Membranes

14 pages, 650 KiB

Open AccessArticle

Integrated Purification Systems for the Removal of Disinfectants from Wastewater

by Aleksandra Klimonda and Izabela Kowalska

Membranes 2025, 15(2), 43; https://doi.org/10.3390/membranes15020043 (registering DOI) - 2 Feb 2025

The efficiency of integrated treatment systems for wastewater generated during the washing of disinfectant production lines was investigated. The high organic load (COD 2000 mg/L, TOC 850 mg/L) and 300 mg/L of toxic benzalkonium chloride (BAC) make wastewater an environmental hazard that requires [...] Read more.

The efficiency of integrated treatment systems for wastewater generated during the washing of disinfectant production lines was investigated. The high organic load (COD 2000 mg/L, TOC 850 mg/L) and 300 mg/L of toxic benzalkonium chloride (BAC) make wastewater an environmental hazard that requires advanced treatment. Initial tests on model BAC solutions (in concentrations corresponding to those found in wastewater), using nanofiltration and ultrafiltration membranes, resulted in up to 70% retention of BAC. To enhance purification, ion exchange and adsorption were introduced as post-membrane treatment steps. In the second part of the investigation, membrane modules characterized by the best separation properties were integrated together with macroporous cation-exchange resin and activated carbon into the purification system to treat wastewater. The research carried out showed that the purification of multicomponent wastewater is a complex task. Significantly lower BAC removal (30%) was achieved in membrane processes compared to the model solutions treatment. In integrated systems, the BAC concentration was reduced to 100 mg/L, TOC to 200 mg/L, and COD to 120 mg/L. Full article

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

19 pages, 3637 KiB

Open AccessArticle

Preparation of Am-MSN/PVDF Mixed Matrix Membranes for Enhanced Removal of Reactive Black 5

by Jihao Zuo, Mengkang Lu, Jinting Cai, Ruopeng Lan, Xinjuan Zeng and Cailong Zhou

Membranes 2025, 15(2), 42; https://doi.org/10.3390/membranes15020042 (registering DOI) - 1 Feb 2025

Abstract

The discharge of large volumes of textile dyeing wastewater, characterized by poor biodegradability and high toxicity, poses severe threats to the environment. In this study, polyvinylidene difluoride (PVDF) membranes were prepared using the nonsolvent-induced phase separation (NIPS) method, with porous amino-functionalized mesoporous silica [...] Read more.

The discharge of large volumes of textile dyeing wastewater, characterized by poor biodegradability and high toxicity, poses severe threats to the environment. In this study, polyvinylidene difluoride (PVDF) membranes were prepared using the nonsolvent-induced phase separation (NIPS) method, with porous amino-functionalized mesoporous silica nanoparticles (Am-MSNs) mixed into the casting solution to fabricate the Am-MSN/PVDF mixed matrix membranes. By varying the amount of Am-MSNs added, the microstructure and overall performance of the membranes were comprehensively analyzed. The results demonstrated that the addition of Am-MSNs significantly enhanced the hydrophilicity of the membranes. The high specific surface area and amino groups of Am-MSNs facilitated interactions with dye molecules, such as Reactive Black 5 (RB5), through hydrogen bonding, electrostatic attraction, and physical adsorption, resulting in a marked improvement in RB5 rejection rates. Static adsorption tests further validated the superior adsorption capacity of the Am-MSN/PVDF mixed matrix membranes for RB5. Additionally, the nanoscale mesoporous structure of Am-MSNs enhanced the mechanical strength of the membranes. The synergistic effects of the mesoporous structure and amino groups significantly increased the efficiency and stability of the Am-MSN/PVDF mixed matrix membranes in dye removal applications, providing an effective and sustainable solution for the treatment of dye-contaminated wastewater. Full article

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

14 pages, 1414 KiB

Open AccessArticle

Silica-Nanocoated Membranes with Enhanced Stability and Antifouling Performance for Oil-Water Emulsion Separation

by Mengfan Zhu, Chengqian Huang and Yu Mao

Membranes 2025, 15(2), 41; https://doi.org/10.3390/membranes15020041 (registering DOI) - 1 Feb 2025

Abstract

Despite the potential of glass fiber (GF) membranes for oil-water emulsion separations, efficient surface modification methods to enhance fouling resistance while preserving membrane performance and stability remain lacking. We report a silica nanocoating method to modify GF membranes through a vapor deposition method. [...] Read more.

