Electrospun Composite Membranes Research Articles

PVC/CNT Electrospun Composites: Morphology and Thermal and Impedance Behavior.

Due to their mechanical robustness and chemical resistance, composite electrospun membranes based on polyvinyl chloride (PVC) are suitable for sensor applications. Aiming to improve the electrical characteristics of these membranes, this work investigated the effects of the addition of carbon nanotubes (CNTs) to PVC electrospun membranes, in terms of morphology and thermal and impedance behavior. Transmission electron microscopy images evidenced that most of the nanotubes were encapsulated within the fibers and oriented along them, while field-emission scanning electron micrographs revealed that the membranes consisted of uniform fibers with an average diameter of 339 ± 31 nm, regardless of the addition of the carbon nanotubes. With respect to the neat resin, the addition of nanotubes caused a significant lowering of the glass transition temperature (up to 20 °C) and a marked change in the second degradation step of PVC. Nyquist plots from electrical impedance spectra showed a charge transfer resistance (RCT) of 38 and 40 MΩ for neat PVC and PVC/CNT 3 wt.% membranes, respectively, indicating that, in the dry state, the encapsulation of CNTs in the fibers and the high porosity of the membranes prevented the formation of a percolation network, increasing the electrical resistance. In the wet state, however, there was a greater change in the impedance behavior, decreasing the resistance RCT to 4.5 and 1.1 MΩ, for neat PVC and PVC/CNT 3 wt.% membranes, respectively. The results of this study, showing a significant variation in impedance behavior between dry and wet membranes, are relevant for the development of various types of sensors based on PVC composites.

Nanocarrier-Assisted Delivery of Berberine Promotes Diabetic Alveolar Bone Regeneration by Scavenging ROS and Improving Mitochondrial Dysfunction.

Oxidative stress and mitochondrial dysfunction are potential contributors to the compromised tissue regeneration capacity of alveolar bone in diabetic patients. Berberine, an active plant alkaloid, exhibits multiple pharmacological effects including antioxidation, blood glucose- and blood lipid-lowering properties. However, it remains uncertain whether berberine can improve impaired osteogenesis in type 2 diabetes mellitus (T2DM), and its poor solubility and oral bioavailability also constrain its applications in bone regeneration. Thus, our study aimed to probe the effects of berberine on bone marrow stem cells (BMSCs) in a diabetic microenvironment, with a greater emphasis on developing a suitable nano-delivery system for berberine and assessing its capability to repair diabetic alveolar bone defects. Firstly, BMSCs were exposed to berberine within a high glucose and palmitate (HG+PA) environment. Reactive oxygen species levels, mitochondrial membrane potential, ATP generation, cell apoptosis, and osteogenic potential were subsequently assessed. Next, we explored the regulatory mechanism of autophagy flux in the positive effects of berberine. Furthermore, a nanocarrier based on emulsion electrospinning for sustained local delivery of berberine (Ber@SF/PCL) was established. We assessed its capacity to enhance bone healing in the alveolar bone defect of T2DM rats through micro-computed tomography and histology analysis. Berberine treatment could inhibit reactive oxygen species overproduction, mitochondrial dysfunction, apoptosis, and improve osteogenesis differentiation by restoring autophagy flux under HG+PA conditions. Notably, Ber@SF/PCL electrospun nanofibrous membrane with excellent physicochemical properties and good biological safety had the potential to promote alveolar bone remodeling in T2DM rats. Our study shed new lights into the protective role of berberine on BMSCs under T2DM microenvironment. Furthermore, berberine-loaded composite electrospun membrane may serve as a promising approach for regenerating alveolar bone in diabetic patients.

