Membranes

16 pages, 1610 KB

Open AccessArticle

Integrated Membrane Filtration for the Recovery of Antioxidants from Lavender Spent Plant Material

by Yoana Stoyanova, Nevena Lazarova-Zdravkova, Swantje Pietsch-Braune, Stoyko Petrin, Anna Stefanova, Stefan Heinrich and Dimitar Peshev

Membranes 2026, 16(2), 76; https://doi.org/10.3390/membranes16020076 - 23 Feb 2026

Viewed by 752

Abstract

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, [...] Read more.

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. Full article

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

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16 pages, 1141 KB

Open AccessArticle

Blackberry Juice Concentrated by Nanofiltration: Characterization, Stability and Application in a Fruit Juice

by Taís Andreza Batista de Jesus, Luiz Carlos Corrêa-Filho, Manuela Cristina P. de Araujo, Flávia dos Santos Gomes, Renata Valeriano Tonon and Lourdes Maria Corrêa Cabral

Membranes 2026, 16(2), 75; https://doi.org/10.3390/membranes16020075 - 23 Feb 2026

Viewed by 640

Abstract

Blackberry (Rubus spp.) is a highly perishable fruit rich in bioactive compounds, particularly anthocyanins, which are associated with significant health benefits. This study investigated the application of nanofiltration using a pilot-scale spiral-wound module (DOW^® NF90-2540) as a mild technology to concentrate [...] Read more.

Blackberry (Rubus spp.) is a highly perishable fruit rich in bioactive compounds, particularly anthocyanins, which are associated with significant health benefits. This study investigated the application of nanofiltration using a pilot-scale spiral-wound module (DOW^® NF90-2540) as a mild technology to concentrate phenolic compounds, especially anthocyanins, in blackberry juice. The process achieved concentration factors (CF) of 2.2 for monomeric anthocyanins and 1.9 for total phenolic content (TPC), reaching values of 54.3 mg C3G·100 mL⁻¹ and 326.85 mg GAE·100 mL⁻¹, respectively. The antioxidant capacity (ABTS⁺ and DPPH methods) also increased significantly in the concentrated fraction (CF 1.9 and 1.7, respectively). Stability of the concentrated juice was evaluated during 90 days of frozen storage, showing that low temperatures effectively preserved anthocyanin levels and visual quality, with only minor variations in color parameters (L*, a*, b*). Furthermore, the concentrated blackberry juice was successfully incorporated into apple–orange juice blends, generating formulations with progressively increased phenolic content, antioxidant activity, and red color intensity as the proportion of blackberry concentrate increased. Anthocyanin bioaccessibility in these juice blends was also evaluated and was not proportional to the increase in anthocyanin content. Strong correlations between anthocyanin concentration, antioxidant capacity, and CIELAB color parameters highlight the dual functional and technological role of blackberry compounds. In conclusion, this study demonstrates the feasibility of nanofiltration as a mild and efficient strategy for concentrating anthocyanins and phenolic compounds from blackberry juice while preserving physicochemical quality and color attributes. Full article

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22 pages, 4077 KB

Open AccessArticle

Life Cycle Assessment of Low-Cost Membrane Bioreactor and Activated Sludge Systems for Decentralized Wastewater Treatment in Arid Regions

by Husnain Haider, Md. Shafiquzzaman, Saleem S. AlSaleem and Abdul Razzaq Ghumman

Membranes 2026, 16(2), 74; https://doi.org/10.3390/membranes16020074 - 22 Feb 2026

Viewed by 808

Abstract

Small communities in the Kingdom of Saudi Arabia (KSA) without a sewerage system commonly rely on septic tanks and long-distance transport of wastewater to the nearest centralized treatment facilities, resulting in high operational costs, social nuisance, and limited opportunities for treated effluent reuse. [...] Read more.

Small communities in the Kingdom of Saudi Arabia (KSA) without a sewerage system commonly rely on septic tanks and long-distance transport of wastewater to the nearest centralized treatment facilities, resulting in high operational costs, social nuisance, and limited opportunities for treated effluent reuse. For a small community of 1300 persons in Al Qaraa (Qassim, KSA), this study performs life cycle analysis (LCA) to evaluate the environmental sustainability of a low-cost membrane bioreactor (LC-MBR)-type for decentralized on-site treatment as an alternative to wastewater transportation to a conventional extended aeration activated sludge process (EA-ASP)-type centralized system operating in the nearest larger city of Al-Bukayriyah. SimaPro^® 8.3.0.0 with the ecoinvent 3.0 database and ReCiPe 16 midpoint methodology shows that the decentralized LC-MBR scenario outperformed the centralized option with a 49 km-long wastewater transportation route in 13 out of 15 selected midpoint categories when considering relative and normalized impacts. In the EA-ASP, primary treatment dominated environmental impacts across most categories, driven by high energy demand for wastewater pumping, whereas freshwater and marine eutrophication were primarily influenced by treatment efficiency. With smaller normalized values, secondary treatment had a greater relative impact on urban and agricultural land occupation categories, attributed to the use of clay and rice bran in low-cost membrane fabrication in an LC-MBR. Tertiary treatment in the LC-MBR scenario, incorporating coagulation and granular activated carbon, significantly reduced freshwater eutrophication. Although normalized endpoint impacts indicated comparable ecosystem impacts for both systems, the LC-MBR resulted in 8% lower impacts on human health and 60% lower on resource depletion. Overall, the findings support decentralized wastewater treatment as a sustainable solution for small communities in arid regions and provide valuable insights for policy and decision-making. Full article

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

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12 pages, 956 KB

Open AccessArticle

Optimization of Tangential Flow Filtration for High-Yield, Scalable Downstream Processing of Adeno-Associated Virus

by Sara Cardoso, Franziska Bollmann and Alexander Tappe

Membranes 2026, 16(2), 73; https://doi.org/10.3390/membranes16020073 - 20 Feb 2026

Viewed by 1187

Abstract

The demand for effective downstream processing of adeno-associated virus (AAV) is increasing as gene therapies advance toward broader clinical applications. Robust, efficient, and scalable ultrafiltration and diafiltration (UF|DF) operations are essential for generating high-quality AAV preparations, with tangential flow filtration (TFF) serving as [...] Read more.

