Membranes最新文献

Per- and polyfluoroalkyl substances (PFAS) represent a class of highly persistent environmental contaminants with exceptional chemical stability. Efficient removal of PFAS from water poses a significant challenge for the chemical industry and constitutes a critical requirement for sustainable environmental development. Membrane technology has demonstrated considerable potential in water treatment due to its low energy consumption and environmentally friendly characteristics. This review comprehensively summarizes recent advances in emerging metal-organic framework (MOF)-, covalent organic framework (COF)-, and hydrogen-bonded organic framework (HOF)-based membranes for highly efficient separation and catalytic degradation of PFAS. We provide a detailed analysis of design strategies for various organic framework membranes (OFMs) and their synergistic separation mechanisms, including size exclusion, electrostatic interactions, adsorption, as well as catalytic degradation based on advanced oxidation processes. Furthermore, we systematically evaluate the performance and applicability of these membranes in practical aquatic environments. Finally, this review outlines future directions toward developing integrated "separation-degradation" membrane processes for practical applications by discussing current challenges concerning material stability, manufacturing costs, and long-term operational efficiency. This review aims to provide theoretical guidance and technical insights for developing next-generation high-performance membranes for PFAS removal.

Chronic wounds remain locked in persistent inflammation with high microbial burden, demanding dressings that suppress infection without sacrificing biocompatibility. Bacterial nanocellulose (BNC) is an attractive matrix due to its biocompatibility, nanofibrillar architecture, and moisture retention, but it lacks antimicrobial activity. Here, we engineer BNC membranes post-functionalized with functionalized graphite (f-Gr; predominantly graphitic with residual surface groups) and/or niobium pentoxide (Nb₂O₅), and evaluate four groups: BNC (matrix control), BNC/Nb₂O₅, BNC/f-Gr, and BNC/f-Gr/Nb₂O₅. Physicochemical analyses (Raman and Voigt fitting, FTIR-ATR, XRD, and SEM) confirm a graphitic carbon phase and physical incorporation of the modifiers into the BNC network, with a noticeable shift in the hydration/polarity profile-more evident in the presence of f-Gr. In standardized microbiological assays, BNC/f-Gr promoted a moderate, contact-dependent reduction in bacterial proliferation, particularly against Staphylococcus aureus, whereas BNC/Nb₂O₅ behaved similarly to pristine BNC under the tested conditions. The combined f-Gr/Nb₂O₅ formulation showed an intermediate antimicrobial response, with no clear synergy beyond f-Gr alone. Cytotoxicity assays indicated cytocompatibility for BNC, BNC/f-Gr, and BNC/Nb₂O₅; the combined group displayed a slight reduction that remained within acceptable limits. Overall, BNC/f-Gr emerges as the most promising antimicrobial dressing, while Nb₂O₅ did not significantly enhance antimicrobial performance under the tested conditions and warrants further optimization regarding loading and distribution.

Anion exchange membranes (AEMs) play a vital role in the performance of water electrolyzers and fuel cells, yet their discovery and optimization remain challenging due to the complexity of structure-property relationships. In this study, we introduce a machine learning framework that leverages conditional graph neural networks (cGNNs) and descriptor-based models and a hybrid graph neural network (HGARE) to predict and interpret ionic conductivity. The descriptor-based pipeline employs principal component analysis (PCA), ablation, and SHAP analysis to identify factors governing anion conductivity, revealing electronic, topological, and compositional descriptors as key contributors. Beyond prediction, dimensionality reduction and clustering are performed by employing t-SNE and KMeans as well as SOM, which reveal distinct membranes clusters, some of which were enriched with high anion conductivity. Among graph-based approaches, the graph convolutional (GCN) achieved strong predictive performance, while the Hybrid Graph Autoencoder-Regressor Ensemble (HGARE) achieved the highest accuracy. Additionally, atom-level saliency maps from GCN provide spatial explanations for conductive behavior, revealing the importance of polarizable and flexible regions. This work contributes to the accelerated and data-driven design of high-performance AEMs.

