Membranes

14 pages, 1415 KiB

Open AccessArticle

Preparation of Tannic Acid-Pectin Coated PVDF Membrane for High-Efficiency Separation of Oil and Water Emulsions

by Liangku Zhai, Jiuyun Cui, Lei Lu, Hailong Wang, Can Wei, Jirong Luo and Atian Xie

Membranes 2025, 15(5), 155; https://doi.org/10.3390/membranes15050155 - 16 May 2025

The simple preparation of superhydrophilic membranes with good stability is of great significance for efficient oil–water separation. In this work, a polyvinylidene fluoride (PVDF) membrane modified with tannic acid (TA) and pectin (PT) was developed through immersion in TA/PT solutions, facilitating the formation [...] Read more.

The simple preparation of superhydrophilic membranes with good stability is of great significance for efficient oil–water separation. In this work, a polyvinylidene fluoride (PVDF) membrane modified with tannic acid (TA) and pectin (PT) was developed through immersion in TA/PT solutions, facilitating the formation of complexes via co-deposition. The optimized PVDF@TA/PT3 membrane exhibited superhydrophilicity/superoleophobicity. The membrane achieved remarkable separation efficiencies exceeding 98.3% and fluxes ranging from 71.3 to 156.3 L m⁻² h⁻¹ for various oil–water emulsions under gravity-driven conditions. Notably, the membrane maintained exceptional durability through 10 separation cycles, retaining about 98% efficiency while exhibiting strong antifouling properties. Excellent separation performance coupled with facile fabrication protocol and chemical stability of the membrane, position the PVDF@TA/PT membrane as a technologically viable candidate for wastewater purification. Full article

(This article belongs to the Special Issue Emerging Superwetting Membranes: New Advances in Water Treatment)

21 pages, 1917 KiB

Open AccessReview

Uncovering the Mechanisms of Intracellular Membrane Trafficking by Reconstituted Membrane Systems

by Shuhan Chen, Yinghui Liu and Haijia Yu

Membranes 2025, 15(5), 154; https://doi.org/10.3390/membranes15050154 - 16 May 2025

Abstract

Intracellular membrane trafficking that transports proteins, lipids, and other substances between organelles is crucial for maintaining cellular homeostasis and signal transduction. The imbalance of membrane trafficking leads to various diseases. It is challenging to uncover the mechanisms of the complicated and dynamic trafficking [...] Read more.

Intracellular membrane trafficking that transports proteins, lipids, and other substances between organelles is crucial for maintaining cellular homeostasis and signal transduction. The imbalance of membrane trafficking leads to various diseases. It is challenging to uncover the mechanisms of the complicated and dynamic trafficking process at the cellular or animal levels. The applications of functional reconstituted membrane systems, which can mimic the intracellular membrane compartments in a clean and simplified pattern, tremendously facilitate our understanding of the membrane trafficking process. In this review, we summarize applications of the in vitro membrane models, including liposomes, nanodiscs, and single-vesicle platforms, in elucidating molecular mechanisms that govern vesicle fusion and non-vesicular lipid transport, the key steps of membrane trafficking. This review highlights how membrane reconstitution approaches contribute to illustrating the protein-mediated molecular choreography of cellular membranes. Full article

(This article belongs to the Special Issue Membrane Systems: From Artificial Models to Cellular Applications)

15 pages, 2533 KiB

Open AccessArticle

Mesoscopic Structure of Lipid Nanoparticles Studied by Small-Angle X-Ray Scattering: A Spherical Core-Triple Shell Model Analysis

by Hao Li, Panqi Song, Yiwen Li, Shuyang Tu, Mehwish Mehmood, Liang Chen, Na Li and Qiang Tian

Membranes 2025, 15(5), 153; https://doi.org/10.3390/membranes15050153 - 16 May 2025

Abstract

Lipid nanoparticles (LNPs) are widely recognized as effective drug delivery systems for RNA therapeutics because their efficacy is critically dependent on structural organization. The mesoscopic architecture of these multicomponent systems, which is governed by interactions among ionizable lipids, structural lipids, nucleic acids, and [...] Read more.

