Membranes doi: 10.3390/membranes16050175

Authors: M. Hamza Asif Awan Ashraf Aly Hassan Asad Ali Zaidi Muhammad Asad Javed

Population growth, industrialization and climate change have placed increasing stress on natural freshwater reserves, making conventional water sources inadequate. Coupled with rising energy constraints and environmental concerns, interest in desalination technologies that can operate more sustainably and efficiently has intensified. Among the available approaches, membrane desalination has gained particular importance because of its modularity, relatively low energy demand, and compatibility with decentralized water treatment. In parallel, thermoelectric devices have emerged as promising components for hybrid desalination systems due to their ability to convert temperature gradients into electricity or provide localized heating and cooling for process enhancement. This article presents a narrative review of thermoelectric integration in desalination systems, with particular emphasis on membrane desalination and membrane-hybrid water treatment configurations powered by renewable-energy or low-grade heat sources. The review examines the role of thermoelectric devices in relation to key membrane-based and hybrid desalination processes, including reverse osmosis, membrane distillation, electrodialysis, nanofiltration, forward osmosis, and selected hybrid systems. Particular attention is given to system configurations, renewable energy coupling pathways, functional roles of thermoelectric devices, water productivity, module output, desalination efficiency, water quality, and economic performance. The reviewed literature indicates that thermoelectric integration can provide meaningful benefits in hybrid desalination, particularly through improved thermal management, enhanced utilization of low-grade heat, and supplementary energy recovery. These opportunities appear especially relevant for thermally driven membrane systems such as membrane distillation and for membrane-hybrid configurations intended for decentralized or renewable-powered applications. However, the available evidence remains highly heterogeneous, with substantial variation in system scale, operating conditions, reporting metrics, and cost assumptions, which limits direct cross-study comparison and broad generalization of performance claims. This review highlights the technical challenges, reporting inconsistencies, and research gaps that currently constrain the practical development of thermoelectric-assisted membrane desalination and outlines future directions for membrane-aligned hybrid desalination research.

Membranes doi: 10.3390/membranes16050174

Authors: Jadwiga Maniewska Katarzyna Gębczak

Biological membranes play a pivotal role in determining cellular organization and functionality, as they provide complex and dynamic environments for interactions with a diverse array of biomolecules and external compounds [...]

Membranes doi: 10.3390/membranes16050173

Authors: Le Deng Lian-Ying Liao Xiao Ling Li Li You-Jie He Miao-Miao Guo

Schisandra chinensis (Turcz.) Baill. (Schisandraceae) is a medicinal plant widely distributed in East Asia and has long been used in traditional herbal medicine. Phytochemical studies have identified lignans as the major bioactive constituents of S. chinensis, among which Schisandrin B (Sch B) is one of the most abundant and pharmacologically active compounds. Previous studies have demonstrated that Sch B exhibits a variety of biological activities, including antioxidant, anti-inflammatory, hepatoprotective, and cytoprotective effects. As a natural lignan compound derived from S. chinensis, Sch B has attracted increasing attention for its potential protective effects against environmental and inflammatory insults. This study aimed to investigate the protective effects of Sch B against PM2.5-induced inflammatory injury in THP-1 cells and to elucidate the underlying molecular mechanisms. An in vitro PM2.5-induced THP-1 cell injury model was established by stimulating THP-1 cells with PM2.5. Subsequently, Sch B was applied to the model, and inflammation-related indicators and pathways were detected using methods such as ELISA, PCR, and Western Blot (WB). The results showed that Sch B significantly inhibited interleukin-1β (IL-1β) secretion and attenuated PM2.5-induced pyroptosis in THP-1 cells. Mechanistically, Sch B alleviated cell membrane damage and inflammatory factor release by suppressing Caspase-1 activation and inhibiting the cleavage of gasdermin D (GSDMD) into its active N-terminal fragment (N-GSDMD). Furthermore, Sch B treatment was associated with the up-regulation of ALG-2, ALIX, and TSG101, suggesting the potential involvement of ESCRT-III-associated membrane repair mechanisms. In conclusion, Sch B, a natural lignan compound derived from S. chinensis, exhibits protective effects against PM2.5-induced THP-1 cell pyroptosis by reducing cell membrane damage and inflammatory cytokine release. These effects are associated with the inhibition of Caspase-1 activity and GSDMD cleavage, as well as the activation of ESCRT-III-associated membrane repair responses. Collectively, these findings highlight the potential of Sch B as a natural cytoprotective compound against particulate matter-induced inflammatory injury.

Membranes doi: 10.3390/membranes16050172

Authors: Benjamin Drukarch Micha M. M. Wilhelmus

Neuronal excitability manifests itself mainly in the form of non-linear, self-regenerative waves of electricity moving along the surface of neuronal axons. These waves are commonly known as action potentials (APs). Theoretical and experimental investigations of the physical and functional characteristics of APs have broadly followed along the lines of the ionic hypothesis and the associated mathematical model introduced by Hodgkin and Huxley (HH). In the current form of this bioelectrical framework, adopted in mainstream physiology and other biological sciences, the axonal membrane is conceptualized as an electronic circuit where electric current is generated and propelled as a result of the time-dependent opening and closure of voltage-operated ion channel proteins, allowing passive flow of specific ions across and along the membrane, powered by their respective electrochemical gradients. Although representing mainstream research, the bioelectric perspective has been criticized for its narrow focus on the electrical characteristics of APs, whilst ignoring other physical manifestations of the nerve signal, particularly mechanical and thermal changes coinciding with AP propagation. As an alternative, a macroscopic thermodynamics-based acoustic theory has been outlined, in which all electric and non-electric manifestations of the nerve signal are considered as a result of a single density pulse in the axonal membrane carried by a reversible lipid membrane phase transition and momentum conservation. Representing a minority view, however, this unified, acoustic perspective on the physical nature of neuronal excitability is largely ignored by representatives of the bioelectric perspective. Here, we draw special attention to the philosophical dimension of the communication failure between the two communities of scientists. We argue that adherents of the bioelectric perspective favor a mechanist type of explanation, whilst supporters of the acoustic perspective are committed to so-called covering-law types of explanation. We conclude that it is this thus far unrecognized philosophical rift, rather than specific scientific differences in opinion, that blocks fruitful interdisciplinary cooperation necessary for building a comprehensive, fully integrated notion of the physical nature of neuronal excitability. Suggestions of how to bridge this conceptual gap are formulated.

Membranes doi: 10.3390/membranes16050171

Authors: Bing Wang Weijia Song Yuqi Sun Enlin Wang Can Li Baowei Su

Organic solvent reverse osmosis (OSRO) is an emerging membrane technology for low-energy separation of organic mixtures, yet developing OSRO membranes with both high permeance and robust stability remains challenging. Herein, we present a surface modification strategy using a D-glucamine/ethanol solution to tailor the physicochemical properties of a crosslinked polyimide-supported polyamide OSRO membrane. D-glucamine, as an amino sugar alcohol compound contains a primary amino group and multiple hydroxyl groups, endowing it with specific chemical reactivity and potential for interface modification. The optimized OSRO membrane exhibited a significantly decreased water contact angle from 52.6° of the control membrane to 36.6°, indicating substantially enhanced surface hydrophilicity. The optimized membrane (TFC-D-0.2) achieves a high water permeance of 12.84 LMH/MPa with a NaCl rejection of 98.25% and demonstrates excellent operational stability and pressure resistance (2.5~4.0 MPa). The membrane also shows good tolerance to most organic solvents, maintaining >96.5% NaCl rejection after 30 days of immersion in all tested solvents except acetone. In concentrating ethyl cinnamate/ethanol mixtures over 50 h, the membrane delivers stable performance with an ethanol permeance of ~2.5 L m−2 h−1 MPa−1 and a solute rejection of >88%. This work provides an effective surface modification strategy for developing high-performance OSRO membranes, holding promise for green separation processes in fine chemical industries.

Membranes doi: 10.3390/membranes16050170

Authors: Li Tian Huixiang Yao Bo Pang Wanting Chen Fujun Cui Qining Wang Yujie Guo Xuemei Wu Xiaobin Jiang Gaohong He

The proton (H+) and vanadium ion (Vn+) selectivity of proton-conductive membrane is one of the key components for vanadium redox flow batteries (VRFBs). In this work, a hydrophobic side chain was designed to accelerate proton conduction with high selectivity of H+ and Vn+ for the VRFB membrane. The grafting of hydrophobic butyl side chains into the membrane (PBIOSO3-But) induced the formation of a high microphase separation capacity to form large and connected ion conductive channels with low ion exchange capacity (IEC). As a result, the PBIOSO3-But membrane with low IEC of 1.26 mmol g−1 shows area resistance of 0.19 Ω cm2 as well as vanadium permeability of 3.2 × 10−9 cm2 s−1, leading to a high H+/Vn+ selectivity of 2.51 × 1010 mS s cm−3 (higher than Nafion 212, 4.62 × 108 mS s cm−3). Notwithstanding its low ion-exchange capacity, this membrane demonstrates H+/Vn+ selectivity surpassing that of recently reported microphase separation membranes. Compared to the Nafion 212 membrane (74.3% EE; 0.81% per cycle), the PBIOSO3-But membrane exhibited superior VRFB performance, achieving an energy efficiency of 83.2% at 200 mA cm−2 and a low retention rate of 0.22% per cycle. These values compare favorably with those of recently reported membranes.

Membranes doi: 10.3390/membranes16050169

Authors: Małgorzata Wolska Małgorzata Kabsch-Korbutowicz Fausto A. Canales Javier Carpintero Halina Urbańska-Kozłowska

This study assessed the performance of three microfiltration (MF) membrane modules: M1 (spiral, polyvinylidene fluoride), M2 (capillary, polypropylene), and M3 (capillary, α-Alumina) in treating backwash water from utility-scale surface water (SW) and infiltration water (IW) plants, each with a capacity of approximately 100,000 m3/day. Considering 168 h (one-week) filtration cycles, the membranes were evaluated for permeate flux, turbidity removal, dissolved organic carbon (DOC) removal, and reduction in total number of microorganisms (TNM). In contrast to most previous studies that have primarily examined surface water sources under laboratory conditions, this research contributes to the literature by evaluating membrane performance using actual backwash water from both SW and IW treatment plants. The comparative assessment of three structurally and materially distinct membrane modules under identical flow-through conditions yields new insights into the trade-offs among hydraulic performance, contaminant removal, and treatment cost. Logarithmic models fitted to permeate flux data yielded determination coefficients (R2) ranging from 0.60 to 0.99, supporting the prediction of early-stage performance. No consistent trend in flux decline was observed, mainly due to fluctuations in the water bacterial load. With a median TNM removal efficiency of 97%, M1 outperformed M2 and M3 (84% and 70%, respectively) in terms of microorganism removal. The effectiveness of DOC removal generally depended on the type of backwash water; the highest efficiency was observed for M2 in the case of backwash from IW treatment and for M1 in the case of backwash from SW treatment. M2 provided the highest permeate flux rates, regardless of water type or operational limitations. The ceramic membrane (M3) exhibited the greatest variability in hydraulic performance and removal efficiency, depending on the type of backwash water. A simplified cost analysis over two filtration cycles found that treatment costs were generally higher for SW backwash, with differences reaching up to 90% between membrane-water type combinations. Although treatment costs are higher than those for raw water treatment, the increasing water scarcity makes it a potential additional source of safe water.

Membranes doi: 10.3390/membranes16050168

Authors: Jehad A. Kharraz

The growing global water crisis continues to place unprecedented pressure on water treatment technologies to deliver higher efficiency, lower energy consumption, and reduced environmental impacts [...]

Membranes doi: 10.3390/membranes16050167

Authors: Karnelia Paul Biswajit Ray Chinmay Saha Anupam Roy Sohini Basu Anindita Seal

Metal homeostasis, which coordinates the influx and efflux of essential elements such as iron (Fe) and manganese (Mn) in chloroplasts, is essential for optimum photosynthesis, especially in metal-accumulating plants. Brassica juncea (Indian mustard) is a metal-tolerant species with a strong metal accumulation capacity, making it a suitable model for studying transition metal homeostasis. In this study, we identified two efflux transporters, BjYSL6.1 and BjYSL6.4, that localize in the endomembrane system of Schizosaccharomyces pombe and interact with the chloroplast Mn influx transporter BjNRAMP4.1 at the plasma membrane and within the chloroplasts. Bimolecular fluorescence complementation and split-ubiquitin yeast two-hybrid assays confirmed specific protein–protein interactions among these transporters, as well as with the membrane-bound thioredoxin BjHCF164, a known regulator of photosynthetic electron transport. Gene expression studies revealed that BjNRAMP4.1 and BjYSL6 isoforms are inversely regulated under Fe and Mn stress conditions, with BjNRAMP4.1 being strongly induced under deficiency, whereas BjYSL6.1 and BjYSL6.4 are downregulated. These findings suggest that a coordinated network involving BjNRAMP4.1, BjYSL6s, and BjHCF164 modulates metal influx and efflux at the chloroplast and plasma membrane interfaces, thereby maintaining metal homeostasis, which is critical for photosynthetic efficiency in B. juncea.

Membranes doi: 10.3390/membranes16050166

Authors: Jadwiga Maniewska Katarzyna Gębczak Łucja Cwynar-Zając Żaneta Czyżnikowska Berenika M. Szczęśniak-Sięga

Oxicam derivatives, a class of nonsteroidal anti-inflammatory drugs (NSAIDs), are important scaffolds for developing biologically active compounds. In this study, arylpiperazine oxicam derivatives (PR24–PR50) were examined for membrane interactions, cytotoxic activity, cyclooxygenase inhibition, and potential binding to COX-2 protein. Membrane interactions were examined using differential scanning calorimetry (DSC) in phospholipid bilayers formed from 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). All compounds altered the thermotropic properties of the lipid bilayer, showing concentration-dependent decreases in phase transition temperature, indicating incorporation to bilayer and partial disruption of lipid organization. Cytotoxicity, assessed using the MTT assay in breast cancer (MCF-7, MCF-7/DX), colorectal cancer (LOVO, LOVO/DX), and normal V79 cell lines, showed moderate effects, particularly against colorectal cancer cells. Cyclooxygenase inhibition was rather weak, with IC50 values in the high micromolar range, indicating limited anti-inflammatory potential compared with reference COX inhibitors, although docking studies suggested possible interactions with the COX-2 active site. The obtained results indicate that the biological activity of the arylpiperazine oxicam derivatives is primarily associated with cytotoxicity and membrane effects rather than COX inhibition. These limitations should be considered in the design of future membrane-targeted bioactive compounds.

Membranes doi: 10.3390/membranes16050165

Authors: Zheng Cao Boguslaw Kruczek Jules Thibault

The permeation of gases through membranes is a fundamental process with wide-ranging applications, from gas separation and fuel cell technology to respiratory physiology. Governed by Fick’s second law of diffusion, the mathematical modelling of such transport processes often becomes analytically and computationally challenging, especially in heterogeneous, mixed matrix, or multilayered systems. To navigate these complexities, this study revisits and expands upon the use of electrical analogies as an intuitive and powerful modelling approach rooted in mid-20th-century analog computing. By leveraging the mathematical equivalence between diffusion and electrical conduction, we construct an equivalent electrical network that mirrors the transient behaviour of gas permeation across membranes. In this framework, concentration gradients are represented as voltage differences, diffusive fluxes as electrical currents, and diffusional resistances as circuit resistances. While traditional applications of electrical analogies have largely focused on steady-state phenomena, our approach enables dynamic analysis, offering conceptual clarity and computational efficiency. This methodology not only simplifies the solution of Fick’s second law but also reinforces the enduring relevance of analogical thinking in modern engineering practice. Comparative results demonstrate that the equivalent electrical circuit closely aligns with both analytical and finite difference solutions, validating its effectiveness and accuracy.

