Membrane Performance Research Articles

Multifunctional Biological Performance of Electrospun PCL Scaffolds Formulated with Silver Sulfide Nanoparticles

Our work describes the green synthesis of silver sulfide nanoparticles (Ag2S NPs) and their formulation into polycaprolactone fibers (PCL), aiming to improve the multifunctional biological performance of PCL membranes as scaffolds. For this purpose, an extract of rosemary (Salvia rosmarinus) was employed as a reducing agent for the Ag2S NPs, obtaining irregular NPs and clusters of 5–60 nm, with a characteristic SPR absorption at 369 nm. Ag2S was successfully incorporated into PCL fibers by electrospinning using heparin (HEP) as a stabilizer/biocompatibility agent, obtaining nanostructured fibers with a ca. 500–800 nm diameter. Different amounts of Ag2S NPs (0.05, 0.5, and 1 wt.%) enhanced the nanostructured membranes’ surface polarity and mechanical performance, with a controlled ion release after 6 days submerged in PBS solution, determined by cyclic voltammetry. As a result, PCL/HEP/Ag2S scaffolds exhibit high antibacterial performance (80–90%) at early stages of contact (3 h) against E. coli and S. aureus. Also, cytotoxicity analysis demonstrated that the nanostructured membranes are biocompatible and exhibit high fibroblast cell regeneration, which is optimal for their application as scaffolds. To validate the regenerative response of PCL/HEP/Ag2S scaffolds, controlled wounds were induced in Wistar rats, presenting a favorable healing response by contact with PCL/HEP/Ag2S 1%, compared with the untreated wound. Our results indicated that nanostructured scaffolds enable the development of novel nanomaterials with multifunctional biological performance.

Improving CO2 Removal Efficiency with Bio-Cellulose Acetate: A Multi-Stage Membrane Separation Approach

In this comprehensive investigation, the sustainable production and utilization of gas separation membranes derived from coconut water (CW) waste was investigated. The research focuses on the synthesis of bacterial cellulose (BC) and cellulose acetate (CA) membranes from CW, followed by a thorough analysis of their characteristics, including morphology, ATR-FTIR spectroscopy, tensile strength, and chemical composition. The study rigorously evaluates membrane performance, with particular emphasis on CO2/CH4 selectivity under various operational conditions, including pressure, membrane thickness, and number of stages. The application of these membranes in gas separation units was optimized for CO2/CH4 separation performance and eco-efficiency through a multi-stage membrane approach. The findings indicate that in double-stage configurations, CA membranes with a thickness of 0.04 mm, operating at 0.28 MPa, achieve a CO2/CH4 selectivity of 35.52, significantly surpassing single-stage performance (selectivity: 19.72). Furthermore, eco-efficiency analysis reveals optimal performance at 0.04 mm thickness and 0.175 MPa, reaching 3.08 CO2/CH4 selectivity/THB. These results conclusively demonstrate the viability of converting agricultural waste into high-performance gas separation membranes, representing a significant advancement in sustainable membrane technology. This research contributes valuable insights to the field and paves the way for further innovations in eco-friendly membrane production and application.

Designing High Content Carbonylated β-Cyclodextrin/PBI Mixed Matrix Membrane as HT-PEM to Reduce H3PO4 Loss.

The high-temperature proton exchange membranes suffer from weak binding strength for phosphoric acid molecules, which seriously reduce the fuel cell efficiency, especially operation stability. Introduction of microporous material in the membrane can effectively reduce the leaching of phosphoric acid. However, due to the poor compatibility between the polymer and fillers, the membrane's performance significantly reduced at high fillers content. Therefore, in this work, the strategy of micropore confinement was developed; the β-cyclodextrin was carbonylated and introduced into PBI casting solution as solution state rather than dry powder for reducing the interface energy between two phases, thus further reducing interface defects and increasing the content of effective confined micropores within the membrane. By this way, carbonylated β-cyclodextrin/PBI (50 wt %) mixed matrix membranes were obtained, the proton conductivity reached 142 ± 4 mS cm-1, while the conductivity attenuation was only 16.6%.

Tetraarylphosphonium Cations with Excellent Alkaline-Resistant Performance for Anion-Exchange Membranes.