Lipid nanoparticles (LNPs) are widely recognized as effective drug delivery systems for RNA therapeutics because their efficacy is critically dependent on structural organization. The mesoscopic architecture of these multicomponent systems, which is governed by interactions among ionizable lipids, structural lipids, nucleic acids, and stabilizers, dictates encapsulation efficiency, biodistribution, and therapeutic performance. Although small-angle X-Ray scattering (SAXS) enables nanostructure characterization, the absence of suitable analytical models has hindered LNP development. Here, we present a core-triple shell SAXS model that resolves LNP hierarchical organization, including the inner lipid layer, intermediate hydrophilic region, and outer PEG corona. For LNPs encapsulating mRNA, a Gaussian distribution model was implemented to characterize the quasi-periodic structure originating from the self-assembly of mRNA-ionizable lipid complexes. Validation studies employing Comirnaty-based LNPs demonstrated that controlled variation of nitrogen-to-phosphorus (N/P) ratios produced distinguishable structural features that establish quantitative correlations between N/P ratios and LNP mesoscopic assembled structure. The modeling framework provides pharmaceutical researchers with robust analytical tools for systematic stability assessment and precision formulation for the optimization of LNPs. These structural insights are expected to advance the development of next-generation RNA therapeutics by potentially enhancing their delivery efficiency and pharmacokinetic properties. Full article

(This article belongs to the Section Biological Membranes)

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14 pages, 933 KiB

Open AccessArticle

Membrane ATPases and Mitochondrial Proteins in Fetal Cerebellum After Exposure to L-Glutamate During Gestation

by Adrián Tejero, David Agustín León-Navarro and Mairena Martín

Membranes 2025, 15(5), 152; https://doi.org/10.3390/membranes15050152 - 16 May 2025

Abstract

L-Glutamate (L-Glu) and its salt derivatives are widely used in the food industry as flavor enhancers. Although the consumption of these compounds is generally considered safe, some studies suggest that chronically consuming L-Glu may be associated with various disorders. In this study, Wistar [...] Read more.

L-Glutamate (L-Glu) and its salt derivatives are widely used in the food industry as flavor enhancers. Although the consumption of these compounds is generally considered safe, some studies suggest that chronically consuming L-Glu may be associated with various disorders. In this study, Wistar pregnant rats were treated daily with 1 g/L of L-Glu in their drinking water throughout the gestational period. OPA-1, DRP-1, and mitofusin 2—key proteins involved in mitochondrial fusion and fission—were analyzed by Western blot. The results showed that L-Glu exposure significantly decreased DRP-1 levels, while OPA-1 and mitofusin 2 levels were unaffected. This was accompanied by a notable decrease in mitochondrial complexes III and V. The activities of Mg²⁺-ATPase and Na⁺/K⁺-ATPase were also analyzed in fetal cerebellar plasma membranes. Maternal L-Glu intake significantly increased Mg²⁺-ATPase activity. Regarding Na⁺/K⁺-ATPase, the data showed that L-Glu exposure did not modulate the protein level or its activity. However, a positive interaction with glutamate receptors was observed in both activities, although neither AMPA nor NMDA receptors appeared to be involved. These results suggest that chronic maternal L-Glu intake during gestation modulates Mg²⁺-ATPase activity and protein markers of mitochondrial dynamics in the fetal cerebellum, which could affect neonatal development. Full article

(This article belongs to the Section Biological Membranes)

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12 pages, 6498 KiB

Open AccessArticle

Fast-Rising Electric Pulses by Reducing Membrane Tension for Efficient Membrane Electroporation

by Ping Ye, Lulu Huang and Kuiwen Zhao

Membranes 2025, 15(5), 151; https://doi.org/10.3390/membranes15050151 - 16 May 2025

Abstract

Membrane electroporation is an emerging minimally invasive ablation technique being rapidly applied in the ablation treatment of tumors and heart conditions. Different rise times of electric fields lead to variations in the distribution and duration of electric field strength on the cell membrane. [...] Read more.

Membrane electroporation is an emerging minimally invasive ablation technique being rapidly applied in the ablation treatment of tumors and heart conditions. Different rise times of electric fields lead to variations in the distribution and duration of electric field strength on the cell membrane. This study investigated the effect of the electric field’s rise time on membrane electroporation characteristics using molecular dynamics simulations. The results showed that fast-rising electrical pulses can significantly reduce the membrane tension induced by the Coulomb force within a short period of time and lead to a trend of the electric field angle distribution towards smaller values below 45°, thereby effectively promoting the pore formation process. Optimizing the electric field’s rise time is an effective electroporation ablation strategy, potentially improving the efficacy of clinical cancer treatment. Full article

(This article belongs to the Special Issue Composition and Biophysical Properties of Lipid Membranes)

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15 pages, 5927 KiB

Open AccessArticle

Fabrication of Composite Membrane by Constructing Helical Carbon Nanotubes in Ceramic Support Channels for Efficient Emulsion Separation

by Kai Yuan, Rizhi Chen and Yiqing Zeng

Membranes 2025, 15(5), 150; https://doi.org/10.3390/membranes15050150 - 15 May 2025

Abstract

Membrane technology has emerged as an effective solution for the purification of oily wastewater, particularly in the separation of oil-in-water (O/W) emulsions. However, challenges, such as membrane fouling and the development of robust ceramic membranes with superior stability, continue to limit their widespread [...] Read more.