The demand for effective downstream processing of adeno-associated virus (AAV) is increasing as gene therapies advance toward broader clinical applications. Robust, efficient, and scalable ultrafiltration and diafiltration (UF|DF) operations are essential for generating high-quality AAV preparations, with tangential flow filtration (TFF) serving as a critical unit operation for vector concentration, impurity reduction, and buffer exchange while maintaining viral functionality. Development of TFF processes requires careful consideration of membrane characteristics—including chemistry, pore size or channel architecture—as these parameters directly influence vector retention, fouling behavior, and overall process efficiency. Equally important is the optimization of critical process parameters such as recirculation rate, transmembrane pressure (TMP), and total processing time, all of which govern hydrodynamic performance and product quality. This study assessed two Sartocon^® Hydrosart^® TFF cassette architectures—ECO-Screen and E-Screen—for the ultrafiltration and diafiltration of AAV8 clarified lysate. Through flux characterization and controlled small-scale evaluations, cassette-specific operating regions were defined. Both configurations supported high viral genome retention; however, the E-Screen geometry achieved faster processing and superior removal of host–cell protein and DNA contaminants, whereas the ECO-Screen format allowed for efficient operation under reduced pump rates and, therefore, lower shear conditions. Reproducibility assessments demonstrated minimal run-to-run variability, confirming the robustness of the optimized operating parameters. A 10-fold scale-up further validated the linearity and predictability of the UF|DF process, with consistent impurity-reduction profiles and only modest deviations in viral recovery. Collectively, these findings provide a quantitative basis for rational cassette selection in AAV purification workflows and establish a scalable, scientifically grounded UF|DF framework applicable across development and manufacturing scales. Full article

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

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13 pages, 1896 KB

Open AccessArticle

Beyond Visual Observations: Establishing the Mechanical Stability Threshold of Nanothin Polyethylene Layers

by Alfonso Lemus-Solorio, Mariana Ramos-Estrada, Salomón R. Vásquez-García and José L. Rivera

Membranes 2026, 16(2), 72; https://doi.org/10.3390/membranes16020072 - 20 Feb 2026

Viewed by 496

Abstract

This paper investigates the mechanical stability and critical thickness of free-standing, ultrathin molten polyethylene films using Molecular Dynamics simulations. By comparing the “interfacial drying” and “film stretching” methodologies, this research establishes that both methods consistently identify a stability threshold where continuous films transition [...] Read more.

This paper investigates the mechanical stability and critical thickness of free-standing, ultrathin molten polyethylene films using Molecular Dynamics simulations. By comparing the “interfacial drying” and “film stretching” methodologies, this research establishes that both methods consistently identify a stability threshold where continuous films transition into fibrillar and void structures known as “crazes”. A key finding is that films at extremely reduced thicknesses exhibit an anisotropic pressure profile in their core—characterized by a positive normal pressure—which serves as a manifestation of positive disjoining pressure and a precursor to film transformation. Consequently, the study proposes a more rigorous stability criterion based on mechanical isotropy, which yields higher critical thickness values (approximately 6.5 nm at 373.15 K and 9.3 nm at 673.15 K) than those previously estimated from short-term (100 ns) visual observations. Ultimately, the work concludes that maintaining a negative disjoining pressure is fundamental to the structural integrity of these polymeric nanomaterials. Full article

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

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20 pages, 904 KB

Open AccessReview

Separation of Organic Carbon and Nutrients from Liquid Waste by Using Membrane Technologies

by Stanislas Ndayishimiye, Samuel Bunani, Emery Nkurunziza and Nalan Kabay

Membranes 2026, 16(2), 71; https://doi.org/10.3390/membranes16020071 - 20 Feb 2026

Viewed by 765

Abstract

Rising concentrations of organic carbon (OC), phosphorus, and nitrogen in liquid waste from urban, industrial, and agricultural sources pose persistent challenges for environmental protection and resource recovery. Despite extensive application of microfiltration (MF) and ultrafiltration (UF) in wastewater treatment, their role in selective [...] Read more.

Rising concentrations of organic carbon (OC), phosphorus, and nitrogen in liquid waste from urban, industrial, and agricultural sources pose persistent challenges for environmental protection and resource recovery. Despite extensive application of microfiltration (MF) and ultrafiltration (UF) in wastewater treatment, their role in selective organic carbon and nutrient fractionation remains insufficiently clear-cut and is often interpreted solely through nominal pore size. This review was guided by the hypothesis that the reported limitations of MF and UF for nutrient separation are not intrinsic to the technologies but arise from simplified interpretations of separation mechanisms. A unified analytical framework was developed by synthesizing recent studies, linking membrane surface charge, pore structure, solute speciation, fouling-induced secondary layers, and operating conditions to the observed separation behavior. The analysis shows that MF fractionates particulate OC and suspended solids, whereas UF extends separation to macromolecular OC and phosphorus mainly via indirect retention mechanisms. Dissolved nitrogen species largely permeate both membranes unless they are transformed into retainable forms. Performance differences between MF and UF are conditional and system-dependent, with enhanced selectivity emerging through process integration. MF and UF can thus be repositioned as strategic fractionation interfaces within integrated treatment systems supporting circular economy–oriented wastewater management. Full article

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

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25 pages, 3717 KB

Open AccessSystematic Review

Sustainable Membrane Technologies for Enhancing Urban Climate Resilience

by Andreea Loredana Rhazzali, Elena Simina Lakatos, Ráhel Portik-Szabó, Elena Cristina Hossu, Lucian-Ionel Cioca and Alina Moldovan

Membranes 2026, 16(2), 70; https://doi.org/10.3390/membranes16020070 - 19 Feb 2026

Viewed by 1185

Abstract

Growing wastewater volumes and intensifying water scarcity are driving the need for affordable, sustainable solutions that enable safe urban water reuse and strengthen climate resilience. Policy frameworks such as SDG6 and EU water reuse requirements highlight that reclaimed water must meet strict environmental [...] Read more.

Growing wastewater volumes and intensifying water scarcity are driving the need for affordable, sustainable solutions that enable safe urban water reuse and strengthen climate resilience. Policy frameworks such as SDG6 and EU water reuse requirements highlight that reclaimed water must meet strict environmental and public health standards. In contrast, conventional biological treatment cannot fully remove many emerging contaminants, underscoring the need for advanced treatment approaches that consistently deliver high-quality reclaimed water. In this context, this review examines the role of membrane technologies (MF, UF, NF, RO, FO) and membrane bioreactors (MBRs) in providing safe water in urban environments and in enhancing urban climate resilience, including decentralized systems and advanced reclamation needs. It also discusses the contribution of membrane-based solutions to sustainable cooling systems and heat-stress mitigation, as well as the integration of membrane technologies into green infrastructure and nature-based solutions for climate adaptation. Technical and economic performance is shaped by fouling, cleaning requirements, and energy use, making life-cycle and operational optimization critical for long-term sustainability. Case studies and EU-funded initiatives demonstrate that, with appropriate governance and design, membrane-based approaches can enable reliable reclaimed water supply, enhance water security, and contribute to circular urban water management. The analysis was based on peer-reviewed open-access publications, which may introduce a degree of selection bias. Full article

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28 pages, 3722 KB

Open AccessEditor’s ChoiceReview

Membrane Separation for Rare Earth Elements (A Review)

by Aaron T. Ben-Elijah, Tammy M. Lutz-Rechtin, S. Ranil Wickramasinghe and Xiaoyu Wang

Membranes 2026, 16(2), 69; https://doi.org/10.3390/membranes16020069 - 19 Feb 2026

Cited by 1 | Viewed by 1508

Abstract

Rare earth elements (REEs) are increasingly critical for advanced technologies like high-tech electronic devices, electric vehicles, catalysts, and supercapacitors. However, separating and purifying the REEs is challenging due to their similar physicochemical properties, such as ionic sizes and oxidation states. Traditional methods like [...] Read more.