Membranes doi: 10.3390/membranes16050164

Authors: Madina Mohamed Pieter Vandezande Anita Buekenhoudt

This laboratory-scale experimental study investigated the purification level of used lubricant oil (ULO) filtration using a large variety of ceramic UF membranes, allowing for treatment at high temperatures unreachable for polymeric membranes. Varying pore sizes (5 nm, 10 nm, 30 nm, and 100 nm) were included as well as a range of materials (Al2O3, TiO2, and ZrO2). Moreover, four different grafting techniques were applied to alter the surface chemistry of the native membranes from hydrophilic to more hydrophobic or oleophilic, intending to further increase UF flux and/or retention. Benchmark native 10 nm TiO2 membranes shows a stable flux of 7 to 9 kg/h·m2 at 110 °C, strong (metal) impurity removal, and unexpected high water retention. All other membranes tested show fluxes that never exceed the ones for the 10 nm benchmark membranes, elucidating that surface chemistry does not help to improve the flux. In general, membrane performance is very similar for all membranes, except for flux and water retention. Systematically, high-flux membranes show high water retention, while very-low-flux membranes preferentially pass water. The variation in flux and water retention as a function of membrane pore size (before grafting) shows that surface chemistry only plays a role when the effective pore size becomes small. The study results allow for the selection of the best membranes for initial ULO treatment.

Membranes doi: 10.3390/membranes16050162

Authors: Chii-Dong Ho Ping-Cheng Hsieh Thiam Leng Chew Jyun-Jhe Li

One-dimensional mass transfer resistance-in-series framework was developed theoretically and validated experimentally using a flat-plate polytetrafluoroethylene/polypropylene (PTFE/PP) membrane module to predict CO2 absorption fluxes and concentration distributions. The decline in CO2 absorption efficiency along the membrane module is primarily attributed to increased concentration polarization resistance and a reduced driving force concentration gradient. To alleviate these limitations, carbon fiber promoters were strategically embedded to suppress concentration polarization, reduce the mass transfer resistances, and enhance turbulence intensity. In the present study, device performance was further improved by implementing properly ascending or descending hydraulic equivalent widths along the absorbent feed channel. Under the descending configuration, an absorption flux enhancement of up to 44.94% was achieved relative to an empty-channel module (i.e., without S-ribbed carbon fiber inserts). Theoretical formulations were established to predict absorption fluxes under varying monoethanolamine (MEA) volumetric flow rates, CO2/N2 mixture flow rates, and inlet CO2 feed concentrations. The model predictions showed good agreement with experimental results obtained using MEA solutions under both ascending and descending hydraulic width operations, demonstrating effective mitigation of polarization effects and enhanced absorption flux along the absorbent feed channel. An economic assessment of the S-ribbed carbon fiber module was conducted by evaluating the trade-off between absorption flux enhancement and incremental power consumption. The results indicate that the proposed design provides a practical and economically viable approach for improving the performance of membrane-based CO2 capture technologies. In addition, an enhanced Sherwood number correlation, expressed in a simplified form, was developed and employed to estimate the mass transfer coefficients of CO2 membrane absorption modules incorporating S-ribbed carbon fiber promoters.

Membranes doi: 10.3390/membranes16050163

Authors: Caiyun Liu Chen Chen Wencai Zhang Hongyang Ma Shyam Venkateswaran Benjamin S. Hsiao

Polyamide thin-film composite reverse osmosis membranes were fabricated through interfacial polymerization (IP), wherein trimesoyl chloride (TMC) and isomeric diamine monomers including o-phenylenediamine (OPD), m-phenylenediamine (MPD), p-phenylenediamine (PPD), and methyl-substituted monomers such as 2,3-diaminotoluene (MOPD), 2,4-diaminotoluene (MMPD), 2,5-diaminotoluene (MPPD), and 2,6-diaminotoluene (2,6-MMPD) were employed. The membranes with high permeation flux and rejection ratio were eventually applied in the desalination of brackish water. The regional effects of the amino and methyl substituent on the desalination performance of the RO membranes in terms of permeation flux and rejection ratio were investigated extensively. A molecular dynamics simulation based on the configuration of monomers was performed to theoretically explore the effects of amino and methyl groups of the monomer on the packing density of the aromatic molecular structure and, consequently, on the desalination performance of the corresponding RO membranes. The RO membranes with integrated monomers exhibited two times higher permeation flux than that of a pristine RO membrane while remaining the high rejection ratio. Moreover, a long-term desalination performance of the RO membrane was also demonstrated, where two times higher permeation flux than that of conventional and commercial RO membranes was achieved, while the rejection ratio was maintained at 97.6% which was comparable with that of the commercial RO membranes.

Membranes doi: 10.3390/membranes16050161

Authors: Semanur Korkusuz-Soylu Rabia Ardic-Demirbilekli Merve Yilmaz Ismail Koyuncu Borte Kose-Mutlu

Urban wastewater treatment plants face increasing challenges in mitigating environmental impacts while achieving high treatment efficiency. This study explores the optimization of quorum-quenching (QQ) media materials for scalable membrane bioreactor (MBR) applications, focusing on their potential to reduce operational footprints and enhance sustainability. Six immobilization media were evaluated—sodium alginate (SA), polyvinyl alcohol (PVA) beads (P), magnetic beads (M), chitosan magnetic beads (CM), polymer-coated beads (PS), and flat media (SAP)—using a multi-criteria decision analysis (MCDA) framework. Key parameters, including porosity, mechanical strength, quorum-quenching activity, and durability in sludge, were quantitatively weighted according to their operational significance. SA demonstrated the most balanced performance, exhibiting superior durability and cost-effectiveness, whereas SAP showed potential in applications prioritizing high porosity and enhanced QQ activity. The incorporation of QQ media led to a significant reduction in membrane fouling, chemical consumption, and energy consumption in pilot-scale MBR systems. Ecological footprint assessment revealed a 15% reduction in indirect blue water footprints and a 20% decrease in Scope 2 carbon emissions, attributable to reduced operational energy demands. These findings highlight the efficacy of QQ media in improving MBR performance and advancing system-level sustainability. Overall, this study highlights the critical importance of material engineering and ecological footprint integration in the development of next-generation urban wastewater treatment technologies.

Membranes doi: 10.3390/membranes16050160

Authors: Akram Abdullah Rathinam Panneer Selvam

Counter-current flow in channels separated by a membrane has been studied by several scientists and researchers. The current study aims to analytically simulate and describe the distribution of pressure, volumetric flow rate, and velocity in square channels separated by a membrane. Consequently, the study was conducted using one-dimensional (1D) analytical solutions to achieve several objectives: avoiding the execution of experimental tests, reducing the effort required for expensive and time-consuming module design, and enabling easy observation of variations in pressure, volumetric flow rate, and velocity. The 1D analytical solution directly simulates flow in square channels separated by a membrane by solving the continuity equation and Darcy’s law, through which pressure, volumetric flow rate, and velocity are calculated. Experimental results were used to validate the 1D analytical solutions. The results of the current study indicate that pressure decreases from the inlet to the outlet of the channel, while the horizontal velocity decreases from the inlet to the midpoint of the channel length and then increases toward the outlet. The 1D analytical solutions show acceptable accuracy when compared with experimental results. Consequently, these solutions can be used to explore and illustrate the distributions of pressure, volumetric flow rate, and velocity in square channels separated by a membrane, enabling the evaluation of hemodialysis prototype module performance and efficiency prior to fabrication.

Membranes doi: 10.3390/membranes16050159

Authors: Andrzej Teisseyre Anna Uryga Kamila Środa-Pomianek Anna Palko-Labuz

Background: Genistein and resveratrol are bioactive compounds isolated from plants, recognized for their diverse biological activities including anti-cancer properties. Both compounds are also known as modulators of various types of ion channels, including voltage-gated potassium channels, Kv1.3. These channels are widely expressed in normal and cancer tissues. Their activity is crucial in regulating cell proliferation and apoptosis in cells that express Kv1.3 channels. The potential clinical application of channel inhibitors may extend to treating cancers characterized by an overexpression of these channels. Methods: This study investigates the inhibitory effects of genistein and resveratrol on Kv1.3 channels expressed in the cancer cell line Jurkat T by applying a whole-cell patch clamp. Results: Applying both compounds at concentrations ranging from 3 μM to 90 μM leads to a dose-dependent inhibition of channel activity, reducing it to approximately 50% of the control level. This inhibitory effect was reversible and associated with a significant reduction in the activation rate. When combined with simvastatin, the inhibitory effect exhibited synergy; however, it was additive when co-applied with mevastatin. Conclusions: The channel inhibition may putatively be linked to the anti-cancer activities of these compounds on Kv1.3 channel-expressing cancer cells, especially when co-applied with the statins.

Membranes doi: 10.3390/membranes16050158

Authors: Doudou Jia Haonan Wang Zhengkun Liu Guangru Zhang Wanqin Jin

Perovskite mixed proton–electron hydrogen-permeable membranes have been widely applied in the field of membrane separation due to their 100% selectivity for hydrogen separation. La5.5WO11.25-δ-La0.87Sr0.13CrO3-δ (LWO-LSF) four-channel hollow fiber membranes were prepared by the phase inversion and sintering technique using a one-step thermal processing (OSTP) approach. The effects of temperature, feed gas concentration, sweep gas flow, permeation mode, and water vapor on hydrogen flux were systematically investigated. At 900 °C, the hydrogen permeation flux of 50% H2/N2 feed from the shell side to the lumen side was 0.613 mL·min−1·cm−2, which was 62.59% higher than that from the lumen side to the shell side. The enhanced hydrogen permeation performance is attributed to the lower gas mass transfer resistance under shell-side feeding. Under humidified conditions on the sweep side, the hydrogen flux increased by an additional 3.42%. The presence of water vapor increased the number of proton carriers, effectively enhancing proton–electron-coupled transport and thereby increasing the hydrogen permeation flux.

Membranes doi: 10.3390/membranes16050157

Authors: Saidulla Faizullayev Akbota Adilbekova Joanna Kujawa Wojciech Kujawski

Commercial TiO2 ceramic membranes were modified using a slip-casting method with coal fly ash (CFA) obtained from a thermal power plant, Almaty, Kazakhstan. The aim was to enhance membrane surface properties for improved oil-in-water emulsion separation while maintaining structural integrity. Suspension of CFA, stabilized with N-dodecylpyridinium chloride (DPC) and polyvinyl alcohol (PVA), was applied as a coating layer on the TiO2 surface and subsequently sintered under controlled conditions. The resulting membranes were characterized by SEM-EDX (scanning electron microscopy with energy-dispersive X-ray), Raman spectroscopy, contact angle measurements, and zeta potential analysis. The modified membranes exhibited increased hydrophilicity, as indicated by a reduction in water contact angle (WCA) from 43.6 ± 2° to approximately 0°, and a decrease in the underoil contact angle of water (UOCA) from 147.6 ± 2° to 87 ± 2°. Raman spectroscopy confirmed that the TiO2 structure remained predominantly rutile, with no additional crystalline phases detected from CFA. Despite the improved wettability, pure water and oil-in-water emulsion fluxes decreased slightly, while filtrates displayed smaller oil droplet sizes, indicating enhanced emulsion stability after passage through the modified surface. These findings demonstrate that CFA-modified TiO2 membranes can serve as a sustainable and cost-effective approach for treating emulsified wastewater, utilizing industrial waste to improve performance without compromising mechanical robustness.

Membranes doi: 10.3390/membranes16050156

Authors: Huali Deng Zhanhao Liu Li Niu Shiyu Gan

Solid-contact ion-selective electrodes (SC-ISEs) are typically constructed using ion-selective membrane (ISM)-based configurations. However, such structures often suffer from water-layer formation and the weak mechanical stability of the ISM. Herein, we report an ISM-free K+-SC-ISE based on a Prussian blue analogue transducer, KMnFe(CN)6, eliminating the need for a conventional ionophore-based ISM layer. KMnFe(CN)6 was synthesized via a one-step citrate-assisted co-precipitation method. The material functions as a bifunctional transducer, in which the open framework structure with ion-transport channels enables selective K+ recognition, while the redox-active Mn centers facilitate ion-to-electron transduction. The fabricated KMnFe(CN)6-based K+ sensor exhibits a near-Nernstian response with a sensitivity of 52.3 ± 1.0 mV dec−1 and a rapid response time of 25 s. The linear range and limit of detection were determined to 10−4 to 10−1 M and 5.8 × 10−5 M, respectively. The sensor also demonstrates selectivity to representative interfering ions, with log Kij of −2.39 ± 0.12 (Na+), −2.86 ± 0.09 (Li+), −3.06 ± 0.09 (Ca2+), −2.74 ± 0.12 (Mg2+) and −0.95 ± 0.08 (NH4+). By eliminating the ISM layer, the water-layer effect is effectively avoided, resulting in excellent long-term stability with a potential drift of 57.2 ± 6.1 μV h−1 over 7 days. The sensor was further applied to the analysis of K+ in real lake water samples, where the measured concentration showed good agreement with ion chromatography results. This work provides an ISM-free SC-ISE strategy for ion analysis in water environments.

Membranes doi: 10.3390/membranes16050155

Authors: Mei Ma Bin Huang Lingling Mei Kan Huang Ke Xing Lida Liao

Intermittently operated, tankless reverse osmosis (RO) systems are widely used in decentralized and point-of-use applications, yet water stagnation during idle periods remains a critical challenge, leading to degraded water quality, accelerated fouling, and performance loss. This study presents an experimentally validated engineering solution that eliminates stagnant water in intermittently operated RO systems. A dual-membrane RO configuration with flexible series–parallel switching was developed, enabling membranes to alternate between production and flushing modes. An adaptive control strategy, integrated into the system hardware, regulates membrane switching and flushing based on real-time feed-water quality. The proposed configuration and control framework was evaluated under representative intermittent operating conditions. Experimental results show that the zero-stagnant-water strategy effectively prevents residual water accumulation during shutdown and maintains stable permeate quality, with total dissolved solids consistently below 10 mg/L. Long-term testing further demonstrates reduced membrane fouling and slower performance degradation compared with conventional fixed-operation schemes, resulting in enhanced desalination efficiency and operational stability. Owing to its modular design and simple control logic, the proposed approach is readily transferable to decentralized and point-of-use membrane water treatment systems requiring reliable, high-quality water under intermittent operation.

Membranes doi: 10.3390/membranes16040154

Authors: Diego Queiroz Faria de Menezes Marília Caroline Cavalcante de Sá Nayher Andres Clavijo Vallejo Thainá Menezes de Melo Luiz Felipe de Oliveira Campos Thiago Koichi Anzai José Carlos Costa da Silva Pinto

Robust numerical frameworks are essential for the simulation, design, monitoring, and control of membrane-based separation units, particularly under highly nonlinear and industrially relevant operating conditions. In this context, a comprehensive phenomenological and numerical framework is proposed for the simulation of hollow-fiber membrane modules, incorporating coupled mass, momentum (through pressure drop), and energy transport equations. The governing equations are discretized using a rigorous orthogonal collocation formulation, and the performances of two numerical solution strategies are systematically investigated for the first time to allow the in-line and real-time implementation of the model: a steady-state approach based on the Newton–Raphson method with careful treatment of initial estimates, and a pseudotransient formulation. Particularly, an original and consistent numerical treatment is introduced for the energy balance at boundaries where the permeate flow vanishes, enabling the stable incorporation of thermal effects and Joule–Thomson phenomena. The results clearly show that the steady-state Newton–Raphson approach provides the best overall performance in terms of computational efficiency, numerical robustness, and accuracy when physically consistent initial profiles are employed. In particular, the combination of a linear initial guess and a numerical mesh constituted of four collocation points yielded the most favorable balance between convergence speed, numerical robustness, and accuracy for the base-case sensitivity analysis. For monitoring-oriented applications, the numerical choice should be weighted primarily toward computational performance once physical consistency and convergence criteria are satisfied, rather than toward maximum mesh-refinement accuracy. In this context, small differences in internal-fiber profiles can be compensated through real-time permeance estimation and are negligible when compared with measurement uncertainty in real industrial processes. Under extreme operating conditions involving low concentrations, low flow rates, and highly permeable species, the pseudotransient formulation proved to be a reliable auxiliary strategy, enabling robust convergence when suitable initial guesses were not readily available. The proposed framework is validated against experimental data from the literature and subjected to extensive convergence and sensitivity analyses, providing a reliable basis for simulation and for assessing computational feasibility in in-line and real-time monitoring-oriented applications. A full demonstration of digital-twin integration, online parameter updating, reduced-order coupling, and closed-loop control is beyond the scope of the present study and will be addressed in future work.

