Nanocomposite Membranes Research Articles

Scalable and universal polyphenol-mediated prussian blue nanocomposite membranes: Underliquid dual superlyophobicity and catalytic self-cleaning

Self-adaptive biomimetic superwetting membranes with distinctive underliquid dual superlyophobic surfaces showcase attractive features for the on-demand separation of multifarious oil/water systems. It yet remains a great challenge for introducing the catalytic function into the design of underliquid dual superlyophobic membranes, to strengthen self-cleaning ability. Herein, a polyphenol-mediated interfacial assembly strategy was proposed to construct multi-functional membranes with underliquid dual superlyophobicity and catalytic self-cleaning, through self-assembly of metal-tannic acid (Fe-TA) networks and then in-situ coordination growth of Prussia blue (PB) nanocrystals at the interface at room temperature. We found that the PB/Fe-TA nanocomposite coating can make hydrophilic and hydrophobic porous membranes, as well as smooth surfaces being underwater superoleophobic and underoil superhydrophobic. The Fe-TA networks were favored for good growth of PB nanocrystals. Using quartz fiber (QF) membrane as the basement substrate, the PB/Fe-TA@QF nanocomposite membrane can separate light/heavy oil/water mixtures and oil-in-water/water-in-oil emulsions under gravity drive, with efficiencies above 99%. The PB/Fe-TA@QF nanocomposite membrane exhibits a superior degradation ability of carmine dye by peroxymonosulfate (PMS) activation, with the removal ratio as high as 99.8% within 30 min and meanwhile has an excellent antifouling and catalytic self-cleaning performance after cycling emulsion separation. Excellent acid, alkali and salt toleration, as well as good repeatability, provide the potential for application in wastewater treatment. This research puts forward a green, versatile and scalable pathway to fabricate multifunctional superwetting membranes for various applications in the fields including the environment, energy and beyond.

Electrochemical Properties of PVDF-GN-SiO2 Nanocomposite Membrane and Comparative Assessment of Fixed Charge Density

Electrochemical Properties of PVDF-GN-SiO2 Nanocomposite Membrane and Comparative Assessment of Fixed Charge Density

Nanocomposite PVDF Membrane for Battery Separator Prepared via Hot Pressing

Polyvinylidene fluoride (PVDF) is one of the materials most commonly used in membrane separators. The structures of pristine PVDF and PVDF nanocomposite films were processed via hot pressing at 140 °C, 170 °C, and 185 °C at a pressure of 2 tons for 15 min. According to a surface investigation using scanning electron microscopy (SEM), the spherulitic character of the PVDF nanocomposite films was preserved up to a pressing temperatures of 140 °C. The cross-sectional SEM images confirmed that higher pressing temperatures (170 °C) caused the structures to be compacted into monolithic films, and a pressing temperature of 185 °C caused the melting of the PVDF matrix and its recrystallization into thin films (21–29 μm). An average crystallinity value of 51.5% was calculated using differential scanning calorimetry (DSC), and this decreased as the pressing temperature increased. Fourier transform infrared (FTIR) measurements confirmed the presence of a dominant γ phases in the PVDF nanocomposite films, whose nanofillers consisted of vermiculite particles (ZnO_V and ZnO_V_CH) and mixed α + γ phases. The percentage of the electroactive γ phase (approximately 79%) was calculated via a FTIR analysis, and the ratio between the β phase and the α phase was determined from the Raman spectra. A hydrophilic surface with contact angles ranging from 61 to 84° was demonstrated for all the PVDF nanocomposite membranes. The superoleophilic surface was measured using poly(dimethylsiloxane) with contact angles ranging from 4 to 13°, and these angles reached lower values when in contact with sulfur particles.