Membrane technology has emerged as an effective solution for the purification of oily wastewater, particularly in the separation of oil-in-water (O/W) emulsions. However, challenges, such as membrane fouling and the development of robust ceramic membranes with superior stability, continue to limit their widespread application. In this work, helical carbon nanotubes (HCNTs) with interlocking structures were grown in ceramic support channels through the airflow-induced chemical vapor deposition (CVD) method to fabricate membrane material with high hydrophilicity and underwater oleophobicity. The influence of CVD parameters on the growth of HCNTs and the membrane separation performance for O/W emulsions were studied systematically. The optimal HCNTs-SiC composite membrane was prepared at 600 °C, featuring a pore size of 0.95 μm and flux of 229.29 L·m⁻²·h⁻¹. This membrane demonstrated exceptional purification efficiency (99.99%) for a 500 ppm O/W emulsion, along with a stable flux of 32.48 L·m⁻²·h⁻¹ under a transmembrane pressure (TMP) of 1.5 bar. Furthermore, the unique membrane structure and surface heterogeneity contributed to its long service life and excellent recovery capability. This work provides a novel strategy for designing high-performance ceramic membranes for oil–water separation, offering potential solutions to current limitations in membrane technology. Full article

(This article belongs to the Special Issue Emerging Superwetting Membranes: New Advances in Water Treatment)

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21 pages, 5143 KiB

Open AccessArticle

The Ammonia Adsorption and Desorption Behavior of Nafion

by Dominik Sachse, Andreas Glüsen, Klaus Wippermann, Martin Müller, Uwe Rau and Ralf Peters

Membranes 2025, 15(5), 149; https://doi.org/10.3390/membranes15050149 - 14 May 2025

Abstract

The electrochemical nitrogen reduction reaction (eNRR) for electrochemical ammonia (NH₃) synthesis is considered a promising alternative to the energy-intensive and highly CO₂-emitting Haber-Bosch process. In numerous experiments, the Nafion membrane has been used as an electrolyte or separator. However, [...] Read more.

The electrochemical nitrogen reduction reaction (eNRR) for electrochemical ammonia (NH₃) synthesis is considered a promising alternative to the energy-intensive and highly CO₂-emitting Haber-Bosch process. In numerous experiments, the Nafion membrane has been used as an electrolyte or separator. However, Nafion adsorbs and desorbs NH₃, leading to erroneous measurements and making reproducibility extremely difficult. This study systematically investigates the interaction between NH₃ and Nafion, underscoring the strength of the interaction between ammonium-ions (NH₄⁺) and protons (H⁺). We found that minute quantities of synthesized NH₃ are prone to persist within the membrane, albeit without affecting the ion conductivity and resistivity of Nafion. Consequently, the removal of NH₃ from the membrane can occur under conditions where synthesis is not viable. The objective of this work is to heighten awareness regarding the interaction between NH₃ and Nafion and contribute to the attainment of reliable and reproducible outcomes in eNRRs. Full article

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

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17 pages, 2921 KiB

Open AccessArticle

Coenzyme Q10 Enhances Resilience of Mitochondrial-like Membranes Against Amyloidogenic Peptides

by Raina Marie Seychell, Adam El Saghir, Gianluca Farrugia and Neville Vassallo

Membranes 2025, 15(5), 148; https://doi.org/10.3390/membranes15050148 - 13 May 2025

Abstract

Mitochondria possess a double-membrane envelope which is susceptible to insult by pathogenic intracellular aggregates of amyloid-forming peptides, such as the amyloid-beta (1-42) (Aβ42) peptide and the human islet amyloid polypeptide (hIAPP). The molecular composition of membranes plays a pivotal role in regulating peptide [...] Read more.

Mitochondria possess a double-membrane envelope which is susceptible to insult by pathogenic intracellular aggregates of amyloid-forming peptides, such as the amyloid-beta (1-42) (Aβ42) peptide and the human islet amyloid polypeptide (hIAPP). The molecular composition of membranes plays a pivotal role in regulating peptide aggregation and cytotoxicity. Therefore, we hypothesized that modifying the physicochemical properties of mitochondrial model membranes with a small molecule might act as a countermeasure against the formation of, and damage by, membrane-active amyloid peptides. To investigate this, we inserted the natural ubiquinone Coenzyme Q10 (CoQ10) in model mito-mimetic lipid vesicles, and studied how they interacted with Aβ42 and hIAPP peptide monomers and oligomers. Our results demonstrate that the membrane incorporation of CoQ10 significantly attenuated fibrillization of the peptides, whilst also making the membranes more resilient against peptide-induced permeabilization. Furthermore, these protective effects were linked with the ability of CoQ10 to enhance membrane packing in the inner acyl chain region, which increased the mechanical stability of the vesicle membranes. Based on our collective observations, we propose that mitochondrial resilience against toxic biomolecules implicit in protein misfolding disorders such as Alzheimer’s disease and type-2 diabetes, could potentially be enhanced by increasing CoQ10 levels within mitochondria. Full article