Rare earth elements (REEs) are increasingly critical for advanced technologies like high-tech electronic devices, electric vehicles, catalysts, and supercapacitors. However, separating and purifying the REEs is challenging due to their similar physicochemical properties, such as ionic sizes and oxidation states. Traditional methods like solvent extraction require extensive use of organic solvents, involving multiple stages that generate large volumes of acidic liquid wastes. This article introduces membrane separation technologies as a more efficient approach that minimizes waste generation and offers higher selectivity and recovery rates in a single step. Membrane separation methods utilize free energy gradients and differences in ionic size or material affinity to selectively reject or allow ion adsorption and diffusion through the membrane pores. In this review paper, we critically evaluate recent advancements in the development and implementation of membrane-based systems and focus on exploring different membrane materials for REE separation, including polymer inclusion membranes, ion-imprinted membranes, nanofiltration membranes, electrodialysis membranes, metal-organic frameworks, and supported liquid membranes. The advantages, potential challenges, and technical issues with implementing these technologies are discussed, and possible areas for improvement and insights for further research are presented. Full article

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

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17 pages, 2242 KB

Open AccessArticle

Spatial Differentiation of Microbial Communities in Hybrid Membrane Bioreactor (HMBR) and Their Impact on Pollutant Removal

by Ying Li, Yuhan Liu, Qiang Liu, Wei Xiang, Jixiang Qu, Yangyang Yang, Xiulei Fan, Huixian Li and Hongmei Du

Membranes 2026, 16(2), 68; https://doi.org/10.3390/membranes16020068 - 19 Feb 2026

Viewed by 615

Abstract

A hybrid membrane bioreactor (HMBR) enhances treatment performance by simultaneously utilizing organisms on both suspended and attached sludge, yet the microbial mechanisms underpinning their efficiency remain poorly understood. In this study, we investigate spatial variability within microbial communities in HMBRs and correlate this [...] Read more.

A hybrid membrane bioreactor (HMBR) enhances treatment performance by simultaneously utilizing organisms on both suspended and attached sludge, yet the microbial mechanisms underpinning their efficiency remain poorly understood. In this study, we investigate spatial variability within microbial communities in HMBRs and correlate this factor with pollutant removal capacity. High-throughput sequencing results revealed significant differences in community structure between suspended sludge, suspended media surfaces, and membrane module surfaces. Suspended sludge exhibited the highest species richness, whereas microbial communities on suspended media resembled those within the sludge, contrasting markedly with membrane surface communities. Key functional groups were enriched at specific locations: Pseudomonas and Comamonas dominate the surface of the suspension culture medium and participate in nitrification; phosphorus-accumulating organisms (PAOs), primarily from the Flavobacteriales and Planctomycetaceae phyla, were most abundant on suspended media surfaces. This spatial partitioning of functional microbes indicates cooperative division of labor. Media surfaces serve as primary sites for nitrification and phosphorus removal, whilst suspended sludge flocs and membrane module surfaces are the principal contributors to denitrification. The results of this study provide microbiological evidence for optimizing HMBR design and operation, confirming that spatial community structure is a key factor influencing performance. Full article

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13 pages, 3690 KB

Open AccessArticle

Mechanically Reinforced Anion-Exchange Composite Membrane with Improved Interface Integrity for Water Electrolysis

by Yuhui Gong, Tongshuai Wang, Han Song, Linjuan Zhang and Mingdong Zhou

Membranes 2026, 16(2), 67; https://doi.org/10.3390/membranes16020067 - 6 Feb 2026

Viewed by 1289

Abstract

Anion exchange membrane water electrolysis (AEMWE) is promising for low-cost hydrogen production, but its progress is limited by the weak mechanical strength and structural instability of polymer membranes. Here, a PPS-PBP/PVA composite membrane was developed using a polyphenylene sulfide (PPS) mesh as the [...] Read more.

Anion exchange membrane water electrolysis (AEMWE) is promising for low-cost hydrogen production, but its progress is limited by the weak mechanical strength and structural instability of polymer membranes. Here, a PPS-PBP/PVA composite membrane was developed using a polyphenylene sulfide (PPS) mesh as the mechanical scaffold, poly(biphenyl piperidinium) (PBP) as the ion-conducting polymer, and poly(vinyl alcohol) (PVA) as an interfacial binder. The membrane shows significantly enhanced tensile strength and puncture resistance, reduced swelling, and improved interfacial integrity. The optimized PPS-PBP/PVA (10 wt%) membrane delivers 6 A cm⁻² at 2.16 V in 1 M KOH at 80 °C and maintains stable operation for 500 h at 1 A cm⁻² with only a slight voltage increase. The results demonstrate that reinforcement coupled with interface regulation is an effective approach to constructing robust and durable composite membranes for AEMWE. Full article

(This article belongs to the Special Issue Ion Exchange Membrane in Water Electrolysis)

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1 pages, 158 KB

Open AccessCorrection

Correction: Castro-Muñoz et al. Merging Proline:Xylitol Eutectic Solvent in Crosslinked Chitosan Pervaporation Membranes for Enhanced Water Permeation in Dehydrating Ethanol. Membranes 2023, 13, 451

by Roberto Castro-Muñoz, Maksymilian Plata-Gryl and Grzegorz Boczkaj

Membranes 2026, 16(2), 66; https://doi.org/10.3390/membranes16020066 - 6 Feb 2026

Viewed by 585

Abstract

In the original publication [...] Full article

(This article belongs to the Special Issue Environmentally Friendly Approaches for Fabrication of Filtration Membranes (Volume II))

21 pages, 4512 KB

Open AccessArticle

Tunable Hydrophilicity in PES-Based Nanofiber Membranes via Oxygen Plasma Treatment

by Rahma Al Busaidi, Bushra Al Abri, Myo Myint, Sergey Dobretsov, Tamadher Al Salmani, Htet Htet Kyaw and Mohammed Al-Abri

Membranes 2026, 16(2), 65; https://doi.org/10.3390/membranes16020065 - 3 Feb 2026

Viewed by 1019

Abstract

To tailor surface chemistry and wettability for advanced membrane applications, this study investigates PES-, PES–PVP-, and PES–GO-based nanofiber membranes modified through oxygen plasma treatment. The plasma process introduced reactive functional groups, including SO₃H, C=O, and OH, onto the fiber surfaces, converting [...] Read more.