Fabrication of nano composite membrane filter from graphene oxide(GO) and banana rachis cellulose nano crystal(CNC) for industrial effluent treatment

Agricultural bio-waste based cellulosic materials are highly biodegradable and naturally occurring with high adsorption and capable of outstanding physico-chemical properties. This study elicits neoteric upliftment and impending significance of graphene oxide(GO) – cellulose nanocrystal(CNC) nano-filter composite membrane (NFCM) for high removal of Cr3+, Co2+, Ni2+, Pb2+, Cd2+ and Methylene blue molecules from industrial wastewater. We tried to direct comparison between conventional filter and NFCM composites filter and their physical and chemical properties, production costs, use and disposal in order to show the potential of Nano structural cellulose materials as a sustainable replacement for NFCM filter for removal of heavy metals and dyes from industrial wastewater treatment technologies. The prepared GO, CNC, and NFCM were characterized by using X-ray Diffraction(XRD), Fourier Transform Infrared (FTIR), Field Emission Scanning Electron Microscopy(FESEM), Thermogravimetric Analysis(TGA) etc. The efficiency of wastewater purification of fabricated NFCM were determined by Ultra Violet(UV)-vis spectrophotometer and Inductively Couple Plasma Optical Emission Spectroscopy(ICP-OES). Whereas the fabricated NFCM were highly crystalline, thermally stable, have good surface activity, exhibit remarkable removal efficiency against the toxic heavy metals and soluble dye. The maximum R% was found for Cd2+ and Pb2+, around 99%. Beside this all dye molecules were removed from the wastewater simultaneously and successfully.

The Method and Study of Detecting Phenanthrene in Seawater Based on a Carbon Nanotube-Chitosan Oligosaccharide Modified Electrode Immunosensor.

Phenanthrene (PHE), as a structurally simple, tricyclic, polycyclic aromatic hydrocarbon (PAHs), is widely present in marine environments and organisms, with serious ecological and health impacts. It is crucial to study fast and simple high-sensitivity detection methods for phenanthrene in seawater for the environment and the human body. In this paper, a immunosensor was prepared by using a multi-wall carbon nanotube (MWCNTs)-chitosan oligosaccharide (COS) nanocomposite membrane loaded with phenanthrene antibody. The principle was based on the antibody-antigen reaction in the immune reaction, using the strong electron transfer ability of multi-walled carbon nanotubes, coupled with chitosan oligosaccharides with an excellent film formation and biocompatibility, to amplify the detection signal. The content of the phenanthrene in seawater was studied via differential pulse voltammetry (DPV) using a potassium ferricyanide system as a redox probe. The antibody concentration, pH value, and probe concentration were optimized. Under the optimal experimental conditions, the response peak current of the phenanthrene was inversely proportional to the concentration of phenanthrene, in the range from 0.5 ng·mL-1 to 80 ng·mL-1, and the detection limit was 0.30 ng·mL-1. The immune sensor was successfully applied to the detection of phenanthrene in marine water, with a recovery rate of 96.1~101.5%, and provided a stable, sensitive, and accurate method for the real-time monitoring of marine environments.

An effective alkaline solid electrolyte with magnetic field-aligned Fe3O4–GO nanofillers in a polybenzimidazole membrane for methanol fuel cells

In this work, alkaline-doped polybenzimidazole/magnetite–graphene oxide (PBI/Fe3O4–GO) nanocomposite membranes are successfully synthesized for enhanced ion conduction and suppressed alcohol permeation for use in direct methanol alkaline fuel cells (DMAFCs). The structural, morphological, and magnetic properties of Fe3O4–GO nanofillers are thoroughly investigated. During the membrane drying step, the Fe3O4–GO nanofillers are aligned in a polymeric PBI matrix using an applied magnetic field (MF). Without an MF, the nanofillers are randomly distributed in the PBI matrix. The composite membrane with the MF demonstrates a 2- to 3-fold increase in hydroxide conductivity (7.6 × 10−2 S cm−1) and a one-order of magnitude reduction in fuel permeability (9.96×10−7 cm2 s−1) compared to the other samples. The potassium hydroxide (KOH)-doped PBI/Fe3O4–GO composite with MF achieves a higher maximum power density (Pmax) of 226 mW cm−2 at 80 °C than the other samples. The composite membrane with an MF demonstrates good long-term durability of 107 h with low voltage decay (6.5 × 10−4 V h−1) at high alkaline concentrations (6 M KOH). The results indicate that a small amount (0.5 wt%) of Fe3O4–GO nanofillers has an extensive effect on membrane properties in DMAFCs.