Despite the potential of glass fiber (GF) membranes for oil-water emulsion separations, efficient surface modification methods to enhance fouling resistance while preserving membrane performance and stability remain lacking. We report a silica nanocoating method to modify GF membranes through a vapor deposition method. The high smoothness (<1 nm r.m.s.) and high conformality of the vapor-deposited silica nanocoatings enabled the preservation of membrane microstructure and permeability, which, combined with the enhanced surface hydrophilicity, led to an oil rejection rate exceeding 99% and more than a 40% improvement in permeate flux in oil-water emulsion separations. Furthermore, the silica nanocoatings provided the membranes with excellent wet strength and stability against organic solvents, strong acids, oxidants, boiling, and sonication. The silica-nanocoated membrane demonstrated enhanced fouling resistance, achieving flux recovery higher than 75% during repeated oil-water emulsion separations and bovine serum albumin and humic acid fouling tests. Full article

(This article belongs to the Special Issue Membrane Separation and Water Treatment: Modeling and Application)

12 pages, 1419 KiB

Open AccessArticle

Conformation and Membrane Topology of the N-Terminal Ectodomain of Influenza A M2 Protein

by Kyra C. Roeke and Kathleen P. Howard

Membranes 2025, 15(2), 40; https://doi.org/10.3390/membranes15020040 (registering DOI) - 1 Feb 2025

Abstract

The N-terminal ectodomain of the influenza A M2 protein is a target for universal influenza vaccine development and novel antiviral strategies. Despite the significance of this domain, it is poorly understood and most structural studies of the M2 protein have disregarded the N-terminal [...] Read more.

The N-terminal ectodomain of the influenza A M2 protein is a target for universal influenza vaccine development and novel antiviral strategies. Despite the significance of this domain, it is poorly understood and most structural studies of the M2 protein have disregarded the N-terminal ectodomain in their analyses. Here, we report conformational properties and describe insights into the membrane topology of sites along the N-terminal ectodomain. Full-length M2 protein is embedded in lipid bilayer nanodiscs and studied using site-directed spin labeling electron paramagnetic resonance spectroscopy. Results are consistent with a turn in the middle of the ectodomain that changes in proximity to the membrane surface upon the addition of cholesterol or the antiviral drug rimantadine. Similarly to other domains of M2 protein, lineshape analysis suggests that the N-terminal ectodomain can adopt multiple conformations. Full article

(This article belongs to the Section Biological Membranes)

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16 pages, 4657 KiB

Open AccessArticle

Electrospun Collagen-Coated Nanofiber Membranes Functionalized with Silver Nanoparticles for Advanced Wound Healing Applications

by Martin Iurilli, Davide Porrelli, Gianluca Turco, Cristina Lagatolla, Alvise Camurri Piloni, Barbara Medagli, Vanessa Nicolin and Giovanni Papa

Membranes 2025, 15(2), 39; https://doi.org/10.3390/membranes15020039 (registering DOI) - 1 Feb 2025

Abstract

Complex wounds pose a significant healthcare challenge due to their susceptibility to infections and delayed healing. This study focuses on developing electrospun polycaprolactone (PCL) nanofiber membranes coated with Type I collagen derived from bovine skin and functionalized with silver nanoparticles (AgNPs) to address [...] Read more.

Complex wounds pose a significant healthcare challenge due to their susceptibility to infections and delayed healing. This study focuses on developing electrospun polycaprolactone (PCL) nanofiber membranes coated with Type I collagen derived from bovine skin and functionalized with silver nanoparticles (AgNPs) to address these issues. The collagen coating enhances biocompatibility, while AgNPs synthesized through chemical reduction with sodium citrate provide broad-spectrum antimicrobial properties. The physical properties of the membranes were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Results showed the formation of nanofibers without defects and the uniform distribution of AgNPs. A swelling test and contact angle measurements confirmed that the membranes provided an optimal environment for wound healing. In vitro biological assays with murine 3T3 fibroblasts revealed statistically significant (p ≤ 0.05) differences in cell viability among the membranes at 24 h (p = 0.0002) and 72 h (p = 0.022), demonstrating the biocompatibility of collagen-coated membranes and the minimal cytotoxicity of AgNPs. Antibacterial efficacy was evaluated against Staphylococcus aureus (SA), Pseudomonas aeruginosa (PA), and Vancomycin-resistant Enterococcus (VRE), with the significant inhibition of biofilm formation observed for VRE (p = 0.006). Overall, this novel combination of collagen-coated electrospun PCL nanofibers with AgNPs offers a promising strategy for advanced wound dressings, providing antimicrobial benefits. Future in vivo studies are warranted to further validate its clinical and regenerative potential. Full article