Membranes doi: 10.3390/membranes16040153

Authors: Nelson Kipchumba Innocentia G. Mkhize Benton Otieno Hilary L. Rutto Seteno K. Ntwampe

The increasing presence of contaminants of emerging concern (CECs) in surface and groundwater is a global concern due to their toxicity, persistence, and bioaccumulation, which lead to undesired effects. Conventional wastewater treatment processes are unable to remove these CECs, necessitating advanced treatment strategies to remove them effectively. Among advanced strategies, photocatalytic membrane treatment has attracted considerable interest among researchers. This review critically examines the fundamental principles governing the performance of photocatalytic membranes. It identifies significant challenges, including photocatalyst leaching, light accessibility, intermediates’ toxicity, and scalability of synthesis and immobilisation techniques. It explains why these factors significantly hinder long-term stability, scalability, and practical deployment of photocatalytic membrane systems and provides potential solutions. Through gap analysis, the review has identified rigorous techno-economic analysis, real-world wastewater validation, and systematic toxicity assessment of degradation intermediates as areas of further study. These targeted actions provide clear pathways to enhance the viability, safety, and commercial readiness of photocatalytic membrane systems.

Membranes doi: 10.3390/membranes16040152

Authors: Syed Farzan Ali Shah Naif A. Darwish Nabil Abdel Jabbar Sameer Al-Asheh Muhammad Qasim Farouq S. Mjalli

Water scarcity has increased the need for efficient treatment technologies such as membrane distillation (MD). PMD performance depends strongly on membrane fabrication parameters, particularly polymer concentration and nanoparticle incorporation, which control key transport and separation properties. This study considers fabrication of membranes using different concentrations of polyvinylidene fluoride (PVDF) with the incorporation of different types of nanoparticles to determine the optimum membrane formulation for membrane distillation applications. The results demonstrate that both PVDF concentration and nanoparticle type play a critical role in membrane performance in terms of permeate flux and salt rejection. Among the nanoparticles studied in this work, carbon nanotubes (CNTs) exhibited the most significant enhancement, leading to a substantial increase in water vapor flux while maintaining excellent separation efficiency. The optimized CNT incorporated membrane achieved approximately 99% salt rejection, with superior flux performance, indicating its strong potential for high-efficiency desalination and water treatment using membrane distillation.

Membranes doi: 10.3390/membranes16040151

Authors: Zongneng Zheng Di Liu Jiahang Wan Jianping Li Kun Zhang Yanxin Li Haiyi Yang Junwei Hou

The produced water from the No. 1 Oil Production Plant of Xinjiang Oilfield is rich in divalent ions, including Ca2+, Mg2+, and SO42−, leading to extremely high scaling tendency that fails to meet the reinjection standard. Therefore, highly efficient water softening technology is urgently required for such wastewater treatment. In this study, a novel negatively charged nanofiltration (NF) membrane was fabricated via interfacial polymerization using 2-carboxypiperazine and trimesoyl chloride as monomers. The membrane was systematically characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR), and its rejection performance was investigated under various conditions. Results show that the maximum rejection rates of the NF membrane reached 99% for SO42−, 81% for Ca2+, and 94% for Mg2+, respectively. With increasing ion concentration, the removal efficiencies of Ca2+ and Mg2+ decreased, while that of SO42− increased slightly. Higher operating pressure significantly enhanced both ion removal and membrane flux, which was mainly attributed to the synergistic effects of Donnan electrostatic exclusion, membrane surface adsorption, and mass transfer resistance. When applied to treat real produced water from the No. 1 Oil Production Plant, the membrane achieved 100% removal of SO42−, and 91% and 95% removal of Ca2+ and Mg2+, respectively. The scaling tendency of the treated effluent was completely eliminated. This work provides theoretical and technical support for the engineering application of nanofiltration technology in oilfield wastewater treatment.

Membranes doi: 10.3390/membranes16040150

Authors: Pasquale Francesco Zito

The use of membranes for gas purification and production is becoming increasingly common as a valid alternative to the conventional technologies (i [...]

Membranes doi: 10.3390/membranes16040149

Authors: Antonio Casañas Gonzalez Federico Antonio Leon Zerpa Alejandro Ramos Martin

This work presents the most recent advancements and operational experiences obtained with the large-active-area, high-rejection FilmTec™ SW30HR-380 and SW30HR-320 reverse osmosis membrane elements, with particular focus on their techno-economic implications, especially regarding energy demand and potential operational cost reductions. The study also examines fouling prevalence and reviews the latest developments in technical mitigation strategies, with emphasis on the new wide-spacer SW30HR-320 elements designed for open-intake applications. Overall, the findings indicate that these new membrane products constitute an effective option for the design of seawater reverse osmosis systems treating both clean and fouling-prone feedwaters. The techno-economic evaluation demonstrates that the adoption of these elements can enable reductions of approximately 20% in capital expenditures, up to 25% in energy consumption, and up to 4% in cleaning-related costs—including downtime—when the SW30HR-320 is operated under high-fouling feedwater conditions.

Membranes doi: 10.3390/membranes16040148

Authors: Yassine Khmiri Feryelle Aouay Afef Attia Hajer Aloulou Lasâad Dammak Catia Algieri Raja Ben Amar

The widespread presence of stable and hazardous organic contaminants, such as synthetic dyes, in industrial effluents necessitates the development of resilient treatment strategies capable of achieving efficient degradation and decolorization of dye pollutants. Conventional treatment processes often fail to remove such recalcitrant compounds, prompting growing interest in integrated advanced systems. Photocatalytic membranes represent a promising solution due to the synergistic combination of physical separation and catalytic degradation. In this study, zinc oxide (ZnO) thin films were deposited by spin coating onto smectite–zeolite ceramic membranes (MS10/Z90), applying one (M1), two (M2), and three (M3) successive coating layers to control catalyst thickness. SEM analysis confirmed that increasing the number of layers resulted in a thicker and more homogeneous ZnO coating, while XRD revealed enhanced crystallinity and larger crystallite size. Water permeability decreased progressively from 623 L·h−1·m−2·bar−1 for the uncoated membrane to 506, 439, and 350 L·h−1·m−2·bar−1 for M1, M2, and M3, respectively. Photocatalytic performance was evaluated using Rhodamine B (RhB) (10 mg·L−1) under UV irradiation (365 nm, 18 W) for 180 min, achieving degradation efficiencies of 83.0%, 94.6%, and 99.1% for M1, M2, and M3, respectively. The degradation kinetics followed a pseudo-first-order model, with rate constants increasing with catalyst layer thickness. Free radical scavenging assays confirmed that hydroxyl radicals (•OH) were the primary reactive species responsible for RhB degradation. These findings highlight the critical influence of ZnO layer thickness and mass transfer on photocatalytic performance, demonstrating the potential of ZnO-coated ceramic membranes for efficient pollutant degradation and in situ photocatalytic regeneration. Permeability measurements after photocatalytic treatment confirmed effective flux recovery, supporting the operational durability of the developed membranes.

Membranes doi: 10.3390/membranes16040147

Authors: Zahid Ali Sana Javed Tuba Ul Haq Muhammad Shahid Noaman Ul Haq Asim Laeeq Khan

Heavy metal contamination of drinking water remains a persistent global challenge, exacerbated by salinity, industrial discharge, and the limitations of existing membrane technologies that are constrained by permeability–selectivity trade-offs. In this study, we develop a hybrid thin film nanocomposite (TFN) forward osmosis (FO) membrane by incorporating a zirconium-based metal–organic framework (UiO-66) and its conductive polymer-functionalized analogue (PANI@UiO-66) into the polyamide active layer via interfacial polymerization. The incorporation of UiO-66 enhances water transport through the introduction of hydrophilic microporous domains, while the polyaniline coating modulates nanoscale transport pathways and interfacial interactions. Systematic variation in filler type and loading reveals distinct functional roles of the two fillers. Membranes incorporating bare UiO-66 exhibit increased water flux, attributed to facilitated transport through MOF-derived nanochannels, but show a moderate increase in reverse solute flux. In contrast, PANI@UiO-66 incorporation results in reduced water flux but significantly suppresses reverse solute flux and enhances chromium rejection, indicating improved control over selective transport. At an optimal loading of 0.15 wt% (TFN-PU3), the membrane demonstrates an improved balance between water permeability and solute selectivity compared to the pristine thin film composite (TFC) membrane under FO conditions. The observed performance is attributed to the combined effects of modified transport pathways and interfacial interactions introduced by the hybrid filler system. The results highlight the potential of conductive polymer–MOF hybridization as a strategy for tuning membrane performance. This work provides a practical framework for designing TFN membranes for selective heavy-metal removal in saline and complex water environments.

Membranes doi: 10.3390/membranes16040146

Authors: Zhiyan Zeng Lixin Song Li Ding Haihui Wang

Two-dimensional (2D) MXene membranes have emerged as a focal platform for ionic separations owing to their exceptional mechanical flexibility, intrinsic hydrophilicity, abundant surface terminations, and high electrical conductivity. This review summarizes recent advances in MXene-based membranes, with an emphasis on structural engineering strategies and their translation to ion-separation applications. We first outline representative fabrication routes for MXene membranes. We then discuss how separation mechanisms can be understood and deliberately tuned across four key scenarios: monovalent/monovalent ion separations, monovalent/multivalent ion separations, anion/cation separations, and heavy-metal ion separations. Finally, we highlight outstanding challenges and future opportunities, aiming to provide actionable guidance for the rational design and scalable manufacturing of high-performance MXene membranes for ionic separations.

Membranes doi: 10.3390/membranes16040145

Authors: Mikhail Tarasenko Andrey Makarov Mark Neshin Valery Skudin Roman Kozlovskiy Maria Myachina Natalia Gavrilova

Oxidative dry reforming of methane (ODRM) in a membrane reactor can become the basis for creating an energy-efficient process for converting greenhouse gases into a sought-after chemical raw material for gas chemistry. The process was carried out in a distribution mode in a reactor with a membrane porous catalyst (MPC) at a temperature of 850 °C. The reagents CH4 and CO2 were supplied to the MPC through a volume of retentate, and O2 mixed with N2 through a volume of permeate. The mixture of reaction products was removed from the shell side. In the experiment, the effect of the O2/CO2 ratio on the conversion of CH4, CO2 and O2, as well as on the thermal effect of the process, was established. When oxygen enters the reactor during dry reforming of methane (DRM), the temperature inversion in the volumes of retentate and permeate occurs, as well as a decrease in electricity consumption in the resistor furnace. The observed effects of the ODRM process in MPC were interpreted using the hypothesis of active mass transfer occurring in pore channels. It is assumed that part of the carbon deposits in MPC will be gasified by oxygen.

Membranes doi: 10.3390/membranes16040144

Authors: Yair Morales Jan Singer Leonardo Acero Harald Horn Florencia Saravia

Membrane distillation (MD) is an attractive technology for desalination driven by renewable energy and low-grade heat sources. However, specific practical guidelines for intermittent operations, typical of such alternative energy sources, are still limited—particularly with respect to established shutdown measures to mitigate adverse effects on the overall system performance. The present study compares continuous and intermittent air-gap MD desalination at a lab-scale by evaluating performance parameters and scaling development. Apart from a slightly lower distillate productivity and a similar distillate quality under intermittent conditions, no direct difference in MD performance between continuous and intermittent experiments was detected. Nevertheless, online monitoring by image analysis with optical coherence tomography revealed more advanced scaling development during intermittent operation, with larger scaling volumes and cover ratios, particularly after implementing a membrane rinsing and preservation protocol with demineralized water. Membrane autopsies revealed that intermittency led to alterations in the development of the crystal morphology of predominantly CaCO3 scaling. These changes were attributed to enhanced nucleation and modified growth kinetics triggered by recurring shutdown and start-up phases. Overall, the findings showed that intermittency had an adverse effect in terms of scaling behavior, highlighting the need for operating protocols tailored to each specific MD application.

Membranes doi: 10.3390/membranes16040143

Authors: Mariana Ferreira

Biological membranes are essential structural and functional components of living systems, forming the boundaries that define cells and organelles while enabling selective transport, signalling, and energy transduction [...]

Membranes doi: 10.3390/membranes16040142

Authors: Zakaria Triki Zineb Fergani Hichem Tahraoui Nassim Moula Jie Zhang Abdeltif Amrane Farid Fadhilah Amine Aymen Assadi

Hybrid desalination systems that combine osmotic and thermal driving forces offer a promising route to improve water recovery and energy efficiency for high-salinity feedwaters where conventional processes face limitations. This study presents a comprehensive mathematical modeling framework and performance analysis of a hybrid forward osmosis–membrane distillation (FO-MD) system for seawater desalination. The novel contributions include: (1) a coupled heat, mass, and solute transport model that explicitly accounts for concentration polarization, temperature polarization, reverse salt flux, and their dynamic interactions through the draw solution loop; (2) a quantitative assessment of the synergistic regeneration effect, showing how MD maintains draw solution concentration and stabilizes FO performance over time; (3) systematic evaluation of parameter sensitivity to polarization effects; and (4) comparative energy analysis quantifying specific energy consumption relative to standalone processes. Model predictions were validated against published experimental data, showing good agreement for both FO and MD fluxes (R2 > 0.94). The MD flux increased from approximately 2–3 LMH at 30 °C to 17 LMH at 50 °C, confirming vapor pressure enhancement. FO water flux increased significantly with draw solution concentration from 0.2 to 1.1 M due to higher osmotic pressure differences. Time-dependent simulations of the integrated FO-MD system showed that MD regeneration reduces draw solution dilution by 60% compared to standalone FO, maintaining FO flux approximately 43% higher after 6 h of operation. Sensitivity analysis revealed that FO predictions are moderately sensitive to mass transfer coefficients (6–9% flux change for 20% parameter variation), while MD shows lower sensitivity to heat transfer coefficients (3–5%). Energy analysis indicates that FO-MD hybridization reduces thermal energy consumption by 15–40% compared to standalone MD, with specific energy consumption of 382 kWh/m3 (40.2 kWh/m3 primary energy equivalent) when using low-grade heat. The obtained results demonstrate that FO-MD hybridization enhances water recovery and operational stability compared to standalone processes, supporting its potential for energy-efficient desalination of high-salinity brines and industrial wastewaters where low-grade heat is available.

Membranes doi: 10.3390/membranes16040140

Authors: Shiji Sun Mengfei Liu Dawei Gong Kaiyun Fu Xianfu Chen Minghui Qiu Ping Luo

Efficient recovery of ammonia from sludge hydrolysate (SH) remains a challenging task. This study developed a superhydrophobic capillary ceramic-membrane contactors (MCs), which, by establishing a stable gas-phase mass transfer interface, provides a reliable guarantee for ammonia recovery under high-temperature, high-pH, and high-organic-load conditions. In a controllable simulation system, the system investigated the effects of key operational parameters such as pH, flow rate, and feed ammonia concentration on ammonia mass transfer behavior, and verified the feasibility of this MCs in efficient ammonia removal. Then, this membrane contactor was applied to the actual sludge hydrolysate (SH) system, and its anti-pollution effects, wetting stability, and adaptability to fluctuating conditions under long-term continuous operation were evaluated. The results showed that after operating for 10 h, the ammonia removal in the simulation system and the actual system reached 93.6% and 90.3%, respectively. During long-term operation, the ammonia recovery reached 90.3%. Meanwhile, the organic matter in SH was completely retained, and (NH4)2SO4 was not contaminated by organic matter. Throughout the entire operation process, the contact angle of the membrane remained above 129.6°. This study provides a theoretical basis and practical reference for recovering ammonia using a hydrophobic capillary ceramic-membrane contactor in SH.

