Membranes

27 pages, 30466 KiB

Open AccessArticle

Electrospun Membranes Loaded with Melanin Derived from Pecan Nutshell (Carya illinoinensis) Residues for Skin-Care Applications

by Michell García-García, Jesús Salvador Jaime-Ferrer, Fernanda Nayeli Medrano-Lango, Elizabeth Quintana-Rodríguez, Tonatiu Campos-García, Erika Rodríguez-Sevilla and Domancar Orona-Tamayo

Membranes 2025, 15(2), 44; https://doi.org/10.3390/membranes15020044 (registering DOI) - 3 Feb 2025

Abstract

This study investigates the incorporation of melanin extracted from pecan nutshell residues into a polyacrylonitrile (PAN) matrix during the electrospinning of microfiber membranes. Melanin concentrations of 0.5, 2.0, and 5.0% w/w were incorporated to enhance the physicochemical and biological properties of [...] Read more.

This study investigates the incorporation of melanin extracted from pecan nutshell residues into a polyacrylonitrile (PAN) matrix during the electrospinning of microfiber membranes. Melanin concentrations of 0.5, 2.0, and 5.0% w/w were incorporated to enhance the physicochemical and biological properties of the fibers. The melanin-loaded PAN fibers exhibited significant antioxidant activity against DPPH and ABTS radicals, with scavenging rates ranging from 46.58% to 62.77% and 41.02% to 82.36%, respectively, while unmodified PAN fibers showed no activity. Furthermore, the melanin-loaded membranes demonstrated antimicrobial effects. The membranes also exhibited an important enzyme inhibition activity against collagenase (37%), hyaluronidase (22%), tyrosinase (36%), and elastase (33%). Molecular docking studies reveal different potential amino acids of the active sites of aging enzymes that interact strongly with melanin pigment, particularly collagenase, followed by hyaluronidase, tyrosinase, and elastase. These results suggest that the novel melanin-loaded PAN membranes possess promising bioactive properties with potential applications in different skin-care applications. Full article

(This article belongs to the Special Issue Recent Advances in Polymeric Membranes—Preparation and Applications)

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28 pages, 1935 KiB

Open AccessReview

Use of Membrane Techniques for Removal and Recovery of Nutrients from Liquid Fraction of Anaerobic Digestate

by Magdalena Zielińska and Katarzyna Bułkowska

Membranes 2025, 15(2), 45; https://doi.org/10.3390/membranes15020045 - 2 Feb 2025

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Abstract

This review focuses on the use of membrane techniques to recover nutrients from the liquid fraction of digestate (LFD) and emphasizes their role in promoting the principles of the circular economy. A range of membrane separation processes are examined, including microfiltration (MF), ultrafiltration [...] Read more.

This review focuses on the use of membrane techniques to recover nutrients from the liquid fraction of digestate (LFD) and emphasizes their role in promoting the principles of the circular economy. A range of membrane separation processes are examined, including microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), forward osmosis (FO), membrane distillation (MD) and new tools and techniques such as membrane contactors (MCs) with gas-permeable membranes (GPMs) and electrodialysis (ED). Key aspects that are analyzed include the nutrient concentration efficiency, integration with biological processes and strategies to mitigate challenges such as fouling, high energy requirements and scalability. In addition, innovative hybrid systems and pretreatment techniques are examined for their potential to improve the recovery rates and sustainability. The review also addresses the economic and technical barriers to the full-scale application of these technologies and identifies future research directions, such as improving the membrane materials and reducing the energy consumption. The comprehensive assessment of these processes highlights their contribution to sustainable nutrient management and bio-based fertilizer production. Full article

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

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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 - 2 Feb 2025

Viewed by 255

Abstract

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 - 1 Feb 2025

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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 - 1 Feb 2025

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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 - 1 Feb 2025

Viewed by 256

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 - 1 Feb 2025

Viewed by 373

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

Viewed by 519

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

Viewed by 736

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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Membranes, Volume 15, Issue 2 (February 2025) – 9 articles

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