Characterization Of Membranes Research Articles

Roles of a Glycolipid MPIase in Sec-Independent Membrane Protein Insertion.

Membrane protein integrase (MPIase), an endogenous glycolipid in Escherichia coli (E. coli) membranes, is essential for membrane protein insertion in E. coli. We have examined Sec-independent membrane protein insertion mechanisms facilitated by MPIase using physicochemical analytical techniques, namely solid-state nuclear magnetic resonance, fluorescence measurements, and surface plasmon resonance. In this review, we outline the physicochemical characteristics of membranes that may affect membrane insertion of proteins. Subsequently, we introduce our results verifying the effects of membrane lipids on insertion and estimate the impact of MPIase. Although MPIase is a minor component of E. coli membranes, it regulates insertion by altering the physicochemical properties of the membrane. In addition, MPIase promotes insertion by interacting with substrate proteins. We propose comprehensive mechanisms for the membrane insertion of proteins involving MPIase, which provide a physicochemical basis for understanding the roles of glycolipids in protein translocation.

Recent Progress on the Development and Application of Polymeric Nanofiltration Membranes: A Mini-Review

Abstract: The inefficiency of conventional water treatment methods in terms of removing micropollutants is prompting research into other technologies. Among these, the process of separation by nanofiltration membranes is particularly promising because of the low operating cost, rapid implementation of the system, high selectivity and easy integration with other treatment processes. Studies in this area are recent and there are many avenues for future research. This mini-review describes the main characteristics of the polymeric membranes used for nanofiltration and the various methods and polymer materials under investigation. At the end, we report the result of a survey conducted on the ScienceDirect, Scopus and Web of Science platforms using different keywords, to depict a global panorama of the current research involving polymeric nanofiltration membranes. The results revealed a particular dearth of published studies involving application of these membranes to remove micropollutants with endocrine disruptive action. Furthermore, research involving nanofiltration membranes utilizing calcium alginate is very recent. This study provides an overview of the investigation of polymeric nanofiltration membranes.

Evaluation of commercial nanofiltration and reverse osmosis membrane filtration to remove per-and polyfluoroalkyl substances (PFAS): Effects of transmembrane pressures and water matrices.

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are now widely found in aquatic ecosystems, including sources of drinking water and portable water, due to their increasing prevalence. Among different PFAS treatment or separation technologies, nanofiltration (NF) and reverse osmosis (RO) both yield high rejection efficiencies (>95%) of diverse PFAS in water; however, both technologies are affected by many intrinsic and extrinsic factors. This study evaluated the rejection of PFAS of different carbon chain length (e.g., PFOA and PFBA) by two commercial RO and NF membranes under different operational conditions (e.g., applied pressure and initial PFAS concentration) and feed solution matrixes, such as pH (4-10), salinity (0- to 1000-mM NaCl), and organic matters (0-10mM). We further performed principal component analysis (PCA) to demonstrate the interrelationships of molecular weight (213-499 g·mol-1 ), membrane characteristics (RO or NF), feed water matrices, and operational conditions on PFAS rejection. Our results confirmed that size exclusion is a primary mechanism of PFAS rejection by RO and NF, as well as the fact that electrostatic interactions are important when PFAS molecules have sizes less than the NF membrane pores. PRACTITIONER POINTS: Two commercial RO and NF membranes were both evaluated to remove 10 different PFAS. High transmembrane pressures facilitated permeate recovery and PFAS rejection by RO. Electrostatic repulsion and pore size exclusion are dominant rejection mechanisms for PFAS removal. pH, ionic strength, and organic matters affected PFAS rejection. Mechanisms of PFAS rejection with RO/NF membranes were explained by PCA analysis.

Predicting solute transfer rate in patients initiating peritoneal dialysis

BackgroundWhile assessment of membrane characteristics is fundamental to peritoneal dialysis (PD) prescription in patients initiating therapy, peritoneal equilibration test has theoretical and practical drawbacks. We wished to determine whether an equation using simple clinical variables could predict fast (above population mean) peritoneal solute transfer rate without dialysate sampling.MethodsWe measured peritoneal solute transfer rate, as determined by peritoneal equilibration test using the 4-h dialysate to plasma creatinine ratio, in consecutive PD outpatients attending a single tertiary hospital for their first clinical follow-up within 3 months of dialysis initiation. An equation estimating peritoneal solute transfer rate based on readily available clinical variables was generated in a randomly selected modeling group and tested in a distinct validation group.ResultsWe included 712 patients, with 562 in the modeling group and 150 in the validation group. Mean age was 58.4 ± 15.9 with 431 (60.5%) men. Mean peritoneal solute transfer rate value was 0.73 ± 0.13. An equation based on gender, race, serum sodium and albumin yielded a receiving operator characteristics (ROC) area under the curve (AUC) to detect fast peritoneal solute transfer rate (> 0.73) of 0.74 (0.67–0.82). Estimated peritoneal solute transfer rate values based on percentiles 15th (> 0.66), 20th (> 0.68), 25th (> 0.69) and 30th (> 0.70) could rule out fast peritoneal solute transfer rate with negative predictive values of 100%, 93.5%, 84.2% and 80.0%, respectively.ConclusionsAn equation based on simple clinical variables allows ruling out fast transport in a significant proportion of patients initiating PD with a high degree of confidence without requiring dialysate sampling. This could prove useful in guiding dialysis prescription of PD patients in daily clinical practice, particularly in low-resource settings.Graphical abstract