Membranes doi: 10.3390/membranes16040139

Authors: Qingyu Zhang Bingjie Yan Xinhao Sun Zhengda Lin Lu Liu Haijuan Guo Fang Ma

Sulfamethoxazole (SMX) is one of the most frequently detected antibiotics in aquatic environments and is difficult to remove by conventional biological treatment because of its persistence, potential toxicity to microbial communities, and associated risk of antibiotic resistance selection. Aerobic granular sludge membrane bioreactors (AGMBRs), which combine the compact and stratified structure of aerobic granular sludge with membrane-based solid–liquid separation, have emerged as a promising platform for SMX-contaminated wastewater treatment because they provide high biomass retention, decoupled sludge retention time (SRT) and hydraulic retention time (HRT), and stable effluent quality. This review systematically summarizes recent advances in AGMBRs for SMX removal, with emphasis on how operating parameters (e.g., dissolved oxygen, hydraulic retention time, organic loading rate, C/N ratio, and sludge retention time) and membrane-related factors (e.g., membrane flux, aeration-induced shear, membrane type, and pore size) affect treatment performance and process stability. The main SMX attenuation pathways in AGMBRs are discussed from three perspectives: sorption and partitioning within granules and extracellular polymeric substances (EPSs), microbial biodegradation and co-metabolism, and membrane retention that prolongs effective contact time and shapes microbial ecology. Particular attention is given to the dual role of EPS and soluble microbial products (SMPs), which contribute to granule stability and SMX tolerance but also accelerate membrane fouling through cake-layer formation, pore blocking, and transmembrane pressure increase. Current challenges include incomplete understanding of transformation products, ARG- and MGE-related risks, long-term fouling–biodegradation interactions, and the lack of pilot-scale validation. Future research should therefore focus on mechanism clarification, integrated control of removal and fouling, energy-efficient operation, and scale-up of AGMBRs for practical antibiotic wastewater treatment.

Membranes doi: 10.3390/membranes16040141

Authors: Lea Kukoc Kalina Velikova Sanja Perinovic-Jozic Maja Biocic Milen Gateshki Spas D. Kolev Tony G. Spassov

Polymer inclusion membranes (PIMs) based on PVDF-HFP as the base polymer and Aliquat 336 as the carrier in a mass ratio of 6:4 with concentrations of embedded glass fibers up to 5 wt% were successfully fabricated. Their microstructure, as well as their mechanical and thermal properties, were characterized using scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), differential thermal analysis/thermogravimetric analysis (DTA/TGA), and tensile testing. Membrane performance and long-term stability in transporting thiocyanate ions were evaluated in a two-compartment transport cell. The results showed that the membranes retained their amorphous structure even with glass-fiber loadings of up to 5 wt%. The addition of glass fibers was found to primarily enhance the elastic modulus and tensile strength, while causing a moderate reduction in plasticity without negatively affecting membrane transport properties and long-term stability. Therefore, it was concluded that the incorporation of glass fibers could improve the suitability of PIMs for industrial applications.

Membranes doi: 10.3390/membranes16040135

Authors: Nasim Khatir Enriqueta Anticó Clàudia Fontàs

This work explores, for the first time, a novel strategy for the preparation of polymer inclusion membranes (PIMs) based on their deposition onto porous supporting substrates, introducing the concept of supported PIMs as a reagent-efficient alternative to conventional free-standing membranes. The approach aims to improve the sustainability of PIM fabrication by significantly reducing the amount of polymer and extractant required while preserving membrane functionality. PIMs were prepared using the two most widely employed base polymers, cellulose triacetate (CTA) and poly(vinyl chloride) (PVC), with Aliquat 336 as extractant. The total reagent consumption was reduced to half of the conventional formulation for CTA-based membranes and to one quarter for PVC-based membranes. Two porous supports with contrasting physicochemical properties—a hydrophilic cellulose filter paper and a hydrophobic Durapore® PVDF membrane—were investigated. The supported membranes were characterized by contact angle measurements, SEM, FTIR, and TGA, confirming the successful integration of the PIM phase onto the porous supports without chemical alteration. Arsenate (As(V)) transport, preconcentration, and membrane reusability were evaluated. CTA-based supported PIMs exhibited transport efficiencies of approximately 90–95%, comparable to free-standing PIMs, whereas PVC-based systems showed a stronger dependence on membrane loading. Notably, CTA-based Durapore®–PIMs retained around 70% transport efficiency after three reuse cycles. These results demonstrate the feasibility of supported PIMs as a strategy for reducing membrane material consumption while preserving functional performance.

Membranes doi: 10.3390/membranes16040138

Authors: Marek Gryta Piotr Woźniak

Polyvinylidene fluoride (PVDF) membranes are used in ultrafiltration systems for car wash water reuse, where frequent alkaline cleaning is required to maintain operational flux rates. Although NaOH-induced degradation of virgin PVDF membranes has been reported, its relevance under real industrial conditions remains poorly understood. This study investigates the long-term exposure of tubular PVDF membranes to alkaline car wash detergents and evaluates how the resulting structural changes influence permeate quality. During several months of pilot-scale operation with synthetic car wash wastewater and daily alkaline cleaning (pH > 11.5), permeate fluxes remained stable at 50–70 LMH despite pronounced membrane aging. Structural analyses revealed enlarged pore size, increased water permeability and reduced dextran retention, while FTIR confirmed dehydrofluorination of the polymer matrix. Despite the extensive degradation of the membrane skin layer, permeate turbidity, dissolved organic carbon, and surfactant concentrations remained stable throughout the operation. This stability was attributed to the persistent fouling layer, which acted as an effective secondary separation barrier and compensated for the loss of intrinsic membrane selectivity. These findings demonstrate that substantial PVDF degradation does not necessarily compromise permeate quality in car wash ultrafiltration systems, highlighting the dominant role of fouling-controlled separation under long-term alkaline cleaning regimes.

Membranes doi: 10.3390/membranes16040137

Authors: Namra Fatima Andrzej Górecki Anna Wiśniewska-Becker

Curcumin, a natural polyphenol derived from Curcuma longa, is widely recognized for its therapeutic properties. However, its clinical utility is limited because of poor solubility, rapid degradation and hence low bioavailability. To overcome these issues, nanoformulation approaches, especially PEGylated liposomes, have been explored as advanced delivery systems. PEGylation, which involves attaching polyethylene glycol (PEG) to the liposomal surface, enhances circulation time by creating a steric shield that reduces protein interactions and clearance by the mononuclear phagocyte system (MPS). However, PEG can alter lipid membrane properties, which may in turn affect curcumin’s solubility and distribution within the liposomal bilayer, ultimately reducing its loading efficiency. To ensure that PEG-modified liposomes can be effectively loaded with curcumin, we investigated curcumin–membrane interactions in saturated (DMPC) and unsaturated (POPC) liposomes, both in the presence and absence of PEG. Based on dissociation constants (Kd) obtained from fluorescence spectroscopy measurements, we found that PEGylated DMPC liposomes exhibit the strongest binding affinity for curcumin. Fluorescence quenching experiments showed that curcumin adopts a transbilayer orientation in all membranes examined. Curcumin’s location within PEGylated and non-PEGylated liposomal membranes was further confirmed by examining its effects on membrane properties, including fluidity, polarity, and oxygen transport. These effects were investigated using electron paramagnetic resonance (EPR) spectroscopy with spin labels. The results indicate that PEG does not impose major changes on membrane properties. Curcumin, however, was found to reinforce the liposomal membranes, increase their polarity, and reduce oxygen availability. Overall, the findings suggest that liposomes, particularly those composed of PEGylated DMPC, are effective vehicles for curcumin delivery.

Membranes doi: 10.3390/membranes16040136

Authors: Rendra Hakim Hafyan Vithushan Indrakumar Judy Lee Siddharth Gadkari

While membrane technologies are critical for preventing microplastics (MPs) release into aquatic ecosystems, MPs-induced fouling remains a persistent bottleneck, necessitating energy-intensive cleaning strategies that introduce their own environmental burdens. This study presents a systematic life cycle assessment (LCA) of fouling mitigation strategies, rigorously comparing hydraulic forward flushing and nitrogen (N2) gas scouring across both unmodified and plasma-modified (acrylic acid, cyclopropylamine, and hexamethyldisiloxane) polysulfone membranes. Results reveal a stark divergence between operational performance and environmental sustainability. Baseline operations and the hydraulic flushing of unmodified membranes have environmentally costly global warming potential (GWP) ~150 kg CO2-eq/m3), driven primarily by high electricity consumption and frequent membrane replacement. Conversely, cyclopropylamine (CPAm) plasma-modified membranes emerging as the optimal strategy, reducing global warming potential to 68 kg CO2-eq/m3 and cutting electricity demand by 44% through superior fouling resistance. Crucially, the study uncovers a significant trade-off regarding gas scouring: While it achieves the highest technical performance (minimal flux decline of 0.33% h−1), the upstream burdens of N2 supply increased environmental impacts by over 100% across all categories. These findings challenge the assumption that maximum fouling control equates to sustainability, suggesting that surface engineering via plasma modification, rather than aggressive physical cleaning, offers the most viable pathway for sustainable MPs remediation.

Membranes doi: 10.3390/membranes16040134

Authors: Konstantin Balashev

This review surveys how nanoparticles and biomolecular nanosized structures interact with model membrane systems, and how these interfacial processes govern their performance in drug and gene delivery, antimicrobial strategies, biosensing, and nanotoxicology. The nanostructures covered include polymeric nanoparticles, lipid-based carriers, peptide nanostructures, dendrimers, and multifunctional hybrids. Model membranes span Langmuir monolayers, supported lipid bilayers, vesicles/liposomes across sizes, and emerging hybrid or asymmetric constructs that better approximate native complexity. Mechanistically, interactions follow recurrent routes—surface adsorption, bilayer insertion, pore formation, and lipid extraction/reorganization—regulated by particle size, morphology, charge, ligand architecture, and lipophilicity, in conjunction with membrane composition, phase state, curvature, and asymmetry. A multiscale toolkit links structure, mechanics, and dynamics: Langmuir troughs and Brewster Angle Microscopy map thermodynamics and mesoscale morphology; atomic force microscopy and quartz crystal microbalance with dissipation resolve nanoscale topography and viscoelasticity; fluorescence microscopy/spectroscopy reports on localization and packing; neutron and X-ray reflectometry quantify vertical structure; molecular dynamics provides atomistic pathways and design hypotheses. Historically, the field advanced from early monolayers and bilayers, through the fluid mosaic model, to raft microdomains and modern biomimetic systems, enabling increasingly realistic experiments. Key advances include cross-method integration linking experimental observations with image-based computational models; persistent debates concern the translation from simplified models to living membranes, the role of dynamic coronas, and scale/force-field limits in simulations. Future efforts should prioritize hybrid models incorporating proteins and asymmetric lipidomes, standardized reporting and reference systems, rigorous coupling of experiments with calibrated simulations and machine learning, and alignment with safety-by-design and regulatory expectations, thereby shifting interfacial measurements from descriptive observation to predictive design rules.

Membranes doi: 10.3390/membranes16040133

Authors: Whitney K. Cosey Edson V. Perez Kenneth J. Balkus John P. Ferraris Inga H. Musselman

Carbon molecular sieve membranes (CMSMs) provide a means to greatly improve gas separations. CMSMs have a pore size distribution comprising micropores and ultramicropores which provide high flux and high selectivity, enabling them to outperform polymeric membranes. CMSMs, however, suffer from physical aging that results from the collapse of the pores that severely reduces their gas permeability. Therefore, reducing physical aging of CMSMs is an important step in the development of these types of materials. In this work, a method for reducing physical aging through the incorporation of metal nanoparticles that serve as a structural scaffold for the membrane pore structure is presented. The pore structure in CMSMs is dependent upon the polymeric precursor, and thus the support system incorporated must be tailored. The copper nanoparticles were formed in situ from soluble, copper-based metal–organic polyhedra 18 (MOP-18) dispersed into Matrimid® 5218, a low free volume polymer. The size (2 to 20 nm) and shape (sphere, rods) of the copper particles were refined by adjusting MOP-18 loading, pyrolysis temperature, and soaking time. The Cu-pillared Matrimid® 5218 CMSMs from this work showed no decline in permeability or selectivity for methane (107 Barrer) and carbon dioxide (1785 Barrer) over a period of 21 d. The results suggest that tailored metal pillars can suppress physical aging in CMSMs, thereby enhancing their long-term stability and applicability in gas separations.

Membranes doi: 10.3390/membranes16040132

Authors: Stacy Ragueneau Clémence Cordier Adeline Lange Laurent Torres Philippe Moulin

Microalgae, being able to produce a variety of bioactive compounds, represent a promising resource for numerous industrial applications. However, their large-scale production remains constrained by biological, technical and economic factors. Open ponds, which are predominantly employed on an industrial scale, yield lower levels of algae in comparison to those obtained in closed reactors. Consequently, the processing of substantial volumes is necessitated during the harvesting process. This study explores the potential of microfiltration as an alternative to conventional harvesting processes to optimise yields and preserve biomass quality. The evaluation of various ceramic membranes, including new-generation prototypes, was conducted according to several operating parameters (flux, backwash mode, recirculation rate). The objective was to obtain microalgae concentrate while preserving cell integrity. Three species (Odontella aurita, Phaeodactylum tricornutum and Dunaliella salina) were considered for issues directly related to industrial cultivation such as seasonality, strain variability and the state of the culture at the time of harvest. An effective cleaning protocol was also developed, applicable to all the conditions tested. The ceramic membranes demonstrated a high degree of resistance to fouling, with their low tortuosity promoting effective backwashing. The membrane process resulted in a high level of cell recovery and volume concentration factors that were comparable to those achieved by conventional methods. In comparison with alternative concentration processes, it is also economically viable, thus confirming its potential as a robust and efficient alternative for industrial-scale microalgae harvesting.

Membranes doi: 10.3390/membranes16040131

Authors: Shabin Mohammed Ahmed Elmekawy Ranwen Ou Hanaa M. Hegab

The rising demand for clean water has reinforced the importance of thin-film composite TFC polyamide membranes in desalination and wastewater treatment. While improvements often target the selective layer, these can sometimes reduce stability or selectivity. An alternative approach is to tailor the porous support, particularly through the incorporation of nanomaterials such as metal oxides, carbon-based nanomaterials, metal–organic frameworks (MOFs), zeolites, and cellulose-based materials, to improve overall membrane performance. The modification of membrane substrates through the incorporation of nanofillers has demonstrated notable advantages, including enhanced hydrophilicity, improved mechanical stability, and increased porosity. These improvements collectively contribute to higher permeability, reduced internal concentration polarization and enhanced separation performance in FO, NF, and RO applications. The review starts by clearly distinguishing substrate modification, in which nanomaterials are localized in the porous support, from interlayer modification, which involves constructing a distinct layer between the support and selective layer. This concise review highlights current developments in the nanomaterial-based support modification of polyamide TFC membranes; it summarizes nanomaterials selections, incorporation techniques, and resulting property changes. Current challenges and potential research opportunities are also discussed.