(This article belongs to the Special Issue Recent Progress in Electrospun Membranes)

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20 pages, 8497 KiB

Open AccessArticle

Synthesis and Characterization of Cellulose Acetate—HBA/Poly Sulfone Blend for Water Treatment Applications

by Lamai Alsulaiman, Abir S. Abdel-Naby, Salha Alharthi, Bushra ALabdullatif, Abeer Al-Dossary, Wafa Al-Mughrabi and Yanallah Alqarni

Membranes 2025, 15(2), 38; https://doi.org/10.3390/membranes15020038 - 26 Jan 2025

Abstract

Cellulose acetate (CA) was chemically modified with p–hydrazinobenzoic acid (HBA) for the fabrication of a CA–HBA polymeric membrane. The CA–HBA was characterized using NMR, UV-Vis, and EDX/SEM techniques. CA–HBA exhibited high hydrophilicity, as it included carboxylic groups as well as the hydroxyl group [...] Read more.

Cellulose acetate (CA) was chemically modified with p–hydrazinobenzoic acid (HBA) for the fabrication of a CA–HBA polymeric membrane. The CA–HBA was characterized using NMR, UV-Vis, and EDX/SEM techniques. CA–HBA exhibited high hydrophilicity, as it included carboxylic groups as well as the hydroxyl group of the CA glycosidic ring. The HBA moieties increased the hydrophilicity and the number of active sites inside the CA polymeric matrix, but they did not improve the thermal stability of the polymer, as shown by the thermogravimetry (TGA). Polysulfone (PSF) was blended with CA-HBA in various compositions to produce highly thermal and effective membranes for water treatment applications. The fabricated membranes (CA–HBA/PSF) (5:95) (10:90) (15:85) were found to exhibit high thermal stabilities. The CA–HBA/PSF 15:85 membrane exhibited the highest efficiency towards the removal of Cu (II) ions, while the 5:95 membrane exhibited the highest salt rejection (89%). Full article

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

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20 pages, 8145 KiB

Open AccessArticle

Assessing a Multilayered Hydrophilic–Electrocatalytic Forward Osmosis Membrane for Ammonia Electro-Oxidation

by Perla Cruz-Tato, Laura I. Penabad, César Lasalde, Alondra S. Rodríguez-Rolón and Eduardo Nicolau

Membranes 2025, 15(2), 37; https://doi.org/10.3390/membranes15020037 - 22 Jan 2025

Abstract

Over the years, the ammonia concentration in water streams and the environment is increasing at an alarming rate. Many membrane-based processes have been studied to alleviate this concern via adsorption and filtration. On the other hand, ammonia electro-oxidation is an approach of particular [...] Read more.

Over the years, the ammonia concentration in water streams and the environment is increasing at an alarming rate. Many membrane-based processes have been studied to alleviate this concern via adsorption and filtration. On the other hand, ammonia electro-oxidation is an approach of particular interest owing to its energetic and environmental benefits. Thus, a plausible alternative to combine these two paths is by using an electroconductive membrane (ECM) to complete the ammonia oxidation reaction (AOR). This combination of processes has been studied very limitedly, and it can be an area for development. Herein, we developed a multilayered membrane with hydrophilic and electrocatalytic properties capable of completing the AOR. The porosity of carbon black (CB) particles was embedded in the polymeric support (CBES) and the active side was composed of a triple layer consisting of polyamide/CB/Pt nanoparticles (PA:CB:Pt). The CBES increased the membrane porosity, changed the pores morphology, and enhanced water permeability and electroconductivity. The deposition of each layer was monitored and corroborated physically, chemically, and electrochemically. The final membrane CBES:PA:VXC:Pt reached higher water flux than its PSF counterpart (3.9 ± 0.3 LMH), had a hydrophilic surface (water contact angle: 19.8 ± 0.4°), and achieved the AOR at −0.3 V vs. Ag/AgCl. Our results suggest that ECMs with conductive material in both membrane layers enhanced their electrical properties. Moreover, this study is proof-of-concept that the AOR can be succeeded by a polymeric FO-ECMs. Full article

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

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17 pages, 5813 KiB

Open AccessArticle

Hybrid Version of the Kedem–Katchalsky–Peusner Equations for Diffusive and Electrical Transport Processes in Membrane

by Andrzej Ślęzak and Sławomir M. Grzegorczyn

Membranes 2025, 15(1), 36; https://doi.org/10.3390/membranes15010036 - 20 Jan 2025

Abstract

One of the most important formalisms used to describe membrane transport is Onsager–Peusner thermodynamics (TOP). Within the TOP framework, a procedure has been developed for the transformation of the Kedem–Katchalsky (K–K) equations for the transport of binary electrolytic solutions across a membrane into [...] Read more.