Nitrogen, a prevalent water pollutant, is a major cause of eutrophication and the formation of black, odorous water bodies, posing significant threats to both ecological security and human health. Effectively controlling nitrogen pollution in wastewater is therefore essential for preserving aquatic ecosystems. The membrane bioreactor (MBR), which integrates the advantages of biological and membrane technologies, has attracted considerable attention for its application potential in wastewater nitrogen removal. This article elucidates the mechanisms and characteristics of nitrogen removal in MBR systems based on the latest research advancements. It provides an in-depth analysis of the key environmental factors affecting nitrogen removal efficiency and comprehensively summarizes enhanced processes centered on MBR technology. Furthermore, the article addresses corresponding strategies for mitigating MBR membrane fouling and offers suggestions and prospects for future research directions.

Efficient water recycling in the hydrometallurgical industry requires the dewatering of hypersaline Na₂SO₄ or similar brines via non-evaporative methods. Unfortunately, many non-evaporative methods require the use of specific solutes and are not compatible with complex hydrometallurgical effluents. Forward Osmosis (FO) uses a draw solution to link known non-evaporative water recycling methods with feed solutions that are otherwise incompatible. There is minimal experimental data on the dewatering performance of today's available commercial FO membranes, especially with hypersaline concentrations (>70,000 mg/L total dissolved solids). This study tests the commercially available Aquaporin HFFO2 hollow fibre FO membrane module with hypersaline Na₂SO₄ or NaCl feed solutions versus a MgCl₂ draw solution. It identifies a key requirement to maintain water flux above a certain threshold to prevent a decrease in Na Rejection or an increase in Mg reverse flux. It also defines a minimum osmotic differential that can be used to parameterize water flux, similar to the temperature of approach in heat exchangers, but to determine the extent of water removal in FO. We demonstrate that even under mildly acidic conditions, existing FO membranes can concentrate Na₂SO₄ to saturation, paving the way for their use in the hydrometallurgical industry.

Chronic and complex wounds require biomaterials that are both cytocompatible and antimicrobial. Herein, electrospun polycaprolactone (PCL) nanofiber membranes were coated with Type I collagen and functionalized with silver nanoparticles (AgNPs). The main objective was to assess fibroblast adhesion, proliferation, and cytotoxicity. Membrane morphology and surface characteristics were analyzed in a previous work by SEM, AFM, and wettability measurements, confirming the transformation from hydrophobic PCL to fully wettable collagen-coated surfaces. In this study, Murine 3T3 fibroblasts were cultured on PCL, PCL-Collagen, PCL-Collagen-Citrate, and PCL-Collagen-AgNPs membranes. Cellular activity was quantified using Alamar Blue assays at 24, 48, and 72 h, while cytotoxicity was determined by LDH release. Cellular viability and adhesion were studied using confocal microscopy. All membrane types supported fibroblast growth, with collagen-coated samples exhibiting the highest metabolic activity. AgNPs-functionalized membranes sustained overall cell viability above 90%, with cytotoxicity values of approximately 10% at 24 h and 20% at 48 h. Antimicrobial evaluations demonstrated complete inhibition of Pseudomonas aeruginosa and vancomycin-resistant Enterococcus, and partial inhibition of Staphylococcus aureus. These results indicate that collagen-coated, AgNPs-functionalized electrospun PCL membranes exhibit both high cytocompatibility and significant antimicrobial activity, supporting their potential as advanced wound-dressing materials.

Many biomedical applications require a detailed understanding of the action of antimicrobial peptides on biological membranes. The cationic hemolytic peptide melittin, a major component of European honey bee (Apis mellifera) venom, is considered a model for elucidating lipid-protein interactions that are important for the function of biological systems. Here, we address the surface properties of human erythrocytes and rat liver mitochondrial membranes under in vitro melittin treatment. These membranes are negatively charged at neutral pH and represent primary targets of melittin's effects in the onset of inflammatory diseases. The correlation between the functional activity of membrane systems and their surface electrical charge was assessed using microelectrophoresis, hemolysis assays, membrane transport measurements, lipid peroxidation analysis, and fluorescence microscopy. A mechanistic hypothesis for the divergent effects of sub-lytic, pre-pore doses of melittin on erythrocytes and mitochondria is discussed. At low concentrations, melittin interacts electrostatically with erythrocyte membranes, resulting in altered proton transport through the Band 3 protein. Melittin also induces changes in erythrocyte morphology and malondialdehyde content, as well as aggregation of mitochondrial vesicles. The electrokinetic mechanism of melittin action, associated with membrane stability, provides a novel perspective on its potential relevance to biomedical applications.

