Search

Membrane materials with osmium nanoparticles have been recently reported for bulk membranes and supported composite membrane systems. In the present paper, a catalytic material based on osmium dispersed in n–decanol (nD) or n–dodecanol (nDD) is presented, which also works as an emulsion membrane. The hydrogenation of p–nitrophenol (PNP) is carried out in a reaction and separation column in which an emulsion in the acid-receiving phase is dispersed in an osmium nanodispersion in n–alcohols. The variables of the PNP conversion process and p–aminophenol (PAP) transport are as follows: the nature of the membrane alcohol, the flow regime, the pH difference between the source and receiving phases and the number of operating cycles. The conversion results are in all cases better for nD than nDD. The counter-current flow regime is superior to the co-current flow. Increasing the pH difference between the source and receiving phases amplifies the process. The number of operating cycles is limited to five, after which the regeneration of the membrane dispersion is required. The apparent catalytic rate constant (kapp) of the new catalytic material based on the emulsion membrane with the nanodispersion of osmium nanoparticles (0.1 × 10−3 s−1 for n–dodecanol and 0.9 × 10−3 s−1 for n–decanol) is lower by an order of magnitude compared to those based on adsorption on catalysts from the platinum metal group. The advantage of the tested membrane catalytic material is that it extracts p–aminophenol in the acid-receiving phase. [ABSTRACT FROM AUTHOR]

Here, polyaniline/polyvinylidene fluoride (PANI/PVDF) nanofiber composite membrane was fabricated using electrostatic spinning technology to remove hexavalent chromium Cr(VI). The employment of PANI not only extremely enhanced the hydrophilic property of the nanofiber membrane, but also facilitated the transfer of Cr2O72− from water to the membrane. The PANI/PVDF membrane had an extremely excellent performance in getting rid of Cr(VI) and a quite large flux (250 L/m2 h). The maximum adsorption quantity of the membrane could reach 334.5 mg/g in which adsorption played 52.12% part and reduction played 47.87% part. The removal rate could reach nearly 100% immediately in the permeate solution under filtration while it needed 240 min to reach 100% only by static adsorption. Therefore, the interception of the membrane and the adsorption reduction of PANI had synergistic effect on removal of Cr(VI). Furthermore, the removal rate of Cr(VI) could still reach 95.97% after reused 8 times. The membrane showed a very good reusability and application prospect. [ABSTRACT FROM AUTHOR]

Industrial wastewater from various manufacturing sectors poses a significant environmental concern due to the release of dyes, heavy metals, and pollutants into natural water streams. Effective treatment of large volumes of industrial wastewater is crucial to mitigate this issue. Conventional industrial wastewater filtration systems often prove to be inefficient, necessitating the exploration of alternative and cost‐effective water filtration methods. In this study, we drew inspiration from the natural adsorption and purification properties of corncob to develop a novel green composite membrane filter. The composite membrane filters, named MCAPCB and MCATPCB, were formulated by incorporating powdered corncob (PCB) and alkali/hydrogen peroxide‐treated powdered corncob (TPCB) into cellulose acetate. The adsorption properties of the composite filters were evaluated using UV–Vis spectrophotometry for dye adsorption and inductively coupled plasma optical emission spectroscopy (ICP‐OES) and atomic absorption spectroscopy (AAS) for heavy metal adsorption. The results demonstrated that MCATPCB20, incorporating 20 wt% TPCB, exhibited remarkable performance in the removal of methylene blue dye, with an adsorption efficiency of 97.46%. In comparison, MCAPCB20, incorporating 20 wt% PCB, achieved a dye adsorption efficiency of 80.15%. Moreover, MCATPCB20 displayed exceptional heavy metal removal capabilities, effectively rejecting 98% and 95% of cadmium and lead, respectively, from water samples containing 1 ppm of each metal. The composite filter membranes containing 20 wt% TPCB exhibited superior adsorption efficiency, flexibility, and stability. This enhanced performance can be attributed to the higher carboxyl content in TPCB, achieved through alkali treatment, which significantly increased the adsorption capacity of MCATPCB20. Characterization studies employing XRD, SEM, contact angle, BET, ICP‐OES, and UV measurements further supported the efficacy of MCATPCB as an effective filter system for water purification. [ABSTRACT FROM AUTHOR]

The development of clean and sustainable nitrogen-fixing methods has always attracted significant attention for decades. In this work, we investigated a strategy to enhance the N2 photo-fixation performance of titanium dioxide (TiO2) films by leveraging the synergistic effect between photon localization effects and iron (Fe) doping. Introducing Fe ions into TiO2 broadens its light absorption spectrum, making it extend into the visible light range, while improving charge separation capabilities. Our findings revealed that the photocatalytic ammonia generation of Fe-doped TiO2 (FT) catalysts, with a Fe3+ concentration of 6%, could reach up to 1.5 times that of pure TiO2. Besides, the photon localization effect of the SiO2 opal photonic crystals (SOPC) could enhance the light harvesting efficiency of the photocatalysts. By coupling the SOPC layer and nanocrystalline FT films, the N2 photo-fixation performance of FT/SOPC composite membranes was further promoted to 55.6 mmol g-1 h-1. This study offered a promising route for nitrogen fixation using solar energy. [ABSTRACT FROM AUTHOR]

Poly-ether-ether-ketone (PEEK), an organic polymer material with good thermal stability and tensile strength, has been regarded as an ideal material for anion-exchange membrane (AEM). Metal-organic framework materials (MOFs) possess excellent chemical stability and mechanical properties. In this work, MOF-801 was impregnated with ionic liquid and the obtained IL@MOF-801 was introduced into imidazole-functionalized PEEK to obtain IL@MOF/Im-PEEK composite anion exchange membranes. The addition of IL@MOF-801 not only increases the ion transport channels but also forms hydrogen bonding network with the imidazole groups on PEEK, which is beneficial for improving ion transport properties and mechanical strength. The anion-exchange membrane consisting of 4% IL@MOF-801/Im-PEEK achieved an anionic conductivity of 116.8 mS/cm at 80 °C and 100% RH and excellent mechanical properties with a tensile strength of up to 208.7 MPa. [Display omitted] • Ionic liquid was impregnated in MOF-801 to obtain IL@MOF-801 with low leakage rate. • IL@MOFs construct new ion channels to improve the ionic conductivity of the membrane. • The combination of PEEK and MOFs produces a composite membrane with high tensile strength. [ABSTRACT FROM AUTHOR]

The present study aims to evaluate the performance of porous hydrophobic Polyvinylidene fluoride − Polytetrafluoroethylene (PVDF-PTFE) composite membranes for desalination by vacuum membrane distillation (VMD) technique. The effect of operating parameters such as feed NaCl concentration (10,000 to 40,000 mg/L), feed temperature (50 °C to 80 °C), and downstream pressure (80 to 120 mmHg) on water permeation rate was studied. The increase in feed temperature enhanced the water permeation rate due to a rise in driving force across the membrane. For a constant downstream pressure of 80 mmHg, feed temperature of 80 °C and feed flow rate of 80 L/h, the membrane exhibited a maximum water flux of 3 kg/m2h with 99.86% salt rejection when aqueous NaCl concentration of 10,000 mg/L was charged as feed. Membrane characterization was performed using various analytical tools to determine physico-chemical properties such as pore size, structural elucidation, thermal stability, crystallinity, and hydrophobicity of the membrane material. Further, a temperature and concentration polarization coefficient-based analysis was performed by solving the mass and heat transport model equations using MATLAB software. The proposed research study promotes the application of VMD for recovering potable water from highly saline sea/brackish water and alleviates brine disposal issues. [ABSTRACT FROM AUTHOR]