To tailor surface chemistry and wettability for advanced membrane applications, this study investigates PES-, PES–PVP-, and PES–GO-based nanofiber membranes modified through oxygen plasma treatment. The plasma process introduced reactive functional groups, including SO₃H, C=O, and OH, onto the fiber surfaces, converting the membranes from hydrophobic to super-hydrophilic and enhancing their surface reactivity. This modification enabled tunable wettability, allowing controlled adjustment of the membrane’s hydrophilic behavior. Overall, the results demonstrate the effectiveness of plasma engineering in developing versatile nanofiber membranes with customizable surface properties for a wide range of applications. Full article

(This article belongs to the Special Issue Towards Water Sustainability: Progress, Applications, and Challenges in Membrane Technology)

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37 pages, 3442 KB

Open AccessEditor’s ChoiceReview

Direct Contact Membrane Distillation: A Critical Review of Transmembrane Heat and Mass Transfer Models

by Nunzio Cancilla, Andrea Cipollina, Luigi Gurreri and Michele Ciofalo

Membranes 2026, 16(2), 64; https://doi.org/10.3390/membranes16020064 - 2 Feb 2026

Cited by 1 | Viewed by 1755

Abstract

The present review summarizes a vast body of literature on the subject of Membrane Distillation (MD), with a special emphasis on the existing results and correlations for the transmembrane transport of heat and mass. The issue of saltwater physical properties is also discussed [...] Read more.

The present review summarizes a vast body of literature on the subject of Membrane Distillation (MD), with a special emphasis on the existing results and correlations for the transmembrane transport of heat and mass. The issue of saltwater physical properties is also discussed in depth, whereas the advective transport of heat and salt concentration in the feed and permeate compartments is only briefly mentioned but is beyond the scope of this review. The paper does not aim to provide a complete treatment of the subject of MD, which can be found in other publications. Rather, it suggests the data and correlations most suitable for the range of operating conditions typically expected in actual units implementing Direct Contact Membrane Distillation (DCMD), including hollow fiber designs, with a view to assist model development. The focus is on MD for water desalination, although some results may apply well to other fields. Full article

(This article belongs to the Special Issue Membrane Distillation and Other Membrane-Related Applications for Water Cleaning and Desalination)

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29 pages, 1711 KB

Open AccessArticle

Clarification of Olive Juice by Advanced Mineral Microfiltration Membranes with High Packing Density

by Alba Gutiérrez-Docio, Alejandro Ruiz-Rodriguez and Marin Prodanov

Membranes 2026, 16(2), 63; https://doi.org/10.3390/membranes16020063 - 2 Feb 2026

Viewed by 816

Abstract

Important advancements in the development of novel materials and designs have led to the creation of advanced mineral membranes with high packing densities and enhanced competitiveness in relation to polymeric and classic mineral membranes. Olive juice represents an underutilised source of phenolic and [...] Read more.

Important advancements in the development of novel materials and designs have led to the creation of advanced mineral membranes with high packing densities and enhanced competitiveness in relation to polymeric and classic mineral membranes. Olive juice represents an underutilised source of phenolic and secoiridoid antioxidants, in which industrial valorisation is hindered by some technical limitations, particularly the effective removal of suspended solids during processing. The efficiency of two recrystallized silicon carbide-based microfiltration membranes with an equivalent industrial filtration packing density of 782 m²/m³ was evaluated. One of them had nominal pore sizes of 500 nm and was made of mixed oxides and the other had nominal pore sizes of 200 nm and was made of α-Al₂O₃. The 500 nm membrane demonstrated superior filtration flux and faster processing compared to the 200 nm membrane, though both achieved complete removal of suspended solids. A greater workload of the 500 nm membrane resulted in a progressive irreversible fouling, caused by the smallest-sized suspended particles and macromolecular colloids. Particle size had a greater impact on fouling than particle load. Both membrane treatments induced a spontaneous increase in the concentrations of up to 24 phenolic, secoiridoid and secoiridoidyl phenylethanoid conjugates. This effect can be considered as an additional benefit of the thus clarified olive juices. Further investigations are warranted to elucidate the underlying mechanisms driving these transformations. Full article

(This article belongs to the Special Issue Towards the Circular Economy—Membrane Processes for the Recovery of Water and Nutrients from Wastewater (2nd Edition))

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16 pages, 3922 KB

Open AccessArticle

Nanomaterial Enhanced PVDF Mixed Matrix Membranes for Microfluidic Electrochemical Desalination

by Haya Taleb, Gopal Venkatesh, Sofian Kanan, Raed Hashaikeh, Nidal Hilal and Naif Darwish

Membranes 2026, 16(2), 62; https://doi.org/10.3390/membranes16020062 - 2 Feb 2026

Viewed by 995

Abstract

This work provides a systematic experimental study for the electrochemical desalination of saline water using an electrospun permselective polyvinylidene difluoride (PVDF) membrane. Several nano additives were initially screened during membrane development; however, only the materials that demonstrated stable dispersion, reproducible membrane formation, and [...] Read more.

This work provides a systematic experimental study for the electrochemical desalination of saline water using an electrospun permselective polyvinylidene difluoride (PVDF) membrane. Several nano additives were initially screened during membrane development; however, only the materials that demonstrated stable dispersion, reproducible membrane formation, and consistent electrochemical behaviour, namely graphene oxide (GO) and carbon nanotubes (CNTs) were selected for full analysis in this study. Accordingly, the study focuses on pure PVDF, PVDF/GO, and PVDF/CNTs membranes integrated with an alternating Ag/AgCl electrode system. The silver electrode is prepared by spray-coating of silver nanoparticles on high surface carbon cloth, whereas the AgCl electrode was prepared electrochemically from the Ag electrode using a three-electrode electrochemical cell. The electrochemical behaviour of various modified electrodes (bare carbon cloth, Ag/carbon cloth, Ag/nafion/carbon black/PVDF, and Ag/nafion/carbon cloth) was evaluated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and X-Ray Diffraction (XRD). The electrode prepared using Nafion and PVDF as binders with carbon black as conductive additive exhibited the highest current response and lowest charge-transfer resistance. When coupled with this optimized electrode, the PVDF/GO membrane delivered the best desalination performance, achieving an ion removal efficiency of 68%, a salt adsorption capacity (SAC) of 775.40 mg/g, and a specific energy consumption (SEC) of 16.17 kJ/mole values superior to those reported in the literature. Full article

(This article belongs to the Special Issue Sustainable Advances in Oil & Gas, Mining, and Environmental Technologies: Innovations in Membrane and Porous Material Technologies)

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20 pages, 3273 KB

Open AccessArticle

Synergistic Effect of NiFe-LDH and PES/SPSf Matrix on Metal Ion Rejection Efficiency from Surface Water

by Raphael N. Biata, Meladi L. Motloutsi, Funeka Matebese, Sithembela A. Zikalala, Richard M. Moutloali and Edward N. Nxumalo

Membranes 2026, 16(2), 61; https://doi.org/10.3390/membranes16020061 - 2 Feb 2026

Viewed by 721

Abstract

Clean water remains a pressing global challenge and developing membranes that are both efficient and durable is critical. This study combined two polymers, polyethersulfone (PES) and sulfone-modified polysulfone (SPSf), with NiFe-layered double hydroxides (LDHs) to create a new class of multifunctional membranes. The [...] Read more.