(This article belongs to the Special Issue Composition and Biophysical Properties of Lipid Membranes)

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12 pages, 2694 KiB

Open AccessArticle

In-Situ Measurement of Gas Permeability for Membranes in Water Electrolysis

by Shuaimin Li, Chuan Song, Li Xu, Yuxin Wang and Wen Zhang

Membranes 2025, 15(5), 147; https://doi.org/10.3390/membranes15050147 - 13 May 2025

Abstract

Water electrolysis (WE) is a green technology for producing hydrogen gas without the emission of carbon dioxide. The ideal membrane materials in WE should be capable of transporting ions quickly and have gas barrier properties in harsh work environments. However, currently, no desirable [...] Read more.

Water electrolysis (WE) is a green technology for producing hydrogen gas without the emission of carbon dioxide. The ideal membrane materials in WE should be capable of transporting ions quickly and have gas barrier properties in harsh work environments. However, currently, no desirable measurement method has been developed for evaluating the gas barrier behavior of the membranes. Hence, an in-situ electrochemical method is developed to measure the gas permeability of membranes in the actual electrolysis environment, with the supersaturated state of H₂ in the electrolyte and H₂ bubbles during the electrolysis process. Four membranes, including Zirfon (a state-of-the-art alkaline WE membrane), polyphenylene sulfide fabric (PPS, a commercial alkaline WE membrane), FAA-3-PK-75 (a commercial anion-exchange membrane), and BILP-PE (a home-made composite membrane) were employed as the standard samples to perform the electrochemical measurement under different current densities, temperatures, and electrolyte concentrations. The results show that an increase in electrolytic current density or temperature or a decrease in KOH concentration can increase the H₂ permeability of the membrane. The two porous membranes, Zirfon and PPS, are more affected by the current density and KOH concentration, while the dense FAA-3-PK-75 and BILP-PE membranes have a stronger ability to hinder H₂ permeation. Under the conditions of 80 °C, 30 wt.% KOH, 101 kPa, and 400 mA·cm⁻², the hydrogen permeability (×10¹⁰ L·cm·cm⁻²·s⁻¹) of Zirfon, PPS, FAA, and BILP-PE are 263, 367, 28.3, and 5.32, respectively. Full article

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

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17 pages, 3066 KiB

Open AccessArticle

Polymer Inclusion Membranes Based on Sulfonic Acid Derivatives as Ion Carriers for Selective Separation of Pb(II) Ions

by Cezary Kozlowski and Iwona Zawierucha

Membranes 2025, 15(5), 146; https://doi.org/10.3390/membranes15050146 - 12 May 2025

Abstract

In this paper, polymer inclusion membranes (PIMs) were created using poly(vinyl chloride)-based alkyl sulfonic acid derivatives as ion carriers and dioctyl terephthalate as a plasticizer for the selective separation of Pb(II), Cu(II), and Cd(II) ions from aqueous nitrate solutions. The ion carriers were [...] Read more.

In this paper, polymer inclusion membranes (PIMs) were created using poly(vinyl chloride)-based alkyl sulfonic acid derivatives as ion carriers and dioctyl terephthalate as a plasticizer for the selective separation of Pb(II), Cu(II), and Cd(II) ions from aqueous nitrate solutions. The ion carriers were dinonylnaphthalenesulfonic acid (DNNSA) and nonylbenzenesulfonic acid (NBSA). The influence of the carrier and the plasticizer concentration in the membrane on the transport efficiency was investigated. For the PIM system, 15% wt. of carrier (DNNSA, NBSA), 20% wt. of plasticizer, and 65% wt. of polymer poly(vinyl chloride) PVC were the optimal proportions, with which the process was the most effective. Research on the transport kinetics has shown that the transport of Pb(II) ions through PIMs containing acidic carriers adheres to a first-order kinetics equation, which is characteristic of a facilitated transport mechanism. The activation parameter for these processes suggests that the high performance of these ion carriers is associated with the immobilization of the carrier within the membrane. It was found that PIMs based on DNNSA facilitate the selective separation of Pb(II)/Cu(II) and Pb(II)/Cd(II) mixtures, achieving high separation factors. Full article

(This article belongs to the Special Issue Recent Advances in Polymer Inclusion Membranes)

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13 pages, 4315 KiB

Open AccessArticle

Electrospun Graphene Oxide/Poly(m-phenylene isophthalamide) Composite Nanofiber Membranes for High Performance

by Enling Tian, Yinping Bi and Yiwei Ren

Membranes 2025, 15(5), 145; https://doi.org/10.3390/membranes15050145 - 12 May 2025

Abstract

Due to its distinctive two-dimensional structure and high specific surface area, graphene oxide (GO) is expected to be a very promising material to be used for membrane separation. Not only can it improve the mechanical strength, surface wettability, and thermal stability of the [...] Read more.