One of the most important formalisms used to describe membrane transport is Onsager–Peusner thermodynamics (TOP). Within the TOP framework, a procedure has been developed for the transformation of the Kedem–Katchalsky (K–K) equations for the transport of binary electrolytic solutions across a membrane into the Kedem–Katchalsky–Peusner (K–K–P) equations. The membrane system with an Ultra Flo 145 Dialyser membrane used for hemodialysis and aqueous NaCl solutions was used as experimental setup. The H version of K–K–P formalism for binary electrolyte solutions was used to evaluate theoretical coefficients characterizing fluxes of energies and efficiencies for membrane transport processes. The coupling coefficients of membrane processes and the dissipative energy flux were calculated on the basis of the Peusner coefficients obtained from transformation of K–K coefficients. The knowledge of dissipative energy flux, which is a function of thermodynamic forces, allows for the determination of the energy conversions during transport processes in a membrane system. In addition, a frictional interpretation of the obtained coefficients is presented. Full article

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

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15 pages, 2566 KiB

Open AccessArticle

Evaluation of Ceramic Membrane Filtration for Alternatives to Microplastics in Cosmetic Formulations Using FlowCam Analysis

by Seung Yeon Kim, Soyoun Kim and Chanhyuk Park

Membranes 2025, 15(1), 35; https://doi.org/10.3390/membranes15010035 - 19 Jan 2025

Abstract

The rapid expansion of the cosmetics industry has significantly increased the adoption of alternative microplastics in response to increasingly stringent global environmental regulations. This study presents a comparative analysis of the treatment performance of silica powder and cornstarch—common alternatives for microplastics in cosmetics—using [...] Read more.

The rapid expansion of the cosmetics industry has significantly increased the adoption of alternative microplastics in response to increasingly stringent global environmental regulations. This study presents a comparative analysis of the treatment performance of silica powder and cornstarch—common alternatives for microplastics in cosmetics—using ceramic membrane filtration combined with flow imaging microscopy (FlowCam) to analyze particle behavior. Bench-scale crossflow filtration experiments were performed with commercially available alumina ceramic membranes. By analyzing high-resolution images from FlowCam, the transport and retention behaviors of the two microplastic alternatives were examined by comparing their morphological properties. Despite their similar particle sizes, the cornstarch demonstrated a higher removal efficiency (82%) than the silica (72%) in the ceramic membrane filtration due to its greater tendency to aggregate. This increased tendency for aggregation suggests that cornstarch may contribute to faster fouling, while the stability and uniformity of silica particles result in less fouling. The FlowCam analysis revealed that the cornstarch particles experienced a slight increase in circularity and compactness over time, likely due to physical swelling and aggregation, while the silica particles retained their shape and structural integrity. These findings highlight the impact of the morphological properties of alternative microplastics on their filtration behavior and fouling potential. Full article

(This article belongs to the Special Issue Ceramic Membranes for Removal of Emerging Pollutants)

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14 pages, 1251 KiB

Open AccessArticle

Enhancing Virus Filter Performance Through Pretreatment by Membrane Adsorbers

by Solomon Isu, Shu-Ting Chen, Raheleh Daneshpour, Hironobu Shirataki, Daniel Strauss, Andrew L. Zydney, Xianghong Qian and Sumith Ranil Wickramasinghe

Membranes 2025, 15(1), 34; https://doi.org/10.3390/membranes15010034 - 17 Jan 2025

Abstract

Virus filtration is used to ensure the high level of virus clearance required in the manufacture of biopharmaceutical products such as monoclonal antibodies. Flux decline during virus filtration can occur due to the formation of reversible aggregates consisting of self-assembled monomeric monoclonal antibody [...] Read more.

Virus filtration is used to ensure the high level of virus clearance required in the manufacture of biopharmaceutical products such as monoclonal antibodies. Flux decline during virus filtration can occur due to the formation of reversible aggregates consisting of self-assembled monomeric monoclonal antibody molecules, particularly at high antibody concentrations. While size exclusion chromatography is generally unable to detect these reversible aggregates, dynamic light scattering may be used to determine their presence. Flux decline during virus filtration may be minimized by pretreating the feed using a membrane adsorber in order to disrupt the reversible aggregates that are present. The formation of reversible aggregates is highly dependent on the monoclonal antibody and the feed conditions. For the pH values investigated here, pretreatment of the feed using a hydrophobic interaction membrane adsorber was the most effective in minimizing flux decline during virus filtration. Ion exchange membranes may also be effective if the monoclonal antibody and membrane are oppositely charged. Consequently, the effectiveness of ion exchange membrane adsorbers is much more dependent on solution pH when compared to hydrophobic interaction membrane adsorbers. Size based prefiltration was found to be ineffective at disrupting these reversible aggregates. These results can help guide the development of more effective virus filtration processes for monoclonal antibody production. Full article