The influence of the type of crosslinking agent for poly(vinyl alcohol) (PVA) (glutaraldehyde or epichlorohydrin) on the structure, morphology, thermal stability, and electrochemical properties of composite membranes based on the domestic perfluorinated sulfonic acid copolymer LSC, an analog of Nafion®, has been studied. The introduction of hydrophilic PVA has led to an increase in the moisture content of the membranes, which, taking into account the structural features, affects the proton conductivity. The presence of up to 5 wt % of cross-linked PVA in the composite membrane has not significantly changed the initial structure of LSC. The degree of crystallinity of the composite membranes upon the introduction of PVA has been slightly increased as compared to the original LSC membrane. With an increase in the amount of PVA in the composite, a domain surface morphology has appeared, its roughness being clearly increased. The increase in the PVA content in the LSC-PVA-GA samples has led to a noticeable increase in the temperature of thermal decomposition of sulfonic acid groups, while it has remained almost unchanged for the LSC-PVA-ECH samples. [ABSTRACT FROM AUTHOR]

Particulate matter (PM), usually formed as aerosols suspended in atmosphere, is becoming a carrier of viruses and bacteria, accelerating the spread of respiratory diseases. Hence, air filtration devices are widely utilized for removing PM. In this study, a regenerated cellulose (RC) film was prepared with the properties of good mechanical strength, antibacterial, and highly efficient filtration (EF) properties, through cellulose dissolution and further crosslinking with P(AGE-DMDAAC)/ZnO. Results exhibited that the Young's modulus of the composite membrane was nearly 4.3 GPa. Additionally, the antibacterial performance against Escherichia coli and Staphylococcus aureus, was up to 99.89% and 99.67%, respectively. Meanwhile, RC composite filter exhibited a high PM 2.5 capture efficiency (over 99.91%). This study introduces an interesting approach to produce antibacterial films with the characteristics of notably good mechanical performance and high fine particle EF that can be utilized in a high humidity environment. [ABSTRACT FROM AUTHOR]

The sensitivity and accuracy of nanopore sensors are severely hindered by the high noise associated with solid-state nanopores. To mitigate this issue, the deposition of organic polymer materials onto silicon nitride ( S i N x ) membranes has been effective in obtaining low-noise measurements. Nonetheless, the fabrication of nanopores sub-10 nm on thin polymer membranes remains a significant challenge. This work proposes a method for fabricating nanopores on polymethyl methacrylate (PMMA) membrane by the local high electrical field controlled breakdown, exploring the impact of voltage and current on the breakdown of PMMA membranes and discussing the mechanism underlying the breakdown voltage and current during the formation of nanopores. By improving the electric field application method, transient high electric fields that are one–seven times higher than the breakdown electric field can be utilized to fabricate nanopores. A comparative analysis was performed on the current noise levels of nanopores in PMMA- S i N x composite membranes and S i N x nanopores with a 5 nm diameter. The results demonstrated that the fast fabrication of nanopores on PMMA- S i N x membranes exhibited reduced current noise compared to S i N x nanopores. This finding provides evidence supporting the feasibility of utilizing this technology for efficiently fabricating low-noise nanopores on polymer composite membranes. [ABSTRACT FROM AUTHOR]

The use of immiscible polymer blends in gas separations is limited due to uncontrollable phase separation. In contrast, compatibilized immiscible polymer blends can be used as precursors with controlled morphologies that allow for a unique pore architecture. Herein, an immiscible polymer blend (1:1) comprising polybenzimidazole (PBI) and the copolyimide 6FDA-DAM:DABA [3:2], derived from reacting 4,4-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) with 2,4,6-trimethyl-1,3-phenylenediamine (DAM) and 3,5-diaminobenzoic acid (DABA), were combined with durene diamine as a compatibilizer. The compatibilizer helped reduce the 6FDD domain sizes from 5.6 µm down to 0.77 µm and induced a more even 6FDA distribution and the formation of continuous thin-selective PBI layers. The carbon–carbon composite membranes derived from the compatibilized immiscible polymer blends showed a 3-fold increase in both H2 permeability and H2/CO2 selectivity compared to the membranes derived from non-compatibilized polymer blends. The H2 permeability of the compatibilized immiscible polymer blends increased from 3.6 to 27 Barrer, and their H2/CO2 selectivity increased from 7.2 to 20. The graphitic domain size of the carbon–carbon composite membranes derived from the polymer blends also increased from 6.3 nm for the non-compatibilized blend to 10.0 nm for the compatibilized blend. [ABSTRACT FROM AUTHOR]

The sustainable management of wastewater through recycling and utilization stands as a pressing concern in the trajectory of societal advancement. Prioritizing the elimination of diverse organic contaminants is paramount in wastewater treatment, garnering significant attention from researchers worldwide. Emerging metal-organic framework materials (MOFs), bridging organic and inorganic attributes, have surfaced as novel adsorbents, showcasing pivotal potential in wastewater remediation. Nevertheless, challenges like limited water stability, elevated dissolution rates, and inadequate hydrophobicity persist in the context of wastewater treatment. To enhance the performance of MOFs, they can be modified through chemical or physical methods, and combined with membrane materials as additives to create membrane composite materials. These membrane composites, derived from MOFs, exhibit remarkable characteristics including enhanced porosity, adjustable pore dimensions, superior permeability, optimal conductivity, and robust water stability. Their ability to effectively sequester organic compounds has spurred significant research in this field. This paper introduces methods for enhancing the performance of MOFs and explores their potential applications in water treatment. It delves into the detailed design, synthesis strategies, and fabrication of composite membranes using MOFs. Furthermore, it focuses on the application prospects, challenges, and opportunities associated with MOF composite membranes in water treatment. [ABSTRACT FROM AUTHOR]

It is urgent to develop a polyamide (PA) thin-film composite (TFC) membrane with a new method in this study by designing and constructing a new nanomaterial support layer instead of the conventional support layer. Polydopamine-wrapped single-walled carbon nanotubes (PDA@MWCNTs) as the place of the polymerization reaction can optimize the PA film structure and performance. The resulting composite membrane presents a higher water flux of 15.8 L·m−2·h−1·bar−1 and a rejection rate of 97% to Na2SO4, simultaneously maintaining this high separation performance in 300 min. It is a new ideal to construct novel support layer by using inorganic nanoparticles and organic polymer nanofiber membranes. [ABSTRACT FROM AUTHOR]

The proton exchange membrane (PEM) is vital in proton exchange membrane fuel cells (PEMFCs), but current PEMs face issues including low conductivity, poor durability, and instability in maintaining proton transport across varying temperatures. This study proposes an innovative approach to address this issue by incorporating UiO-66-(COOH) 2 as a filler in a polymeric matrix comprising polyvinylpyrrolidone and polyvinylidene fluoride (abbreviated as PP). Significantly, this facilitates forming hydrogen bonds between UiO-66-(COOH) 2 and the PP matrix. The UiO-66-(COOH) 2 @PP composite membranes are comprehensively characterized through PXRD, TGA-DSC, FTIR, and SEM analyses. The remarkable water adsorption performance observed in the UiO-66-(COOH) 2 @PP-X series creates favourable conditions for enhancing proton conductivity. Proton conductivity studies highlight exceptional performance, particularly UiO-66-(COOH) 2 @PP-30 achieving a remarkable 5.8 × 10−3 S cm−1 at 98% RH, with sustained conductivity over one week. At 32% RH, UiO-66-(COOH) 2 @PP-30 exhibits a significantly reduced activation energy of 0.09 eV, indicating a stable proton transport pathway across a wide temperature range. Mechanism studies unveil that the collaborative interaction between UiO-66-(COOH) 2 and PP establishes a continuous network of hydrogen bonds, strengthened by PP's hydrophilic properties. Additionally, the stabilization of water within UiO-66-(COOH) 2 channels significantly contributes to the overall efficiency of proton conduction. • Blending UiO-66-(COOH) 2 with polyvinylpyrrolidone and polyvinylidene fluoride forms advanced UiO-66-(COOH) 2 @PP-X membrane. • UiO-66-(COOH) 2 @PP-30 achieves high conductivity (5.8 × 10−3 S cm−1) at 98% RH for a week. • At 32% RH, UiO-66-(COOH) 2 @PP-30 shows low activation energy of 0.09 eV, highlighting its efficiency. • Cooperative hydrogen bonding between UiO-66-(COOH) 2 and PP enables continuous proton transfer channels. [ABSTRACT FROM AUTHOR]