Clean water remains a pressing global challenge and developing membranes that are both efficient and durable is critical. This study combined two polymers, polyethersulfone (PES) and sulfone-modified polysulfone (SPSf), with NiFe-layered double hydroxides (LDHs) to create a new class of multifunctional membranes. The membranes were characterized using FTIR, SEM, water contact angle, and zeta potential. The addition of NiFe-LDH fillers improved the hydrophilicity and surface structure of the membranes and enhanced the separation performance of the resulting membranes. The best-performing membrane (M3, with 2 wt.% NiFe-LDH) delivered pure water flux of about 218 L.m⁻²h⁻¹, which was nearly three times higher than that of the pristine PES/SPSf membrane. Furthermore, M3 removed approximately 92.4% of bovine serum albumin (BSA), attributed to the synergistic combination of size exclusion, electrostatic repulsion, and hydrophilicity. The membrane also showed excellent antifouling properties, maintaining over 65.9% and 71.2% flux recovery after three fouling–cleaning cycles for BSA solution and surface water, respectively. Importantly, the M3 membrane achieved high removal efficiencies for heavy metals, rejecting 91% of Cd²⁺, 93% of Pb²⁺, and 88% of Cu²⁺. These results highlight how the synergy between PES/SPSf and NiFe-LDH can overcome the common challenges of fouling and low metal ion rejection, offering a promising route toward practical and sustainable water treatment solutions. Full article

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

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15 pages, 1595 KB

Open AccessEditor’s ChoiceArticle

Influence of Module Design and Concentration Polarization on Pore Size Determination for Nanofiltration Membranes

by Henrik Schröter and Udo Kragl

Membranes 2026, 16(2), 60; https://doi.org/10.3390/membranes16020060 - 2 Feb 2026

Viewed by 684

Abstract

Nanofiltration is an important part of pressure-driven membrane separation processes. A comprehensive understanding of the interplay between module hydrodynamics, concentration polarization, and solute rejection is essential for predicting NF performance and for scaling up processes. For two different membrane modules, the characterization and [...] Read more.

Nanofiltration is an important part of pressure-driven membrane separation processes. A comprehensive understanding of the interplay between module hydrodynamics, concentration polarization, and solute rejection is essential for predicting NF performance and for scaling up processes. For two different membrane modules, the characterization and determination of concentration polarization as well as pore-size determination according to the Donnan steric pore model are described. The results show that an optimized channel design allows for a more reliable determination of true retention rates without concentration polarization. Differences between observed retention rates and intrinsic retention rates considering mass transfer coefficients can be neglected. These results are obtained at significantly lower cross-flow rates, allowing for better applicability at the lab scale. Full article

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

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14 pages, 1411 KB

Open AccessArticle

Pilot-Scale Evaluation of Flat-Sheet Membrane Bioreactor for In Situ Retrofitting Textile Dyeing Wastewater Treatment Plant

by Chaoqun Zhou, Chunhai Wei, Huarong Yu, Hongwei Rong and Kang Xiao

Membranes 2026, 16(2), 59; https://doi.org/10.3390/membranes16020059 - 2 Feb 2026

Viewed by 672

Abstract

It is promising to in situ retrofit the activated sludge process with a membrane bioreactor (MBR) to increase treatment capacity and improve effluent quality in a textile dyeing wastewater treatment plant (WWTP). Membrane selection among commercial products for real engineering applications is critical [...] Read more.

It is promising to in situ retrofit the activated sludge process with a membrane bioreactor (MBR) to increase treatment capacity and improve effluent quality in a textile dyeing wastewater treatment plant (WWTP). Membrane selection among commercial products for real engineering applications is critical for this specific wastewater, and little information is available in the literature. This study systematically evaluated the application potential of two flat-sheet microfiltration membranes made of polyvinylidene fluoride (PVDF) and polyether sulfone (PES) in pilot-scale MBRs for in situ retrofitting textile dyeing WWTP. During the four stages with different loads, both membranes achieved nearly the same effluent quality and rejection performance. Both membranes showed little trans-membrane pressure (TMP) increase at an average flux of 15 L/(m²·h) with sub-critical flux characteristics, and showed a sharp TMP increase with super-critical flux characteristics observed at an average flux of 18/22.5 L/(m²·h). After 74 d of filtration, at an average sludge concentration of 12,000 g/L, the PVDF membrane showed less variation in pore size distribution and bubble point pressure, while the PES membrane showed less change in permeability and contact angle. Both membranes met general MBR requirements due to the minimizing pristine effects of both membranes by this specific wastewater matrix. The PVDF membrane showed better anti-fouling capability, especially during high-/over-load stages, and thus was suggested for MBR retrofit, with a sustainable membrane flux below 18 L/(m²·h). Full article

(This article belongs to the Collection Feature Papers in 'Membrane Physics and Theory')

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18 pages, 6762 KB

Open AccessArticle

Investigation of the Effect of Alkyl Chain Length on the Size and Distribution of Thiol-Stabilized Silver Nanoparticles for Proton Exchange Membrane Fuel Cell Applications

by Md Farabi Rahman, Haoyan Fang, Aniket Raut, Aaron Sloutski and Miriam Rafailovich

Membranes 2026, 16(2), 58; https://doi.org/10.3390/membranes16020058 - 2 Feb 2026

Viewed by 952

Abstract

This article reports on how the length of the alkyl chain influences the morphological properties of thiol-stabilized silver nanoparticles (Ag NPs) and their subsequent effects on the performance and durability of proton exchange membrane fuel cells (PEMFCs). We synthesized thiol-stabilized Ag NPs by [...] Read more.