Due to its distinctive two-dimensional structure and high specific surface area, graphene oxide (GO) is expected to be a very promising material to be used for membrane separation. Not only can it improve the mechanical strength, surface wettability, and thermal stability of the membrane, but it can also improve the filtration performance and shelf life of the polymer membrane. Graphene oxide/poly(meta-phenylene isophthalamide) (GO/PMIA) nanofiber membranes were prepared by means of an electrospinning technique. The effects of adding different amounts of GO on the PMIA nanofiber membranes were studied. The results indicated that the GO had a strong affinity with the PMIA matrix by forming hydrogen bonds. The composite nanofiber membranes exhibited better filtration and thermostability performance than those of the pristine membrane. As the loading amount of GO was 1.0 wt%, the air filtration efficiency of the composite nanofiber membrane was 97.79%, the pressure drop was 85.45 Pa and the glass transition temperature was 299.8 °C. Full article

(This article belongs to the Special Issue Prospects for Nanocomposite Membrane Applications)

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29 pages, 10395 KiB

Open AccessArticle

Performance Analysis of DCMD Modules Enhanced with 3D-Printed Turbulence Promoters of Various Hydraulic Diameters

by Chii-Dong Ho, Ming-Shen Chiang and Choon Aun Ng

Membranes 2025, 15(5), 144; https://doi.org/10.3390/membranes15050144 - 10 May 2025

Abstract

Theoretical and experimental investigations were conducted to predict permeate flux in direct contact membrane distillation (DCMD) modules equipped with turbulence promoters. These DCMD modules operate at moderate temperatures (45 °C to 60 °C) using a hot saline feed stream while maintaining a constant [...] Read more.

Theoretical and experimental investigations were conducted to predict permeate flux in direct contact membrane distillation (DCMD) modules equipped with turbulence promoters. These DCMD modules operate at moderate temperatures (45 °C to 60 °C) using a hot saline feed stream while maintaining a constant temperature for the cold inlet stream. The temperature difference between the two streams creates a gradient across the membrane surfaces, leading to thermal energy dissipation due to temperature polarization effects. To address this challenge, 3D-printed turbulence promoters were incorporated into the DCMD modules. Acting as eddy promoters, these structures aim to reduce the temperature polarization effect, thereby enhancing permeate flux and improving pure water productivity. Various designs of promoter-filled channels—with differing array configurations and geometric shapes—were implemented to optimize flow characteristics and further mitigate polarization effects. Theoretical predictions were validated against experimental results across a range of process parameters, including inlet temperatures, volumetric flow rates, hydraulic diameters, and flow configurations, with deviations within 10%. The DCMD module with the inserted 3D-printed turbulence promoters in the flow channel could provide a relative permeate flux enhancement up to 91.73% under the descending diamond-type module in comparison with the module of using the no-promoter-filled channel. The modeling equations demonstrated technical feasibility, particularly with the use of both descending and ascending hydraulic diameters of 3D-printed turbulence promoters inserted into the saline feed stream, as compared to a module using an empty channel. Full article

(This article belongs to the Special Issue Solar-Assisted Thermal-Driven Membrane Distillation)

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50 pages, 7741 KiB

Open AccessArticle

X-Ray Crystal and Cryo-Electron Microscopy Structure Analysis Unravels How the Unique Thylakoid Lipid Composition Is Utilized by Cytochrome b₆f for Driving Reversible Proteins’ Reorganization During State Transitions

by Radka Vladkova

Membranes 2025, 15(5), 143; https://doi.org/10.3390/membranes15050143 - 8 May 2025

Abstract

The rapid regulatory mechanism of light-induced state transitions (STs) in oxygenic photosynthesis is particularly appealing for membrane-based applications. This interest stems from the unique ability of the thylakoid membrane protein cytochrome b₆f (cytb₆f) to increase or decrease [...] Read more.