Membranes doi: 10.3390/membranes16040130

Authors: Fei Jiang Wenyan Huang Yifang Mi

Wastewater contamination by toxic heavy metal ions poses a huge threat to ecosystem integrity and human health. Herein, we designed a polyelectrolyte (T-PEI) with a tunable positive charge property to construct a layer-by-layer (LBL) nanofiltration membrane for efficient heavy metal ion removal. The T-PEI was obtained via a Mannich reaction between polyethyleneimine (PEI) and tetrakis (hydroxymethyl) phosphonium chloride (THPC). The introduction of THPC imparted T-PEI with a strong and tunable positive charge, attributed to the quaternary phosphonium groups in THPC. Converting the weakly charged PEI into the strongly charged T-PEI allowed regulation of both T-PEI’s deposition behavior and the electrostatic interactions with sodium polystyrenesulfonate (PSS) during LBL assembly. As a result, after depositing only one bilayer, the positively charged PSS/T-PEI membrane achieved a pore size radius of 0.35 nm, meeting the typical criteria for nanofiltration membranes. Under the optimal preparation conditions, the resultant membranes exhibited a water flux of 38.1 L m−2 h−1 and high rejections to various heavy metal ions at low operation pressure, such as Cr3+ (99.8%), Ni2+ (96.1%), Cu2+ (92.5%), and Mn2+ (90.3%). Additionally, the membrane possessed robust operation stability, along with excellent antifouling/bacterial performance. After cyclic filtration of a lysozyme solution, the flux recovery ratio reached 94.7%. The membrane also exhibited effective bactericidal activity against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with no visible microbial colonies observed. This work highlights the effectiveness of tailoring polyelectrolyte characteristics in enhancing the LBL membrane performance and presents a promising LBL nanofiltration membrane for heavy metal ion removal.

Membranes doi: 10.3390/membranes16040129

Authors: Tonantzi Pérez-Moreno Jesús Humberto Chávez-Meza Jesús-Salvador Jaime-Ferrer Gabriel Luna-Bárcenas Luis G. Arriaga Janet Ledesma-García

To enhance the functionality of collagen (Coll)-based scaffolds, we developed a double-crosslinking strategy incorporating an electroconductive chitosan (Ch) and polypyrrole (Ppy) composite. Successful pre-crosslinking of Ch and Ppy was achieved using glutaraldehyde (GTA) at 100 µM. This facilitated imine linkage formation, confirmed by FTIR, enabling synergistic integration with Coll and successful nanofiber scaffold fabrication via electrospinning. While increasing the Ch-Ppy-GTA ratio affected the spinning process and higher GTA concentrations compromised fiber homogeneity, all other measured properties generally improved with increasing ratios. Crucially, this methodology allowed the membranes to maintain their morphology and significantly extended their degradation profile up to 20–30 days in PBS medium at 37 °C. Furthermore, the scaffolds exhibited electroactivity characterized by pseudocapacitance in the presence of Na+ and Ca2+ ions. These findings demonstrate a robust, tunable method for creating electroactive and structurally stable nanofiber scaffolds suitable for advanced tissue engineering.

Membranes doi: 10.3390/membranes16040128

Authors: Luca Pasquini Murli Manohar Riccardo Narducci Emanuela Sgreccia Maria Luisa Di Vona Philippe Knauth

Sulfonated aromatic polymers (SAPs) represent promising alternatives to perfluorinated ionomers for proton-exchange membrane fuel cells (PEMFCs), but their high hydrophilicity and limited chemical stability often require structural reinforcement and controlled cross-linking. In this study, composite membranes based on sulfonated poly(phenylsulfone) (SPPSU) and sulfonated poly(ethersulfone) (SPES) were fabricated with and without electrospun PPSU nanofiber mats and subsequently cross-linked through a solvent-induced sulfone-bridge formation at 180 °C. SPPSU/SPES blends (70/30, 50/50, 30/70) displayed good miscibility, while PPSU fibers improved dimensional stability and suppressed excessive swelling. Cross-linking strongly influenced membrane properties: intermediate treatment (20 h) enhanced mechanical strength and solvent resistance with limited loss of IEC, whereas extended treatment (30 h) produced highly stable, low-swelling networks. Despite lower IEC and water uptake, 30 h-treated membranes exhibited higher proton conductivity, attributed to reduced tortuosity and more continuous ionic pathways. Mechanical and hydration analyses identified SPPSU-50, SPPSU-70, and SPPSU-100 as the most balanced compositions. Proton mobility analysis revealed high membrane tortuosity, consistent with dense cross-linked structures reinforced by fibers. Overall, the combined use of SPPSU/SPES blending, PPSU nanofiber reinforcement, and sulfone-bridge cross-linking yields robust, water-insoluble membranes with improved electrochemical performance suitable for PEMFCs and other applications.

Membranes doi: 10.3390/membranes16040127

Authors: Chengbo Mao Chaoping Rao Jitao Liang Jiahao Wang Peirong Ji Yi Zheng

The proton exchange membrane (PEM) electrolyzer is vital for converting surplus renewable energy (RE) into hydrogen, underpinning the efficient and stable operation of the electric–hydrogen system. However, frequent start–stop cycles and load variations accelerate the degradation of proton exchange membranes and catalyst layers, incurring significant lifetime costs that existing studies ignore. To explore how the PEM electrolyzer’s dynamic traits impact system performance, we introduce an optimized operation approach for the electricity–hydrogen integrated energy system (IES) that incorporates these dynamic features and the novel Loss of Life Cost (LLC) model. Initially, to rectify the inadequacy in modeling the PEM electrolyzer within the current electricity–hydrogen IES operational framework, we integrate its dynamic characteristics based on electrochemical properties and establish a quantitative relationship between operational cycles and degradation costs. This enhanced model accurately reflects how operational conditions affect the electrolyzer’s hydrogen production efficiency and lifetime consumption, enabling precise performance simulation and economic assessment. This, in turn, promotes high-quality renewable energy utilization via hydrogen production while ensuring asset longevity, meeting the rising demand for hydrogen energy applications. Building on this, we further factor in constraints related to diverse energy conversion and safe operation within the electricity–hydrogen IES, as well as the operational limits of hydrogen fuel cells, various energy storage (ES) options, cogeneration units, and other pertinent equipment, aiming to minimize the system’s total daily costs (operational plus degradation costs). Consequently, we develop an optimization operation model for the electricity–hydrogen IES that accounts for the PEM electrolyzer’s dynamic characteristics and degradation economics. Finally, through simulation examples validated against published experimental data, we comprehensively analyze how the PEM electrolyzer’s dynamic traits influence system operation, confirming the effectiveness of our proposed model and methodology. Simulation findings reveal that, under varying electrolyzer capacities, ignoring the PEM electrolyzer’s dynamic characteristics can result in a deviation in system operating. Compared with the proposed method, it can reduce the equipment degradation speed by a maximum of 5.78 times.

Membranes doi: 10.3390/membranes16040126

Authors: Cuijing Liu Jingyi Xu Linbo Li

Polymers of intrinsic microporosity (PIMs) represent a novel class of microporous materials tailored for membrane separation. Initially explored predominantly for gas separation, they have subsequently found widespread utility in organic solvent nanofiltration. In recent years, their applicability has been further extended to ion separation. However, few comprehensive reviews have been dedicated to summarizing the advances of PIMs in this burgeoning field to date. This review provides a systematic overview of the recent progress in PIM membranes for ion separation. First, the structural features of PIMs employed in ion separation are summarized, with an emphasis on structure–performance correlations. Subsequently, their diverse applications in ion separation are elaborated in detail, encompassing ion resource recovery, water treatment, and electrochemical energy storage systems. Next, the current challenges facing the application of PIMs in ion separation are outlined, and finally, conclusions are provided. This review aims to provide insightful guidance for the development of high-performance PIM-based membranes in this rapidly evolving research area.

Membranes doi: 10.3390/membranes16040125

Authors: Amal S. Al Saadi Ismail Al-Yahmadi Sharif H. Zein Natarajan Rajamohan Intisar K. Al-Busaidi Nabila Al-Rashdi Safa Al Habsi Saada Al Shukaili Ali Alawi Rashid Al Mashrafi

Naturally Occurring Radioactive Materials (NORMs) in industrial wastewater present significant environmental and public health challenges due to their persistence and radiotoxic effects. This comprehensive review analyzes 108 peer-reviewed publications from 2014 to 2025 on NORM treatment technologies for industrial wastewater. While previous reviews have focused on individual treatment methods or laboratory-scale studies, this work provides comparative performance analysis across multiple technologies under realistic industrial conditions, including high-salinity environments and competing ions. We emphasize membrane filtration, electrocoagulation (EC), ion exchange, and advanced oxidation processes, evaluating both their economic feasibility and environmental sustainability for practical industrial implementation. The review discusses the advantages and limitations of existing techniques, highlighting the need for integrated strategies that combine physical, chemical, and biological processes for enhanced remediation. Hybrid systems combining multiple technologies outperform individual approaches by 15–25% in removal efficiency. These advances are critical for ensuring safe water reuse and protecting water resources from radioactive contamination. Additionally, regulatory frameworks governing NORM management are examined, underscoring the importance of standardized disposal and treatment protocols. The review concludes by identifying research gaps and future directions. Priority areas include developing standardized treatment protocols and strengthening academia–industry collaboration to achieve scalable solutions aligned with UN Sustainable Development Goal 6.

Membranes doi: 10.3390/membranes16040124

Authors: Gary Q. Yang Weibin Cai Ying Wan

Liposomes, spherical bilayer lipid-containing vesicles, are promising nanocarriers used for constructing drug delivery systems (DDS). Various strategies can be employed to loosen or break the liposome and release drugs as the tumor cells-targeting DDS made of liposomes reach the targeted sites. One of the most commonly used strategies is to heat the liposomal DDS by letting the gold nanoparticles or other light-absorbing substances that partition in various portions (inner water core, lipid bilayer or outside) of the liposome absorb light irradiation. Then, which portion can lead to the largest liposome structure change due to the same temperature variation? The answer is essential to aid the design of liposomal DDS; thus, wet lab experiments were carried out. However, even though irradiation-absorbing substances in different portions were irradiated for the same time and with the same irradiation intensity, it was impossible to ensure the three portions have the same temperature increase in the experiments. Furthermore, it is impossible to learn the related micromechanism and molecular-level details of the effects of temperature changes on the liposome structure with experimental methods. The molecular dynamics (MD) method is extensively employed by researchers to obtain in-depth molecular-level insights. Most researchers tend to simulate only a planar lipid bilayer structure, but Amărandi et al. demonstrated that such simplification strategy may give wrong simulation results contrary to the experimental results. Though Jämbeck et al. and Zhu et al. established whole spherical liposome systems with a diameter of about a dozen nanometers and simulated the systems with MD simulations, they did not simulate temperature-relevant properties of the liposome. Therefore, currently there is a lack of research on simulating the structure change in a whole spherical liposome due to temperature variations. So, we established the whole spherical structure of the liposome, simulated how it changes with temperatures and obtained molecular-level research results. It is observed that the temperature increase in the lipid bilayer causes the largest increase in lipid strand sway amplitude, the largest changes in lipid positions, the largest decrease in the distribution density of lipids and water around a lipid and the largest decrease in the interactions between lipids and lipids and between lipids and water, leading to the largest change in the liposome structure. We also studied how the degree of lipid tail unsaturation affects liposome structure changes with temperatures. Due to the C3 kinks in the unsaturated lipid tails, the distribution density of unsaturated lipids is not as high as saturate ones, leading to smaller attraction interactions and consequently larger liposome structure change with temperature. The obtained results are useful for the liposomal DDS design for the purpose of improving DDS performances and delivery outcomes.

Membranes doi: 10.3390/membranes16040122

Authors: Zhenming Yi Zilin Pan Feng Ye Shuanshi Fan Xuemei Lang Yanhong Wang Gang Li

Conventional high-temperature calcination for activating MFI zeolite membranes is energy-intensive and prone to inducing defects. Here, we demonstrate that a rapid ozonation treatment at 200 °C for only 1 h effectively decomposes organic templates while preserving membrane integrity. The resulting membrane exhibits H2/CH4 and H2/N2 ideal selectivities of 10.3 and 6.5, respectively, at room temperature, with C3H8 and SF6 permeances below the detection limit. These results confirm a dense, defect-minimized architecture and good molecular sieving performance of the zeolite membrane. In contrast, extending ozonation to 48 h leads to defect formation and a marked reduction in selectivity. For H2/CH4 mixture separation, the membrane achieves a selectivity of 23.8 at 100 °C, which is highly competitive among reported MFI membranes. In isopropanol dehydration, it achieves a water flux of 2.3 kg·m−2·h−1 and a separation factor of 3278 at 70 °C with a 10 wt% water feed, while maintaining >99.5 wt% water content in the permeate over a broad operating temperature range (30–70 °C). This work establishes rapid ozonation as a scalable, energy-efficient activation method for high-performance MFI zeolite membranes in both gas and liquid separations.

Membranes doi: 10.3390/membranes16040123

Authors: Meng Wang Youxin Li Lu Bai Robert Field Dengyue Chen Bing Wang Jun Jie Wu

This study proposes an innovative spacer design for use in spiral-wound membrane filtration systems as a high-performance alternative to conventional woven spacers. By eliminating interwoven filaments, this structure fundamentally reshapes flow patterns while maintaining mechanical support. A novel aspect of this methodology is the inaugural application of coupled computational fluid dynamics (CFD) and the discrete phase model (DPM) for modeling microbial particle transport and deposition dynamics, which has been a critical gap in prior studies that focused solely on hydrodynamic analysis without addressing biocolloid dynamics. Numerical simulations demonstrated that the novel design reduces stagnant zones by a significant amount compared to standard woven spacers and achieves a greater velocity uniformity. For all eight configurations of the novel design, the DPM-derived microbial distribution maps revealed a reduction of circa 65% in particle colonization density on the spacer surface, and this reaches a 77% reduction for the optimal design. These measurements directly linking structural geometry to antifouling efficacy provide mechanistic insight unattainable through conventional velocity field analysis alone. Experimental validation using optical coherence tomography (OCT) revealed a 40% reduction in TOC deposition, while confocal laser scanning microscopy (CLSM) quantified a 54% decrease in biofilm viability through adenosine triphosphate (ATP) measurements. The incorporation of the optimal spacer in the plate-and-frame test module demonstrated that the lower degree of fouling caused both a 23% increase in permeation flux together with 76% lower energy consumption compared to the commercial design.

Membranes doi: 10.3390/membranes16040121

Authors: Yani Jiang Zihao Zhao Xianbo Yu Quangang Cheng Shaoyu Zou Yang Zeng Qiang Huang Ziran Zhu Weiwei Zhu Liping Zhu Baoku Zhu

Poly(vinylidene fluoride) (PVDF)-based ultrafiltration membranes play key roles in aqueous separation fields. However, the inherent hydrophobicity of PVDF always generates higher water permeation resistance and a greater fouling tendency in the filtration process. Different to the widely reported and widely used blending methods of increasing the hydrophilicity of PVDF membranes, the mass-produced hydrophilic PVDF copolymer is expected to be more efficient in producing high performance membranes. For this purpose, the present research offers a new and scalable approach to improving the hydrophilic properties of PVDF-based membranes through amphiphilic copolymers. Using 2-trifluoromethylacrylic acid (MAF) and hexafluoropropylene (HFP), carboxylated PVDF (PVHM) was synthesized following simple radical suspension copolymerization. Via a non-solvent-induced phase separation (NIPS) method, PVHM membranes were prepared and characterized. It was found that the PVHM membranes had enhanced hydrophilicity, permeability, fouling resistance, and alkali resistance compared with PVDF membranes. For the PVHM containing 8.3 wt% MAF, its membrane demonstrated superior static/dynamic fouling resistance to sodium alginate (FRR up to 99.1% for SA). Therefore, carboxylated PVDF polymers show potential for use in the industrial production of high-performance ultrafiltration membranes.