Blending metal-organic frameworks to optimize proton transport pathways is one of the strategies to improve the proton conductivity of proton exchange membranes (PEM). In this paper, amino-sulfonic acid bifunctionalized UiO-66 (NUS) by one-pot solvothermal method is synthesized, and sulfonated poly (ether ether ketone)/NUS-X (SPEEK/NUS-X) hybrid membranes are prepared by mixing NUS into SPEEK matrix. Among them, SPEEK/NUS-1.5 has the highest proton conductivity (177.76 mS cm−1, 70 °C, 100% RH) and maintain a 300 h conductivity stability. And its maximum power density was 423.2 mW cm−2, exceeding pristine SPEEK by 2.20 times. Compare to the pristine SPEEK membrane, it is interesting to note the disappearance of SAXS scattering peak of SPEEK/NUS-1.5. It is speculated that this phenomenon was caused by the generation of acid-base pairs between –NH 2 and –SO 3 H, and the improved hydrogen bonding network provides more proton transport channels and immobilizes sulfonic acid groups for improved durability. The resultant proton conductivity is stable over 300 h with about 90% retention. • A 'short-ranged acceleration zone' is constructed by NUS prepared by one-pot solvothermal method to accelerate proton conduction in membrane. • Little difference in electron density of the composite membranes lead to the disappearance of the SAXS scattering peak. • Improved hydrogen bonding network provides more proton transport channels and immobilizes sulfonic acid groups for improved durability, and the resultant proton conductivity is stable over 300 h with about 90% retention. • In-depth mechanism discussions reveal a cooperative interaction between SPEEK and NUS, inter-NUS, intra-SPEEK and intra-NUS, resulting in a more complete hydrogen bonding network. [ABSTRACT FROM AUTHOR]

Nanofiltration composite membranes with high selectivity are one of the most critical cores in water treatment, and regulating the surface charge and pore structure of active separation layers in thin film composite membranes is one of the most effective means to improve the selectivity of composite membranes. This article synthesized a novel monomer with positive charge and a rigid twisted Tröger's base structure (named TBDA‐SO3), which was manipulated to improve the microporous structure and surface charge of the composite membrane. By interfacial polymerization, TBDA‐SO3, and piperazine were co‐reacted with trimesoyl chloride to successfully prepare positively charged, highly selective, and strongly microporous polyamide composite nanofiltration membranes. The best‐performing composite nanofiltration membrane in this article has a permeability similar to that of the control group's poly(piperazine amide) (PPA) membrane (pure water flux, 7.8 L m−2 h−1 bar−1), but has excellent divalent cation selectivity (52.57), which is 4.4 times that of the control group's PPA membrane. [ABSTRACT FROM AUTHOR]

A functionally graded membrane (FGM) with a special spiral-structured cellulose acetate (CA) membrane was prepared by electrospinning under different collection distances. The membrane morphology was analyzed by scanning electron microscopy (SEM). FESEM images revealed that the high concentration shows the formation of fibers with an irregular diameter, with a large diameter distribution range. The fiber collected at a short distance of 10 cm experiences the strong electrostatic force, resulting in the short flight time for the polymer jet. This causes the bending instability of the polymer jet forming the comparatively thick fiber diameters, whereas the fiber collected at 15 cm shows the presence of a smooth, homogeneous diameter. Furthermore, the water flux of the membrane was determined using 50 mL of Amicon stirred cells. The fiber collected at different distances showed diameter variation, which is used to design a special spiral structure on the membrane by auto-moving the collector between the fixed distances of 10–20 cm. This technique will reveal a new approach for the fabrication of a special spiral structure on the nanofibrous membrane for different biomedical applications from different polymers. Meanwhile, the fabricated FGM with a special spiral-structure CA membrane demonstrates high water permeation flux. [ABSTRACT FROM AUTHOR]

The dermal–epidermal junction (DEJ), located between the dermal–epidermal layers in human skin tissue, plays a significant role in its function. However, the limitations of biomaterial properties and microstructure fabrication methods mean that most current tissue engineered skin models do not consider the existence of DEJ. In this study, a nanofiber membrane that simulates the fluctuating structure of skin DEJ was prepared by the composite molding process. Electrospinning is a technique for the production of nanofibers, which can customize the physical and biological properties of biomaterials. At present, electrospinning technology is widely used in the simulation of customized natural skin DEJ. In this study, four different concentration ratios of poly (lactic-co-glycolic acid) (PLGA) and polycaprolactone (PCL) nanofiber membranes were prepared based on electrospinning technology. We selected a 15%PLGA + 5%PCL nanofiber membrane with mechanical properties, dimensional stability, hydrophilicity, and biocompatibility after physical properties and biological characterization. Then, the array-based microstructure model was prepared by three-dimensional (3D) printing. Subsequently, the microstructure was created on a 15%PLGA + 5%PCL membrane by the micro-imprinting process. Finally, the cell proliferation and live/dead tests of keratinocytes (HaCaTs) and fibroblasts (HSFs) were measured on the microstructural membrane and flat membrane. The results showed that 15%PLGA + 5%PCL microstructure membrane was more beneficial to promote the adhesion and proliferation of HaCaTs and HSFs than a flat membrane. [ABSTRACT FROM AUTHOR]

In this work, we used a previously described computational fluid dynamics (CFD) model of a roll‐to‐roll coating process for the fabrication of thin‐film composite membranes to predict the final coating thickness for PolyActive™, a commercially available multiblock copolymer utilized for CO2 removal membranes. We found a strong thickening effect that could not be explained by our previous model. We investigated the process experimentally. In addition, we conducted a variety of simulations with extensions of the initial CFD model. Based on our findings, we conclude that the Marangoni effect, that is, gradients of surface tension that induce secondary flow patterns in the meniscus region, is the most likely source of the observed thickening. We explain the simulation results in order to understand the physical mechanisms at play and to show how especially surface tension gradients that arise from the particular flow structure in the meniscus may explain the additional transfer of polymer solution to the membrane. Finally, we draw some conclusions on future research and give ideas on future improvements of the process. To our knowledge, Marangoni effects for the coating of PolyActive™ were not described so far in the literature, even though it is a well‐known polymer for gas separation membranes targeted at CO2 removal. Roll‐to‐roll coating is a well‐established coating method and often believed to be suitable for the scale‐up of membrane production, therefore we think that this work will help membrane researchers who are using similar coating devices to be cautious about possible complications in the process. [ABSTRACT FROM AUTHOR]

Low-sulfonation-level polyether sulfone octyl sulfonamide (LSPSO) was blended with a layered double hydroxides (LDHs, Mg2AlCl)/sepiolite nanostructure clay as a filler to create an electrolyte membrane for fuel cell applications. Comprehensive characterization of the composite membranes was conducted, encompassing Fourier-transform infrared spectroscopy, X-ray diffraction, mechanical stability assessment, thermal gravimetric analysis, ion exchange capability, swelling characteristics, water uptake performance, and electrochemical impedance spectroscopy analysis. In comparison to the pristine LSPSO membrane, the presence of LDHs/sepiolite nanoarchitecture material within LSPSO exhibited superior water retention and proton conductivity values, especially at elevated temperatures. The proton conductivity of the composite membranes reached approximately 250 mS/cm, while the unmodified LSPSO membrane only achieved 35 mS/cm at 100 °C. Moreover, LSPSO composite membranes demonstrated enhanced chemical and thermal stability along with higher proton conductivity when compared to pristine LSPSO membranes. These findings highlight the potential of developing tailored LSPSO composite membranes to advance the prospects of commercial applications in proton exchange membrane fuel cells. [ABSTRACT FROM AUTHOR]