Conditional Optimization on the Photocatalytic Degradation Removal Efficiency of Formaldehyde using TiO2 – Nylon 6 Electrospun Composite Membrane

Conditional Optimization on the Photocatalytic Degradation Removal Efficiency of Formaldehyde using TiO2 – Nylon 6 Electrospun Composite Membrane

A gel polymer electrolyte obtained from cellulose acetate/polyvinylidene fluoride composite electrospun membrane for safe lithium metal batteries with high-rate capability

Li metal battery is a promising next-generation power storage devices, but faces the serious safety issues caused by the uncontrolled Li dendrite growth and leakage of the flammable organic electrolyte. Herein, a low-cost CA/PVDF (cellulose acetate/polyvinylidene fluoride) composite membrane is prepared via electrospinning technology for safe lithium metal batteries. This membrane (45 μm) exhibits the high porosity (76.9 %) and excellent thermally stability (>180 °C) preventing the short circuit during abuse. The CA/PVDF-based gel polymer electrolyte (GPE), fabricated with CA/PVDF electrospun membrane swelled by carbonate-based organic liquid electrolyte, delivers the ionic conductivity of 1.82 mS cm−1 and Li + transfer number of 0.506, which achieve uniform Li+ ion electrodeposition and inhibit the formation of lithium dendrites. As the results, the symmetrical cell Li/CA/PVDF-based GPE/Li exhibits the impressive reversible Li stripping/plating behavior over 300 h at 1 mA cm−2 with the capacity of 1 mA h cm−2. Furthermore, the assembled LiFePO4/GPE/Li battery exhibits the capacity of 101.2 mA h g−1 at 5C with the capacity retention of 94.6 % after 400 cycles, which exceeds that of traditional liquid electrolytes. This research provides a low-cost gel polymer electrolyte via the electrospinning technique for rechargeable lithium batteries with good electrochemical performance and high security.

Antibacterial Potential and Biocompatibility of Chitosan/Polycaprolactone Nanofibrous Membranes Incorporated with Silver Nanoparticles.

This study addresses the need for enhanced antimicrobial properties of electrospun membranes, either through surface modifications or the incorporation of antimicrobial agents, which are crucial for improved clinical outcomes. In this context, chitosan-a biopolymer lauded for its biocompatibility and extracellular matrix-mimicking properties-emerges as an excellent candidate for tissue regeneration. However, fabricating chitosan nanofibers via electrospinning often challenges the preservation of their structural integrity. This research innovatively develops a chitosan/polycaprolactone (CH/PCL) composite nanofibrous membrane by employing a layer-by-layer electrospinning technique, enhanced with silver nanoparticles (AgNPs) synthesized through a wet chemical process. The antibacterial efficacy, adhesive properties, and cytotoxicity of electrospun chitosan membranes were evaluated, while also analyzing their hydrophilicity and nanofibrous structure using SEM. The resulting CH/PCL-AgNPs composite membranes retain a porous framework, achieve balanced hydrophilicity, display commendable biocompatibility, and exert broad-spectrum antibacterial activity against both Gram-negative and Gram-positive bacteria, with their efficacy correlating to the AgNP concentration. Furthermore, our data suggest that the antimicrobial efficiency of these membranes is influenced by the timed release of silver ions during the incubation period. Membranes incorporated starting with AgNPs at a concentration of 50 µg/mL effectively suppressed the growth of both microorganisms during the early stages up to 8 h of incubation. These insights underscore the potential of the developed electrospun composite membranes, with their superior antibacterial qualities, to serve as innovative solutions in the field of tissue engineering.

Low cytotoxicity, antibacterial property, and curcumin delivery performance of toughness-enhanced electrospun composite membranes based on poly(lactic acid) and MAX phase (Ti3AlC2)

MXenes, synthesized from their precursor MAX phases, have been extensively researched as additives to enhance the drug delivery performance of polymer matrices, whereas there is a limited number of previous reports on the use of MAX phases themselves for such applications. The use of MAX phases can exclude the complicated synthesis procedure and lessen resultant production and environmental costs required to convert MAX phases to MXenes. Herein, electrospun membranes of poly(lactic acid) (PLA) and a MAX phase (Ti3AlC2) have been fabricated for curcumin delivery. The composite membrane exhibits significantly higher toughness (8.82 MJ m−3) than the plasticized PLA membrane (0.63 MJ m−3) with low cytotoxicity, supporting proliferation of mouse fibroblast L929 cells. The curcumin-loaded composite membrane exhibits high water vapor transmission (∼7350 g m−2 day−1), porosity (∼85 %), water wettability, and antibacterial properties against E. coli and S. aureus. Seven-day curcumin release is enhanced from 45 % (PLA) to 67 % (composite) due to curcumin diffusion from the polymer fibers and MAX phase surface that contributes to overall increased curcumin adsorption and release sites. This work demonstrates the potential of the MAX phase to enhance both properties and curcumin delivery, promising for other eco-friendly systems for sustainable drug delivery applications.