Membranes doi: 10.3390/membranes16040120

Authors: Meixuan Xin Huamei He Feifei Wei Xia Zheng Yuan Xiang

Traditional membrane separation materials suffer from drawbacks such as a high carbon footprint, significant energy consumption, membrane fouling, and the potential for secondary pollution. Under the dual drivers of carbon neutrality and carbon peak strategies, as well as the deepening of environmental governance, low-carbon membrane separation materials have emerged as a pivotal direction for the green transformation of membrane technology, leveraging their core advantages of green raw materials, low-energy preparation, and high application adaptability. This green transition is primarily achieved through the development of green raw materials and preparation processes, the enhancement of separation efficiency, and a reduction in operational energy consumption. Consequently, this review systematically summarizes the low-carbon design principles, key performance metrics, separation mechanisms, catalytic coupling technologies, and the recent application progress of several mainstream types of low-carbon membrane materials. It further identifies current bottlenecks in the research of low-carbon membrane materials such as performance trade-offs, challenges in scalable fabrication, and long-term operational instability. Finally, the review proposes future research directions aimed at developing novel membrane materials that integrate low-carbon attributes, excellent separation performance, and multifunctionality.

Membranes doi: 10.3390/membranes16040119

Authors: Xiujuan Feng Haoyu Zhang Haotong Guo Chuhao Huang Yiwen Fu Shuqi Wang Jing Yang Jie Li Yankun Ma

Membrane technology demonstrates broad prospects in the field of methane capture and purification due to its high efficiency and low energy consumption characteristics. This paper systematically reviews the research progress in membrane technology for methane separation in recent years, focusing on the design and optimization of membrane material systems, in-depth analysis of mass transfer mechanisms, and practical applications in areas such as biogas upgrading and natural gas decarbonization. Researchers have significantly enhanced membrane separation performance for CO2/CH4, CH4/N2, and other systems by developing novel material systems such as polymer membranes, inorganic membranes, and mixed matrix membranes (MMMs), combined with strategies like pore structure regulation, interface optimization, and functionalization. Although membrane technology has shown good economic feasibility and application potential in some scenarios, challenges such as long-term material stability, anti-plasticization capability, and large-scale manufacturing remain the main current obstacles. Future research should further focus on the development of novel membrane materials, process integration optimization, and intelligent process control to promote a greater role for membrane technology in the efficient utilization of methane resources and energy structure transformation.

Membranes doi: 10.3390/membranes16040118

Authors: Mengfan Xu Yanhong Wang Mingfen Niu Qiang Zhou Wang Yang

To address the limited selectivity of conventional membrane materials toward sulfonamide antibiotics, this study employed a DFT calculation approach to optimize the design of a molecularly imprinted system for sulfadiazine (SDZ). A hierarchical set of template molecules—aniline (ANL), sulfanilamide (SNM), and SDZ—was introduced to systematically elucidate structure-dependent template–monomer matching mechanisms in sulfonamide imprinting systems. Through rational screening, trifluoroethyl methacrylate (TFEMAA) was identified as the optimal functional monomer, with an optimal imprinting molar ratio of 1:4 (SDZ to TFEMAA). Guided by the simulation results, SDZ molecularly imprinted polymers (MIPs) were synthesized via precipitation polymerization and systematically characterized for their morphology and recognition properties. The MIPs exhibited a well-defined spherical morphology with abundant imprinted cavities, achieving adsorption equilibrium within 1.5 h. The adsorption kinetics followed a pseudo-second-order model, indicating a chemisorption-dominated process. Scatchard analysis revealed the presence of both high- and low-affinity binding sites in the MIPs. Selectivity experiments, quantified by distribution coefficients (Kd) and selectivity coefficients (k), demonstrated a significantly higher adsorption capacity for SDZ than for structural analogs and non-analogs. In real water samples, the MIPs outperformed conventional HLB sorbents and showed strong anti-interference capability (RSD < 3%). This work provides a material foundation for developing highly selective SDZ-imprinted membranes and advances the application of molecular imprinting technology in membrane separation systems.

Membranes doi: 10.3390/membranes16040117

Authors: Jiaming Jin Sicheng He Tao Zhang Shengji Xia

Nanofiltration (NF) is increasingly applied for advanced drinking water treatment, but achieving stable operation at high recovery rates remains challenging for surface waters with high scaling potential. This pilot study investigated the performance and optimization of a three-stage NF270 system (4:2:1 tapered array) for treating coagulated surface water in northern Jiangsu, China, aiming to identify sustainable operating conditions for high-recovery applications. The NF system was operated at recoveries of 80–90% with a feed flux of 20–23 LMH, and the effects of forward flushing frequency, acid dosing location, and concentrate recirculation on fouling behavior were evaluated. The NF270 membrane achieved consistent removal of organic matter (effluent chemical oxygen demand (CODMn) < 0.5 mg/L), hardness (40–60% rejection), and alkalinity (~20% rejection), meeting Jiangsu Province drinking water standards. However, operation at 90% recovery resulted in rapid third-stage fouling, with permeate flow declining by >60% within 2.5 h. Osmotic pressure analysis (local concentrate osmotic pressure: 3.8–4.2 bar; net driving pressure: 0.8–2.2 bar) confirmed physical scaling rather than hydraulic limitation as the dominant mechanism. Stage-wise concentration factor calculations (CF1 = 1.6, CF2 = 2.9, CF3 = 4.4) revealed local Langelier Saturation Index (LSI) values of 1.8–2.2 in the third stage, identifying CaCO3 supersaturation as the primary scaling cause. Reducing recovery to 85% and flux to 20 LMH with 2 h forward flushing extended stable operation. Acid addition effectively mitigated scaling, but dosing location was critical: first-stage addition (pH 8.1 → 7.6) reduced third-stage LSI to 0.7–0.9 and stabilized performance, whereas third-stage addition (pH 8.0 → 7.3) inadvertently promoted Al(OH)3 precipitation from residual coagulant (feed Al: 0.07–0.11 mg/L). Concentrate recirculation (90% ratio) did not alleviate fouling. These findings demonstrate that for aluminum-rich coagulated surface waters, optimizing recovery, flushing frequency, and acid dosing location is essential for sustainable NF operation, and provide engineering guidance for full-scale applications.

Membranes doi: 10.3390/membranes16040116

Authors: Tianyu Zheng Songlin Wen Yi Wu Pengyu Shuai Delong Hou Yao Jin

This work investigated the membrane fouling mechanisms during the microfiltration of oat protein–β-glucan complexes. Microfiltration experiments were conducted under various pH conditions, protein-to-polysaccharide ratios, and ionic strengths. The fouling behavior was analyzed using multiple membrane fouling models to systematically elucidate the relationships among the particle characteristics, rheological behaviors, and membrane fouling. When the pH was adjusted to 7.8, the multimodal particle size distribution of the complexes promoted the formation of a loosely structured cake layer on the membrane surface, accompanied by partial obstruction of membrane pore entrances. On the contrary, the complexes, shown as having a monomodal particle size distribution and similar particle size to the membrane pore, formed compact cake layers and strong membrane fouling resistance. At pH 4.8, protein hydrophobic aggregation generated large particulate clusters that formed a loose cake layer during microfiltration, resulting in a decrease in membrane fouling resistance. Increasing the β-glucan content reduced membrane resistance through enhancing steric hindrance and hydrophilicity. This research provides a theoretical foundation for optimizing membrane separation process parameters in the production of diversified oat-based products.

Membranes doi: 10.3390/membranes16040115

Authors: Tabita Kreko-Pierce Lihua Chen Guojie Qu Stefanie L. Cassoday Lena Al-Harthi Xiu-Ti Hu

HIV-associated neurocognitive disorders (HAND) persist despite combination antiretroviral therapy (cART) and can be exacerbated by repeated cocaine (COC) exposure. Because COC, HAND, and cART independently disrupt medial prefrontal cortex (mPFC) function, their combined neurotoxic impact is a critical clinical concern. Using patch-clamp electrophysiology in HIV-1 transgenic (Tg) and non-Tg rats, we examined mPFC pyramidal neuron activity following repeated exposure to COC and/or cART. In non-Tg rats, COC and cART independently increased neuronal firing, trending toward an additive hyperactive effect when combined. Conversely, HIV-1 Tg rat neurons exhibited plateaued excitability, with no further firing elevations induced by COC or cART. Under intense depolarizing stimuli, treated neurons displayed overactivation-induced firing declines. These findings indicate that while COC and cART additively disrupt mPFC function in non-Tg rats, excitability mechanisms appear saturated in the HIV-1 Tg model. This restricted experimental context highlights the overlapping neurobiological impacts of cART and stimulant use, providing foundational insights into the comorbidity of COC use disorder and HAND.

Membranes doi: 10.3390/membranes16040114

Authors: Marian Turek Ewa Bernacka Krzysztof Mitko

Increasing the recovery in electrodialysis desalination may be achieved using a single-pass operation at different linear flow velocity values in the diluate and concentrate compartments. The risk of inner leakage as well as membrane bulging and damage can be minimized by controlling the pressure difference between the diluate and concentrate compartments. This solution has been tested in a pilot plant for initial demineralization of river water using an electrodialyzer of our own design. Both under- and overlimiting regimes have been tested, as well as long work cycles between electrode polarity reversals. Water with a conductivity of about 500 µS/cm was desalinated at a recovery of 70–75%, and the desalination degree was 75–96%. It was also found that the unit cost could be decreased by 52% compared to a commercial solution when the diluate conductivity was 74.3 μS/cm. A deep demineralization, from 511 μS/cm down to 17.9 μS/cm in a single-stage EDR or 8.52 μS/cm in a two-stage EDR, was also confirmed experimentally at the pilot scale.

Membranes doi: 10.3390/membranes16040113

Authors: Antonio Casañas Gonzalez Veronica García Molina Federico Antonio Leon Zerpa Alejandro Ramos Martin

Water is increasingly acknowledged as a limited and strategically critical resource, particularly in regions where hydrological imbalances are structurally persistent. Across Europe, countries such as Spain, Turkey, Italy, and Greece face recurrent water scarcity driven by precipitation regimes characterized by low annual rainfall, pronounced temporal variability, and marked spatial heterogeneity. In response to rising water demand associated with tourism, agricultural intensification, and sustained demographic pressures, Spain has implemented a series of national water-management strategies over the past two decades. Notably, the National Hydrological Plan, enacted in July 2005, introduced more than one hundred immediate actions focused on modernizing hydraulic infrastructure and reinforcing the country’s desalination capacity. Furthermore, the Royal Decree issued in December 2007 established a comprehensive regulatory framework to promote and standardize water reuse practices nationwide. Within this context, reverse osmosis has emerged as a central technology for the desalination of seawater and brackish water, as well as for advanced water-reclamation applications. This work presents a consolidated examination of Spain’s water-resource management framework, drawing on historical material and recent advances to outline the current context of desalination and water reuse. It presents operational performance data from several full-scale reverse osmosis facilities, and reviews recent technological developments in the field, including newly engineered membrane modules, innovative system architectures, and the latest generation of large-diameter RO elements. Together, these advancements illustrate the evolving role of membrane-based desalination and water reuse in supporting water security in semi-arid regions.

Membranes doi: 10.3390/membranes16030112

Authors: Chii-Dong Ho

The separation of substances from one another, such as distillation, extraction, absorption, crystallization, and drying, comprises a main sector of the industry engineering field and has substantial potential to play an increasingly important role in the application of separation technologies and innovations [...]

Membranes doi: 10.3390/membranes16030111

Authors: Krzysztof Mitko Marian Turek Mònica Reig Xanel Vecino

Electromembrane processes are a separate class of membrane methods that utilize ion transport across the ion exchange membranes [...]

Membranes doi: 10.3390/membranes16030110

Authors: Rania Chihi Mouna Ibn Mahresi Fadhila Ayari Lamjed Mansour Amel Ben Othman

The development of sustainable ceramic membranes remains a major challenge for advanced wastewater treatment, particularly regarding the trade-off between mechanical durability and the removal of dissolved micropollutants. While bentonite membranes offer high stability, they often lack the selective adsorption sites required for complex effluents, and the recovery of high-capacity powder adsorbents remains technically prohibitive. This paper addresses these gaps by developing an integrated hybrid system that combines eco-friendly bentonite-based tubular membranes with regenerable clam shell-derived adsorbents. The membranes were synthesized using natural plasticizers and binders with optimization at a sintering temperature of 1000 °C yielding an average pore size of 1.7 µm, a high flexural strength of 24.06 MPa, and a permeability of 525 L h−1 m−2 bar−1. To enhance the performance, clam shell powder was integrated as a functional adsorbent layer. When applied to real textile effluent from a jeans washing plant, this integrated process achieved superior removal efficiencies: 85.6% COD, 86.5% BOD5, 86.5% TSS, and 96.5% color. A key scientific contribution of this paper is the successful application of a photochemical regeneration approach, which ensures complete adsorbent recovery and maintains membrane flux, directly supporting circular economy objectives. These results demonstrate that combining low-cost ceramic scaffolds with marine waste-derived materials provides a unique, efficient, and green solution for the scalable treatment of industrial wastewater.

Membranes doi: 10.3390/membranes16030109

Authors: Akram Abdullah Rathinam Panneer Selvam

Several studies have investigated counterflow and concurrent flow in channels separated by a membrane to simulate mass transfer through membranes; however, few of them have used computational fluid dynamics (CFD). The current study aimed to numerically simulate and physically describe the distribution of pressure and velocity in counter-current flow by solving Navier-Stokes (N-S) equations in the channel and membrane pores (vertical channels). This is in contrast to most previous studies, in which the channel flow was simulated using N-S equations while ultra-filtration membrane flow was simulated using Darcy’s law. Consequently, the current study was executed using a CFD simulation to achieve several significant features: avoiding the execution of experimental tests, reducing the effort of model design and the expense and time consumption of fabrication, and facilitating the easy observation of variations in the pressure and the horizontal and vertical velocity for each point in the model. Two-dimensional CFD methods directly simulated the flow in channels and membrane pores to solve the N-S equations for each point in the whole domain, for which the velocity (horizontal and vertical) and pressure were calculated. In the current study, it was found that the pressure decreased from the inlet to the outlet of the channel, the horizontal velocity decreased from the inlet to the middle of the channel length and then increased to the outlet of the channel, and the vertical velocity decreased from the inlet to the middle of the channel length (L/2) with an upward direction (positive) and from L/2 to the outlet of the channel with a downward direction (negative). The analytical solution (1D model) was used to validate a numerical simulation (CFD) for the current study, but there were slight differences in the results between them. The results were perfectly explored and displayed the flow distribution patterns inside the channels and the membrane pores (vertical channels). The current study model represents the hemodialysis process.

Membranes doi: 10.3390/membranes16030108

Authors: Maria Grazia De Angelis Matteo Minelli

This Special Issue of Membranes celebrates the scientific achievements, international vision, and collaborative spirit of Professor Giulio C [...]

Membranes doi: 10.3390/membranes16030107

Authors: Elena Kalinina

The Special Issue entitled “Fabrication, Characterization and Application of Organic/Inorganic Film Membranes and Advanced Materials (Volume III)” continues the themes of the previous Special Issue entitled “Fabrication, Characterization and Application of Organic/Inorganic Film Membranes and Advanced Materials (Volume II) [...]

Membranes doi: 10.3390/membranes16030106

Authors: Evangelia Koliamitra Vasileios Mitrousis Tzouliana Kraia Giorgos Kardaras Nikoleta Lazaridou Triantafyllia Grekou Kyriakos Fotiadis Dimitrios Koutsonikolas Akrivi Asimakopoulou Michael Bampaou Kyriakos D. Panopoulos

The shipping sector is responsible for a considerable share of global CO2 emissions and is under pressure to reduce emissions and adopt carbon-neutral fuels. Among the proposed alternatives, methanol produced from green hydrogen and biogenic CO2 represents a promising option. However, the feasibility of its production is significantly influenced by the composition and variability of the bio-CO2 feedstock, which can negatively impact the complete value chain. To address these challenges, sampling campaigns were carried out at actual bio-CO2-emitting sites, namely biogas and biomass combustion facilities, to characterize the impurity profiles and determine the appropriate conditioning requirements. A novel membrane gas absorption system with a Diethanolamine solution was deployed directly in the field to capture, as well as purify to a certain extent, the CO2 stream. The system demonstrated high efficiency in removing most impurities, achieving high CO2 capture rates and impurity reduction close to 90%. However, residual chlorine species were detected in the CO2 streams from biogas plants, suggesting the need for additional conditioning to meet the purity specifications required for methanol synthesis. Given that the feedstock composition and upstream process conditions could significantly affect the final output and present considerable variations, the implementation of additional cleaning measures is recommended before synthesis.