An innovative methodology was employed to fabricate ion exchange membranes tailored for fuel cell applications. This approach entailed blending low sulfonated polyether sulfone octyl sulfonamide (LSPSO) with Hectorite (Hect) clay at varying weight percentages (1 wt%, 3 wt%, and 6 wt%). The resultant composite membranes underwent comprehensive characterization via Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis, aiming to assess their surface morphology and thermal resilience. Remarkably, the thermal stability of the composite membrane exhibited a substantial enhancement in comparison to the pristine LSPSO membrane. Moreover, the incorporation of 6 wt% Hectorite into the composite membrane yielded a noteworthy amplification in proton conductivity, achieving a fourfold increase (141.66 mS/cm) as opposed to the LSPSO membrane in isolation (35.04 mS/cm). Consequently, the Hect/LSPSO composite membrane exhibits remarkable potential as an electrolyte membrane for fuel cells operating at temperatures surpassing 100 °C. [ABSTRACT FROM AUTHOR]

In the context of recycling and reusing textile wastewater, the quest for a membrane possessing superior efficiency has garnered considerable attention. This research endeavors to advance this objective by introducing a novel asymmetric ultrafiltration membrane constructed from PVDF (Polyvinylidene Fluoride) modified with MXene through bulk modification, thereby augmenting its resistance to fouling for textile wastewater treatment applications. The investigation employed a comprehensive array of characterization techniques. The proposed interaction mechanism between the contents of PVDF/MXene and the interaction mechanism of composite membrane with water molecules were also presented. Comparative analysis with pure membranes revealed that the incorporation of MXene resulted in enhanced hydrophilicity and porosity, concurrently reducing its surface roughness when compared to a pristine membrane. The lowest water contact angle about 38.5 (0) was observed in the mixed matrix membrane containing 0.5 wt% MXene. The developed membranes exhibited a maximum pure water flux of 538 LMH and a flux of 467.8 LMH for EBT dye solution. Furthermore, optimization of the nanocomposite membrane composition led to nearly complete rejection of Eriochrome black T (EBT). A continuous improvement in the flux recovery ratio (FRR%) culminating in a peak value of 85.6% for the MMMs prepared from 0.5 wt% MXene. [ABSTRACT FROM AUTHOR]

Composite membranes constructed using both graphene oxide and carbon nanotubes (CNTs) were designed to strengthen the forward osmosis (FO) technology for the removal of organic contaminants. The nano-membrane was chemically treated with organic acids, which were citric acid in this case for more efficiency in permeability and pollutant removal. The efficiency of the composite membranes in organic pollutants removal was estimated by checking the levels of COD (chemical oxygen demand), TKN (total nitrogen analysis), and (TOC) organic carbon in the water sample before and after applying the technology. The analysis of the study recommends that the nano-membranes may be appropriately used to reduce organic pollutants significantly, to 98.20% efficiency, in addition to elevating water quality standards. This was caused by the higher degree of selectivity and permeability of the membranes that was consequent to the treatment of the organic acid. In brief, the employment of citric acid in the pre-treatment procedures for the preparation of composite graphene oxide-carbon nanotube membranes for FO technology could take water cleaning technologies a step ahead toward sustainable technology. The application of the composite membrane with graphene oxide and carbon nanotubes is not only efficient in cleaning out organic contaminants but it has a lot of added benefits. These membranes are easily manufactured with a long lifespan which, in turn, makes them cost-effective and environmentally friendly. Also, forward osmosis technology reduces the energy demand compared to other water remediation methods, making it a more sustainable solution. The final point of this article is that the using of composite graphene oxide-carbon nanotube membranes treated with an organic acid, such as citric acid, in FO technology not only assists with the water treatment problem but also elevates sustainablility due to its effectiveness and is environmentally friendly. [ABSTRACT FROM AUTHOR]

Selective recovery of recyclables is a major challenge when treating textile wastewater. For this reason, there is an urgent need to develop nanofiltration membranes with high permeability and selective filtration. In response, a novel composite PVDF loose nanofiltration membrane was developed by combining two different mixed amines system/dopamine (DA) followed by interfacial polymerization with benzoyl chloride (TMC). The two different amines systems were a mixture of GAZ and PEI and a mixture of PIP and PEI, respectively. The effects of GAZ/PEI and PIP/PEI on the microstructure was characterized by SEM, AFM, FTIR and XPS and performance of the membrane was also investigated. The effects of GAZ/PEI and PIP/PEI on the microstructure and the selective layer of membranes were different. The results stated that with the increase of GAZ/PEI the thickness of the selective layer, surface roughness decreased, while the fluxes of pure water and dye wastewater increased. However, with increasing PIP/PEI, surface nodules and roughness both increased. Contrarily, the thickness of the selective layer and PEG800 rejection first decreased and then increased, while the flux of pure water and the dye wastewater first increased and then decreased. The optimal GAZ/PEI and PIP/PEI were 9/91 and 50/50, respectively. When the GAZ/PEI was 9/91, the pure water flux and the RB5 wastewater flux were 20.7 L⋅(m²⋅h)-1 and 11.5 L⋅(m²⋅h)-1. The dye (RB5) retention rate was 94.3% and salt retention rate was 2.1%. However, when the PIP/PEI was 50/50, the pure water flux and RB5 wastewater flux were 26.6 L⋅(m²⋅h)-1 and 17.1 L⋅(m²⋅h)-1 increased by 87.3% and 134.2% respectively. The retention rates of RB5 and NaCl were 96.3% and 1.7%. The above results indicate that the composite PVDF LNF membranes prepared with mixed amine monomers instead of single amine monomers have good selective filtration performance. [ABSTRACT FROM AUTHOR]

Thin-film nanocomposite (TFN) forward osmosis (FO) membranes have attracted significant attention due to their potential for solving global water scarcity problems. In this study, we investigate the impact of titanium oxide (TiO2) and titanium oxide/reduced graphene (TiO2/rGO) additions on the performance of TFN-FO membranes, specifically focusing on water flux and reverse salt diffusion. Membranes with varying concentrations of TiO2 and TiO2/rGO were fabricated as interfacial polymerizing M-phenylenediamine (MPD) and benzenetricarbonyl tricholoride (TMC) monomers with TiO2 and its reduced graphene composites (TiO2/rGO). The TMC solution was supplemented with TiO2 and its reduced graphene composites (TiO2/rGO) to enhance FO performance and reverse solute flux. All MPD/TMC polyamide membranes are characterized using various techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle measurements. The results demonstrate that incorporating TiO2/rGO into the membrane thin layer improves water flux and reduces reverse salt diffusion. In contrast to the TFC membrane (10.24 L m−2h−1 and 6.53 g/m2 h), higher water flux and higher reverse solute flux were detected in the case of TiO2and TiO2/rGO-merged TFC skin membranes (18.81 and 24.52 L m−2h−1 and 2.74 and 2.15 g/m2 h, respectively). The effects of TiO2 and TiO2/rGO stacking on the skin membrane and the performance of TiO2 and TiO2/rGO skin membranes have been thoroughly studied. Additionally, being investigated is the impact of draw solution concentration. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) nanosheets have attracted widespread interest in the construction of advanced separation membranes. However, dense stacking and a single functionality have limited the membrane development. Here, an advanced two-/three-dimensional (2D/3D) g-C3N4/TiO2@MnO2 membrane is constructed by intercalating 3D TiO2@MnO2 nanostructures into g-C3N4 nanosheets. The 3D flower-like nanostructures broaden the transport channels of the composite membrane. The membrane can effectively separate five oil-in-water (O/W) emulsions, with a maximum flux of 3265.67 ± 15.01 L·m−2·h−1·bar−1 and a maximum efficiency of 99.69% ± 0.45% for toluene-in-water emulsion (T/W). Meanwhile, the TiO2@MnO2 acts as an excellent electron acceptor and provides positive spatial separation of electrons–holes (e−–h+). The formation of 2D/3D heterojunctions allows the material with wider light absorption and smaller bandgap (2.10 eV). These photoelectric properties give the membrane good degradation of three different pollutants, with about 100% degradation for methylene blue (MB) and malachite green (MG). The photocatalytic antibacterial efficiency of the membrane is also about 100%. After cyclic experiment, the membrane maintains its original separation and photocatalytic capabilities. The remarkable multifunctional and self-cleaning properties of the g-C3N4 based membrane represent its potential value for complex wastewater treatment. [ABSTRACT FROM AUTHOR]