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

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18 pages, 2710 KiB

Open AccessArticle

Reverse Osmosis Coupled with Ozonation for Clean Water Recovery from an Industrial Effluent: Technical and Economic Analyses

by Ivette Montero-Guadarrama, Claudia Muro Urista, Gabriela Roa-Morales, Edith Erialia Gutiérrez Segura, Vianney Díaz-Blancas, Germán Eduardo Dévora-Isiordia and Jesús Álvarez-Sánchez

Membranes 2025, 15(1), 33; https://doi.org/10.3390/membranes15010033 - 16 Jan 2025

Abstract

Technical and economic criteria were used to evaluate the feasibility of the treatment of an industrial effluent (10 m³/h) for water recovery and reuse. The treatment evaluation included the following: (1) effluent characteristic determination; (2) selection and evaluation of the effluent [...] Read more.

Technical and economic criteria were used to evaluate the feasibility of the treatment of an industrial effluent (10 m³/h) for water recovery and reuse. The treatment evaluation included the following: (1) effluent characteristic determination; (2) selection and evaluation of the effluent treatment at lab scale, establishing operating conditions and process efficiency; (3) scaling up the treatment process to the industrial level; (4) treatment plant design and commercial availability analysis of the required equipment; and (5) the costs of the inversion and operation of the plant treatment, cost/m³ for water recovery, and time of investment recovery. The physicochemical characteristics of the effluent exposed the polluted wastewater with sodium chloride salts and colourants, predominating a mixture of tartrazine, Red 40, and brilliant blue from the synthesis of food additives. Other contributions of organic compounds and salts could be in minor content. According to the effluent conditions, a coupled process, integrated with ozonation and reverse osmosis, was indicated to be a treatment for water recovery. Scaling up the plant treatment design resulted in 130 m² of area, producing 7.7 m³/h of clean water. The cost of the effluent treatment was 1.4 USD/m³, with an inversion return of 3.4 years and cost investment of USD 860,407. The treatment process resulted a viable project for water recovery. Full article

(This article belongs to the Special Issue Current Research into Membranes in Water Desalination Technology and Engineering)

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14 pages, 3431 KiB

Open AccessArticle

Spacer Designs for Improved Hydrodynamics and Filtration Efficiency in Sea Water Reverse Osmosis

by Sarah Kerdi, Adnan Qamar, Henry J. Tanudjaja and Noreddine Ghaffour

Membranes 2025, 15(1), 32; https://doi.org/10.3390/membranes15010032 - 16 Jan 2025

Abstract

Reverse osmosis (RO) filtration performance is heavily influenced by the design of the feed spacer. Spacer design impacts hydrodynamic patterns within the system, affecting water production and concentration polarization. Two spacer designs, namely pillar (P) and standard (S), were investigated to improve the [...] Read more.

Reverse osmosis (RO) filtration performance is heavily influenced by the design of the feed spacer. Spacer design impacts hydrodynamic patterns within the system, affecting water production and concentration polarization. Two spacer designs, namely pillar (P) and standard (S), were investigated to improve the performance of a commercially available spacer design (C) in the RO process. Two approaches were employed to evaluate spacer performance. First, direct numerical simulation (DNS) was utilized to fundamentally understand the hydrodynamics generated by each spacer design. Second, laboratory RO experiments were conducted to confirm the simulation results. The P and S spacers induced higher flow velocity and vorticity than the C spacer, as confirmed by simulations and experiments. Reduced dead zones were also demonstrated using P and S spacers. However, the standard spacer design exhibited a clear advantage in promoting more efficient mixing within the filtration channels. This enhanced mixing substantially reduced salt concentration at the membrane surface, improving the filtration performance. In agreement with the permeation velocity computation, the S spacer achieved the highest improvement (13%) in both flux yield and specific flux relative to the C spacer. This finding confirms the S spacer’s ability to enhance RO performance while reducing energy consumption. Full article

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

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20 pages, 13636 KiB

Open AccessArticle

Cross-Linked Self-Standing Graphene Oxide Membranes: A Pathway to Scalable Applications in Separation Technologies

by Juan A. G. Carrio, Vssl Prasad Talluri, Swamy T. Toolahalli, Sergio G. Echeverrigaray and Antonio H. Castro Neto

Membranes 2025, 15(1), 31; https://doi.org/10.3390/membranes15010031 - 15 Jan 2025

Abstract

The large-scale implementation of 2D material-based membranes is hindered by mechanical stability and mass transport control challenges. This work describes the fabrication, characterisation, and testing of self-standing graphene oxide (GO) membranes cross-linked with oxides such as Fe₂O₃, Al₂ [...] Read more.

