple solution cast method. The breaking strength of the reinforced membrane has the potential to reach 81 MPa, which is about 6 times and 2.5 times that of its non-reinforced counterpart and the commercial Nafion 117 (N117) membrane, respectively. The area swelling ratio of the reinforced membrane is lowered to merely 3%, which is only about 1/12 that of N117, in water at 100 °C. Despite ionic conduction being hindered by the fiberglass cloth, the reinforced PFSA membrane shows an area-specific resistance of only 0.069 Ω·cm2, which is 58% lower than that of N117, under 80 °C and 100% humidity. This research provides a promising technological pathway for the development of high-performance ionic conductive membranes. Full article
(This article belongs to the Section Membrane Fabrication and Characterization)
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15 pages, 2234 KiB  
Article
Moving Rubber Blade (MRB) for Fouling Control in Anaerobic Ceramic Membrane Bioreactors (AnCMBRs) Treating High-Strength Food Wastewater: Development and Long-Term Application
by Young-Jae Lee, Hyung-Soo Kim, Hyunsup Jang, Sung-Gwan Park, Ji-Yeon Kim, Sung-Jae Lee, Youngjin Kim, Moon-Hyun Hwang and Sangyoup Lee
Membranes 2025, 15(6), 165; https://doi.org/10.3390/membranes15060165 - 1 Jun 2025
Viewed by 543
Abstract
This study investigates membrane fouling control in a submerged anaerobic ceramic membrane bioreactor (AnCMBR) treating high-strength food wastewater (chemical oxygen demand (COD): 10–30 g/L). A hybrid strategy combining mechanical cleaning via a moving rubber blade (MRB) (termed anaerobic ceramic blade MBR (AnCBMBR)) with [...] Read more.
This study investigates membrane fouling control in a submerged anaerobic ceramic membrane bioreactor (AnCMBR) treating high-strength food wastewater (chemical oxygen demand (COD): 10–30 g/L). A hybrid strategy combining mechanical cleaning via a moving rubber blade (MRB) (termed anaerobic ceramic blade MBR (AnCBMBR)) with intermittent salt-assisted backwash (SAB) was tested to manage transmembrane pressure (TMP) and sustain treatment performance. During more than 300 days of field operation, MRB alone maintained stable TMP below 0.15 kgf/cm2 without backwashing, achieving more than 90% COD removal at a very short hydraulic retention time (HRT) of 1–2 days. Introducing intermittent SAB further stabilized operations and enhanced total phosphorus (T-P) removal by facilitating struvite formation through the interaction of MgCl2 and phosphorus in the reactor. The AnCBMBR system demonstrated reliable, long-term fouling control and treatment efficiency, even under high organic loads, proving its viability for small-scale facilities managing concentrated food wastewater. This study advances practical strategies for sustainable anaerobic MBR operation under challenging industrial conditions. Full article
(This article belongs to the Special Issue Advanced Membranes and Membrane Technologies for Wastewater Treatment)
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15 pages, 2665 KiB  
Article
Development of Thermo-Responsive and Salt-Adaptive Ultrafiltration Membranes Functionalized with PNIPAM-co-PDMAC Copolymer
by Lauran Mama, Johanne Pirkin-Benameur, Vincent Bouad, David Fournier, Patrice Woisel, Joël Lyskawa, Karim Aissou and Damien Quemener
Membranes 2025, 15(6), 164; https://doi.org/10.3390/membranes15060164 - 28 May 2025
Viewed by 603
Abstract
Access to clean water remains a critical global challenge, exacerbated by population growth, industrial activity, and climate change. In response, this study presents the development and characterization of thermo-responsive and salt-adaptive ultrafiltration membranes functionalized with a poly(N-isopropylacrylamide)–co-poly(dimethylacrylamide) (PNIPAM-co-PDMAC) copolymer. By combining the thermo-responsive [...] Read more.