Flexible and highly ultraviolet (UV) sensitive materials garner considerable attention in wearable devices, adaptive sensors, and light‐driven actuators. Herein, a type of nanofilms with unprecedented fully reversible UV responsiveness are successfully constructed. Building upon this discovery, a new system for ultra‐fast, sensitive, and reliable UV detection is developed. The system operates by monitoring the displacement of photoinduced macroscopic motions of the nanofilms based composite membranes. The system exhibits exceptional responsiveness to UV light at 375 nm, achieving remarkable response and recovery times of < 0.3 s. Furthermore, it boasts a wide detection range from 2.85 µW cm−2 to 8.30 mW cm−2, along with robust durability. Qualitative UV sensing is accomplished by observing the shape changes of the composite membranes. Moreover, the composite membrane can serve as sunlight‐responsive actuators for artificial flowers and smart switches in practical scenarios. The photo‐induced motion is ascribed to the cis–trans isomerization of the acylhydrazone bonds, and the rapid and fully reversible shape transformation is supposed to be a synergistic result of the instability of the cis‐isomers acylhydrazone bonds and the rebounding property of the networked nanofilms. These findings present a novel strategy for both quantitative and qualitative UV detection. [ABSTRACT FROM AUTHOR]

A novel Fe–RGO/TiO2/PTFE photocatalytic composite membrane was developed for the purification of MB wastewater. The properties of the prepared membranes were characterized using XRD, SEM, FT-IR spectroscopy, the BET method, and water contact angle, membrane flux, and BSA adsorption measurements. The photocatalytic properties of the surface-modified membranes were investigated in filtration experiments using MB as a representative organic contaminant. The results of the experiments showed that the Fe–RGO/TiO2 particles were securely loaded onto the surface of the PTFE membrane, demonstrating excellent chemical stability of the composite membrane. The incorporation of Fe3+ inhibited the agglomeration of TiO2 particles and enhanced the photocatalytic reaction rate. The introduction of RGO could broaden the photoresponsive range of TiO2, increase the specific surface area of the photocatalyst, introduce a large number of hydrophilic groups to enhance the hydrophilicity of the composite membrane, and subsequently increase the membrane flux. The MB wastewater was treated with the Fe–RGO/TiO2/PTFE composite membrane system for 3 h and the removal rate of MB reached 95.8% and 60.1% under UV and visible light, respectively. Reaction kinetic analysis indicated that the removal process of MB wastewater by Fe–RGO/TiO2/PTFE involves an adsorption–degradation–filtration synergy mechanism. [ABSTRACT FROM AUTHOR]

In this study, loose nanofiltration membranes made of polysulfone dissolved in co-solvents PolarClean and gamma-Valerolactone were prepared via slot die coating (SDC) on a roll-to-roll (R2R) system by directly coating them onto a support layer or free standing. A solution flow rate of 20 mL/min, substrate speed of 17.1 mm/s, and coating gap of 0.1 mm resulted in the formation of membranes without structural defects. Pre-wetting the support layer with dope solution minimized shrinkage of membrane layer thickness and improved interfacial adhesion. Membrane samples produced using SDC exhibited properties and performance consistent with bench-scale doctor blade extruded samples; pre-wetted and uncompressed samples (SDC-3) exhibited the highest rejection of bovine serum albumin (99.20% ± 1.31%) and along with adequate mean permeability during filtration (70.5 ± 8.33 LMH/bar). This study shows that combining sustainable materials development with SDC provides a holistic approach to membrane separations to bridge materials discovery and membrane formation. [ABSTRACT FROM AUTHOR]

Incorporating hydrophilic and charged porous nanofillers to prepare high-performance thin film nanocomposite (TFN) nanofiltration (NF) membranes is an effective method to achieve efficient water treatment. In this study, we synthesize the sulfonated covalent organic framework nanosheets (S-CONs) with higher hydrophilicity and electronegativity by immobilizing sulfonic acid groups (–SO3H) on TpPa-1 nanosheets. The S-CONs are incorporated in the PA layer by interfacial polymerization (IP) reaction. The results indicated that the S-CONs could modulate the hydrophilicity, thickness, and electronegativity of TFN-NF membranes. At the optimal addition of S-CONs (0.006 g), the pure water permeance increases to 8.84 L ⋅ m − 2 ⋅ h − 1 ⋅ bar − 1 , which is about 1.75 times than the TFC membrane, with a high Na2SO4 rejection reaching 98.97%. The improvement of the separation performance mainly results from the reduction of PA layer thickness (from ~178.00–198.00 to ~100.00–128.00 nm) and the increase of surface electronegativity (from −20.37 to −44.41 mV at pH = 7.00). More interestingly, the amide bond formed between the S-CONs and TMC improved the chlorine resistance of the membranes. This study reveals the potential of using functionalized 2D CONs as nanofillers to modify TFC membranes for efficient nanofiltration. [ABSTRACT FROM AUTHOR]

Composite membranes with a polyvinyl alcohol (PVA) selective layer composed of well-dispersed hydrophilic kaolinite particles coated on a polyvinylidene fluoride (PVDF) support were developed. They were applied to the pervaporation dehydration of the industrially important epichlorohydrin (ECH)/isopropanol (IPA)/water ternary mixture. In comparison with raw kaolinite (RK), hydrophilic kaolinite (HK) enhanced the mechanical properties, hydrophilicity, and thermal stability of the PVA selective layer, as confirmed by universal testing, the contact angle, and TGA analyses, respectively. The pervaporation results revealed that the addition of HK particles significantly enhanced the separation factor (3-fold). Only a marginal reduction in flux was observed with ECH/IPA/water, 50/30/20 (w/w %) at 40 °C. An HK particle concentration of 4 wt.% with respect to PVA delivered the highest flux performance of 0.86 kg/m2h and achieved a separation factor of 116. The PVA–kaolinite composite membrane exhibited pronounced resistance to the ECH-containing feed, demonstrating a sustained flux and separation factor throughout an extended pervaporation stability test lasting 250 h. [ABSTRACT FROM AUTHOR]

The time-lag method is the most useful technique to determine gas permeability, diffusivity, and solubility. However, it is difficult to evaluate the transport properties of the membrane accurately because gas permeability depends on the technique used to assess gas flow. The significance of the present study is to design an economic isochoric apparatus to accurately measure micro-range gas flow rates ranging from 10−6 to 10 cm3(STP) s−1. A strategic procedure is demonstrated to eliminate possible artifacts while conducting the gas permeation experiments, including utilizing downstream pressure rise profiles to identify nanoscale defects as well as transient and steady-state permeation. An indigenous apparatus was developed to estimate the polymeric intrinsic properties of the dense and thin-film composite membranes. The device has been successfully used to measure the gas permeation flow rate ranging from 1 × 10−5 to 1 × 10−1cm3 (STP) s−1, which indicates the broad applicability and reproducibility of the data suggesting the reliability of the designed apparatus. Permeation flow rates of binary mixtures of CO2/CH4 through the defect-free membranes were compared with the numerical estimations to validate the measured transport properties. [ABSTRACT FROM AUTHOR]