Role of molybdenum disulfide (MoS2) nanosheets doping position on the thin-film nanocomposite (TFN) membrane during brackish water treatment

Brackish water desalination based on nanofiltration (NF) has been regarded asa feasible solution to address the scarcity of freshwater. However, the trade-off effect and membrane fouling are challenges for the thin-film composite NF membranes, restricting their further application in desalination. Herein, modified thin-film nanocomposite (TFN) membranes were constructed with molybdenum disulfide (MoS2) nanosheets incorporated either into the polyamide layer (P-TFN) or as an interlayer (I-TFN). The surface morphology, chemical element, electronegativity, pore size, hydrophilicity, separation performance and antifouling property of the membranes were systematically evaluated and compared. The P-TFN membrane exhibited superior salt rejection of Na2SO4 up to 98.4% and preeminent flux recovery ratios (FRRs) of 95.4% and 92.2% for humic acid (HA) and bovine serum albumin (BSA) filtration, respectively, which possessed high electronegativity and small effective pore size. While, without compromising its salt retention and foulant resistance, the I-TFN membrane exhibited 51% better permeability than the control TFC membrane, due to its unique crumpled structure of the PA layer and the “dragging effect” of the interlayer on water molecules. Furthermore, we elaborated on the mechanism underlying the differences in surface properties, and verified the effectiveness of the modified membranes in authentic brackish water desalination. Significantly, the comparison provides novel insight for the customization and regulation of the PA layer.

Thin film nanocomposite polyamide membrane doped with amino-functionalized graphene quantum dots for organic solvent nanofiltration

Thin film nanocomposite (TFN) organic solvent nanofiltration (OSN) membrane with improved separation performance was fabricated via interfacial polymerization reaction between amine-functionalized graphene quantum dots (af-GQDs) doped aqueous monomer solution of m-phenylenediamine (MPD) and n-hexane solution containing trimesoyl chloride (TMC) monomer. We emphasize the employment of extra-low content for both af-GQDs and MPD, so that we could maximize the function of these nanomaterials and eliminate their aggregation at the same time. The af-GQDs nanomaterials could regulate the interfacial polymerization process and could be strongly anchored in the polyamide film via covalent bonding, hence could prevent their loss while providing more channels for faster solvent penetration. As a result, the optimized OSN membrane, TFN-50, shows a super-smooth surface, with a surface roughness as low as 4.3 ± 0.2 nm, and excellent pure solvent permeances which reach 135.8, 112.7, and 69.8 L m−2 h−1 MPa−1 for methanol, DMF and ethanol, respectively, as well as a very high Rhodamine B (RDB, 479 Da) rejection of up to 99.2%, and an ethanol permeance of 61.4 L m−2 h−1 MPa−1. Furthermore, the TFN-50 OSN membrane still shows excellent filtration performance after being submerged in DMF for 336 h or continuous crossflow filtration with Rose bengal (RB, 1017 Da)/DMF solution for 136 h, demonstrating its excellent solvent resistance.

Grand Challenges in the Development of Adsorptive Membrane for Water and Wastewater Treatment

Integrating nanotechnology and membrane technology has resulted in the development of adsorptive nanocomposite membranes with exceptional properties for various applications, including water reclamation. The application of adsorptive membranes in wastewater treatment is a promising technology that combines the advantages of adsorption and membrane filtration techniques. Literature reviews reported that various adsorptive membranes were successfully developed and efficiently removed emerging contaminants such as heavy metals and persistent organic pollutants from water over the last decades. However, grand challenges in developing adsorptive membranes require more attention, such as aggregation and agglomeration of nanoadsorbents within membrane matrix, mechanical strength distortion, extreme water permeability, and alterations in surface charge. These challenges, as mentioned earlier, could deteriorate the performance of adsorptive membranes. Consequently, future research should focus on overcoming these challenges to employ adsorptive membranes to preserve the environment.

