Membranes最新文献

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

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

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

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

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

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

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

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

This study evaluates the partial dealcoholization of red wine using reverse osmosis (ACM3) and nanofiltration (TS80) membranes at 25 and 35 bar, targeting 2% and 4% ethanol reductions. Membrane performance was assessed through fouling analysis and ethanol partitioning, while wine phenolic (flavan-3-ols, anthocyanins) and color characteristics (CIELab parameters) were determined. The 2% reduction process with ACM3 at 25 bar resulted in minimal phenolic changes. The 4% reduction process revealed distinct performance profiles: ACM3 exhibited exceptional stability (3.35-5.30% permeability loss, linear flux decline with R² > 0.93) and ethanol rejection of 17.6-25.5%, while TS80 achieved processing rates three to six times faster with moderate fouling (16.3% loss, 7.7-13.3% rejection). Decreases in flavan-3-ols and anthocyanin concentrations correlated with fouling intensity rather than processing duration. Proanthocyanidin structure remained stable, and color shifts reflected changes in polymeric pigments rather than anthocyanin loss. Reverse osmosis at low transmembrane pressure proved most suitable for quality preservation. The operational trade-off is clear: TS80 offers three to six times faster processing but with greater phenolic loss, while ACM3 requires longer batch times with minimal fouling. Both processes demonstrate that membrane-based dealcoholization without fluid replacement is feasible, providing winemakers with a valuable method to reduce alcohol while preserving quality.

Fabricating polyimide (PI) membranes with outstanding anti-plasticization ability and gas separation performance remains a challenge. In this study, two novel diamine monomers, DAMBO (methyl 3,5-diamino-4-methylbenzoate) and DAPGBO (3-hydroxypropyl 3,5-diamino-4-methylbenzoate), were synthesized through esterification reactions. Then, we copolymerized each of these two new monomers with 4,4'-diaminodiphenylmethane (DAM) and 4,4'-(Hexafluoroisopropylidene) diphthalic anhydride (6FDA) separately to yield two monoesterified PIs. Following this, we further prepared the ester-crosslinked PIs by inducing a transesterification crosslinking reaction within the PI-PGBO membrane via thermal treatment. As expected, we found that the formation of cross-linked structures can effectively regulate the microporous structure, enhance its sieving performance, and thus improve the membrane's gas selectivity. Furthermore, the resulting network structure endowed the thermally treated PI membrane with excellent anti-plasticization ability. Physical characterization results show that after heat treatment, both the d-spacing and BET surface area of the PI membrane decreased, but the solvent resistance of the thermally treated PIs was significantly improved. Gas separation experiments revealed that the representative membrane (PI-PGBO-300) exhibited the optimal CO₂/CH₄ separation performance, with a CO₂ permeability of 371.05 Barrer, a CO₂/CH₄ selectivity of 28.11, and a CO₂ plasticization pressure exceeding 30 bar. This study provides valuable insights into the design of cross-linked polyimides (PIs) via transesterification reactions, which are capable of enhancing the performance of membrane-based gas separation processes.