A tri-layer sandwiched composite nonwoven membrane, composed of two electrospun PVA/Melamine layers and one ZIF-67@cellulose acetate composite nonwoven layer, for high power lithium-ion batteries. [Display omitted] • High-power and high-safety lithium-ion batteries composite membrane was developed. • ZIF-67 filler deposited on cellulose acetate fibers (Z 67 @CA) by in situ growth method. • Sandwich structure developed with electrospun poly(vinyl alcohol)/melamine nonwoven membranes (Esp-PVAM). • The Esp-PVAM/15%Z 67 @CA/Esp-PVAM membrane exhibited good capacity retention of 90.34% (1C) for 100 cycles. • The Esp-PVAM/15%Z 67 @CA/Esp-PVAM membrane has a good dendrite suppression and thermo-resistant properties. Due to the poor thermal stability of conventional separators, lithium-ion batteries require a suitable separator to maintain system safety for long-term cycling performance. It must have high porosity, superior electrolyte uptake ability, and good ion-conducting properties even at high temperatures. In this work, we demonstrate a novel composite membrane based on sandwiching of zeolitic imidazole frameworks-67 decorated cellulose acetate nanofibers (ZIF-67@CA) with electrospun poly(vinyl alcohol)/melamine (denoted as PVAM) nonwoven membranes. The as-prepared sandwich-type membranes are called PVAM/x%ZIF-67@CA/PVAM. The middle layer of composite membranes is primarily filled with different weight percentages of ZIF-67 nanoparticles (x = 5, 15, and 25 wt%), which both reduces the non-uniform porous structure of CA and increases its thermal stability. Therefore, our sandwich-type PVAM/x%ZIF-67@CA/PVAM membrane exhibits a higher thermal shrinkage effect at 200 °C than the commercial polyethylene (PE) separator. Due to its high electrolyte uptake (646.8%) and porosity (85.2%), PVAM/15%ZIF-67@CA/PVAM membrane achieved high ionic conductivity of 1.46 × 10-3 S cm−1 at 70 °C, as compared to the commercial PE separator (ca. 6.01 × 10-4 S cm−1 at 70 °C). Besides, the cell with PVAM/15%ZIF-67@CA/PVAM membrane shows an excellent discharge capacity of about 167.5 mAh g−1after 100 cycles at a 1C rate with a capacity retention of 90.3%. The ZIF-67 fillers in our sandwich-type composite membrane strongly attract anions (PF 6 -) through Lewis' acid-base interaction, allowing uniform Li+ ion transport and suppressing Li dendrites. As a result, we found that the PVAM/15%ZIF-67@CA/PVAM composite nonwoven membrane is applicable to high-power, high-safety lithium-ion battery systems that can be used in electric vehicles (EVs). [ABSTRACT FROM AUTHOR]

Taking chitosan (CS) and soybean protein isolate (SPI) as composite membrane substrates and natural antioxidants as active substances, an edible active preservative film with inhibitory effect on lipid oxidation was developed. After optimizing the type and concentration of antioxidants through the mechanical properties, microstructure, physical properties, and antioxidant properties of the composite membrane, the preservation effect of the composite membrane on walnut oil was investigated. Results showed that, eight antioxidants significantly improved the oxygen-barrier ability of the composite membranes (P<0.05). Especially, the peroxide value of walnut oil was reduced by about 80% and maintained excellent mechanical properties with the addition of astaxanthin, grape seed extracts and vitamin C. When the addition of astaxanthin was 0.3%, the composite membrane exhibits the best performance, then the tensile strength, elongation at break, DPPH free radical scavenging capacity and water vapor permeability of the composite membrane were 6.546 MPa, 69.962%, 80.1%, 1.21 g⋅mm/m²⋅h⋅kPa, respectively. Scanning electron microscopy revealed that the surface of the membrane was smooth, regular and uniform. Fourier transform infrared spectroscopy showed that membrane-forming materials were extremely compatible. The differential scanning calorimeter analysis showed that the composite membrane had the highest thermal enthalpy, reaching 233.940 J/g, with the best thermal stability. When the walnut oil was coated with a composite membrane containing astaxanthin, the oil's peroxide value was reduced by 81.8%, conjugated diene by 44.4% and conjugated triene values by 66.4% compared to the control. Chitosan/soybean protein isolate composite membrane with astaxanthin significantly delayed the process of walnut oil oxidation. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) is a biodegradable and bio-based aliphatic polyester. It has received extensive attention due to its great environmental and economic value. As a biodegradable material, Polylactic acid (PLA) has poor impact toughness, resulting in a limitation of application. Blending PLA with polybutylene adipate terephthalate (PBAT) can significantly enhance its toughness. PLA/PBAT composite films, as a biodegradable material, is widely used due to its advantages of abundant raw materials, low cost, and environmental friendliness. This article outlines the different preparation methods and current research status of PLA/PBAT composite membranes. The modification technologies of composite membranes, including inorganic fillers, chain expansion and compatibilization, crosslinking agent modification, starch modification, and synergistic modification are summarized. Finally, the application and development prospect of PLA/PBAT composite films in food packaging is introduced, which provide theoretical references and new ideas for future research on PLA/PBAT films in food packaging. [ABSTRACT FROM AUTHOR]

The investigation of dual-layer fibrous membranes with asymmetric wettability is gaining growing interest. Here, we conceive a novel composite fibrous membrane base on cellulose acetate (CA), characterized by a hydrophobic-on-hydrophilic configuration, using a designed co-electrospinning system. A thin layer of hydrophobic thermoplastic polyurethane (TPU) side is overlaid onto a hydrophilic CA/TPU membrane to achieve directional water transport and oil–water separation. The core–shell CA/TPU bicomponent fibers exhibit a much higher tensile stress (3.6 MPa) and tensile strain (72.15%), when compared with CA fibrous membrane. The TPU membrane displays beads-on-string morphology, which promote the directional water transport capacity, and the possible mechanism is discussed. The measurements show that our composite membrane can effectively separate various oil–water mixtures, solely driven by gravity. Interestingly, the membrane shows high oil–water separation flux (up to 109,918 Lm−2 h−1). This study expands the range of potential applications for CA fibrous membranes. [ABSTRACT FROM AUTHOR]

This study investigates the impact of solvent post-treatment on polyamide-based thin film composite (TFC) membranes, specifically examining the effect on commercial nanofiltration (NF) and reverse osmosis (RO) membranes. Na2SO4 rejection and increase in pure water permeance (PWP) were considered as the output parameters. The disparity in Hansen solubility parameters (HSP) between the post-treatment solution and the polyamide layer of the TFC membrane, denoted by Ra, is well adapted to understand the enhancement in water permeance through the membranes upon treatment. Aqueous solutions of dimethylformamide with a Ra value of 4, acetonitrile with a Ra value of 8.3, and ethanol with a Ra value of 12.7 were used as the post-treatment solutions. Our experimental design, based on the Box–Behnken design of Response Surface Methodology, incorporates variables such as the concentration of the solvent in the solution (% v/v), Ra value, and treatment time (s). Our findings demonstrate that the effect of post-treatment on the TFC membranes is not governed by the Ra value. Notably, while the post-treatment with the aqueous solution of acetonitrile, 80% v/v for 30 s, had considerable effects on NF membranes (124.5% enhancement in PWP; reduction of 3.5% in Na2SO4 rejection), its impact on RO membranes was negligible. Several factors explain this discrepancy, including the limitations of the HSP model for composite polymers, the inaccuracy of the PWP or salt rejection as a swelling indicator, variations in the HSP values of the polyamide layers for different membranes, and possible modifications in the interface between the support membrane and the polyamide layer. In summary, our study provides insights into the complex interactions between solvents and composite membranes, indicating that HSP alone is not a decisive factor in predicting post-treatment effects on polyamide-based TFC membranes. [ABSTRACT FROM AUTHOR]

Fine design of surface charge properties of polyamide membranes is crucial for selective ionic and molecular sieving. Traditional membranes face limitations due to their inherent negative charge and limited charge modification range. Herein, we report a facile ionic liquid-decoupled bulk/interfacial diffusion strategy to elaborate the double charge flips of polyamide membranes, enabling on-demand transformation from inherently negative to highly positive and near-neutral charges. The key to these flips lies in the meticulous utilization of ionic liquid that decouples intertwined bulk/interfacial diffusion, enhancing interfacial while inhibiting bulk diffusion. These charge-tunable polyamide membranes can be customized for impressive separation performance, for example, profound Cl−/SO42− selectivity above 470 in sulfate recovery, ultrahigh Li+/Mg2+ selectivity up to 68 in lithium extraction, and effective divalent ion removal in pharmaceutical purification, surpassing many reported polyamide nanofiltration membranes. This advancement adds a new dimension to in the design of advanced polymer membranes via interfacial polymerization. Currently polyamide membranes fabricated by interfacial polymerization are limited by inherently negative charge as well as narrow charge tailoring window restricting the application of these membranes. Here, the authors report a facile ionic liquid-decoupled bulk/interfacial diffusion strategy to fabricate polyamide membranes which can transform on-demand from inherently negative to highly positive and near-neutral charge. [ABSTRACT FROM AUTHOR]