Effects of MWCNTs on O2/N2 separation performance and morphology of sPEEK/PEI composite membranes: Experimental and molecular dynamics simulation studies

This study involved the development of blend membranes using sulfonated poly (ether ether ketone) (sPEEK) and poly (etherimide) (PEI) with varying amounts of multi-wall carbon nanotubes (MWCNTs) (up to 2 % by weight). The gas separation performance of these membranes was evaluated for the separation of O2 and N2 gases. In order to achieve a degree of sulfonation of 70 %, PEEK was sulfonated directly. The manufactured membranes were characterized using X-ray diffraction (XRD), scanning field emission electron microscopy (FESEM), Fourier transformed infrared spectroscopy (FTIR). Their operational evaluation was performed through permeability tests for pure gases of O2 and N2. The effect of sPEEK/PEI composition on membrane selectivity and gas permeability in the blend was studied. The selectivity and gas permeability values varied between those of individual polymers, fluctuating systematically with sPEEK/PEI content variation in the blends. The addition of MWCNTs to the blend improved the selectivity and permeability of O2 and N2 simultaneously. To further investigate the potential industrial application and stability of these membranes, experiments were conducted under different feed pressures (2 to 8 bar). The membrane containing 1 % of MWCNTs showed the best performance for O2 gas. Molecular dynamics simulations (MDS) were performed using the COMPASS force field to estimate the diffusivity of O2 and N2 gases through selected membrane systems. The simulated results agreed well with the available experimental data. With compared to the reported separating data, the prepared nanocomposite membrane was greatly efficient, which makes it promising platform to separate mixed gas flows and other related environmental processes.

Nanocomposite polymer blend membrane molecularly re-engineered with 2D metal-organic framework nanosheets for efficient membrane CO2 capture

Membrane gas separation technology is an energy-efficient alternative to the traditional industrial processes for CO2 capture towards the mitigation of global warming. To overcome the inherent performance trade-off behavior of polymeric membranes, many nanoarchitectures have been incorporated for developing high-performance mixed matrix membranes. Yet, a successful nanocomposite membrane design remains challenging, especially for CO2 capture, because of polymer-filler incompatibility and interfacial defects. Herein, 2D Cu-TCPP nanosheets were synthesized and incorporated into Pebax/Poly (ethylene glycol) methyl ether acrylate (PEGMEA) blends to design MMMs with exceptional CO2/N2 separation performance. This synergistic polymer blend after crosslinking, offers a highly accommodating and robust matrix environment for the homogenous distribution of nanosheets. Cu-TCPP particles were also produced as 3D nanoflowers to probe their morphological effect on gas transport. The finely dispersed 2D nanosheets expanded the free volume of the resultant nanocomposite membranes, leading to a significantly enhanced CO2 permeability of up to 1183 Barrer which was 93% higher than the neat polymers, while they also increased the transport pathway tortuosity that contributes to a very high CO2/N2 selectivity of 57.6 at a loading of merely 0.1 wt%. Not only do such separation performances surpassed the Robeson upper bound by a large margin and outcompeted many existing advanced MMM designs, but they also remained stable after long-term operations. By carefully elucidating the gas transport tuning effect of 2D metal-organic framework nanosheets in nanocomposite membranes, this work could help broaden their applicability for other environmentally important molecular separations.

NMR Investigation of Water Molecular Dynamics in Sulfonated Polysulfone/Layered Double Hydroxide Composite Membranes for Proton Exchange Membrane Fuel Cells.