The large-scale implementation of 2D material-based membranes is hindered by mechanical stability and mass transport control challenges. This work describes the fabrication, characterisation, and testing of self-standing graphene oxide (GO) membranes cross-linked with oxides such as Fe₂O₃, Al₂O₃, CaSO₄, Nb₂O₅, and a carbide, SiC. These cross-linking agents enhance the mechanical stability of the membranes and modulate their mass transport properties. The membranes were prepared by casting aqueous suspensions of GO and SiC or oxide powders onto substrates, followed by drying and detachment to yield self-standing films. This method enabled precise control over membrane thickness and the formation of laminated microstructures with interlayer spacings ranging from 0.8 to 1.2 nm. The resulting self-standing membranes, with areas between 0.002 m² and 0.090 m² and thicknesses from 0.6 μm to 20 μm, exhibit excellent flexibility and retain their chemical and physical integrity during prolonged testing in direct contact with ethanol/water and methanol/water mixtures in both liquid and vapour phases, with stability demonstrated over 24 h and up to three months. Gas permeation and chemical characterisation tests evidence their suitability for gas separation applications. The interactions promoted by the oxides and carbide with the functional groups of GO confer great stability and unique mass transport properties—the Nb₂O₅ cross-linked membranes present distinct performance characteristics—creating the potential for scalable advancements in cross-linked 2D material membranes for separation technologies. Full article

(This article belongs to the Special Issue Graphene Oxide Membrane for Sustainable Energy and Environmental Applications)

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12 pages, 5296 KiB

Open AccessArticle

A Study on the Safety and Efficacy of an Innovative Hydrophilic Dialysis Membrane

by Francisco Maduell, Victor Joaquín Escudero-Saiz, Elena Cuadrado-Payán, Maria Rodriguez-Garcia, Miquel Gómez, Lida María Rodas, Néstor Fontseré, Maria del Carmen Salgado, Gregori Casals, Nayra Rico and José Jesús Broseta

Membranes 2025, 15(1), 30; https://doi.org/10.3390/membranes15010030 - 14 Jan 2025

Abstract

The dialysis membrane based on a hydrophilic polymer (Hydrolink NV) was designed to enhance the movement of adsorbed water at the blood–membrane interface, aiming to achieve antithrombogenic and antifouling effects. This study aimed to assess the performance and albumin loss of the Hydrolink [...] Read more.

The dialysis membrane based on a hydrophilic polymer (Hydrolink NV) was designed to enhance the movement of adsorbed water at the blood–membrane interface, aiming to achieve antithrombogenic and antifouling effects. This study aimed to assess the performance and albumin loss of the Hydrolink NV dialyzer in hemodialysis (HD) and post-dilution hemodiafiltration (HDF) with different infusion flows (Qis) and compare it with the hydrophilic FX CorAL dialyzer in post-dilution HDF. A prospective study was carried out in 20 patients. Patients underwent five dialysis sessions with the same routine dialysis parameters: four sessions with the Toraylight NV 2.1 (HD, post-dilution HDF with 50, 75 or auto-substitution Qi) and one with the FX CorAL 800 (post-dilution HDF with auto-substitution Qi). The reduction ratios’ (RRs’) wide range of molecular weight molecules were assessed and the dialysate albumin loss was quantified. The lowest β₂-microglobulin, indoxyl-sulfate, and p-cresyl sulfate RR values were observed with the Toraylight NV 2.1 in HD, and they improved progressively with an increased Qi, without differences being observed between the two dialyzers in auto-substitution. A different removal profile was observed in terms of myoglobin, kFLC, prolactin, α₁-microglobulin, α₁-acid glycoprotein, and λFLC, whose RRs also improved progressively with an increased Qi but were significantly higher with the Toraylight NV than the CorAL in the same convective condition. There were significant differences in the albumin dialysate losses, with the highest value obtained with the Toraylight NV in auto-substitution HDF, with more than 50% of patients surpassing 5 g per session. The Toraylight NV dialyzer has great potential for efficacy but should be used at the optimal convective volume (Qi not exceeding 75 mL/min or FF not exceeding 25%) to avoid excessive albumin loss. Full article