To realize the robust anion exchange membrane (AEM)-based water splitting modules and fuel cells, the design and synthesis of tetraarylphosphonium (TAP) cations are described as a new class of cationic building blocks that exhibit remarkable alkaline stability under harsh conditions. TAP cations with highly sterically demanding aromatic substituents were efficiently synthesized from triarylphosphine derivatives and highly reactive arynes, whose alkaline degradation proved to be suppressed dramatically by the sterically demanding substituents. In the case of bis(2,5-dimethylphenyl)bis(2,4,6-trimethylphenyl)phosphonium, for example, approximately 60% of the cation survived for 27 d under the forced conditions (i.e., in 4 M KOH/CD3OH at 80 °C), while tetraphenylphosphonium degraded completely within 10 min in 1 M KOH/CD3OH at that temperature. Through the decomposition of the alkaline-stable TAP cations, not only triarylphosphine oxides, which are often reported to form via the nucleophilic attack toward the cationic phosphorus center, but also triarylphosphines were detected, which suggested the presence of other degradation mechanisms due to the sterically demanding aromatic substituents. In kinetic analyses, bis(2,5-dimethylphenyl)bis(2,4,6-trimethylphenyl)phosphonium was found to exhibit 52 times higher stability compared to benzyltrimethylammonium, which is often employed as the cationic building block for AEMs.

Learning from history to improve the performance of blood purification devices and dialysis membranes: from engineering points of view.

Abel JJ, Rowntree LG and Turner BB (Baltimore Trio) proposed the concept of vividiffusion and developed a vividiffusion apparatus in 1912. In a 1914 paper, they laid out the most important rule of device design. We named this rule an ART law taken from the initials of the Baltimore Trio. The ART law means that a blood purification device with a shape that can secure as large a dialysis membrane area as possible for as small a volume of blood filling as possible will achieve high dialysis performance. Rather than using 8mm inner diameter collodion tubes in the original vividiffusion apparatus, the solution to the device shape that fits this rule is to hold down the tube from both top and bottom to make it as flat as possible, or if it is a flat membrane, to bring two flat membranes as close together as possible, and in the case of tubes and hollow fibers, to make their inner diameter as small as possible of approximately 200μm. In other words, the dialysis performance is greatly improved by narrowing the blood flow path. This is exactly the ART law, predicting the shape of today's blood purification devices.

Novel Co-Polyamides Containing Pendant Phenyl/Pyridinyl Groups with Potential Application in Water Desalination Processes

This study explores the development and evaluation of a novel series of aromatic co-polyamides featuring diverse pendant groups, including phenyl and pyridinyl derivatives, designed for water desalination membrane applications. These co-polyamides, synthesized with a combination of hexafluoroisopropyl, oxyether, phenyl, and amide groups, exhibited excellent solubility in polar aprotic solvents, thermal stability exceeding 350 °C, and the ability to form robust, flexible films. Membranes prepared via phase inversion demonstrated variable water permeability and NaCl rejection rates, significantly influenced by the pendant group chemistry. Notably, pyridinyl-substituted membranes achieved water fluxes up to 17.7 L m−2 h−1 and a NaCl rejection of 37.3%, while phenyl-substituted variants provided insights into the interplay of hydrophobicity and porosity. These findings highlight the critical role of pendant group functionality in tailoring membrane performance, offering a foundation for further structural modifications to enhance efficiency in water treatment technologies.

Packing Engineering of Zirconium Metal-Organic Cages in Mixed Matrix Membranes for CO2/CH4 Separation.

Metal-organic cages (MOCs) have been considered as emerging zero-dimensional (0D) porous fillers to generate molecularly homogeneous MOC-based membrane materials. However, the discontinuous pore connectivity and low filler concentrations limit the improvement of membrane separation performance. Herein, we propose the dimension augmentation of MOCs in membranes using three-dimensional (3D) supramolecular MOC networks as filler materials in mixed matrix membranes (MMMs). We further explore the packing engineering of MOC networks to produce distinct polymorphs (α and β phases) for tailoring membrane performance. Synchrotron X-ray absorption and positron annihilation lifetime spectroscopy were employed to differentiate distinct MOC polymorphous networks within membranes. Gas permeation tests revealed that the corresponding MMMs showed superior CO2/CH4 separation performance, exceeding the Robeson upper bound. Our proposed approach is expected to enrich the repertoire of reticular chemistry pertaining to molecular-based networks.