Access to clean water remains a critical global challenge, exacerbated by population growth, industrial activity, and climate change. In response, this study presents the development and characterization of thermo-responsive and salt-adaptive ultrafiltration membranes functionalized with a poly(N-isopropylacrylamide)–co-poly(dimethylacrylamide) (PNIPAM-co-PDMAC) copolymer. By combining the thermo-responsive properties of PNIPAM with the hydrophilic characteristics of PDMAC, these membranes exhibit dual-stimuli responsiveness to temperature and ionic strength, allowing for precise control of permeability and fouling resistance. The experimental results demonstrated that the copolymer’s hydration state and dynamic pore size modulation are sensitive to changes in salinity and temperature, with sodium chloride (NaCl) significantly influencing the transition behavior. Preliminary fouling tests confirmed the antifouling capabilities of these membranes, with salt-triggered hydration transitions effectively reducing irreversible fouling and extending membrane durability. The membranes’ reversible properties and adaptability to dynamic operating conditions highlight their potential to enhance the efficiency and sustainability of water treatment processes. Future investigations will focus on scaling up the fabrication process and assessing the long-term stability of these membranes under real-world conditions. This study underscores the promise of smart membrane systems for advancing global water sustainability. Full article
(This article belongs to the Special Issue Advanced Fabrication Techniques and Applications for High-Performance Polymer Membranes)
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17 pages, 4450 KiB  
Article
Location and Dynamics of Nymphaeol A in a Complex Membrane
by José Villalaín
Membranes 2025, 15(6), 163; https://doi.org/10.3390/membranes15060163 - 28 May 2025
Viewed by 589
Abstract
Nymphaeol A (NYA) is a tetrahydroxyflavanone anchored to a hydrophobic geranyl group, isolated from different sources and a component of propolis, a complex mixture produced by honeybees and used since ancient times as a healthy drug. This complex exhibits significant antioxidant, antifungal, antibacterial, [...] Read more.
Nymphaeol A (NYA) is a tetrahydroxyflavanone anchored to a hydrophobic geranyl group, isolated from different sources and a component of propolis, a complex mixture produced by honeybees and used since ancient times as a healthy drug. This complex exhibits significant antioxidant, antifungal, antibacterial, antiviral, anticancer and antimicrobial properties and NYA is one of its main components. NYA is a lipophilic molecule with two domains, one polar and one hydrophobic. NYA can be inserted into membranes, and its membrane properties depend not only on its location but also on the membrane’s lipid composition. This work uses molecular dynamics to obtain the dynamics, orientation, location and interactions of NYA in a complex biomembrane. This work shows that in an aqueous solution, NYA forms high-order aggregates where the molecules are joined together by the hydrophobic chain. In the presence of a membrane but initially located in the aqueous media, NYA is capable of inserting itself spontaneously into the membrane. Inside the membrane, NYA can be found in the monomeric form, as well as forming aggregates, tending to remain in its most extended conformation. NYA moves along the x-, y- and z-axes, with the movement along the z-axis larger than that of the membrane’s lipids. NYA forms an approximate angle of 35° perpendicular with respect to the membrane and is inserted between the phospholipid hydrocarbon chains, slightly increasing membrane fluidity. Furthermore, NYA prefers POPC and PSM but not POPE or CHOL. NYA’s location and movement within the membrane should be well-suited for its potent bioactivity. Full article
(This article belongs to the Special Issue Recent Advances in Biomembrane Models for Studying Interactions with Bio-/Molecules)
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46 pages, 4813 KiB  
Review
Overcoming the Limitations of Forward Osmosis and Membrane Distillation in Sustainable Hybrid Processes Managing the Water–Energy Nexus
by Muhammad Suleman, Basel Al-Rudainy and Frank Lipnizki
Membranes 2025, 15(6), 162; https://doi.org/10.3390/membranes15060162 - 26 May 2025
Viewed by 1039
Abstract
Energy-efficient and cost-effective water desalination systems can significantly replenish freshwater reserves without further stressing limited energy resources. Currently, the majority of the desalination systems are operated by non-renewable energy sources such as fossil fuel power plants. The viability of any desalination process depends [...] Read more.