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

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23 pages, 1609 KiB

Open AccessReview

Intracellular Membrane Contact Sites in Skeletal Muscle Cells

by Matteo Serano, Stefano Perni, Enrico Pierantozzi, Annunziatina Laurino, Vincenzo Sorrentino and Daniela Rossi

Membranes 2025, 15(1), 29; https://doi.org/10.3390/membranes15010029 - 14 Jan 2025

Abstract

Intracellular organelles are common to eukaryotic cells and provide physical support for the assembly of specialized compartments. In skeletal muscle fibers, the largest intracellular organelle is the sarcoplasmic reticulum, a specialized form of the endoplasmic reticulum primarily devoted to Ca²⁺ storage [...] Read more.

Intracellular organelles are common to eukaryotic cells and provide physical support for the assembly of specialized compartments. In skeletal muscle fibers, the largest intracellular organelle is the sarcoplasmic reticulum, a specialized form of the endoplasmic reticulum primarily devoted to Ca²⁺ storage and release for muscle contraction. Occupying about 10% of the total cell volume, the sarcoplasmic reticulum forms multiple membrane contact sites, some of which are unique to skeletal muscle. These contact sites primarily involve the plasma membrane; among these, specialized membrane contact sites between the transverse tubules and the terminal cisternae of the sarcoplasmic reticulum form triads. Triads are skeletal muscle-specific contact sites where Ca²⁺ channels and regulatory proteins assemble to form the so-called calcium release complex. Additionally, the sarcoplasmic reticulum contacts mitochondria to enable a more precise regulation of Ca²⁺ homeostasis and energy metabolism. The sarcoplasmic reticulum and the plasma membrane also undergo dynamic remodeling to allow Ca²⁺ entry from the extracellular space and replenish the stores. This process involves the formation of dynamic membrane contact sites called Ca²⁺ Entry Units. This review explores the key processes in biogenesis and assembly of intracellular membrane contact sites as well as the membrane remodeling that occurs in response to muscle fatigue. Full article

(This article belongs to the Section Biological Membranes)

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2 pages, 283 KiB

Open AccessCorrection

Correction: Robertson et al. Al³⁺ Modification of Graphene Oxide Membranes: Effect of Al Source. Membranes 2022, 12, 1237

by Ellen J. Robertson, Yijing Y. Stehle, Xiaoyu Hu, Luke Kilby, Katelyn Olsson, Minh Nguyen and Rebecca Cortez

Membranes 2025, 15(1), 28; https://doi.org/10.3390/membranes15010028 - 14 Jan 2025

Abstract

The authors wish to make a correction to the published paper [...] Full article

13 pages, 5339 KiB

Open AccessArticle

Recovery of Iodine in the Gaseous Phase Using the Silicone Hollow Fiber Membrane Module

by Yoshio Yamabe, Naotake Takahashi, Jun Sawai, Tamotsu Minami, Mikio Kikuchi and Toshimitsu Ishii

Membranes 2025, 15(1), 27; https://doi.org/10.3390/membranes15010027 - 13 Jan 2025

Abstract

Iodine, being an important resource, must be recovered and reused. Iodine is not only attracted to the hydrophobic silicone membrane but also easily vaporized. In this study, we explored the use of five types of silicone hollow fiber membrane modules (SFMMs) for separating [...] Read more.

Iodine, being an important resource, must be recovered and reused. Iodine is not only attracted to the hydrophobic silicone membrane but also easily vaporized. In this study, we explored the use of five types of silicone hollow fiber membrane modules (SFMMs) for separating iodine in the gaseous phase. In the SFMM, iodine gas and the recovery solution (sodium sulfite and sodium carbonate at a concentration of 10 mM each) were flowed outside and inside the silicone hollow fiber, respectively, in a co-current-flow manner. At an iodine gas flow rate of 0.2 L/min (8.4 × 10⁻³ mmol-I₂/L), the capture efficiency of iodine into the SFMM was approximately 100% for all five SFMMs. With increasing feed gas flow rates, the capture efficiency of iodine decreased, reducing to approximately 50% at 0.8 L/min. However, the recovery efficiency of iodine in the recovery solution was 60–30% at 0.2–0.8 L/min. This decrease in capture efficiency with increasing flow rates was because iodine could not spread and diffuse successfully in the SFMM, resulting in a low recovery efficiency of iodine. Thus, we next improved the structure of the SFMM by placing a perforated pipe in the center of the module. The perforated pipe effectively directs the iodine feed gas from the holes in the pipe to the hollow fiber membrane bundle wrapped around the pipe. With the improved SFMM, the capture efficiency markedly increased to approximately 100% in the range of the flow rates tested in our experiments. The recovery efficiency also increased to ≥70%. These data illustrate the potential application of the improved SFMM for recovering iodine in the gaseous phase. Full article