Carbon dot/polylactic acid nanofibrous membranes for solar-mediated oil absorption/separation: Performance, environmental sustainability, ecotoxicity and reusability

Carbon dots (CDs) are promising photothermal nanoparticles that can be utilized in environmental treatments. They exhibit favorable physicochemical properties, including low toxicity, physical and chemical stability, photo-dependant reversible behaviour, and environmentally friendly synthesis using benign building blocks. Here, we synthesized innovative CDs/polylactic acid (PLA) electrospun composite membranes for evaluating the removal of hydrophobic compounds like long-chain hydrocarbons or oils in biphasic mixtures with water. The ultimate goal was to develop innovative and sustainable solar-heated oil absorbents. Specifically, we fabricated PLA membranes with varying CD contents, characterized their morphology, thermal, and mechanical properties, and assessed the environmental impact of membrane production according to ISO 14040 and 14044 standards in a preliminary “cradle-to-gate” life cycle assessment study. Solar radiation experiments demonstrated that the CDs/PLA composites exhibited greater uptake of hydrophobic compounds compared to pure PLA membranes, ascribable to the CDs-induced photothermal effect. The adsorption and regeneration capacity of the new CDs/PLA membrane was demonstrated through multiple uptake/release cycles. Ecotoxicity analyses confirmed the safety profile of the new adsorbent system towards freshwater microalgae, further emphasizing its potential as an environmentally friendly solution for the removal of hydrophobic compounds in water treatment processes.

Composite Quasi-Solid-State Electrolytes with Organic-Inorganic Interface Engineering for Fast Ion Transport in Dendrite-Free Sodium Metal Batteries.

Quasi-solid-state electrolytes (QSSE) are a promising candidate for addressing the limitations of liquid and solid electrolytes. However, different ion transport capacities between liquid solvents and polymers can cause localized heterogeneous distribution of Na+ fluxes. In addition, the continuous side reactions occurring at the interface between QSSE and sodium anode lead to uncontrollable dendrites growth. Herein, a novel strategy is designed to integrate the composite electrospun membrane of Na3Zr2Si2PO12 and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) into QSSE, aiming to introduce new fast ion conducting channels at the organic-inorganic interface. The efficient ion transfer pathways can effectively promote the homogenization of ion migration, enabling composite QSSE to achieve an ultrahigh ionic conductivity of 4.1 mS cm-1 at room temperature, with a Na+ transference number as high as 0.54. Moreover, the PVDF-HFP is preferentially reduced upon contact with the sodium anode to form a "NaF-rich" solid electrolyte interphase, which effectively suppresses the growth of dendrites. The synergistic combination of multiple strategies can realize exceptional long-term cycling stability in both sodium symmetric batteries (≈700h) and full batteries (2100 cycles). This study provides a new insight for constructing high performance and dendrite-free solid-state sodium metal batteries.

Electrospun Sulfonated Silica/P(VDF-TrFE)-Based Composite Membranes for PEM Fuel Cells