Membranes doi: 10.3390/membranes16030105

Authors: Elena Kalinina

The Special Issue ‘Fabrication, Characterization and Application of Organic/Inorganic Film Membranes and Advanced Materials (Volume II)’ includes 13 articles covering various aspects of the formation and application of organic and inorganic membranes and various membrane-based devices [...]

Membranes doi: 10.3390/membranes16030104

Authors: Keyuan Zhang Yan Wu Yue Jiang Qi Han Minmin Zhang Li Feng Liqiu Zhang

Forward osmosis (FO) membranes face challenges in balancing high water permeability, low reverse salt flux (RSF), and mechanical durability. Although nanopores in graphene have great theoretical potential, the existing methods make it difficult to independently optimize the nanopores of the graphene layer and the microstructure of the substrate without damaging each other. Here, we propose a defect engineering strategy based on oxygen plasma etching to address this collaborative optimization challenge. Monolayer porous graphene (PG) was integrated with polysulfone (Psf) substrates, followed by oxygen plasma etching to introduce nanopores and oxygen-containing functional groups (e.g., carboxyl, hydroxyl). By controlling the etching time to 10 s, the resulting membrane (S-PG10) exhibited a water flux of 0.24 LMH in 0.5 M NaCl, representing an order-of-magnitude increase compared to the pristine graphene membrane (S-G). Remarkably, S-PG10 maintained a high salt rejection (>96%) and a low Js/Jw (<0.35 g·L−1). Substrate modification via short-term plasma etching (5 min) further doubled the water flux of S*5-PG10 (0.47 LMH in 0.5 M NaCl) by increasing porosity (81.8%→85.6%) and hydrophilicity. However, prolonged etching (>15 min) degraded mechanical strength and increased RSF due to pore structure disruption. To enhance robustness, Poly(D,L-lactic acid) (PDLLA)-doped substrates (S#-PG) were engineered, with 0.1 wt.% PDLLA optimizing mechanical properties while maintaining low RSF and high flux. Excessive PDLLA (10 wt.%) induced hydrophobicity and crystalline structures, reducing permeability. The study demonstrates that synergistic optimization of plasma etching duration on the graphene selective layer (5~10 s) and substrates (5 min) as well as PDLLA doping (0.1 wt.%) balances pore architecture, surface chemistry, and substrate integrity, achieving FO membranes with superior water-salt selectivity and mechanical stability. These findings provide critical insights into designing high-performance graphene-based membranes for sustainable desalination and water purification.

Membranes doi: 10.3390/membranes16030103

Authors: Xinhui Sun Yukta Sharma Landysh Iskhakova Zishu Cao Junhang Dong

In the original publication [...]

Membranes doi: 10.3390/membranes16030102

Authors: Denis Kalugin Jumanah Bahig Ahmed Shoker Amira Abdelrasoul

In the original publication [...]

Membranes doi: 10.3390/membranes16030101

Authors: Mohd Muzammil Zubair Ahmed T. Yasir Abdelbaki Benamor Syed Javaid Zaidi

Globally, freshwater scarcity is driving the urgent demand for advanced and new desalination technologies to overcome the shortage of clean water. Reverse osmosis (RO) membranes dominate seawater and brackish water treatment but are limited by the permeability–selectivity trade-off, fouling, and structural instability. To overcome these challenges, we employed a phase inversion process to fabricate polysulfone (PSF) supports embedded with a graphene oxide–poly(amidoamine) (GO-PAMAM) nanocomposite at three concentrations (0.03, 0.06, and 0.10 wt%), alongside a pristine control membrane with no GO-PAMAM. Systematic variation in GO-PAMAM loading revealed that a 0.06 wt% nanoparticle helps in producing a more uniform polyamide layer that achieves a high NaCl rejection (95.88%) and higher water flux (42.6 L m−2 h−1). The performance was evaluated at an operating pressure of 20 bar with a feed flow rate of 4 L min−1. The optimized membrane also demonstrated an improved fouling resistance, retaining 93% of its initial flux after fouling. This scalable approach highlights substrate-level modification as an effective strategy for next-generation RO membranes, advancing sustainable and energy-efficient desalination to meet escalating global water demands.

Membranes doi: 10.3390/membranes16030100

Authors: Qianliang Liu Xin Guo Hengyu Ai Hongbo Liang Fen Li Caihong Liu

Membrane distillation (MD) was a promising approach for treating highly concentrated ammonia–nitrogen wastewater. However, membrane wetting often limited large-scale application. To address this, we built an anti-wetting layer on a commercial PVDF membrane surface by coating fluoride and depositing SiO2 nanoparticles. Three PVDF/ SiO2/F membranes were prepared with different silicon contents: 1%, 6%, and 12% (volume) of tetraethyl orthosilicate (TEOS). These processes created different surface roughness on the modified membranes. Results showed that the membrane containing 6% TEOS exhibited the best resistance to sodium dodecyl sulfate (SDS) in NaCl solution. This optimized membrane was subsequently tested with real wastewater, including source-separated urine and landfill leachate. In 10 h, it removed 97.5% of total organic carbon (TOC) from urine, achieving an ammonia absorption rate of 55.1% and removed 92.4% from leachate, with an ammonia absorption rate of 37.58%. These results provide a reference for membrane fabrication parameter optimization to enhance the membrane’s anti-wetting ability.

Membranes doi: 10.3390/membranes16030099

Authors: Robert F. Melendy Daniel H. Blue

The Hodgkin–Huxley equations have successfully described neuronal excitability for over seventy years, yet their mathematical structure remains empirically justified rather than theoretically explained. Why are gating variables bounded between 0 and 1? Why does sodium conductance depend on m3h rather than other combinations? Why does potassium depend on n4? Why do all rate functions contain exponential voltage dependencies? Why are the kinetics first-order? We demonstrate that these structural features arise naturally from three fundamental physical symmetries governing ion channel dynamics: the compactness of conformational state space, the scaling invariance of membrane conductance, and temporal translation invariance. Using Lie group theory, we show that these symmetries uniquely determine a mathematical structure in which: (1) gating variables are necessarily bounded, (2) voltage dependencies must be exponential, (3) exponents must be integers, and (4) kinetics must be first-order. The Hodgkin–Huxley equations, rather than mere empirical fits, emerge from fundamental symmetry principles. This framework establishes that neural electrophysiology obeys the same theoretical principles as modern physics, where symmetries constrain the form of dynamical equations. It further provides a principled basis for interpreting deviations from classical behavior as manifestations of additional symmetries or symmetry breaking.

Membranes doi: 10.3390/membranes16030098

Authors: Jonatan C. S. de Carvalho Pedro Nobre-Azevedo Pedro V. da Silva-Neto Bianca T. M. Oliveira Lucas A. Tavares Diana M. Toro Andrews O. Borges Murillo A. Nascimento Eurico Arruda Ronaldo B. Martins Fausto Almeida Carlos A. Sorgi

Sphingolipids (SL) are essential structural and bioactive components of cell membranes, remarkably involved in inflammatory signaling and membrane dynamics. Dysregulation of SL metabolism contributes to pathological inflammation and cellular stress. Selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine (FXT), are known inhibitors of acid sphingomyelinase (aSMase), although their impact on macrophage SL remodeling and inflammatory responses remains unclear. Here, we investigated the modulation of FXT on SL species composition and inflammatory activation in THP-1-derived macrophages stimulated with inactivated SARS-CoV-2 particles, which is a model of viral-induced inflammation. Sphingolipidomic profiling revealed that FXT pre-treatment markedly reduced ceramide (Cer) species while increasing sphingomyelin (SM) and sphingosine-1-phosphate (S1P) levels, consistent with inhibition of the aSMase-Cer axis. These changes were accompanied by attenuation of proinflammatory components, including interleucin (IL)-6, IL-1β, and matrix metalloproteinase (MMP)-9, indicating that SL remodeling correlates with reduced macrophage activation. Despite pronounced alterations in membrane lipid composition, the quantification of extracellular vesicles (EVs) released by FXT-treated macrophages remained unchanged, however the EVs size distribution was smaller compared to non-treated cells. Altogether, our findings demonstrate that FXT reshapes SL metabolism and lipid membrane composition, thereby diminishing macrophage activation without affecting EVs biogenesis. This study emphasizes the immunometabolic role of SL on membrane reprogramming as a mechanism by which pharmacological aSMase inhibition modulates viral inflammation responses.

Membranes doi: 10.3390/membranes16030097

Authors: Bshaer Nasser Hisham Kazim Moin Sabri Muhammad Tawalbeh Amani Al-Othman

This paper reviews artificial intelligence (AI) applications in the design and optimization of proton exchange membrane (PEM) materials for hydrogen fuel cells. Clean energy conversion is a substantial benefit of PEM fuel cells, which conventional membrane development struggles with due to time-consuming trial-and-error methods, which are not adequate in capturing the different interdependencies of the membrane structure, and environmental variables. The review establishes foundational design principles of PEMs and outlines their challenges and computational methodologies are constructed to address them. Various advanced AI methods have been highlighted which include graph neural networks, multitask frameworks, and physics-informed models that facilitate rapid prediction of polymer properties. Optimization methods have been reported with 10–30% performance improvements, for instance, NSGA-II frameworks achieving 13–27% gains in power density. Experimental requirements are reduced by 40–60%, as seen with Bayesian optimization, identifying optimal designs within as few as 40 iterations. Current challenges include data availability, generalizability, and scalability, which are closely assessed in this review.

Membranes doi: 10.3390/membranes16030096

Authors: Tingbao Ning Yangjian Zhou Haixia Xu Shiri Guo Ke Wang Deng-Guang Yu

In the original publication [...]

Membranes doi: 10.3390/membranes16030095

Authors: Carlos del Pozo-Rojas Sandra Montalvo-Quirós Lourdes Rufo José María Bueno Macarena Calero Francisco Monroy Diego Herráez-Aguilar

Red blood cell (RBC) membrane flickering arises from the interplay between thermal fluctuations, cytoskeletal elasticity, and metabolically driven non-equilibrium processes, making it a sensitive reporter of membrane mechanical state. Here, we introduce a computational microscopy framework that integrates bright-field morphometry with high-speed flickering spectroscopy to phenotype single-cell RBC mechanics under flavonoid exposure. As a proof of concept, human erythrocytes from a single donor were incubated with structurally distinct flavonoids (quercetin, apigenin, and rutin) prepared at sub-hemolytic concentrations, ensuring preservation of membrane integrity. Static shape descriptors and dynamic fluctuation spectra were extracted from segmented cell contours and analyzed through Fourier-mode decomposition to obtain compound-specific mechanical signatures. While gross morphology remained largely discocytic across conditions, flavonoid treatment induced reproducible alterations in flickering spectra and effective mechanical parameters, revealing distinct dynamical phenotypes that depend on flavonoid structure. In particular, aglycone flavonoids exhibited modulation patterns that differed from the glycosylated compound, consistent with differential membrane interactions. The combined analysis of geometry and dynamics provided enhanced discriminative power compared to either modality alone. These results establish computational microscopy as a sensitive, label-free approach to map compound-specific perturbations of RBC membrane mechanics and flickering, with potential applications in membrane biophysics, drug–membrane interaction screening, and single-cell mechanical phenotyping.

Membranes doi: 10.3390/membranes16030094

Authors: Mohamed Fadel Anass Ma-el-ainine Rachid Boukhili Oumarou Savadogo

Bipolar Polymer Membranes (BPMs) enable the creation of large, stable pH gradients by driving water dissociation (WD) at the cation/anion junction under reverse bias, a process central to electrodialysis, CO2 capture, and emerging acid–alkaline water electrolysis. Yet despite decades of study, the mechanism by which intense interfacial electric fields accelerate WD remains debated and is often modeled with ad hoc assumptions. In this study, we present a power dissipation model in which minority ions from water autoprotolysis act as carriers that continuously dissipate field-supplied power in the hydrated nanometric junction. This dissipative input increases the local probability of heterolytic O–H bond cleavage and analytically leads to a quadratic dependence of the dissociation rate constant on the field. Without adjustable parameters, the model reproduces the required orders of magnitude for the enhancement ratio kd(E)/kd(0), where kd(E) is the field-enhanced water dissociation rate constant and kd(0) is its zero-field value across typical BPM fields, and yields a quadratic current–voltage junction law. A proof-of-principle measurement on a commercial Fumasep® FBM bipolar membrane confirms the quadratic current–voltage trend, supporting a power-dissipation-driven water dissociation mechanism and providing a concise, falsifiable baseline for future studies.

Membranes doi: 10.3390/membranes16030093

Authors: Anthony Hana Youngwoo Kim Joy Bidros Katie Neglia Robin L. Cooper

Maintaining a membrane electrical potential of biological cells is a dynamic process, as some cells have a continually changing potential, like pacemaker cells, while other cells may function with large or small changes in the membrane potential. Additionally, some cells may change their electrical potential when stimulated or inhibited by electrical signals, chemical compounds, or both—either simultaneously or episodically. The persistent leak of K+ through two-pore-domain potassium channels (K2P) and of Na+ through Na+ leak channels (NALCNs) and the action of pumps and exchangers are primarily responsible for maintaining a resting potential. Ca2+ ions are known to block the NALCNs and result in a more hyperpolarized membrane potential, with a reduction in Ca2+ resulting in a depolarized state. Using the larval muscles of Drosophila, the membrane potentials were monitored as Ca2+ and Mg2+ concentrations were altered. Changes as large as 20 mM of Mg2+ had only small effects (1 to 2 mV) on the membrane potential compared to 3–5 mM changes in Ca2+ having larger effects (5–10 mV). Although, it appears raised [Mg2+] may dampen the changes induced by Ca2+. Simulations of the G-H-K equation estimate the changes in permeability of Na+ (pNa). These experiments are significant, as the clinical severity of hypocalcemia and hypercalcemia may also depend on Mg2+ levels.

Membranes doi: 10.3390/membranes16030092

Authors: Iwona Zawierucha Cezary Kozlowski Bernadeta Gajda Katarzyna Witt

Ionic liquid (IL) N-methyl-N′-1-(4-t-butylphenylphosphinyl)butylimidazolium bis(trifluoromethylsulphonyl) imide was used for the first time as an ion carrier in membrane systems to selectively transport Au(III), Pt(IV), and Pd(II) ions. Au(III), Pd(II), and Pt(IV) were transported from HCl solutions utilizing a polymer inclusion membrane (PIM) with cellulose triacetate as the support, o-nitrophenyl pentyl ether as the plasticizer, and ionic liquid as the mentioned ion carrier. The modifications of source and receiving aqueous phase compositions are examined. High selectivity for Au(III) using the ionic liquid in the membrane was achieved at elevated HCl concentrations (≥0.5 M). When a 0.010 M KI solution was used as the receiving phase and a membrane with the optimal composition was applied, the extraction of Au(III) ions reached a maximum recovery rate of 93%. Moreover, PIM studies showed that carrier molecules doped in the membrane creates complexes with the Au(III) ion with a molar ratio of 1:1. The extractability of Au(III) through PIMs exceeded that of other metal ions, with the selectivity of transported metal ions ranked as follows: Au(III) >> Pt(IV), Pd(II). The recovery factors for gold, platinum, and palladium ions after 6 h of transport were 94%, 8%, and 1%, respectively.