(This article belongs to the Special Issue Hollow Fiber Membranes for Gas and Vapor Separation: Fundamentals, State-of-the-Art, and Recent Advancements)

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19 pages, 6147 KiB

Open AccessArticle

Simultaneously Enhanced Permeability and Selectivity of Pebax-1074-Based Mixed-Matrix Membrane for CO₂ Separation

by Rujing Hou, Junwei Xie, Yawei Gu, Lei Wang and Yichang Pan

Membranes 2025, 15(1), 26; https://doi.org/10.3390/membranes15010026 - 13 Jan 2025

Abstract

Membrane technology is a promising methodology for carbon dioxide separation due to its benefit of a small carbon footprint. However, the trade-off relationship between gas permeability and selectivity is one obstacle to limiting its application. Herein, branched polyethyleneimine (BPEI) containing a rich amino [...] Read more.

Membrane technology is a promising methodology for carbon dioxide separation due to its benefit of a small carbon footprint. However, the trade-off relationship between gas permeability and selectivity is one obstacle to limiting its application. Herein, branched polyethyleneimine (BPEI) containing a rich amino group was successfully grafted on the surface of the metal–organic framework (MOF) of AIFFIVE-1-Ni (KAUST-8) through coordination between N in BPEI and open metal sites in the MOF and with the resultant maintained BET surface area and pore volume. Both the strengthened CO₂ solubility coefficients coming from the additional CO₂ adsorption sites of amino groups in BPEI and the reinforced CO₂ diffusivity coefficients originating from the fast transport channels created by KAUST-8 led to the promising CO₂ separation performance for KAUST-8@BPEI/Pebax-1074 MMM. With 5 wt.% KAUST-8@BPEI loading, the MMM showed the CO₂ permeability of 156.5 Barrer and CO₂/N₂ selectivity of 16.1, while the KAUST-8-incorporated MMM (5 wt.% loading) only exhibited the CO₂ permeability of 86.9 Barrer and CO₂/N₂ selectivity of 13.0. Such enhancement is superior to most of the reported Pebax-1074-based MMMs for CO₂ separation indicating a wide application for the coordination method for MOF fillers with open metal sites. Full article

(This article belongs to the Special Issue Advanced Membrane Materials for CO₂ Capture and Separation)

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15 pages, 3138 KiB

Open AccessArticle

Large-Area Clay Composite Membranes with Enhanced Permeability for Efficient Dye/Salt Separation

by Yixuan Fu, Shuai Wang, Huiquan Liu, Ke Zhang, Lunxiang Zhang, Yongchen Song and Zheng Ling

Membranes 2025, 15(1), 25; https://doi.org/10.3390/membranes15010025 - 13 Jan 2025

Abstract

The escalating discharge of textile wastewater with plenty of dye and salt has resulted in serious environmental risks. Membranes assembled from two-dimensional (2D) nanomaterials with many tunable interlayer spacings are promising materials for dye/salt separation. However, the narrow layer spacing and tortuous interlayer [...] Read more.

The escalating discharge of textile wastewater with plenty of dye and salt has resulted in serious environmental risks. Membranes assembled from two-dimensional (2D) nanomaterials with many tunable interlayer spacings are promising materials for dye/salt separation. However, the narrow layer spacing and tortuous interlayer transport channels of 2D-material-based membranes limit the processing capacity and the permeability of small salt ions for efficient dye/salt separation. In this work, a novel sepiolite/vermiculite membrane was fabricated using Meyer rod-coating and naturally occurring clay. The intercalation of sepiolite Nanofibers between vermiculite Nanosheets provides additional transport nanochannels and forms looser permeable networks, producing composite membranes with remarkably enhanced flux. As a result, the optimized membranes with 80% sepiolite exhibit remarkable flux as high as 78.12 LMH bar⁻¹, outstanding dye rejection (Congo Red~98.26%), and excellent selectivity of dye/salt of 10.41. In addition, this novel all-clay composite membrane demonstrates stable separation performance under acidity, alkalinity and prolonged operation conditions. The large-scale sepiolite/vermiculite membranes made by the simple proposed method using low-cost materials provide new strategies for efficient and environmentally-friendly dye/salt separation. Full article

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

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