Here, a simple spraying-induced in situ growth of inorganic particles strategy was adopted to fabricate composite membranes. Sodium alginate was first sprayed on a polyvinylidene fluoride membrane to provide active sites, and subsequently, alternate spraying of Ca2+ and CO32− induced in situ growth of CaCO3 particles to construct hierarchical structures. The optimal membrane exhibited superhydrophilicity/underwater superoleophobicity. The membrane has good oil–water separation efficiency (>99%) and high flux (>2238 L m−2 h−1) for several oil–water emulsions. Importantly, the membrane retained acceptable separation performance even after 10 cycles, proving its good mechanical stability and anti-fouling features. The current work may open up a new avenue for the large-scale fabrication of super-wetting membranes for oily wastewater remediation. [ABSTRACT FROM AUTHOR]

This study aims to determine the most effective utilization of ZIF-8 type metal-organic framework (MOF) doped polybenzimidazole (PBI) composite membrane in high-temperature polymer electrolyte membrane fuel cells (HT-PEMFC) and investigate how ZIF-8 filler affects performance. ZIF-8 particles were prepared by solvothermal method and added to the PBI polymer using a weight percentage varying from 1 to 5 %. XRD, BET, and TEM examined the prepared ZIF-8. Composite membrane properties were investigated by XRD, SEM analysis, proton conductivity measurements, acid doping, and acid stripping tests. The HT-PEMFC performances of the membranes were carried out using Hydrogen and dry air at 150–180. The highest performance was acquired with the composite ZIF8/PBI-2 membrane as 0.432 W/cm2 at 170 °C. The obtained result is explained by easier proton transfer over ZIF-8's enlarged tunnel network. This study proposes a promising strategy to use ZIF-8 to prepare a PBI composite membrane with excellent proton conductivity, acid doping, and low acid leaching for HT-PEMFC application. The current study's findings can support future research on PBI/MOF-based composite membranes for HT-PEMFC applications. • ZIF-8 was revealed as an effective filler for HT-PEMFC. • The composite membranes exhibit excellent HT-PEMFC performance. • A maximum power density of 0.432 W/cm2 is achieved without humidity. • PBI/MOF composite membranes can be good candidates for HT-PEMFC applications. [ABSTRACT FROM AUTHOR]

Composite membranes with asymmetric traits have gained attention in liquid separation, featuring gradient chemical and physical attributes that align or oppose mass transfer direction. Chemically asymmetric configurations harness internal driving forces to heighten separation efficiency, rendering them an appealing option for heightened separation efficiency and fouling prevention. Concurrently, the internal hierarchical structure differences within composite membranes—such as fiber‐based structural adjustments and the gradient density of functional layers—yield the dual benefits of effective liquid repelling and heightened transport efficiency. Unlike conventional phase‐change methods, electrospinning technology possesses advantages in constructing and governing composite fibrous membrane materials with asymmetric chemistry and hierarchical structures, driven by its adaptable stacking methodologies. Notably, the inherent pore structure of electrospun nanofibrous membranes emerges as a proven solution for minimizing transport resistance. In recent times, interest has surged in electrospun nanofibrous membranes endowed with internal asymmetric properties. However, the spotlight has predominantly graced Janus membranes, spotlighting opposite wettability on different sides, leaving other facets of asymmetric membrane enhancement somewhat underexplored. This comprehensive work unveils recent strides in design, fabrication, facilitated transport mechanisms, and real‐world liquid separation applications, all under the aegis of electrospun nanofiber membranes, each endowed with distinct asymmetric properties. [ABSTRACT FROM AUTHOR]

The effect of laser etching on the surface properties of composite polyelectrolyte complex (PEC) based membranes as mixed matrix membranes was studied. The PECs were prepared by the stoichiometric mixing of cationic PDDA (poly(diallyl dimethyl ammonium chloride)) and anionic PSS (poly(sodium 4-styrene sulfonate)) as polyelectrolytes with various contents of ZIF-8 as filler. Composite membranes usually display improved bulk properties depending on the nature of the filler, but the surface properties are often dictated by the matrix covering the surface. The PEC composite membranes were then subjected to laser etching, resulting in the enhanced exposure of embedded ZIF-8 particles within the PEC structure in an attempt to improve the surface properties of the composite membrane. The crystal structure, morphology, and distribution of zinc at the PECs surface, before and after laser etching, were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS), respectively. In order to evaluate the improvement of the surface properties of the laser-etched membranes, a model experiment involving a catalytic reaction was chosen. The pristine and laser treated surfaces were tested for their catalytic activity for the transesterification of triglycerides present in soybean oil with methanol at a temperature of 150°C. Interestingly, the laser-etched PECs displayed substantially enhanced activity compared to the original composite PEC membranes as a result of surface erosion. These results could be interesting for the future development of composite membranes with improved surface properties where the filler needs to expose the surface of the membranes. [ABSTRACT FROM AUTHOR]

The perfluorosulfonic acid (PFSA) membrane doped with two-dimensional conductive filler Ti3C2Tx is a fuel cell proton exchange membrane with high application potential. Experimental studies showed that the proton conductivity of Nafion/Ti3C2Tx composite membrane is improved significantly compared with that in pure Nafion. However, the microscopic mechanism of doping on the enhancement of membrane performance is remain unclear now. In this work, molecular dynamics simulation was used to investigate the microscopic morphology and proton transport behaviors of Nafion/Ti3C2Tx composite membrane at the molecular level. The results shown that there were significant differences about the diffusion kinetics of water molecules and hydroxium ions in Nafion/Ti3C2Tx at low and high hydration levels in the nanoscale region. With the increase of water content, Ti3C2Tx in membrane was gradually surrounded by ambient water molecules to form a hydration layer, and forming a relatively continuous proton transport channel between Nafion polymer and Ti3C2Tx monomer. The continuous proton transport channel could increase the number of binding sites of proton and thus achieving high proton conductivity and high mobility of water molecules at higher hydration level. The current work can provide a theoretical guidance for designing new type of Nafion composite membranes. [ABSTRACT FROM AUTHOR]

Aligned with the recent trend and imperative to reduce separation layer thickness in gas separation membranes to the nanometer scale in order to raise permeance to levels that can render them competitive with respect to other gas separation technologies, a novel approach and device for fabricating defect-free composite hollow fiber (HF) membranes by dip-coating is described. The presented method avoids the fundamental drawbacks of state-of-the-art techniques for applying a thin gas separation layer onto a porous HF substrate, providing a safe but, at the same time, easily up-scalable way of producing HF membranes at a relatively high production rate. As a basic concept, hanging HF substrates are coated by allowing the coating solution to flow and drip along their external surface. The adaptability of this method, stemming from the array of available coating solutions (a plethora of dispersed nanofillers) and the multitude of substrate options, holds great promise for the fabrication of highly selective and defect-free composite HF membranes. [ABSTRACT FROM AUTHOR]

Poly(acrylonitrile-co-methyl acrylate) (PAN-co-MA) electrospun nanofiber (ENF) was used as the support for the formation of polyamide (PA) thin films. The ENF support layer was post-treated with heat-pressed treatment followed by NaOH hydrolysis to modify its support characteristics. The influence of heat-pressed conditions and NaOH hydrolysis on the support morphology and porosity, thin-film formation, surface chemistry, and membrane performances were investigated. This study revealed that applying heat-pressing followed by hydrolysis significantly enhances the physicochemical properties of the support material and aids in forming a uniform polyamide (PA) thin selective layer. Heat-pressing effectively densifies the support surface and reduces pore size, which is crucial for the even formation of the PA-selective layer. Additionally, the hydrolysis of the support increases its hydrophilicity and decreases pore size, leading to higher sodium chloride (NaCl) rejection rates and improved water permeance. When compared with membranes that underwent only heat-pressing, those treated with both heat-pressing and hydrolysis exhibited superior separation performance, with NaCl rejection rates rising from 83% to 98% while maintaining water permeance. Moreover, water permeance was further increased by 29% through n-hexane-rinsing post-interfacial polymerization. Thus, this simple yet effective combination of heat-pressing and hydrolysis presents a promising approach for developing high-performance thin-film nanocomposite (TFNC) membranes. [ABSTRACT FROM AUTHOR]