Nafion® membranes are the most widely used commercially available membranes for PEM fuel cells due to their good chemical and mechanical stability as well as high ionic conductivity at fully humidified conditions. However, their high cost and inadequate conductivity at lower humidity levels can be addressed as the main drawbacks of Nafion® membranes which needs to be overcome. In this regard new strategies such as complete replacement of these membranes with alternative cost-effective membranes or modifying their properties via synthesizing of Nafion® containing composite membranes by incorporation of some inorganic additives such as silica were extensively investigated previously [1].In this study, we developed two types of electrospun composite membranes: in the first route: membranes were prepared with using P(VDF-TrFE) or PVDF as carrier polymers which are decorated with sulfonated silica (S-SiO2) nanoparticles, as a proton conducting additive. Here S-SiO2 nanoparticles were synthesized via hydrothermal method, then these nanoparticles were added to the electrospinning solutions to prepare the hybrid membranes. The effect of S-SiO2 amount in final properties of these membranes were investigated via preparing samples with three different S-SiO2/ carrier polymer ratios [2]. In the second approach, a combination of sol-gel and dual electrospinning methods were employed to fabricate proton conducting membranes comprising sulfonated silica network, Nafion®, and PVDF or P(VDF-TrFE) as the carrier polymers. For this purpose, the obtained S-SiO2 network via sol-gel method was incorporated into the Nafion®/carrier polymer mixed fibrous-mats during dual electrospinning process [3]. In both approaches after electrospinning all electrospun mats were transformed to compact membranes via hot-pressing process. Then fabricated mats and compact membranes, were characterized by various techniques including FTIR, XPS, SEM, TEM, ionic conductivity, ion exchange capacity (IEC), water uptake and mechanical tests. Finally, membrane-electrode-assemblies (MEAs) were prepared via composite electrospun membranes and fuel cell performance tests were performed. The results showed an enhancement in ionic conductivity for both set of membranes (102 and 132 mS/cm) compared to commercial Nafion® membranes at the same conditions. Moreover, the fuel cell test exhibited that presence of sulfonated silica in the composite membranes improved the performance at lower humidity conditions (344 mW/cm2 at 60% RH) due to enhanced water retention ability of the resultant composite membranes.

Biomineralized tetramethylpyrazine-loaded PCL/gelatin nanofibrous membrane promotes vascularization and bone regeneration of rat cranium defects

Conventional electrospinning produces nanofibers with smooth surfaces that limit biomineralization ability. To overcome this disadvantage, we fabricated a tetramethylpyrazine (TMP)-loaded matrix-mimicking biomineralization in PCL/Gelatin composite electrospun membranes with bubble-shaped nanofibrous structures. PCL/Gelatin membranes (PG), PCL/Gelatin membranes containing biomineralized hydroxyapatite (HA) (PGH), and PCL/Gelatin membranes containing biomineralized HA and loaded TMP (PGHT) were tested. In vitro results indicated that the bubble-shaped nanofibrous surface increased the surface roughness of the nanofibers and promoted mineralization. Furthermore, sustained-release TMP had an excellent drug release efficiency. Initially released vigorously, it reached stabilization at day 7, and the slow-release rate stabilized at 61.0 ± 1.8% at 28 days. All membranes revealed an intact cytoskeleton, cell viability, and superior adhesion and proliferation when stained with Ghost Pen Cyclic Peptide, CCK-8, cell adhesion, and EdU. In PGHT membranes, the osteogenic and vascularized gene expression of BMSCs and human vascular endothelial cells was significantly upregulated compared with that in other groups, indicating the PGHT membranes exhibited an effective vascularization role. Subsequently, the membranes were implanted in a rat cranium defect model for 4 and 8 weeks. Micro-CT and histological analysis results showed that the PGHT membranes had better bone regenerative patterns. Additionally, the levels of CD31 and VEGF significantly increased in the PGHT membrane compared with those in other membranes. Thus, PGHT membranes could accelerate the repair of cranium defects in vivo via HA and TMP synergistic effects.Graphical

Copper‐PCL/PVP virucidal nanofibers against coronavirus produced by electrospinning technology

AbstractThis work investigated the virucidal property of copper‐loaded poly(ε‐caprolactone) (PCL)/polyvinylpyrrolidone (PVP) blended nanofibers against coronavirus. Electrospinning solutions were prepared with 0.25, 0.75, and 1.50% [w/v] of copper salt and their properties of electrical conductivity, surface tension, and viscosity were measured. The copper‐PCL/PVP nanofibers produced electrospun composite membranes of 30.5–38 g m−2. IR spectra confirmed the blended PCL/PVP, and SEM/EDS images revealed the morphology of the randomly oriented nanofibers with homogeneously incorporated copper in the electrospun nanofibers. The copper quantification indicated the final incorporation of 5.50 ± 0.31, 14.00 ± 1.03, and 27.10 ± 3.00 mg g−1 of copper, as measured by atomic absorption spectrometry, into electrospun composite membranes for 0.25, 0.75, and 1.50% [w/v] copper solution formulations, respectively, and these compositions also affected the nanofibers mechanical properties. Copper release assays showed that copper‐PCL/PVP nanofibers readily release ions into aqueous media. The 0.75% copper‐PCL/PVP composite membrane was virucidal against coronavirus, reaching 99.99% inactivation in 1 hour and 99.999% inactivation in 24 h, and non‐cytotoxic to L929 cells in 24 h of exposure. This work presents a virucidal composite membrane with potential use in personal protective equipment against viral outbreaks or pandemics.