This article reports on how the length of the alkyl chain influences the morphological properties of thiol-stabilized silver nanoparticles (Ag NPs) and their subsequent effects on the performance and durability of proton exchange membrane fuel cells (PEMFCs). We synthesized thiol-stabilized Ag NPs by varying the alkyl chain length: 1-hexane thiol (C6), 1-octanethiol (C8), 1-decanethiol (C10), 1-dodecanethiol (C12), and 1-tetradecanethiol (C14), which we achieved using the two–phase Brust–Schiffrin method. X-ray Diffraction (XRD) patterns confirm the formation of crystalline Ag NPs. A morphological study conducted using a Transmission Electron Microscope (TEM) demonstrated that smaller alkyl chain length thiols (C6, C8, and C10) tend to coalesce, while C12 shows better uniformity with no agglomeration. C14 produces larger nanoparticles. A distinct pressure-area isotherm was observed when Ag NPs were spread at the water/air interface of a Langmuir–Blodgett (LB) trough. After obtaining the monolayer formation pressure range, we coated the Nafion 117 membrane of a polymer electrolyte membrane fuel cell with these nanoparticles to form monolayers of different Ag NPs (C6, C8, C12, C14) at various surface pressures (2 mN/m, 6 mN/m and 10 mN/m). Maximum power output enhancement was observed for C12, while other nanoparticles (C6, C8, C10, C14) did not exhibit noticeable power enhancement for PEMFCs. C12 Ag NPs deposited at surface pressure 6 mN/m give maximum power density increase (26.5%) at the fuel cell test station. In addition, we examined the carbon monoxide (CO) resistance test by mixing 0.1% CO with hydrogen (H2), and C12 Ag NPs showed the highest resistance to CO poisoning. However, no enhancement in power or CO tolerance was observed when C12 Ag NPs were coated by spray coating. These outcomes showcase that alkyl chain length plays a critical role in controlling the size and distribution of thiol-stabilized nanoparticles, which eventually has a direct impact on the performance and CO resistance of PEMFCs when applied to polymer electrolyte (Nafion 117). In addition, surface pressure during monolayer formation controls the distribution of Ag NPs (the distance between nanoparticles at the membrane interface), which is necessary to achieve catalytic activity for power improvement and to prevent platinum (Pt) poisoning by CO oxidation at ambient conditions. Full article

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

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34 pages, 21439 KB

Open AccessReview

Recent Advances in Fluorine- and Silicon-Integrated Organic Solvent Nanofiltration Membranes for Non-Polar Solvent Separation

by Shuo He, Weijia Song, Rongkai Che, Enlin Wang, Can Li and Baowei Su

Membranes 2026, 16(2), 57; https://doi.org/10.3390/membranes16020057 - 2 Feb 2026

Viewed by 930

Abstract

Organic solvent nanofiltration (OSN), also known as solvent-resistant nanofiltration (SRNF), is an emerging membrane-based separation technique capable of efficiently separating molecules in the 200–1000 Da range within organic media. It holds considerable promise for applications in organic solvent systems, which are prevalent in [...] Read more.

Organic solvent nanofiltration (OSN), also known as solvent-resistant nanofiltration (SRNF), is an emerging membrane-based separation technique capable of efficiently separating molecules in the 200–1000 Da range within organic media. It holds considerable promise for applications in organic solvent systems, which are prevalent in the petrochemical, pharmaceutical and food processing industries. While OSN has been extensively studied in polar solvent systems, increasing attention is now being directed toward its performance in non-polar environments, driven by their substantial practical demand and application potential. Fluorinated and organosilicon-based materials have emerged as key components in the fabrication of high-performance OSN membranes for separation in non-polar solvent environments due to their exceptional chemical, thermal, and mechanical stability. This review systematically summarizes recent advances in the design and fabrication of fluorinated and organosilicon-based composite OSN membranes. Key separation mechanisms are discussed, with particular focus on their roles in the recovery and reuse of homogeneous catalysts in chemical and pharmaceutical processes. Finally, future research directions are proposed to guide the continued development and industrial deployment of the fluorine- and silicon-based OSN membranes in non-polar solvent applications. Full article

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17 pages, 2733 KB

Open AccessArticle

A Crown Ether-Based Covalent Organic Polymer Composite Membrane and Its Application in Molecular Separation

by Yike Chen, Wenju Shi, Meitong Liu, Zhihong Huang, Jianshe Hu and Zhangpei Chen

Membranes 2026, 16(2), 56; https://doi.org/10.3390/membranes16020056 - 2 Feb 2026

Viewed by 736

Abstract

Organic dyes are critical components in industries ranging from textiles, plastics, and paper to food, cosmetics, and pharmaceuticals. However, their widespread use leads to significant environmental pollution. Consequently, developing efficient methods to treat dye wastewater is urgently needed. In this work, a high-performance [...] Read more.

Organic dyes are critical components in industries ranging from textiles, plastics, and paper to food, cosmetics, and pharmaceuticals. However, their widespread use leads to significant environmental pollution. Consequently, developing efficient methods to treat dye wastewater is urgently needed. In this work, a high-performance composite membrane was developed with a poly(dibenzo-18-crown-6) covalent organic polymer (COP) interlayer. The chemical structure of the COP was verified by FT-IR, and BET analysis indicated that the as-synthesized material possesses a predominantly mesoporous structure with a minor microporous contribution. Subsequently, the membrane was fabricated by depositing a COP colloid on a nylon-66 support via vacuum filtration, followed by the formation of a dense polyamide (PA) active layer through interfacial polymerization (IP) between amine and acyl chloride monomers. Systematic evaluation of dye separation performance using a cross-flow filtration setup identified optimal operating conditions. Under these conditions, the membrane demonstrated effective molecular sieving behavior, achieving both high dye rejection and favorable solvent permeability. In long-term stability tests, the membrane maintained a rejection rate of over 99% for Congo red over 48 h, while sustaining a water flux of 103.2 L m⁻² h⁻¹ bar⁻¹ (LMH/bar). Furthermore, the membrane exhibited promising potential for dye desalination applications, achieving a high Congo red/potassium chloride separation selectivity of 186.8 with a flux of 138.2 LMH/bar. This study confirms that the poly(dibenzo-18-crown-6)-based composite membrane is a reliable and efficient material for molecular separation in wastewater treatment. Full article

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

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19 pages, 1276 KB

Open AccessArticle

Sulfonated Graphene Oxide Doped Imidazolium-Functionalized PVDF Ion Exchange Membrane with Enhanced Ion Conductivity

by Jiangtao Yu, Wenkang Li, Wei Niu, Manman Zhang, Junqing Bai, Pengtao Li, Liang Wang, Yuqing Cui, Shuanfang Cui, Xueyan Que, Jun Ma and Long Zhao

Membranes 2026, 16(2), 55; https://doi.org/10.3390/membranes16020055 - 31 Jan 2026

Viewed by 782

Abstract

A novel membrane was synthesized in this work by grafting 1-vinyl-3-ethylimidazolium tetrafluoroborate ([C₂VIm][BF₄]) onto a polyvinylidene fluoride (PVDF) backbone, followed by the introduction of a sulfonated graphene oxide (SGO) dispersion into the polymer solution. This composite was transformed into [...] Read more.