The development of nanocomposite membranes based on hydrocarbon polymers is emerging as one of the most promising strategies for overcoming the performance, cost, and safety limitations of Nafion, which is the current benchmark in proton exchange membranes for fuel cell applications. Among the various nanocomposite membranes, those based on sulfonated polysulfone (sPSU) and Layered Double Hydroxides (LDHs) hold promise regarding their successful utilization in practical applications due to their interesting electrochemical performance. This study aims to elucidate the effect of LDH introduction on the internal arrangement of water molecules in the hydrophilic clusters of sPSU and on its proton transport properties. Swelling tests, NMR characterization, and Electrochemical Impedance Spectroscopy (EIS) investigation allowed us to demonstrate that LDH platelets act as physical crosslinkers between -SO3H groups of adjacent polymer chains. This increases dimensional stability while simultaneously creating continuous paths for proton conduction. This feature, combined with its impressive water retention capability, allows sPSU to yield a proton conductivity of ca. 4 mS cm-1 at 90 °C and 20% RH.

Development of micropollutants removal process using thin-film nanocomposite membranes prepared by green new vapour-phase interfacial polymerization method

The presence of emerging micropollutants in water bodies and potable water, has become a topic of great concern globally. In this study, a newly modified vapour-phase interfacial polymerization (VP-IP) method has been used to fabricate thin-film composite (TFC) and thin-film nanocomposite (TFN) nanofiltration (NF) membranes to study the removal of micropollutants, diclofenac (DIC) and triclosan (TRI) from water. The method used is an economically and environmentally greener method as the reaction takes place between the aqueous monomer solution and vapours of the organic phase, thereby avoiding the utilization of organic solvent hence named as vapour-phase interfacial polymerization (VP-IP) method. Polydopamine (PDA) coated polyethersulfone (PES) membranes were used to support the TFC and TFN membranes. The TFN membranes were incorporated with different concentrations of amine-functionalized cloisite Na+ 2D clay nanosheets (NH2-CMMT) to enhance the physicochemical properties of the TFN membranes. The performance study of the prepared TFN membranes based on different hours and pressures demonstrated an excellent rejection percentage of ∼99 ± 0.5% for both DIC and TRI compared to the TFC membrane. The membranes showed improved water permeate fluxes of ∼109 ± 5 Lm-2h-1 for DIC and ∼150 ± 5 Lm-2h−1 for TRI. The prepared TFN membranes demonstrated positive results for the antifouling test as well as exhibited antibacterial activity tested against Escherichia coli (E. coli) bacteria. The findings of this study show that our prepared TFN membranes combined with NH2-CMMT 2D clay nanosheets exhibit enhanced hydrophilicity, improved flux rate, excellent removal efficiency, antibacterial activity, and improved antifouling properties, indicating the potential to be used for removing emerging micropollutants from water.

Enhancing dye removal and antifouling properties of conductive polyethersulfone nanocomposite membranes by analogous zwitterion-functionalized separation layers with tunable surface-charge orientation

Membrane separation has been demonstrated to have enormous potential for alleviating the global scarcity of clean water. However, membrane fouling extremely limits its applications, and on-demand and precise molecular separation is very challenging for traditional membranes. Here, a novel smart voltage-gated membrane with an analogous zwitterion-functionalized separation layer is prepared by combining blending, surface segregation and co-deposition. Intriguingly, amphiphilic sodium styrene-maleic anhydride copolymer (SMANa) anchored on CNTs not only promotes their dispersion in the membrane but also enhances the electroconductivity through the synergistic ionic-electronic conducting effect. More importantly, positively and negatively charged molecular chains mounted on the membrane surface could form different “electric double” layers in response to the voltage stimuli. Consequently, the optimized membrane as the cathode exhibits superior permeations and separations of Congo red (99.9 %, 313.6 L/m2·h·bar) and indigo carmine (96.9 %, 420 L/m2·h·bar), and as the anode displays outstanding permeations and separations of methyl green (98 %, 381.6 L/m2·h·bar), crystal violet (95.7 %, 368.2 L/m2·h·bar) and methyl orange (94.6 %, 166.4 L/m2·h·bar) due to the effective combination of size sieving, electro-enhanced electrostatic repulsion and adsorption-induced electrostatic repulsion effects. Simultaneously, high flux recovery ratios are also achieved due to the superposition of a stable hydration layer and electrochemistry, indicating excellent antifouling properties.