Ammonia (NH₃) recovery from animal manure offers both environmental and economic benefits by reducing nitrogen emissions and producing valuable fertilisers. Hollow fibre membrane contactors (HFMCs) are a promising technology for this purpose, yet their performance is strongly influenced by the complex composition of manure. In this study, the effects of solids concentration and organic foulants concentration on the mass transfer coefficients governing NH₃ recovery were systematically investigated. Total suspended solids (TSS) were reduced through graded filtration, and protein concentrations in the ammonium solutions were quantified to assess their role in limiting mass transfer. Results showed that TSS concentration primarily affected the shell-side film resistance. After extensive filtration, residual proteins attached to the membrane surface induced partial wetting, thereby reducing the effective membrane mass transfer coefficient. Using a penalty function approach, it was possible to separately describe TSS- and protein-related resistances, enabling improved prediction of effective model coefficients under real world conditions. These findings highlight the dual importance of solid-liquid separation and protein management in optimising HFMC operation for NH₃ recovery and provide a framework for up-scaling the technology in agricultural nutrient management systems.

In a standard diffuser system in a membrane bioreactor (MBR), uneven air distribution scouring the membrane surface causes transmembrane pressure to reach its ultimate value earlier, which requires membrane cleaning more frequently. In this study, a Venturi-integrated innovative diffuser design is proposed to improve membrane bioreactor (MBR) technology. The proposed design aims to increase filtration efficiency by creating a homogeneous scouring effect on the membrane surface. To compare the performance of the proposed diffuser configuration (V-MBR) with that of a conventional diffuser (S-MBR), computational fluid dynamics models were established for each of the two configurations. The results showed that the V-MBR model produced about 50% higher average shear stress on the membrane surfaces. Statistical analysis also showed that the V-MBR model generally produced low variance and non-zero shear stress values. Along with shear stress distribution, other parameters such as volume fraction, velocity, turbulent kinetic energy, and turbulent eddy distribution were evaluated to compare the performance of two diffuser system configurations. These parameters also supported the superior performance of the new V-MBR model over the conventional S-MBR. It is concluded that homogeneous shear stress distribution on the membrane surface is an important parameter that increases filtration efficiency by preventing the formation of dead zones.

In bipolar membrane electrodialysis (BPED), proton transport through the anion-exchange membrane (AEM) is a major factor that reduces overall process efficiency. In this study, we propose a composite AEM incorporating a proton-blocking layer that combines strongly basic and weakly basic functional groups on top of a strongly basic AEM, providing proton-blocking capability while minimizing degradation of membrane conductivity. The proton-blocking layer is prepared by reacting brominated poly(phenylene oxide) (BPPO) with diamines having different alkyl chain lengths, namely N,N,N',N'-tetramethyl-1,6-hexanediamine (TMHDA), N,N,N',N'-tetramethyl-1,3-propanediamine (TMPDA), and N,N,N',N'-tetramethylethylenediamine (TMEDA). When TMHDA, which has the longest alkyl chain, is introduced into PPO, the resulting membrane exhibits high conductivity but low proton-blocking performance. In contrast, when TMEDA, which has the shortest alkyl chain, is introduced, the membrane shows low conductivity and high proton-blocking performance. Therefore, the balance between membrane conductivity and proton-blocking performance can be optimized by adjusting the molar ratio of the two diamines. The composite AEM prepared with the optimal composition simultaneously demonstrates superior conductivity and proton-blocking performance compared to the commercial proton-blocking membrane (ACM, Astom Corp., Tokyo, Japan). Furthermore, the application of this membrane has been shown to effectively improve both the energy efficiency and current efficiency of the BPED process for lithium hydroxide recovery.