A novel membrane was synthesized in this work by grafting 1-vinyl-3-ethylimidazolium tetrafluoroborate ([C₂VIm][BF₄]) onto a polyvinylidene fluoride (PVDF) backbone, followed by the introduction of a sulfonated graphene oxide (SGO) dispersion into the polymer solution. This composite was transformed into a composite proton-conducting membrane via a solution casting process and subsequently underwent protonation. Successful grafting was confirmed using analytical techniques including Fourier Transform Infrared Spectroscopy (FTIR), ¹H Nuclear Magnetic Resonance (NMR) and X-ray Photoelectron Spectroscopy (XPS). Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS) analysis verified the homogeneous distribution of the SGO filler. Analysis reveals that incorporating SGO as a filler substantially augments the performance of anion exchange membranes. Key enhancements include a tensile strength increase to 37.97 MPa, water uptake of 10.34%, an ion exchange capacity of 1.68 mmol/g, and the through-plane proton conductivity of 15.47 mS/cm. While vanadium permeability rose marginally to 2.02 × 10⁻⁷ cm²/min, it remains drastically lower than that of Nafion 115. The composite proton-conducting membrane also displayed robust chemical stability. The membrane was finally integrated into a vanadium redox flow battery (VRFB) for performance evaluation. At a current density of 100 mA/cm², it exhibits a satisfactory coulombic efficiency (CE) of 97.84%, excellent capacity retention, and superior cycling stability. These results demonstrate that the PVDF-g-IL/SGO-based composite proton-conducting membrane is an ideal candidate material for vanadium flow battery applications. Full article

(This article belongs to the Special Issue Advanced Membranes for Fuel Cells and Redox Flow Batteries: 2nd Edition)

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24 pages, 2252 KB

Open AccessEditor’s ChoiceReview

Structural Design and Performance Optimization of Proton Exchange Membranes for Water Electrolysis: A Review

by Yi Chen, Hongyang Ma and Benjamin S. Hsiao

Membranes 2026, 16(2), 54; https://doi.org/10.3390/membranes16020054 - 31 Jan 2026

Cited by 2 | Viewed by 1780

Abstract

The trade-off between the ionic conductivity and the stability of the proton exchange membrane (PEM) is a major concern in the development of PEM water electrolysis (PEMWE). This review focuses on the design and fabrication of homogeneous and composite PEMs for water electrolysis [...] Read more.

The trade-off between the ionic conductivity and the stability of the proton exchange membrane (PEM) is a major concern in the development of PEM water electrolysis (PEMWE). This review focuses on the design and fabrication of homogeneous and composite PEMs for water electrolysis and establishes the structure–performance relationships between the membrane chemical/physical structures and their efficiency metrics—specifically, proton conductivity, hydrogen permeability, and chemical and mechanical stability. A special focus is placed on the fundamental connection between the microstructure and performance of membrane materials. At the molecular level, we systematically illustrate the design principles for main chains, side chains, and sulfonate groups, covering both fluorinated PEMs (encompassing perfluorinated and partially fluorinated membranes) and non-fluorinated PEMs (including aromatic polymers with heteroatom backbones and all-carbon backbones). At the macroscopic level, the review provides an in-depth exploration of two primary modification strategies: creating composites with organic polymers and with inorganic nanofillers. In summary, this review elucidates how these composite approaches leverage material synergies to improve the membrane’s mechanical integrity, proton conduction efficiency, and chemical resistance and offers a theoretical framework for the rational design of next-generation, high-performance PEMs to advance the commercialization of PEMWE technology. Full article

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33 pages, 3946 KB

Open AccessArticle

Characterization of a Commercial Anion-Exchange Membrane Modified with Electrosynthesized Polyaniline Deposits at Different Temperatures

by Luis Manuel Álvarez Cerda, Antonio Montes-Rojas and Luz María Torres Rodríguez

Membranes 2026, 16(2), 53; https://doi.org/10.3390/membranes16020053 - 30 Jan 2026

Viewed by 688

Abstract

Phenomena associated with an ion-exchange membrane (IEM) in contact with an ionic solution, such as its selectivity and ionic transport, commonly occur when an ion approaches the membrane surface. Because of this, if a change occurs in the IEM/Solution interfacial region, then it [...] Read more.

Phenomena associated with an ion-exchange membrane (IEM) in contact with an ionic solution, such as its selectivity and ionic transport, commonly occur when an ion approaches the membrane surface. Because of this, if a change occurs in the IEM/Solution interfacial region, then it is expected that these processes will be affected. For example, if the IEM surface is modified with an electronic conducting polymer (ECP), then its selectivity and the phenomena associated with ionic transport will change. These changes can be quantified by parameters such as the permselectivity, the contact angle, and others, and are associated with the hydrophilic/hydrophobic balance of its surface. This work reports the characterization of commercial anion-exchange membrane samples modified voltammetrically with polyaniline (PAni) obtained at different temperatures (10, 15, and 20 °C). Among the main results obtained, it was found that with an increase in synthesis temperature of the PAni, the membrane’s permselectivity will increase from 0.757 to 0.782 to 0.808. While contrary behavior is observed in the case of the contact angle, since an increase in the synthesis temperature will cause a greater hydrophilic character when going from 67° to 53° to 50°. According to this work, these trends in the properties of the modified membranes are related to the morphological characteristics of PAni deposits conferred by the variation in the synthesis temperature. Full article

(This article belongs to the Special Issue Nanocomposite Membranes for Electrolysis, Fuel Cells, Batteries, and Desalination)

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13 pages, 3161 KB

Open AccessArticle

Effect of Non-Woven Backing on Support PVDF Membranes for Acidic Electrochemical Applications

by Chiari J. Van Cauter, Maarten Cools, Simon Van Buggenhout, Nathalie Lenaerts, Daan Op De Beeck and Ivo F. J. Vankelecom

Membranes 2026, 16(2), 51; https://doi.org/10.3390/membranes16020051 - 28 Jan 2026

Viewed by 846

Abstract

In composite membranes, non-woven substrates are often included to offer higher mechanical strength. The use of non-wovens is currently limited in electrochemical applications, apart from lab-made electrospun non-woven membranes. In this manuscript, three commercial non-wovens are compared to test their potential use in [...] Read more.