Bi2ZnB2O7 – PVDF electrospun composite membrane for waste water treatment utilizing photo-piezocatalysis

To enhance the piezoelectric capabilities of the β-phase of poly(vinylidene fluoride), a new composite membrane was prepared via electrospinning. This consist of Bi2ZnB2O7 and poly(vinylidene fluoride). A comparison of electrospun and composite fibers showed a significant increase in β-phase content. XRD and FTIR were used to characterize the samples' structures. FE-SEM and HR-TEM were also used to examine sample morphology. The optical properties of the BBZO-PVDF membrane were further assessed using UV–visible diffuse reflectance spectroscopy. The composite membrane's effectiveness was tested using photocatalysis, piezocatalysis, and photo-piezocatalysis. Methylene blue (MB) dye was degraded by these methods. The synergy between light and piezoelectric actions improved degradation performance significantly. It achieved a 74% degrading efficiency and a kinetic rate constant of 7.3 × 10−3 min−1. The findings show that the BBZO-PVDF composite membrane has great potential for enhanced environmental remediation and catalytic processes.

Ethyl cellulose composite membranes containing a 2D material (MoS2) and helical carbon nanotubes for efficient solar steam generation and desalination

With the increasing water consumption, water evaporators have been investigated for clean water production. Herein, the fabrication of electrospun composite membrane evaporators based on ethyl cellulose (EC), with the incorporation of light-absorption enhancers 2D MoS2 and helical carbon nanotubes, for steam generation and solar desalination is described. Under natural sunlight, the maximum water evaporation rate was 2.02 kg m−2 h−1 with an evaporation efficiency of 93.2 % (1 sun) and reached 2.42 kg m−2 h−1 at 12:00 pm (1.35 sun). The composite membranes demonstrated self-floating on the air–water interface and minimal accumulation of superficial salt during the desalination process due to the hydrophobic character of EC. For concentrated saline water (21 wt% NaCl), the composite membranes maintained a relatively high evaporation rate of up to ~79 % compared to the freshwater evaporation rate. The composite membranes are robust due to the thermomechanical stability of the polymer even while operating under steam-generating conditions. Over repeated use, they exhibited excellent reusability with a relative water mass change of >90 % compared to the first evaporation cycle. Moreover, desalination of artificial seawater produced a lower cation concentration (~3–5 orders of magnitude) and thereby yielded potable water, indicating the potential for solar-driven freshwater generation.

Novel Electrospun Composite Membranes Based on Polyhydroxybutyrate and Poly(vinyl formate) Loaded with Protonated Montmorillonite for Organic Dye Removal: Kinetic and Isotherm Studies.

The use of biodegradable polyesters derived from green sources and their combination with natural abundantly layered aluminosilicate clay, e.g., natural montmorillonite, meets the requirements for the development of new sustainable, disposable, and biodegradable organic dye sorbent materials. In this regard, novel electrospun composite fibers, based on poly β-hydroxybutyrate (PHB) and in situ synthesized poly(vinyl formate) (PVF), loaded with protonated montmorillonite (MMT-H) were prepared via electrospinning in the presence of formic acid, a volatile solvent for polymers and a protonating agent for the pristine MMT-Na. The morphology and structure of electrospun composite fibers were investigated through SEM, TEM, AFM, FT-IR, and XRD analyses. The contact angle (CA) measurements showed increased hydrophilicity of the composite fibers incorporated with MMT-H. The electrospun fibrous mats were evaluated as membranes for removing cationic (methylene blue) and anionic (Congo red) dyes. PHB/MMT 20% and PVF/MMT 30% showed significant performance in dye removal compared with the other matrices. PHB/MMT 20% was the best electrospun mat for adsorbing Congo red. The PVF/MMT 30% fibrous membrane exhibited the optimum activity for the adsorption of methylene blue and Congo red dyes.