Membranes doi: 10.3390/membranes16030091

Authors: Rizqan Jamal Yuta Kayukawa Ryouki Kitamura Manabu Miyamoto Yasuhisa Hasegawa Yasunori Oumi Shigeyuki Uemiya

The rapid synthesis of high-performance silicalite-1 membranes was systematically investigated by examining the effects of seed size, solution volume, and reactor configuration on membrane growth, microstructure, and gas separation performance. Silicalite-1 seeds (~100 nm and ~1 µm) were dip-coated onto capillary α-alumina supports, followed by secondary growth under controlled conditions. Small seeds (~100 nm) produced high nucleation density, uniform intergrowth, and defect-free membranes, yielding consistently high ideal separation factor for H2/SF6 (181–295) and low SF6 permeance (~10−9 mol m−2 s−1 Pa−1) after only 45 min of synthesis. In contrast, larger seeds (~1 µm) enabled faster growth but resulted in less uniform layers with inferior selectivity. Furthermore, a novel reactor design with enhanced heat transfer enabled the rapid silicalite-1 membrane synthesis on conventional large-diameter tubular supports, producing well-intergrown and uniform membranes with high H2 permeance (4.7 × 10−6 mol m−2 s−1 Pa−1) and high ideal separation factors of up to 349 for H2/SF6 and 223 for N2/SF6. Overall, this study demonstrates that optimization of seed properties, synthesis parameters, and reactor design enables rapid and scalable fabrication of silicalite-1 membranes with robust molecular sieving performance, highlighting their strong potential for SF6 purification applications.

Membranes doi: 10.3390/membranes16030090

Authors: Hajar Zeggar Soufian El-Ghzizel Mustapha Tahaikt Mohamed Taky

This study employs an integrated modeling approach to elucidate the mechanisms of nitrate ion transport through nanofiltration (NF) and reverse osmosis (RO) membranes. The investigation first applied models from irreversible thermodynamics, specifically the Kedem–Katchalsky and Spiegler–Kedem models, to describe convective/diffusive contributions and the impact of the initial nitrate concentration (50–150 mg/L) on phenomenological parameters (reflection coefficient σ, and solute permeability Ps). The results revealed a marked sensitivity of NF membranes to the initial nitrate concentration, in contrast to the stable performance of RO membranes. To deepen this analysis, Response Surface Methodology (RSM) was used as a robust statistical tool to systematically model and quantify the synergistic effects of the initial concentration and other key operational parameters, transmembrane pressure (TMP) and recovery rate (Y) on NF performance. The results highlight the complementarity between transport modelling and statistical approaches for analysing nitrate rejection and permeate flux. The proposed approach provides useful insight into NF membrane-specific behaviour and relative sensitivity to operating conditions, within the scope and limitations of the studied membrane and experimental configurations.

Membranes doi: 10.3390/membranes16030089

Authors: Samanta Moffa Serena Pilato Michele Ciulla Pietro Di Profio Antonella Fontana Fabrizio Masciulli Gabriella Siani

Stimuli-responsive liposomal membranes have attracted growing interest as dynamic soft materials capable of regulating permeability, fusion, and cargo release in response to external or internal triggers. By incorporating functional molecular or nanostructured guests, such as photochromic compounds, plasmonic nanoparticles, or ionizable lipids, bilayers can be endowed with reversible and tunable properties. These modifications often rely on the precise control of lipid packing, phase behaviour, and the formation of transient membrane defects that facilitate molecular transport. This review aims to provide an overview of the molecular design strategies and underlying mechanisms used to engineer such responsive liposomal systems, with particular emphasis on light- and heat-triggered behaviours and on supramolecular approaches that modulate membrane structure and dynamics. Emerging trends, current limitations, and opportunities for future development in functional lipid-based materials and biointerfaces will also be discussed.

Membranes doi: 10.3390/membranes16030088

Authors: Muhammad Shabbir Mustansar Mubeen Muhammad Umer Aqleem Abbas Amjad Ali Sarmad Qureshi Muhammad Rao Yasir Iftikhar Esmael Alyami Ahmed Ahmed

Membrane lipid remodeling plays a pivotal role in regulating plant growth, reproductive development, and adaptive responses to environmental stress. However, several lipid-modifying enzymes remain uncharacterized in Arabidopsis thaliana. Here, we provide the first comprehensive in silico functional characterization of the unannotated gene AT5G35460, integrating domain architecture, AlphaFold-supported structural validation, and phylogenetic, expression, and regulatory analyses. Domain architecture and conserved DUF2838 signatures, together with transmembrane topology and validation using AlphaFold-predicted structural data, support its identity as a glycerophosphocholine acyltransferase (GPCAT1). Phylogenetic reconstruction showed that GPCAT1 clustered closely with its orthologs of major angiosperms, suggesting deep evolutionary preservation. Expression profiling revealed over a tenfold higher transcript abundance in mature pollen, detected 6–8 times more than during leaf senescence, indicating strong developmental control. Co-expression network analysis revealed links to the lipid metabolism genes (CDS2, LACS8, and SBH1) as well as factors involved in response to stress, indicating that AT5G35460 may act at the level of phosphatidylcholine remodeling, membrane resistance and stress response. Analysis of the promoter sequences showed AACTAAA, ABRE and G-box elements (pollen-specific, ABA-responsive and stress-inducible motif respectively), suggesting appropriate transcriptional regulation consistent with its expression profile. As a whole, the findings revealed that AT5G35460 is an unexplored membrane-localized acyltransferase involved in lipid maintenance during reproductive development and environmental responses. This study serves as a basis for subsequent functional characterization and identifies AT5G35460 as a potential target for modifying pollen viability, senescence kinetics and stress tolerance in plants.

Membranes doi: 10.3390/membranes16030087

Authors: Zhibo Zhang Geting Xu Yangbo Qiu Junbin Liao Tong Mu Wanji Zhou Yunfang Gao Jianquan Weng Jiangnan Shen

The industrial application of modified ion-exchange membranes is limited by complex, discontinuous ex-situ processes. This study introduces an in-situ electro-assembly strategy that enables the direct fabrication of a selective layer within an electrodialysis stack without disassembly. By utilizing a programmed current reversal to orchestrate the sequential deposition of polyethyleneimine (PEI), glutaraldehyde cross-linking, and polystyrene sulfonate (PSS) adsorption, we achieve meticulous interfacial engineering on a commercial cation exchange membrane. Comprehensive characterization confirms the successful construction of a hydrophilic, charge-tuned multilayer, which enhances ion transport kinetics and raises the limiting current density. This method culminates in a membrane with an exceptional Li+/Mg2+ selectivity of 107.9 and robust stability, retaining a significant selectivity of 47 over 10 cycles in real salt lake brine. This synergistic integration of operational simplicity, interfacial precision, and superior performance establishes a transformative and scalable platform for manufacturing high-performance membranes for selective ion separation from complex brine sources.

Membranes doi: 10.3390/membranes16030086

Authors: Elorm Obotey Ezugbe Sudesh Rathilal Emmanuel Kweinor Tetteh

Repurposing usage of oil refinery wastewater with retrofitted desalination technology necessitates the optimization of a forward osmosis (FO) technology. Herein, factors such as draw solution concentration (DS-C) and feed and draw solution flow rates (FS-FR, DS-FR) play significant roles. In this study, the individualistic and interaction effects of these factors were explored to ascertain the FO performance. The effects of these operating factors, DS-C (20–50 g/L), DS-FR (7.5–9.4 L/h), and FS-FR (7.5–9.4 L/h), and their interactive effects on the permeation flux and rejection of Cl−, SO42− and CO32− from oil refinery effluent, were studied using the Box–Behnken design (BBD) of response surface methodology (RSM). Statistical models were developed to optimize the operating conditions. The analysis of variance and the developed response models were used to evaluate the data at a 95% confidence level. Three confirmatory runs were conducted based on the optimum conditions (FS-FR: 9.2 L/h; DS-FR: 9.4 L/h; DS-C: 32.6 g/L). At a desirability of 81%, average rejections of 94.59 ± 0.32% for CO32− and 100% for SO42− were obtained. Average Cl− enrichment was 35.5 ± 5.15% and average permeation flux of 3.64 ± 0.13 L/m2 h were achieved, suggesting that RSM was a suitable tool for optimizing FO for desalinating the effluent. In addition, the average recovered permeation flux of 86.01 ± 2.66% demonstrated the effectiveness of the FO membrane after cleaning.

Membranes doi: 10.3390/membranes16030085

Authors: Slobodanka Galovic Milena Cukic Radenkovic Edin Suljovrujic

Analytical models of transdermal drug delivery (TDD) often represent deeper skin layers using ideal sink assumptions or phenomenological interfacial resistances. While mathematically convenient, these approaches obscure the physical role of the dermis and hypodermis in controlling molecular transport. Here, we develop an impedance-based analytical model for diffusion across multilayer skin membranes, in which the epidermal barrier is dynamically coupled to a finite diffusive backing layer representing the dermis–hypodermis composite. Diffusion impedance links transport conductivity, storage capacity, and layer thickness, while preserving continuity of concentration and flux at all interfaces. Closed-form expressions in the Laplace domain describe concentration fields and interfacial fluxes, and cumulative drug uptake is computed in the time domain via inverse Laplace transformation. The model identifies distinct short- and long-time transport regimes. Commonly used Dirichlet and Robin boundary conditions emerge as limiting cases but cannot reproduce the regime-dependent behavior of a backing layer. In particular, Robin formulations reduce the backing layer to a constant effective resistance, neglecting its storage capacity and time-dependent impedance. By replacing ad hoc boundary conditions with a physically grounded impedance framework, this approach provides a unified and extensible method for analyzing multilayer transport systems, including extensions to anomalous or memory-dependent diffusion.

Membranes doi: 10.3390/membranes16030084

Authors: Lei-Yang Xue Chu-Ya Luo Han-Mei Xu Jia-Xin Hua Xue Zhang Lian-Wen Zhu Jun Wu

This work presents a novel, membrane-inspired hybrid framework composed of Ag2Mo3O10·1.8H2O nanowires grown in situ on carbon fiber cloth (CFC) for the continuous and selective recovery of high-value sulfur-containing molecules from organic wastewater. The framework forms an integrated hierarchical porous network rich in micro-/nano-channels, which facilitates efficient, capillary-driven water transport. Owing to its mesoporous texture and specific Ag–S coordination affinity, the material shows exceptional selectivity toward sulfur-containing dyes, enabling rapid adsorption (>94% removal of methylene blue within 10 min) and high specificity in mixed solutions. The hybrid also exhibits excellent reusability, maintaining high recovery efficiency over repeated adsorption–desorption cycles. When configured into a continuous-flow system, the framework operates without external pressure and achieves a water transport rate of 1875 mL·h−1·m−2. These findings underscore the potential of the Ag2Mo3O10·1.8H2O/CFC hybrid as an efficient, scalable, and sustainable platform for resource-oriented wastewater treatment.

Membranes doi: 10.3390/membranes16030083

Authors: Sofia M. Morozova Nataliia V. Talagaeva Nadezhda N. Dremova Ulyana M. Zavorotnaya Andrey S. Starikov Nikita A. Emelianov Evgeny A. Sanginov Alexander M. Korsunsky Alexey V. Levchenko Alexey V. Vinyukov

Perfluorinated sulfonic acid ionomer (PFSAI) dispersions are widely used for fabrication of ion-conducting membranes and catalyst layers for hydrogen fuel cells. The conformation and concentration of PFSAIs affect the properties of the final product and depend on the liquid phase in dispersion. Here we present a novel method of preparing water/alcohol dispersions based on Nafion and Aquivion PFSAI by using a high-pressure homogenizer. The proposed route is faster and much safer and allows achieving higher PFSAI concentrations in comparison with the autoclave technique used for commercial dispersion preparation. The comparison of dispersion viscosity and PFSAI aggregate size was performed for both techniques and demonstrated similar values. Analysis of the morphology of membranes obtained from different dispersions by the casting method revealed differences in structure, which disappeared after annealing. These results highlight an important novel method of preparing PFSAI dispersions and the use of membrane morphology analysis for membrane quality evaluation.

Membranes doi: 10.3390/membranes16030082

Authors: Sławomir Kempa Mariola Rajca

The purpose of this study was to assess the suitability of tubular polymeric ultrafiltration membranes for use in a closed-loop water system within a rubber manufacturing plant. This research focused on determining the transport and separation properties of polymeric tubular membranes during the ultrafiltration of wastewater generated from washing vulcanised rubber hoses. The tests were conducted using the installation of the UF-1 membrane supplied by APEKO Sp. z o.o. This study evaluated the performance of modified PES membranes with a molecular weight cut-off (MWCO) of 4 kDa and PVDF membranes with MWCO of 100 kDa in the wastewater treatment process, as well as the effectiveness of membrane regeneration. Given the characteristics of wastewater, the key parameters for evaluating ultrafiltration performance included the determination of contaminant separation coefficients (R, %) for non-ionic surfactants (NIS) and chemical oxygen demand (COD), as well as turbidity reduction. The results demonstrated that the tested membranes substantially improved the visual quality of the wastewater by reducing turbidity by more than 95% and exhibited high separation efficiency for the analysed contaminants, with initial values of RNIS = 95% and RCOD = 85% at the beginning of the ultrafiltration cycle, decreasing to RNIS < 10% and RCOD < 10% after several hours of operation. During closed-loop filtration, when a twentyfold concentration of contaminants in the retentate was reached, membrane fouling occurred, significantly reducing filtration performance. Chemical cleaning enabled the recovery of approximately 70% of the initial performance for modified PES membranes and 60% for PVDF membranes.

Membranes doi: 10.3390/membranes16030081

Authors: Simona Renda

The increasing demand for clean and safe water across the globe represents one of the most pressing challenges of modern society [...]

Membranes doi: 10.3390/membranes16030080

Authors: Md. Ashrafuzzaman Jack A. Tuszynski

Biomembrane transport mechanisms [...]

Membranes doi: 10.3390/membranes16030078

Authors: Ahmed M. Khalil

Membrane technologies comprise a broad range of materials and structural designs tailored for specific separation applications, including gas separation [...]

Membranes doi: 10.3390/membranes16030079

Authors: Hao Wu Zhong-Can Ou-Yang

Biological membranes are the quintessential functional interface of life, where lipid bilayer mechanics, compositional heterogeneity, and dynamic protein interactions converge to govern cellular physiology [...]

Membranes doi: 10.3390/membranes16030077

Authors: Pierre Le-Clech Jia Wei Chew Chuyang Tang Anja Drews

Professor Anthony (Tony) Fane needs no introduction within the membrane community [...]

Membranes doi: 10.3390/membranes16020076

Authors: Yoana Stoyanova Nevena Lazarova-Zdravkova Swantje Pietsch-Braune Stoyko Petrin Anna Stefanova Stefan Heinrich Dimitar Peshev

The present study explores the possibility of combining membrane concentration, spray drying, and low-temperature precipitation into a single process for the valorization of spent lavender biomass as a source of ingredients rich in antioxidants. Lavender spent plant material was subjected to solid–liquid extraction, and the obtained hydroalcoholic extracts were further concentrated using a dead-end membrane filtration cell (METcell) with a polyamide–urea thin-film composite X201 membrane. The feed and the obtained retentate were subsequently spray dried using a Nano Spray Dryer B-90 (BÜCHI) under different temperature conditions (120 °C and 85 °C). Low-temperature precipitation was further applied for the retentate. An eight-fold concentration of the extracts was achieved, with membrane rejection coefficients of 100% for antioxidant activity and 98.5% for dry solids content. The permeate flux ranged from 2.25 to 0.201 L·m−2·h−1. Spray drying at a lower inlet temperature resulted in minimal losses for antioxidant activity (below 6%). The low-temperature storage of the membrane concentrate led to clear phase separation, allowing for the recovery of a precipitated fraction. The obtained results demonstrate that the integrated approach may support the sustainable and scalable valorization of lavender by-products.