Silica and Sulfonated Silica Functionalized Nexar Nanocomposite Membranes for Application in Proton Exchange Membrane Fuel Cell

Silica and Sulfonated Silica Functionalized Nexar Nanocomposite Membranes for Application in Proton Exchange Membrane Fuel Cell

Explication of polydopamine modified g-C3N4 as effective additive in PVDF nanocomposite membrane fabrication for enhanced ultrafiltration and self-cleaning performance

Nanocomposite membranes (NCMs) incorporated with nanomaterials have recently received increasing attention, but the preparation of high-performance membranes is still challenging due to the hydrophilicity and self-aggregation of the nanoparticles. In this study, graphite carbon nitride containing nitrogen defects was modified using dopamine (PDA@DCN) for effective alleviation of the agglomeration of nanoparticles resulting in a uniform casting solution. A non-solvent-induced phase separation method was adapted to prepare PVDF NCMs by using PDA@DCN as an effective additive. Superior permeability and selectivity were exhibited by the PDA0.25 @DCN/PVDF2 membrane (where a DA concentration of 0.25 g/100 mL was used in PDA@DCN preparation and 2% PVP was added during the membrane preparation) with the pure water flux of 390 L/(m2·h) and Bovine serum albumin (BSA) rejection of 95.9%. The extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory revealed that the improvement of the flux recovery rate of PDA0.25 @DCN/PVDF2 was due to the decreased attractive interaction for fouling. Ternary phase diagram and viscosity experiments confirmed that the addition of PDA0.25 @DCN accelerated phase inversion rate (as evident from thermodynamics and kinetics) and increased the porosity with smaller average surface pore size, which is expected to have good permeability and selectivity as an ultrafiltration membrane. Moreover, an excellent self-cleaning performance was demonstrated by PDA0.25 @DCN/PVDF2, with a flux recovery rate of 84.5%, simply under visible light irradiation, which indicates its potential for environment-friendly practical application.

Polyphenol synergistic cerium oxide surface engineering constructed core-shell nanostructures as antioxidants for durable and high-performance proton exchange membrane fuel cells

The chemical degradation of proton exchange membranes (PEMs) suffering from radical attack is a crucial issue in the development of proton exchange membrane fuel cells (PEMFCs), while incorporating cerium oxide (CeO2) nanoparticles (NPs) with regenerative redox properties to eliminate radicals could effectively alleviate degradation. However, the low stability and restricted activity of CeO2 in the PEMFC operating condition and the poor compatibility with PEM due to CeO2 agglomeration stimulate the urgency for structural modulation of CeO2. Achieving a balance of membrane performance and oxidation resistance through a rational surface modification strategy of CeO2 is important for expanding PEMFC applications. Herein, polyphenols surface functionalized CeO2 core-shell structure (CeO2@TP) were constructed via assembling oxidation-induced coupling tea polyphenols (TP) on CeO2 NPs. The TP oligomeric shell as a protective layer enhances the stability of CeO2, mitigating radical scavenging activity degradation and improving compatibility with PEMs. Physicochemical characterisation shows that the overall performance of the nanocomposite membrane is improved due to the interaction of CeO2@TP nanoparticles with the polymer matrix. Gratifyingly, the phenolic hydroxyl-rich reductive TP oligomeric shell accelerates the regeneration of Ce(IV) to Ce(III), increasing the proportion of Ce(III) and oxygen vacancies on the CeO2 surface, thus boosting antioxidation efficiency. As a result, the CeO2@TP-based PEMs exhibited an OCV decay rate of 0.22 mV h−1, a maximum power density of 1.06 W cm−2, an H2 crossover value of 2.18 mA cm−2, thickness retention (91.1%), and negligible Ce migration after 404 h of accelerated degradation testing. It is proven that the desired consequences of doping antioxidants in PFSA matrix can be intensified by surface modulation of the physicochemical properties of CeO2.