Bismuth vanadate-reduced graphene oxide-polyvinylidene fluoride electrospun composite membrane for piezo-photocatalysis

We have used the electrospinning method to fabricate a polyvinylidene fluoride (PVDF) membrane, bismuth vanadate-polyvinylidene fluoride (BiVO4-PVDF, referred to as BV-PVDF) and bismuth vanadate-reduced graphene oxide-polyvinylidene fluoride (BV-rGO-PVDF) composite membranes. Compared to costly noble metals such as platinum (Pt), rGO is a more economical and ecologically friendly alternative for enhancing photocatalytic activity. After characterization, the fiber membranes were used as a catalyst material to investigate the relationship between the structure and catalytic activity with a 10 ml solution of 5 mg/L methylene blue (MB) dye. Furthermore, ethylenediaminetetraacetic acid (EDTA), benzoquinone (BQ) and isopropanol (IPA) scavengers were utilized to investigate the degradation intermediates. It has been discovered that the electrospun BV-rGO-PVDF composite has piezocatalytic and photocatalytic capabilities that are superior to those of PVDF and BV-PVDF. The degradation process is carried out with MB as a model dye, and we discovered that the BV-rGO-PVDF composite leads to a maximum dye degradation of 82% in under 180 min of process time, with a degradation rate of 0.0088 min−1. Consequently, we concluded that the hybrid 1D structure of the piezocatalytic and photocatalytic material is appropriate for the breakdown of organic contaminants.

Synthesis of transparent electrospun composite nanofiber membranes by asymmetric solvent evaporation process

Currently, transparent and flexible electrospun nanofiber membranes have attracted considerable attention due to their potential use in electronic displays, solar cells, air filtration, and medical and health fields (i.e., transparent wound dressings). Developing transparent nanofibrous membranes is still very intriguing because of severe light reflection and absorption into the fibrous membranes. Herein, we report a successful fabrication technique of transparent composite nanofibrous membranes by combining electrospinning and a particular post-treatment of the prepared membranes. Firstly, randomly organized polyurethane (PU) nanofibers were prepared via electrospinning. These PU nanofibers mats were then impregnated into different concentrations (i.e., 5, 10, and 15 wt%) and embedded time (i.e., 30 and 60 min) of poly (methyl methacrylate) (PMMA) and polydimethylsiloxane (PDMS) solutions to prepare transparent composite nanofibrous membrane using solution immersion technique. The resulting composite nanofibrous membranes exhibit excellent performance, including optical transparency (i.e., up to 82% for PMMA and ∼ 6% for PDMS), lacking affinity to water, mechanically robust, reasonable water vapor transmission rate (WVTR, ∼ 1 kg/m2 day), and good thermal stability. The composite nanofiber membranes have promising optical transparency, suitable mechanical strength, and high hydrophobicity. Therefore, they have the potential in various applications, including windshields for highly moving objects, displays, and particularly as transparent wound dressings in medicine.

Superhydrophobic composite asymmetric electrospun membrane for sustainable vacuum assisted air gap membrane distillation

Membrane distillation (MD) relies on superhydrophobic membranes that must achieve the competing goals of high liquid entry pressure (LEP) and high permeability. In this study, we developed the first superhydrophobic composite electrospun asymmetric membrane using fluorinated graphite (FG). We also provided among the first comparisons of the relative benefits of membrane asymmetry and composite coatings via 3D electrospinning and spraying. FG particles increased the roughness and reduced the zeta potential of the membranes. Superhydrophobic composite membranes had a contact angle of 157° (sliding angle of 7°) and an LEP of 327 kPa. Long-term MD testing revealed that FG particles could increase MD's sustainability while decreasing membrane wetting. Vacuum-assisted air gap membrane distillation (V-AGMD) showed that the composite asymmetric membrane outperformed the non-asymmetric version (composite nanofiber) membrane by 21 % in average water flux and 25 % in average thermal efficiency because of the asymmetric structure of the membrane. The numerical model developed for the V-AGMD system also successfully predicted the water flux generated experimentally from the composite nanofiber and composite asymmetric membranes. Our results confirmed that electrospun asymmetric FG membranes with high contact angle, low sliding angle, high permeability, and high gained output ratio (GOR) would be promising candidates for sustainable MD.