Energy-efficient and cost-effective water desalination systems can significantly replenish freshwater reserves without further stressing limited energy resources. Currently, the majority of the desalination systems are operated by non-renewable energy sources such as fossil fuel power plants. The viability of any desalination process depends primarily on the type and amount of energy it utilizes and on the product recovery. In recent years, membrane distillation (MD) and forward osmosis (FO) have drawn the attention of the scientific community because of FO’s low energy demand and the potential of MD operation with low-grade heat or a renewable source like geothermal, wind, or solar energy. Despite the numerous potential advantages of MD and FO, there are still some limitations that negatively affect their performance associated with the water–energy nexus. This critical review focuses on the hybrid forward osmosis–membrane distillation (FO-MD) processes, emphasizing energy demand and product quality. It starts with exploring the limitations of MD and FO as standalone processes and their performance. Based on this, the importance of combining these technologies into an FO-MD hybrid process and the resulting strengths of it will be demonstrated. The promising applications of this hybrid process and their advantages will be also explored. Furthermore, the performance of FO-MD processes will be compared with other hybrid processes like FO–nanofiltration (FO-NF) and FO–reverse osmosis (FO-RO). It will be outlined how the FO-MD hybrid process could outperform other hybrid processes when utilizing a low-grade heat source. In conclusion, it will be shown that the FO-MD hybrid process can offer a sustainable solution to address water scarcity and efficiently manage the water–energy nexus. Full article
(This article belongs to the Section Membrane Applications for Water Treatment)
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22 pages, 4021 KiB  
Article
DPPC Membrane Under Lateral Compression and Stretching to Extreme Limits: Phase Transitions and Rupture
by Subhalaxmi Das, Nikos Ch. Karayiannis and Supriya Roy
Membranes 2025, 15(6), 161; https://doi.org/10.3390/membranes15060161 - 26 May 2025
Viewed by 767
Abstract
Dipalmitoylphosphatidylcholine (DPPC), is one of the key bilayer membranes of the phosphatidylcholine (PC) family which constitutes 40–50% of total cellular phospholipids in mammal cells. We investigate the behavior of an initially planar DPPC membrane under lateral pressures from −200 to 150 bar at [...] Read more.
Dipalmitoylphosphatidylcholine (DPPC), is one of the key bilayer membranes of the phosphatidylcholine (PC) family which constitutes 40–50% of total cellular phospholipids in mammal cells. We investigate the behavior of an initially planar DPPC membrane under lateral pressures from −200 to 150 bar at 323 K using microsecond-scale simulations. We identify, with very high precision, the pressure range for the occurrence of critical phenomena, mainly undulation and rupture. Notably, under compression, the membrane initially thickens, leading to a phase transition to an undulated state between 40 and 50 bar, as gauged by the sharp changes in the diverse structural metrics. Stretching induces systematic membrane thinning, with rupture becoming probable at −170 bar and certain at −200 bar. The reverse compression cycle shows pressure hysteresis with a 10-bar shift, while the reverse stretching cycle retraces the pathway. System size has a minimal impact on the observed trends. Under extreme mechanical stress, particularly near critical phenomena, simulation times on the order of microsecond are needed to accurately capture phase behavior and structural alterations. This work provides important insights into understanding membrane behavior under extreme conditions, which are relevant to numerous biological and technological applications. Full article
(This article belongs to the Special Issue Composition and Biophysical Properties of Lipid Membranes)
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22 pages, 5832 KiB  
Article
Carbonized Dual-Layer Balsa Wood Membrane for Efficient Oil–Water Separation in Kitchen Applications
by Mamadou Souare, Changqing Dong, Xiaoying Hu, Junjiao Zhang, Juejie Xue and Quanjun Zheng
Membranes 2025, 15(6), 160; https://doi.org/10.3390/membranes15060160 - 24 May 2025
Viewed by 801
Abstract
Wood-based membranes have garnered increasing attention due to their structural advantages and durability in the efficient treatment of oily kitchen wastewater. However, conventional fabrication methods often rely on toxic chemicals or synthetic processes, generating secondary pollutants and suffering from fouling, which reduces performance [...] Read more.