The sluggish commercial application of proton exchange membrane fuel cells (PEMFCs) with low Pt loading is chiefly hindered by concentration polarization loss, particularly at high current density regions. Addressing this, our study concentrates on the ionomer membranes in the cathode catalyst layer (CCL) and explores the potential of incorporating additional hydrophilic or hydrophobic components to modify these ionomers. Therefore, an all-atom model was constructed and for the ionomer and hydrophilic and hydrophobic modifications were implemented via incorporating SiO2 and PTFE, respectively. The investigation was conducted via molecular dynamics (MD) simulations to predict the morphology and structure of the ionomer and analyze the kinetic properties of oxygen molecules and protons. The simulation results elaborate that the hydrophilic and hydrophobic modifications favor the phase separation and the self-diffusion coefficients of oxygen molecules and protons are enhanced. Considering the hydration level of the ionomer films, hydrophilic modification facilitates mass transfer under low-hydration-level conditions, while hydrophobic modification is more effective in optimizing mass transfer as the hydration level increases. The optimal contents of SiO2 and PTFE for each hydration level in this work are 9.6% and 45%, respectively. This work proposes a reliable model and presents a detailed analysis of hydrophilic and hydrophobic modifications, which provides theoretical guidance for quantitative preparations of various composite membranes. [ABSTRACT FROM AUTHOR]

[Display omitted] • The continuously welded 2D nano-networks were constructed based on hierarchical phase separation. • The impact of the polymer concentrations on the phase behavior in the ternary system was investigated. • The synergistic effect of sieving and adhesion was used to capture the PM. • The interaction between PM and PVB nanowires was proposed. • The spider web-inspired membrane shows excellent air filtration performance and stable long-term recycling capacity. Air pollution has garnered significant worldwide attention; however, the existing air filtration materials still suffer from issues related to monotonous structure and the inherent trade-off between PM rejection and air permeability. Herein, a spider web-inspired composite membrane with continuous monolayer structured 2D nano-networks tightly welded on nanofibers in the electrospun membrane scaffold is designed via a hierarchical phase separation strategy. The resultant biomimetic hierarchical-structured membranes possess the integrated features of hierarchical multiscale structures of 2D ultrafine networks composed of nanowires with a diameter of 31 nm self-assembled by nanoparticles, exceptional characteristics involving small average aperture, extremely low network thickness, high porosity and promising pore channel connectivity, combined with rich surface polar functional groups (3.02D dipole moment). Consequently, the composite membrane exhibits a high PM 0.3 capture efficiency of 99.6 % and low pressure drop of 58.8 Pa, less than 0.06 % of atmosphere pressure, with outstanding long-term PM 2.5 recycling filtration performance. The hierarchical phase separation–driven 2D nano-networks construction strategy, by virtue of their feasibility and tunability, holds great promise for widespread application across diverse membrane-related domains for air filtration. [ABSTRACT FROM AUTHOR]

The composite membrane is synthesized using chitosan as a matrix membrane with montmorillonite (MMT) as a filler and modified using polyvinyl alcohol (PVA). The main aim of this study is to find out the influence of PVA concentration and the working temperature toward the permeability of chitosan-MMT/PVA composite membrane. Fourier transform infrared spectroscopy (FTIR) characterization is performed in order to identify the interaction between the chitosan matrix and the modified MMT with PVA. The presence of new absorption at 1116.82 and 619.17 cm-1 indicated the interaction between MMT and PVA. Further, the widening of OH absorption indicated the hydrogen bond which is formed between chitosan matrix and PVA. This interaction is also demonstrated by the evenly distributed surface on scanning electron microscope (SEM) topography analysis. The thermal stability of composite membrane is determined by thermal gravimetry analysis (TGA). In addition, the composite membrane containing PVA has four patterns decomposed. When the TVA is absent from the composite membrane, it has three decomposition patterns, which are shown by TGA analysis. Based on its tensile strength, the composite membrane has good mechanical properties. The proton conductivity of the composite membranes are directly proportional to the PVA concentration. On the other hand, the methanol permeability of composite membranes is inversely proportional with the PVA concentration. The highest proton conductivity was obtained with the addition of 2 % PVA of 2.94×10-4 S cm-1. Further, it also has the lowest methanol permeability with the value of 5.05×10-6 cm2 s-1. As a result, the crosslinked composite membrane chitosan- -MMT prepared by PVA-crosslinking technique has the potential to be exploited for the direct methanol fuel cell application. [ABSTRACT FROM AUTHOR]

To improve the hydrophilicity of polyethersulfone (PES) membranes, SMANa/PES composite membranes were prepared by non solvent induced phase separation (NIPS) using styrene maleic anhydride copolymer (SMANa) at different alkali treatment temperatures as an additive. On this basis, the MXene/ZnO membrane was prepared using vacuum filtration method, and the structure, morphology, and separation performance of the separation membrane were tested. The results showed that the transformation of SMA to SMANa was accompanied by improved compatibility with PES. The electrical conductivity was as high as 0.73 S/cm when the loading of MXene was 0.18 g/m². When the content of ZnO further increased to 15%, the water contact angle decreased from 38.5° to 22.4°. The addition of ZnO not only effectively prevents the stacking between MXene layers, but also endows the conductive separation membrane with excellent hydrophilicity. When the ZnO content was 15%, the rejection rate of MXene/ZnO membrane for Congo red dye increased from 58.84% at 0 V to 77.07% at 1 V, and the permeate flux did not change greatly. [ABSTRACT FROM AUTHOR]

In dealing with the oil–water separation process, improving the oil–water selectivity of the membrane surface and increasing the porosity within the membrane are effective means to achieve durable and efficient oil–water separation. Therefore, polystyrene/polyacrylonitrile‐polyvinylidene fluoride/Polydimethylsiloxane Fe3O4 nanoparticles (PS/PAN‐PVDF/PDMS@Fe3O4) composite membranes with superhydrophobicity and lipophilicity were prepared by electrospinning technique. By controlling the filling concentration of Fe3O4 nanoparticles, a stable superhydrophobic and lipophilic rough structure was constructed, and micro–nano multilayer rough voids existed inside the membrane. The results showed that the composite fiber membrane exhibited exceptional superhydrophobicity (156.2°), thermal stability (338°C), mechanical properties (tensile strength of 3.0 MPa, elongation of 33.9%), and oil adsorption capacity (30–100 g/g). Moreover, even under corrosive environments, this composite fiber membrane maintained its superhydrophobic properties (above 152°) and achieved high oil–water separation efficiency (above 97%). Remarkably, after 40 cycles, the composite membrane could sustain a separation flux of 5000 L m−2 h−1. Consequently, the composite fiber membrane manufactured using this strategy exhibits promising potential for applications in oil–water separation. [ABSTRACT FROM AUTHOR]

The aim of this work is to prepare ternary blended polyvinyl alcohol (PVA)–urea hydrogels containing Ormocarpum cochinchinense, Cinnamomum zeylanicum and antibiotic cephalexin by freezing-thawing method in order to assess the wound healing qualities. In addition to being a synthetic polymer, PVA is a recyclable and biocompatible artificial polymer blend that has attracted a lot of interest in biological applications. The freezing-thawing process with PVA–urea blend is used to make hydrogel film. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and swelling investigations were carried out for the composite membranes. Biological studies involving antibacterial, antifungal, cytotoxicity and wound healing activities were also carried out for the composite membranes. The composite membrane developed has a lot of potential for wound dressing and other applications. [ABSTRACT FROM AUTHOR]