Packing Engineering of Zirconium Metal‐Organic Cages in Mixed Matrix Membranes for CO2/CH4 Separation

AbstractMetal‐organic cages (MOCs) have been considered as emerging zero‐dimensional (0D) porous fillers to generate molecularly homogeneous MOC‐based membrane materials. However, the discontinuous pore connectivity and low filler concentrations limit the improvement of membrane separation performance. Herein, we propose the dimension augmentation of MOCs in membranes using three‐dimensional (3D) supramolecular MOC networks as filler materials in mixed matrix membranes (MMMs). We further explore the packing engineering of MOC networks to produce distinct polymorphs (α and β phases) for tailoring membrane performance. Synchrotron X‐ray absorption and positron annihilation lifetime spectroscopy were employed to differentiate distinct MOC polymorphous networks within membranes. Gas permeation tests revealed that the corresponding MMMs showed superior CO2/CH4 separation performance, exceeding the Robeson upper bound. Our proposed approach is expected to enrich the repertoire of reticular chemistry pertaining to molecular‐based networks.

Preparation of polyvinylidene fluoride membranes with enhanced hydrophobicity and its applications in chromium recovery using supported liquid membranes in practical scale

This study focuses on the development of polyvinylidene fluoride (PDVF) membranes with enhanced hydrophobicity and their application for supported liquid membrane (SLM)-based solvent extraction. Flat sheet membranes were prepared via vapor-induced phase separation (VIPS), followed by non-solvent-induced phase separation (NIPS). PVDF flat sheet membrane was prepared with different solvents, namely N-methylpyrrolidone, dimethylformamide (DMF), dimethylacetamide, and dimethylsulfoxide, and at different VIPS times. The effect of different solvents and VIPS time on the membrane characteristics and performance was studied. PVDF membrane prepared with DMF solvent with VIPS time of 7.5 min gave optimum results in terms of membrane characteristics and performance with a water contact angle of 95.5°. The optimized PVDF flat sheet membrane was used as support in a SLM setup for the extraction and recovery of chromium from a simulated aqueous feed solution similar to tannery effluent with concentrations ranging from 5 to 75 ppm. Dodecane, modified with 1-dodecanol and decalin, was used as an organic solvent with tri-caprylmethylammonium chloride (Aliquat 336) as an extractant. NaNO3 solution was used as a stripping solution. The processes of extraction and stripping were carried out simultaneously in a single-step operation to recover chromium. The extraction of chromium achieved in 3 h using an in-house-prepared hydrophobic PVDF membrane as support for the liquid membrane varies from 63.08% for feed containing 5 ppm chromium to 50.59% for feed containing 75 ppm chromium, with a maximum extraction of 70.92% for feed with 50 ppm chromium.

Promoting proton conduction performance of Nafion composite membrane through doping simple and low-cost hydrated calcium terephthalate

Metal-organic frameworks (MOFs) are one kind of promising competitive candidates as fillers of Nafion proton exchange membrane (PEM). More and more efforts have been made to explore the method of...

Modeling and optimization of surface modification process of ultrafiltration membranes by guanidine-based deep eutectic solvent.

Low performance and the high fouling tendency of Polyetherimide (PEI) membranes prevent their widespread commercial utility. In this study, we utilized a deep eutectic solvent (DES) as a versatile agent for surface modification of the PEI membrane using a simple and sustainable method. To attain an efficient PEI membrane, modeling and optimization of the modification condition were conducted via response surface methodology (RSM). The effects of two effective variables, including the choline/guanidine (Ch/Gu) ratio (0.5-2) and modification time (12-48h), were evaluated on four responses, i.e., pure water flux (PWF), flux recovery ratio (FRR), irreversible fouling ratio (Rir), and total resistance (Rt). The structural and chemical characteristics and filtration performance of the fabricated membranes were evaluated. The optimum condition was obtained at a 0.8 Ch/Gu ratio and 30h of modification time to reach the best performance of the DES-PEI membrane. The industrial application of optimally modified DES/PEI membrane was investigated by filtering penicillin and cephalexin antibiotics. The rejection data showed higher performance of the modified membrane (>95%) compared to the bare membrane (∼63%). Furthermore, the long-term filtration evaluation in dead-end and cross-flow setups indicated stable flux and rejection of the DES/PEI-modified membrane. The DES, including Ch/Gu, can be viewed as an agent to enhance both PWF and antifouling properties while broadening membrane applications in separating antibiotics for PEI membranes through an eco-friendly and cost-effective method.