Wood-based membranes have garnered increasing attention due to their structural advantages and durability in the efficient treatment of oily kitchen wastewater. However, conventional fabrication methods often rely on toxic chemicals or synthetic processes, generating secondary pollutants and suffering from fouling, which reduces performance and increases resource loss. In this study, an innovative bilayer membrane was developed from balsa wood by combining a hydrophilic longitudinal layer for water transport with a polydimethylsiloxane (PDMS)-impregnated carbonized transverse layer to enhance hydrophobicity, resulting in increased separation efficiency and a reduction in fouling by 98.38%. The results show a high permeation flux of 1176.86 Lm–2 h–1 and a separation efficiency of 98.60%, maintaining low fouling resistance (<3%) over 20 cycles. Mechanical tests revealed a tensile strength of 10.92 MPa and a fracture elongation of 10.42%, ensuring robust mechanical properties. Wettability measurements indicate a 144° contact angle and a 7° sliding angle with water on the carbonized side, and a 163.7° contact angle with oil underwater and a 5° sliding angle on the hydrophilic side, demonstrating excellent selective wettability. This study demonstrates the potential of carbonized wood-based membranes as a sustainable, effective alternative for large-scale wastewater treatment. Full article
(This article belongs to the Special Issue Preparation, Characterization, and Application of Advanced Separation Membrane Materials)
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14 pages, 1533 KiB  
Article
Cholesterol Sulfate in Biological Membranes: A Biophysical Study in Cholesterol-Poor and Cholesterol-Rich Biomimetic Models
by Ana Reis, Maria João Sarmento, Mariana Ferreira, Paula Gameiro and Victor de Freitas
Membranes 2025, 15(6), 159; https://doi.org/10.3390/membranes15060159 - 24 May 2025
Viewed by 591
Abstract
As a surface-located molecule in biological membranes, cholesterol sulphate (CholS) plays a major role in membrane-driven cell–cell processes and events including platelet-cell adhesion, T-cell receptor signalling, sperm–egg interaction, membrane fusion, and skin differentiation. Despite this, little is known about the biophysical implications of [...] Read more.
As a surface-located molecule in biological membranes, cholesterol sulphate (CholS) plays a major role in membrane-driven cell–cell processes and events including platelet-cell adhesion, T-cell receptor signalling, sperm–egg interaction, membrane fusion, and skin differentiation. Despite this, little is known about the biophysical implications of CholS at the membrane in cells and organelles. In this study, we investigate the effect of increasing the content of CholS on the biophysical properties in cholesterol-poor and cholesterol-rich biomimetic models. Data obtained show that increasing amounts of CholS result in a slight increase in anisotropy, evidence for decreased membrane fluidity at higher CholS content (10 mol%) in cholesterol-poor systems but only negligible in rigidified epithelial-like cholesterol-rich systems. On the other hand, incorporation of CholS has an overall increasing ordering effect on membrane organisation and on-surface potential that is influenced by the lipid composition and cholesterol content. Though further research is needed to gain better insights on the (patho)physiological levels of CholS in cells and organelles, our findings are discussed in the context of diet–microbiota–host interactions in membrane-driven events in inflammatory-related disorders. Full article
(This article belongs to the Special Issue Composition and Biophysical Properties of Lipid Membranes)
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18 pages, 2611 KiB  
Article
The Impact of Graphene Oxide Nanoparticles Decorated with Silver Nanoparticles (GrO/AgNP) on the Cellulose Acetate (CA) Membrane Matrix Used for Hydrocarbon Removal from Water
by Marian Băjan, Diana Luciana Cursaru and Sonia Mihai
Membranes 2025, 15(6), 158; https://doi.org/10.3390/membranes15060158 - 23 May 2025
Viewed by 532
Abstract
Adding nanomaterials to polymer membranes can improve certain properties, such as the photocatalytic degradation of contaminants and antibacterial qualities. However, the interaction between nanomaterials and polymers is often limited by the presence of functional groups that can trap nanostructures within the polymer matrix. [...] Read more.
Adding nanomaterials to polymer membranes can improve certain properties, such as the photocatalytic degradation of contaminants and antibacterial qualities. However, the interaction between nanomaterials and polymers is often limited by the presence of functional groups that can trap nanostructures within the polymer matrix. This study focuses on the synthesis of silver-decorated graphene oxide nanoparticles and their integration into cellulose acetate membranes. Characterization of the membranes was conducted using various techniques, including electron microscopy (SEM), thermogravimetric analysis, FTIR, goniometry, and filterability tests. The results indicate that CA membranes with decorated nanoparticles exhibit improved thermal stability, making them more effective for removing heavy hydrocarbons without the risk of nanomaterial elution during temperature fluctuations in the contaminated water flow subjected to filtration. Furthermore, these decorated structures enhance hydrophobicity due to interactions between the oxygenated groups of GrO and silver ions. While these additional networks may reduce the permeate flow rate, they significantly increase the efficiency of contaminant removal. Full article
(This article belongs to the Special Issue Synthesis, Characterization, and Application of Nanostructure Membrane Materials in Water Treatment)
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