The rapid regulatory mechanism of light-induced state transitions (STs) in oxygenic photosynthesis is particularly appealing for membrane-based applications. This interest stems from the unique ability of the thylakoid membrane protein cytochrome b₆f (cytb₆f) to increase or decrease its hydrophobic thickness (d_P) in parallel with the reduction or oxidation of the PQ pool induced by changes in light quality. This property appears to be the long-sought biophysical driver behind the reorganizations of membrane proteins during STs. This study decisively advances the hydrophobic mismatch (HMM) model for cytb₆f-driven STs by thoroughly analyzing thirteen X-ray crystal and eight cryo-electron microscopy cytb₆f structures. It uncovers the lipid nanoenvironments that cytb₆f, with different hydrophobic thicknesses, selectively attracts. Under optimal, stationary conditions for photosynthesis in low light, when there is hydrophobic matching between the hydrophobic thicknesses of cytb₆f d_P and that of the bulk thylakoid lipid phase d_L, d_P = d_L, cytb₆f predominantly binds to anionic lipids—several phosphatidylglycerol (PG) molecules and one sulfoquinovosyldiacylglycerol (SQDG) molecule. Upon the induction of the transition to State 2, when d_P increases and induces a positive HMM (d_P > d_L), the neutral, non-bilayer-forming lipid monogalactosyldiacylglycerol (MGDG) replaces some of the bound PGs. Upon the induction of the transition to State 1, when d_P decreases and induces a negative HMM (d_P < d_L), PGs and SQDG detach from their binding sites, and two neutral, bilayer-forming lipids such as digalactosyldiacylglycerol (DGDG) occupy two sites. Additionally, this research uncovers two lipid-mediated signaling pathways from Chla to the center of flexibility, the Phe/Tyr124^fg^-loop-suIV residue—one of which involves β-carotene. This study identifies two novel types of lipid raft-like nanodomains that are devoid of typical components, such as sphingomyelin and cholesterol. These findings firmly validate the HMM model and underscore the STs as the first recognized functional process that fully utilizes the unique and evolutionarily conserved composition of just four thylakoid lipid classes. This research contributes to our understanding of membrane dynamics in general and STs in particular. It introduces a novel and simple approach for reversible protein reorganization driven purely by biophysical mechanisms, with promising implications for various membrane-based applications. Full article

(This article belongs to the Special Issue Biological Membrane Dynamics and Reorganization Induced by Light Changes)

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15 pages, 4044 KiB

Open AccessArticle

Development and Application of a Novel Ultrafiltration Membrane for Efficient Removal of Dibutyl Phthalate from Wastewater

by Qiang Zhou, Meiling Chen, Yushan Jiang, Linnan Zhang and Yanhong Wang

Membranes 2025, 15(5), 142; https://doi.org/10.3390/membranes15050142 - 7 May 2025

Abstract

This study successfully developed a novel molecularly imprinted ultrafiltration membrane (MIUM) for energy-efficient and selective removal of dibutyl phthalate (DBP) from wastewater. Guided by Gaussian simulations, methacrylic acid (MAA) was identified as the optimal functional monomer, achieving the strongest binding energy (ΔE = [...] Read more.

This study successfully developed a novel molecularly imprinted ultrafiltration membrane (MIUM) for energy-efficient and selective removal of dibutyl phthalate (DBP) from wastewater. Guided by Gaussian simulations, methacrylic acid (MAA) was identified as the optimal functional monomer, achieving the strongest binding energy (ΔE = −0.0698 a.u.) with DBP at a 1:6 molar ratio, providing a foundation for precise cavity construction. DBP-imprinted polymers (MIPs) synthesized via bulk polymerization were integrated into polysulfone membranes through phase inversion. The optimized MIUM (81.27% polymer content) exhibited exceptional performance under low-pressure operation (0.2 MPa), with a water flux of 111.49 L·m²·h⁻¹ and 92.87% DBP rejection, representing a 43% energy saving compared to conventional nanofiber membranes requiring 0.4 MPa. Structural characterization confirmed synergistic effects between imprinted cavities and membrane transport properties as the key mechanism for efficient separation. Notably, MIUM demonstrated remarkable selectivity, achieving 91.57% retention for DBP while showing limited affinity for structurally analogous phthalates (e.g., diethyl/diisononyl phthalates). The membrane maintained > 70% retention after 10 elution cycles, highlighting robust reusability. These findings establish a paradigm for molecular simulation-guided design of selective membranes, offering an innovative solution for low-energy removal of endocrine disruptors. The work advances wastewater treatment technologies by balancing high permeability, targeted pollutant removal, and operational sustainability, with direct implications for mitigating environmental risks and improving water quality management. 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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20 pages, 4427 KiB

Open AccessArticle

Separation and Characterization of Heterogeneity Among Various Sizes of Outer Membrane Vesicles Derived from the Probiotic Escherichia coli Nissle 1917

by Ning Li, Hongbo Xin and Keyu Deng

Membranes 2025, 15(5), 141; https://doi.org/10.3390/membranes15050141 - 5 May 2025

Abstract

Outer membrane vesicles (OMVs) are extracellular vesicles secreted by Gram-negative bacteria with diameters of 20–250 nm. OMVs contain various biologically active substances from their parent bacteria, such as proteins, lipids, and nucleic acids. Escherichia coli Nissle 1917 (EcN) is a Gram-negative probiotic that [...] Read more.