Preparation and performance of MXene-based electric field-responsive separation membranes

Preparation and performance of MXene-based electric field-responsive separation membranes

Multi-objective optimization of the drainage performance of dual-flow channel proton exchange membrane fuel cells driven by machine learning surrogate model

Multi-objective optimization of the drainage performance of dual-flow channel proton exchange membrane fuel cells driven by machine learning surrogate model

Enhancing filtration performance and recovery potential of polyvinylidene fluoride membrane by incorporating MOF@MWCNT: Using synthetic and real foulants

Enhancing filtration performance and recovery potential of polyvinylidene fluoride membrane by incorporating MOF@MWCNT: Using synthetic and real foulants

Amino acid-based nanoparticles-incorporated thin-film nanocomposite forward osmosis membranes for efficient desalination and heavy metal ions rejection

The current study explores potential applications of state-of-the-art thin-film nanocomposite forward osmosis (TFN-FO) membranes, modified with histidine-functionalized graphene quantum dots (His-GQDs) and MIP-202(Zr) nanoparticles (NPs), for sustainable desalination and heavy metal ions rejection. The porous and layered structure of the applied NPs, along with various hydrophilic functional groups on their surface, contribute to improving the fabricated membranes' ion/water separation performance. The successful preparation and incorporation of desired NPs into the polyamide layer was investigated using typical analytical methods. Under the common FO test conditions, the best-performing TFN-MQ2 membrane displayed a water flux of 21.8 LMH, which was over 1.5 times greater than the water flux of blank TFC. Simultaneously, the selectivity was found to be approximately 1.7 times greater than that of the unmodified TFC membrane. Moreover, the optimal TFN-MQ2 membrane exhibited superior rejection rates for Cu2+ ions (98.5 %) and Pb2+ ions (98.1 %), surpassing all other samples in heavy metal ion rejection. The findings of this study suggest that carefully choosing cost-efficient and eco-friendly nanofillers (such as amino acid-based NPs) can enhance the desalination performance of TFN-FO membranes and bolster their resistance to fouling and rejection of heavy metal ions. Not to mention, the overall costs of membrane production will be reduced.

Electrospun composite membranes of ethyl cellulose and MXene (Ti3C2Tx): Biocompatible platforms for enhanced drug delivery and antibacterial wound healing.

Ethyl cellulose (EC), a degradable cellulose derivative, served as a primary component in membranes fabricated by electrospinning for in vitro drug delivery applications. An effective strategy to enhance drug release was incorporating high-surface-area nanomaterials into polymeric drug carriers, which facilitated drug attachment to both the polymer matrix and additive surfaces, promoting release. MXene (Ti3C2Tx) demonstrated promising potential in improving tensile mechanical properties, antibacterial activity, and curcumin (Cur) release performance of EC membrane. Compared to Cur-loaded EC/MXene membranes, the toughness of Cur-loaded EC-based carriers significantly increased by 53.58%, reaching 3.821kJ/m3. This composite membrane exhibited exceptional antibacterial efficacy, notably reducing Staphylococcus aureus colonies by 52.4×107CFU/mL after 168h, through the dilution spread plate method. Using MTT assay, the composite membrane demonstrated biocompatibility, as evidenced by >70% viability of mouse fibroblast L929 cells with observable cell attachment after 168h. Importantly, the EC/MXene membrane achieved a Cur release amount of 69.82% compared to 7.11% from Cur-loaded EC membranes within 168h, representing a 62.71% enhancement in Cur release. The EC/MXene composite membrane is a promising drug delivery candidate, particularly for Cur, by utilizing the sustainability of EC as the primary drug carrier component.