Synthesis and characterization of p-carboxy phenyl amino maleimide-g-cellulose acetate/ZrO2 nanocomposite membrane for water desalination

Abstract The reaction of p-carboxy phenyl amino maleimide (CHM) with cellulose acetate (CA) led to the formation of a modified cellulose acetate polymer (MCA), which was characterized by UV/Vis, 1H NMR, and 13C NMR. The active sites of the reaction were the –NH group of (CHM) and the OAc of CA. CA was grafted with (CHM) to build branches on its main chains, using benzoyl peroxide as an initiator. The results of 1H NMR and 13C NMR revealed the presence of (CHM) moieties inside the polymeric matrix. The (CA-g-CHM) ZrO2 was fabricated into a membrane, using a phase inversion technique. The effect of ZrO2 content on the water flux was discussed. The SEM/EDS was also used to characterize the membrane contents and morphology. The morphology of the membrane showed the grafted parts and the EDS confirmed the presence of nitrogen atoms in the polymeric matrix. The thermogravimetry (TGA) results showed that the membrane exhibited high thermal stability which would adjust the membrane for the desalination process. The desalination test indicated the removal of NaCl salt by the membrane, as shown by the EDS and 1H NMR spectroscopy results. The membrane exhibited good antibacterial and antifungal properties.

Functionalized g-C3N4 nanosheet interlayer enables enhanced separation performance of nanofiltration membranes

Thin film nanocomposite membrane with a nanomaterial interlayer (TFNi) has attracted extensive attention in recent years. Herein, for the first time, tannic acid (TA) functionalized g-C3N4 nanosheets are used to construct an interlayer for the fabrication of TFNi nanofiltration membranes with enhanced separation performance. The TA-C3N4 nanosheet interlayers possess high hydrophilicity, low resistance for water transport, and strong structural stability, which is conducive to improving water permeance of the TFNi membranes. Meanwhile, the uniformity of interfacial polymerization on the interlayers is improved by virtue of the smooth surface of the interlayer, enabling the formation of an integral and dense polyamide layer with a thickness of only about 10 nm. The TFNi membranes exhibit excellent performance with water permeance of 34.25 L m−2 h−1 bar−1 and Na2SO4 rejection of 98.53%, which are obviously higher than those of the corresponding membrane without TA-C3N4 nanosheets (21.03 L m−2 h−1 bar−1 and 92.04%). The TFNi membranes also show significant selectivity improvement toward divalent/monovalent ions. This work gives inspiration for designing advanced nanofiltration membranes with functionalized nanomaterials acting as interlayers.

Antimicrobial Activities of Polyethylene Terephthalate-Waste-Derived Nanofibrous Membranes Decorated with Green Synthesized Ag Nanoparticles.

Thermoplastic polymers are one of the synthetic materials produced with high tonnage in the world and are so omnipresent in industries and everyday life. One of the most important polymeric wastes is polyethylene terephthalate (PET), and the disposal of used PET bottles is an unsolved environmental problem, and many efforts have been made to find practical solutions to solve it. In this present work, nanofibrous membranes were produced from waste PET bottles using the electrospinning process. The surface of membranes was modified using NaOH and then decorated with green synthesized Ag nanoparticles (10 ± 2 nm) using an in situ chemical reduction method. The morphology, size, and diameter of the Ag nanoparticles decorating the nanofibers were characterized through transmission electron microscopy (TEM), a field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV-visible spectroscopy techniques. Finally, the antimicrobial activity of the nanofibrous membranes was tested against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus using disc diffusion and colony-forming count methods. The growth of bacteria was not affected by the pure nanofibrous membranes, while the Ag-decorated samples showed inhibition zones of 17 ± 1, 16 ± 1, and 14 ± 1 mm for Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus, respectively. The planktonic culture results of Pseudomonas aeruginosa showed that the membranes had a relatively low inhibitory effect on its growth. The obtained results showed that Pseudomonas aeruginosa has a relatively low ability to form biofilms on the nanostructured membranes too. A good agreement was observed between the data of biofilm formation and the planktonic cultures of bacteria. The plastic-waste-derived PET/Ag nanocomposite membranes can be used for wound dressings, air filters, and water purification applications.