Outer membrane vesicles (OMVs) are extracellular vesicles secreted by Gram-negative bacteria with diameters of 20–250 nm. OMVs contain various biologically active substances from their parent bacteria, such as proteins, lipids, and nucleic acids. Escherichia coli Nissle 1917 (EcN) is a Gram-negative probiotic that resides in the human intestine. EcN-derived OMVs are pivotal in modulating intestinal immune responses. However, few studies have addressed the heterogeneity of EcN-derived OMVs in terms of size, significantly limiting the research on their clinical applications. Currently, there are a lack of feasible methods for obtaining EcN-derived OMVs of different sizes. To address this knowledge gap, we developed a membrane filtration method to isolate EcN-derived OMVs of varying sizes. In this study, we first used gradient filtration to isolate high-purity EcN-derived OMVs and conducted a proteomic analysis. Subsequently, we used membrane filtration to separate the EcN-derived OMVs by size. We successfully obtained EcN-derived OMVs of three specific sizes: <50 nm, 50–100 nm, and 100–300 nm. We then performed proteomic analyses of these EcN-derived OMVs and compared their protein profiles. Finally, we compared the ability of each EcN-derived OMV type to induce RAW264.7 macrophages to secrete the pro-inflammatory factor interleukin (IL)-1β and the anti-inflammatory factor IL-10. The EcN-derived OMVs contained 646 different proteins overall; those of different sizes contained different protein types. Among them, the EcN-derived OMVs in the <50 nm group contained significantly fewer proteins (262 different types in total) than those in the 50–100 nm (1603 types) and 100–300 nm (1568 types) groups. Furthermore, the <50 nm group had fewer membrane proteins (40) than the 50–100 nm (215) and 100–300 nm (209) groups. We also found that RAW264.7 macrophages secreted different concentrations of IL-1β and IL-10 following co-incubation with the three EcN-derived OMV types. The 50–100 nm EcN-derived OMV group showed a stronger effect in terms of inducing inflammatory cytokine secretion compared to the other two groups. This study provides direct experimental evidence that EcN-derived OMVs of different sizes exhibit heterogeneous properties. Full article

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

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16 pages, 546 KiB

Open AccessReview

Applications of Reverse Osmosis and Nanofiltration Membrane Process in Wine and Beer Industry

by Yogesh Kumar, Atul Khalangre, Rajat Suhag and Alfredo Cassano

Membranes 2025, 15(5), 140; https://doi.org/10.3390/membranes15050140 - 2 May 2025

Abstract

Reverse osmosis (RO) and nanofiltration (NF) membranes are traditionally employed in wine and beer production for concentration, clarification, and stabilization. Their applications now extend to dealcoholization, addressing rising demand for low-alcohol beverages. RO/NF selectively reduce ethanol while retaining volatile aromas and non-volatile flavors, [...] Read more.

Reverse osmosis (RO) and nanofiltration (NF) membranes are traditionally employed in wine and beer production for concentration, clarification, and stabilization. Their applications now extend to dealcoholization, addressing rising demand for low-alcohol beverages. RO/NF selectively reduce ethanol while retaining volatile aromas and non-volatile flavors, outperforming thermal methods that degrade sensory profiles. This review examines RO/NF roles in alcohol adjustment, sugar modification, and by-product recovery, emphasizing mechanisms and efficiency. Operational challenges such as membrane fouling (polysaccharides, polyphenols), selectivity–permeation flux trade-offs, and energy costs are assessed. By balancing tradition with innovation, RO/NF technologies offer transformative potential for meeting health and sustainability goals in beverage industries. However, gaps in standardization, sensory consistency, and cost-effectiveness necessitate targeted research to optimize industrial adoption and consumer acceptance. Full article

(This article belongs to the Special Issue Membrane Processes for Water Recovery in Food Processing Industries)

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14 pages, 1767 KiB

Open AccessArticle

Toluidine Blue for the Determination of Binding of Anionic Polysaccharides to Lipid Raft Domains by Absorption Spectroscopy

by Sandra Gębczyńska, Julia Gdowska, Agata Mikos, Iga Gawrońska, Teresa Janas, Aleksander Czogalla and Tadeusz Janas

Membranes 2025, 15(5), 139; https://doi.org/10.3390/membranes15050139 - 2 May 2025

Abstract

The complexes of negatively charged polysaccharides with lipid vesicles have been shown to have applications in medicine, bioremediation, water purification, and construction of nano-biosensors. This article presents research on the formation of these complexes based on the interactions between three types of liposomes, [...] Read more.