Synthesis and Performance of Polysulfone-Chitosan Ultrafiltration Membranes for Humic Acid Removal

Natural organic matter (NOM) constitutes a significant contaminant in water sources, adversely affecting drinking water quality and complicating purification processes. To mitigate these contaminants, the current state of the application uses membrane filtration along with structural and surface modification of membranes. This study presents the development of polysulfone (PSU) flat-sheet ultrafiltration (UF) membranes, modified with three different concentrations of chitosan (0.05, 0.06, and 0.08g), a natural polymer, to enhance NOM removal. The membranes were rigorously characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and water contact angle (WCA), porosity, and pore size analysis. Furthermore, the study delves into the interaction mechanisms between chitosan and the PSU polymer matrix, as well as the transport phenomena involved. The findings indicate that increasing the chitosan content from 0.05 to 0.08g markedly enhanced the membrane's surface properties, reducing the contact angle from 72.8° to 53.5° and nearly doubling the permeation rate despite the decrease in porosity and pore size. The PSU UF membrane with 0.08g chitosan demonstrated a superior humic acid (HA) rejection rate of 90%, underscoring chitosan's potential for improving polymeric membranes in NOM removal applications.

Construction of proton exchange membrane with high proton conductivity based on 3D self-assembly structures as multiple proton transport channels

Proton exchange membranes are currently of a great interest due to their tunable proton transport channels in design. However, the construction of proton transport channels in composite membranes still encounters enormous challenges. In this study, a series of composite membranes composed of nanocomposites reinforced with electrostatically self-assembly of zirconium phosphate (ZrP) and poly(diallyldimethylammonium chloride) (PDDA)modified sulfonated halloysite (PSHNT) were designed and prepared. Further, long-range ordered proton transport channels were constructed in the membrane owing to synergistic effect of ZrP and PSHNT. It is revealed that acidic groups of ZrP nanoparticles and PSHNT yield more acidic sites for effective proton transport, and hollow tubular halloysite creates a fast channel for proton transport via a vehicle-type mechanism. The excellent hydrophilicity of ZrP/PSHNT and their good dispersion in polymer matrices result in a much higher water absorption of 45.5% and a lower swelling rate of 6.4% at 80⁰C. More impressively, SPI-ZrP/PSHNT-6 exhibits a remarkable proton conductivity of 288.2 mS cm-1 at 80°C under hydrated conditions. In addition, due to its excellent proton conductivity, a high peak power density up to 230.2 mW cm-2 has been achieved in H2-Air fuel cell. The excellent material performance of such proton exchange membranes in this study paves a new way towards the commercialization of high-performance proton exchange membranes in future applications for hydrogen fuel cell.

Biological testing unification for hemodialysis membranes evaluation: A step towards standardization.

Current hemodialysis treatments can cause adverse effects, many of which are linked to the membranes used in the process. These issues are being addressed through new materials and technologies, making it urgent to establish minimum guidelines for evaluating such membranes. This review proposes standardizing the biological tests and variables to evaluate the performance of new membranes, aiming to replicate hemodialysis conditions closely. The tests were categorized into protein adsorption, protein transmission, platelet adhesion, platelet activation, blood coagulation times, hemolysis, complement activation, and cytotoxicity. For protein adsorption, static tests are recommended as an initial step to rule out membrane adhesion, followed by dynamic tests that must be conducted using a crossflow system (>250mL/min flow) and a solution mimicking real conditions (BSA, lysozyme, trypsin, pepsin, creatinine, urea, albumin, fibrinogen, and γ-globulin). Protein transmission tests must employ dynamic conditions, using human blood or platelet-rich plasma for a minimum time of 3.5h. Complement activation should be tested using human blood and ELISA assays to detect C3, C5 TCC, and SC5b-9. Blood coagulation times (APTT, TT, FT, TCT, and TAT) should be measured with platelet-poor and platelet-rich plasma. Hemolysis tests should transition from water bath to continuous mode for at least 3.5h. Cytotoxicity tests should compare the MTT assay with other methods (Alamar Blue, Lactate Dehydrogenase Assay, Flow Cytometry, or Trypan Blue Exclusion Test) and use different cell types for comprehensive validation. By implementing these minimum biological tests, membrane evaluations would more accurately reflect the real-world applications, ensuring biocompatibility, effectiveness, and efficiency.

Rejection of antibiotics using modified polyvinylidene fluoride (PVDF) membranes with polyethyleneimine co-blending: Relating membrane performances to operating conditions

Rejection of antibiotics using modified polyvinylidene fluoride (PVDF) membranes with polyethyleneimine co-blending: Relating membrane performances to operating conditions