In composite membranes, non-woven substrates are often included to offer higher mechanical strength. The use of non-wovens is currently limited in electrochemical applications, apart from lab-made electrospun non-woven membranes. In this manuscript, three commercial non-wovens are compared to test their potential use in acid-based electrochemical applications, for instance redox flow batteries, and are also compared to a woven fabric substrate. The three non-wovens are found to have variable suitability in terms of the stability of solvents used in further membrane processing. However, all are deemed limiting due to their relatively high area resistance (0.37–1.47 ohm.cm²). In comparison, free-standing and selective commercial ion exchange membranes have area resistances around 0.08–0.27 ohm.cm². More open substrate backings such as a woven structure are recommended instead to allow for lower resistance of the resulting composites. Full article

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

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23 pages, 8357 KB

Open AccessArticle

Eco-Friendly Ceramic Membranes from Natural Clay and Almond Shell Waste for the Removal of Dyes and Drugs from Wastewater

by Jamila Bahrouni, Feryelle Aouay, Christian Larchet, Lasâad Dammak and Raja Ben Amar

Membranes 2026, 16(2), 52; https://doi.org/10.3390/membranes16020052 - 27 Jan 2026

Cited by 3 | Viewed by 773

Abstract

This study investigates the influence of sintering temperature (850–950 °C) and almond shell content (2–10 wt.%) on the structural, mechanical, and functional properties of natural-clay-based ceramic membranes. Several membranes were prepared by incorporating different proportions of almond shell powder and 2 wt.% lime [...] Read more.

This study investigates the influence of sintering temperature (850–950 °C) and almond shell content (2–10 wt.%) on the structural, mechanical, and functional properties of natural-clay-based ceramic membranes. Several membranes were prepared by incorporating different proportions of almond shell powder and 2 wt.% lime as additives and sintered under controlled thermal conditions to optimize their performance. The results demonstrate that both sintering temperature and almond shell content significantly affect membrane porosity, mechanical strength, and water permeability. Among all of the tested samples, the membrane designated MP2-900, composed of natural clay, 2 wt.% almond shell powder, and 2 wt.% lime, sintered at 900 °C, exhibited the most balanced performance. It showed high mechanical strength (≈28 MPa), low shrinkage (<5%), and good water permeability (35 L·h⁻¹·m⁻²·bar⁻¹). When tested for the removal of crystal violet (CV) dye and paracetamol (PCT) from synthetic wastewater, the MP2-900 membrane achieved a removal efficiency of 87% for both pollutants. Overall, the MP2-900 membrane represents the optimal configuration, providing an excellent balance between mechanical robustness, porosity, and separation performance. These findings highlight the potential of sustainable clay-based ceramic membranes derived from agricultural by-products for the efficient removal of recalcitrant pollutants from wastewater. Full article

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

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23 pages, 6790 KB

Open AccessArticle

Quantitative Characterization of Microfiltration Membrane Fouling Using Optical Coherence Tomography with Optimized Image Analysis

by Song Lee, Hyongrak Cho, Yongjun Choi, Juyoung Andrea Lee and Sangho Lee

Membranes 2026, 16(2), 50; https://doi.org/10.3390/membranes16020050 - 26 Jan 2026

Viewed by 732

Abstract

Membrane fouling reduces permeate flux and treatment efficiency, yet most diagnostic methods are destructive and require offline analysis. Optical coherence tomography (OCT) enables in situ, real-time visualization; however, quantitative image extraction of thin foulant layers is often limited by manual processing and subjective [...] Read more.

Membrane fouling reduces permeate flux and treatment efficiency, yet most diagnostic methods are destructive and require offline analysis. Optical coherence tomography (OCT) enables in situ, real-time visualization; however, quantitative image extraction of thin foulant layers is often limited by manual processing and subjective thresholding. Here, we develop a reproducible OCT image-analysis workflow that combines band-pass filtering, Gaussian smoothing, and unsharp masking with a dual-threshold subtraction strategy for automated fouling-layer segmentation. Seventeen global thresholding algorithms in ImageJ (289 threshold pairs) were benchmarked against SEM-measured cake thickness, identifying Triangle–Moments as the most robust combination. For humic-acid fouling, the OCT-derived endpoint thickness (14.23 ± 1.18 µm) closely agreed with SEM (15.29 ± 1.54 µm). The method was then applied to other microfiltration foulants, including kaolin and sodium alginate, to quantify thickness evolution alongside flux decline. OCT with the optimized image analysis captured rapid early deposition and revealed periods where flux loss continued despite minimal additional thickness growth, consistent with changes in layer permeability and compaction. The proposed framework advances OCT from qualitative visualization to quantitative, real-time fouling diagnostics and supports mechanistic interpretation and improved operational control of membrane systems. Full article

(This article belongs to the Special Issue Membrane Fouling and Antifouling Strategies for Water and Wastewater Treatment)

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19 pages, 2553 KB

Open AccessArticle

A QCM-D Study of the Interaction of Early Endosomal Antigen 1 (EEA1) Protein with Supported Lipid Bilayers Mimicking the Early Endosomal Lipid Composition

by Fotini Papagavriil, Pablo Mateos-Gil, Janelle Lauer, Marino Zerial and Electra Gizeli

Membranes 2026, 16(2), 49; https://doi.org/10.3390/membranes16020049 - 26 Jan 2026

Viewed by 1189

Abstract

The combination of supported lipid bilayers (SLBs) with the Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) has been proven to be a powerful tool to simultaneously monitor mass and viscoelastic changes related to membrane binding-events. In this work, the above methodology is employed [...] Read more.

The combination of supported lipid bilayers (SLBs) with the Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) has been proven to be a powerful tool to simultaneously monitor mass and viscoelastic changes related to membrane binding-events. In this work, the above methodology is employed for the study of the interaction of the Early Endosomal Antigen 1 (EEA1) to a model lipid bilayer that mimics the early endosome (EE) membrane, focusing on the membrane composition. Starting with the formation of a lipid bilayer through the vesicles fusion technique, we investigated the formation of SLBs that incorporate phosphatidylinositol 3-phosphate (PI(3)P), a key component for EEA1 binding, in combination with other lipids, e.g., (1,2-dioleoyl-sn-glycero-3)-phosphocholine (DOPC), -phosphoserine (DOPS), -phosphoethanolamine (DOPE), and cholesterol (Chol). The interaction of the full-length coiled-coil EEA1 to the formed SLBs was further studied in real time with the QCM-D and characterized with respect to the lipid composition and pH. Our findings confirm that PI(3)P is essential for the EEA1–membrane interaction, while it was shown that Chol and phosphatidylserine greatly influence the binding event. In fact, including 30% Chol in a PI(3)P (3%):PS (6%) SLB resulted in almost double EEA1 binding than in the absence of Chol. Moreover, we employed the QCM-viscoelastic model available to analyze the QCM-D data with emphasis on the study of the protein conformation. Our results showed that, in our in vitro system, EEA1 is not fully extended and/or highly packed, but is mainly in a bent, distorted conformation with an average size close to 100 nm. This study complements previous works employing in vitro assays, also demonstrating the ability to reconstitute more complex biomimetic EE membranes containing inositol phospholipids on a QCM surface for the study of EEA1 binding. Full article

(This article belongs to the Section Biological Membranes)

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Membranes, Volume 16, Issue 2 (February 2026) – 28 articles

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