The complexes of negatively charged polysaccharides with lipid vesicles have been shown to have applications in medicine, bioremediation, water purification, and construction of nano-biosensors. This article presents research on the formation of these complexes based on the interactions between three types of liposomes, DOPC liposomes (which contain a lipid bilayer in the liquid-disordered (Ld) state), RAFT liposomes (which contain liquid-ordered (Lo) lipid raft domains surrounded by lipids in the Ld state) and SPH–CHL liposomes (which contain a lipid bilayer in the Lo state), and two selected anionic polysaccharides, polysialic acid (PSA) and polygalacturonic acid (PGA). The analysis was conducted using a toluidine blue (TB) probe and the absorption spectroscopy technique. In contrast to DOPC and SPH–CHL liposomes, binding of negatively charged PSA or PGA chains to RAFT liposomes induced a TB absorption maximum shift from 630 nm to 560 nm. The obtained results indicate that toluidine blue can be applied for monitoring the formation of these nano-complexes, and that the boundaries between Ld/Lo domains within membranes in RAFT liposomes can significantly enhance the binding affinity of negatively charged polysaccharides to the lipid bilayer surface. The observed metachromatic shift in TB absorption suggests that negatively charged PSA and PGA chains interact with the Ld/Lo boundaries within RAFT liposome membranes. Full article

(This article belongs to the Section Biological Membranes)

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29 pages, 3853 KiB

Open AccessReview

Membrane Technology for Valuable Resource Recovery from Palm Oil Mill Effluent (POME): A Review

by Que Nguyen Ho, Woei Jye Lau, Juhana Jaafar, Mohd Hafiz Dzarfan Othman and Naoko Yoshida

Membranes 2025, 15(5), 138; https://doi.org/10.3390/membranes15050138 - 2 May 2025

Abstract

Palm oil mill effluent (POME), a byproduct of palm oil processing, has substantial resource recovery potential. Its rich biodegradable content supports methane (CH₄) production via anaerobic digestion, enabling renewable energy generation. Additionally, the significant water content of POME can be reclaimed [...] Read more.

Palm oil mill effluent (POME), a byproduct of palm oil processing, has substantial resource recovery potential. Its rich biodegradable content supports methane (CH₄) production via anaerobic digestion, enabling renewable energy generation. Additionally, the significant water content of POME can be reclaimed for use in boiler feed, irrigation, and drinking water. However, selecting appropriate technologies to recover valuable resources from POME is challenging, particularly for the purification and upgrading of biogas. Membrane technologies offer an effective approach for transforming POME treatment from an energy-intensive process into a resource recovery system, supporting the decarbonization of palm oil production and advancing global sustainability objectives. This technique is cost-effective and ecofriendly for biogas purification and water reclamation. For biogas purification and upgrading, membrane systems offer the lowest capital and operational costs at 5.654 USD/m³, compared to other technologies, such as 6.249 USD/m³ for water scrubbers and 6.999 USD/m³ for chemical absorbers. This review primarily explores the potential of membranes for gas purification from POME and examines their integration with other processes to develop advanced systems, such as ultrasonicated membrane anaerobic systems and membrane anaerobic systems, to enhance biogas production. In addition, water reclamation from POME is discussed, with ultrafiltration membranes emerging as the most promising candidates. Proton exchange membranes, such as Nafion, are used extensively in microbial fuel cells to improve electricity generation, and this is also summarized. Finally, challenges and future perspectives are highlighted, emphasizing the broader potential of membrane technology in POME wastewater resource recovery. Full article

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

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14 pages, 4249 KiB

Open AccessArticle

Effect of Microfiltration Membrane Configuration in Microplastics Recovery from Wastewater Treatment Effluent

by Rubén Rodríguez-Alegre, Sergi Durán-Videra, Laura Pérez Megías, Montserrat Pérez-Moya, Julia García-Montaño, Carlos Andecochea Saiz and Xialei You

Membranes 2025, 15(5), 137; https://doi.org/10.3390/membranes15050137 - 2 May 2025

Abstract

Water scarcity has driven the use of wastewater treatment plant (WWTP) effluents as reclaimed water, highlighting the need to overcome challenges such as the presence of emerging contaminants, particularly microplastics (MPs), which WWTPs are unable to effectively remove. Membrane-based processes, such as microfiltration, [...] Read more.

Water scarcity has driven the use of wastewater treatment plant (WWTP) effluents as reclaimed water, highlighting the need to overcome challenges such as the presence of emerging contaminants, particularly microplastics (MPs), which WWTPs are unable to effectively remove. Membrane-based processes, such as microfiltration, have demonstrated high efficiency in the removal of suspended solids, and their application for MP removal is currently under investigation. This study assesses the influence of microfiltration membrane spacer size (1 mil and 80 mil) and geometry—diamond and corrugated—on MP recovery performance, using synthetic wastewaters with varying MPs concentrations. The results indicate the superior performance of large corrugated and small diamond-shaped membranes, as both exhibited the highest and comparable permeate flux, with no MP retention within the membrane element. All microfiltration membranes achieved an 80% recovery of the influent as safe reclaimed water and demonstrated an MP recovery efficiency exceeding 99%, with 100% rejection for fragments and up to 98% rejection for fibres. Full article

(This article belongs to the Special Issue Membrane Technologies for Water Purification)

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