Composite electrospun membranes based on polyacrylonitrile and cellulose nanofibrils: Relevant properties for their use as active filter layers

Electrospun membranes comprising polyacrylonitrile (PAN) and 0.2 to 0.6 wt% cellulose nanofibrils (CNF) were prepared and characterized for their use as active layers of Filtering Facepiece Respirators (FFRs) and medical masks. Composite membranes with up to 0.4 wt% of CNF exhibited storage modulus values up to approximately 5 times higher and tensile strength and elastic modulus about 2 times and 6 times higher, respectively, compared to neat PAN. All membranes presented filtration efficiencies (FE) superior to 90% for aerosols with a median count diameter of 75 ± 20 nm and geometric standard deviation less than 1.86. For most membranes produced from an equal volume of solution, the increase in CNF content decreased the pressure drop (Δp, up to approximately five times) and increased the quality factor (QF, up to about 4 times) of the composite membranes, compared to neat PAN, due to the formation of more heterogeneous fibers, larger pores, a trend of increasing porosity and lower packing density. The presence of CNF also increased the air permeability (permeability coefficients, k1 and k2) of the composite materials. Following a yet not explored approach, it was demonstrated that the presence of CNF in the composition of PAN composite electrospun membranes led to materials with better performance as active filter layers than neat PAN.

Novel covalent organic frameworks based electrospun composite nanofiber membranes as pipette-tip strong anion exchange sorbent for determination of inorganic arsenic in rice

Novel covalent organic frameworks (COFs) based PAN@TpBD(NH2)2 electrospun composite nanofiber membranes (ECNMs) were fabricated as strong anion exchange sorbent by implementing electrospinning technology. The finished sorbent was characterized, and key parameters of pipette-tip solid phase extraction (PTSPE) procedures were investigated. Inorganic arsenic (iAs) was successfully separated from rice under the optimal precondition conditions, and quantified by hydride generation-atomic fluorescence spectrometry (HG-AFS). This PTSPE-HG-AFS methodology achieved 0.015 μg L-1 detection limit, 4.67 % relative standard deviation, and 86.48～99.11 % recoveries. In this work, preparation and characterization of this novel COFs-based anion exchange sorbent, PAN@TpBD(NH2)2 ECNMs, is described and its suitability for PTSPE applications is demonstrated.

Efficient selective methylene blue adsorption by polyurethane/montmorillonite‐based antifouling electrospun composite membranes

AbstractA robust antifouling membrane with pollutant‐removing capacity is in high demand for industrial wastewater treatment. Here, we report a new multifunctional polyurethane/montmorillonite‐oxidized multi‐walled carbon nanotube (PU/MMT) nanofibrous composite membrane, beneficial for both water filtration and selective methylene blue adsorption. It was observed that oxidized multi‐walled carbon nanotube (o‐MWCNT) imparted high flexibility with a high percentage elongation (318%–405%) to the composites, whereas montmorillonite (Mt) improved the hydrophilicity, antifouling property, and dye adsorption capacity of the fibrous PU membrane. The sample with 20 wt% Mt (PU/20‐MMT) showed a minimum water contact angle of 57°. It showed a high water flux, oil rejection, and flux recovery ratio compared to the pristine electrospun PU membrane. The Hermia fouling mechanism suggested that electrospun PU obeyed an intermediate blocking model, whereas PU/20‐MMT was best fitted with a cake formation model. During adsorption, the cationic dye methylene blue (MB) was selectively adsorbed on the sample from a methyl orange/methylene blue (MO/MB) mixture. It showed a maximum adsorption capacity (qm) of 112.35 mg/g. The anionic dye methyl orange, on the other hand, remained unadsorbed. The adsorption kinetics and the adsorption isotherm were pseudo‐second‐order kinetics and the Langmuir adsorption isotherm, respectively. The developed, robust electrospun composite membrane opens a new avenue for the selective adsorption of MB from dye mixtures and contaminated water.