Synthesis of high-performance biocompatible polymeric membranes incorporated with zirconium-based MOF for an enhanced brackish water RO desalination

A nanosized zirconium 1,4- dicarboxybenzene metal-organic framework (UiO-66-MOF) was synthesized and impregnated into cellulose acetate (CA) polymeric matrix to enhance the membrane characteristics for brackish water desalination. Phase inversion was used for the fabrication of CA/UiO-66 hybrid membranes (CAU-X), where X is the concentration of immobilized UiO-66 nanoparticles (UiO-66-NPs) into CA polymeric matrix. Morphological structure and functional groups were investigated through different characterization techniques to prove the successful synthesis of the prepared UiO-66-NPs, the blank CA membrane, and hybrid CAU-X membranes. For more CAU-X characteristics, porosity, contact angle, and tensile strength were measured. The obtained data demonstrated that the impregnation of zirconium-based-NPs had a positive influence on the blank CA membrane properties. Additionally, the performance of the fabricated membranes was investigated in reverse osmosis (RO) bench-scale unit. The performance results for the pristine CAU-0 membrane showed a high salt rejection (SR) of 99.8% and a permeate water flux (PWF) of 1.14 L/m2.h. In comparison to pristine CA membrane, CAU-X hybrid membranes have a slightly lower SR and a higher PWF. It was found that the hybrid CAU-0.02 membrane had almost a doubled PWF of 2.8 L/m2.h with only 2% sacrificed SR of 97.6% compared with CAU-0 membrane. Moreover, a much better PWF of 3.4 L/m2h and a sufficient SR of approximetly 92% were obtained by CAU-0.05 membrane. Thus, CAU-0.05 was selected to further test its performance under different operating parameters. Results revealed that the optimum parameters were recorded for a sodium chloride feed stock of 5000 ppm operating at 25 °C temperature and pressure up to 15 bar.Graphical

Effects of di-ions structure of the core layer ionomer on anion exchange membrane characteristics of anti-protein fouling and electrodialysis desalination

To investigate the effects of di-ions structure of the core layer ionomer on anti-protein fouling and electrodialysis (ED) desalination performance of the tailored anion exchange membranes (AEMs), three highly conductive structural-controlled ionomers containing aliphatic bridging cage quaternary di-ammoniums, aliphatic liner quaternary di-ammoniums, and aromatic quaternary di-ammoniums respectively have been synthesized. With the help of the previously established bi-directional in-situ interpenetration method, a series of double-sided anti-fouling AEMs were successfully fabricated from the gradient cross-linked anti-fouling thin layer CA(2% SA-0.10Ca) and the tailored ionomers. These AEMs have basic and electrochemical properties suitable for ED applications, and significant anti-protein fouling ability. The results of the ED desalination evaluations at high current density with salted egg white confirm further that DABCO-MeI-CA having aliphatic-bridging-cage-di-ions with the best electrochemical properties displays the best ED performance (desalination rate (DR) = 32.16%, energy consumption (EC) = 0.27 kWh kg−1) and good ED stability. Its ED performance is better than that of commercial AMX, with an increase of 20.74% in DR and a reduction of 34.15% in EC. Protein biuret detections verify no protein-through-membrane pollution occurred in the tests. The properties of DABCO-MeI-CA are promising for high current density ED desalination of organic macromolecule-contaminated salted systems.

Plasma Technology Applications in Proton Exchange Membrane Fuel Cell Systems

AbstractFuel cells have become a prominent research focus in the realm of clean energy, owing to their attributes of environmental sustainability, high efficiency, and renewable potential. The catalytic activity of electrode materials and the characteristics of proton exchange membranes are considered pivotal determinants of fuel cell performance. Plasma is abundant in high‐energy electrons and active species, proven to be a rapid, facile, and green approach for the preparation and treatment of catalytic materials and polymers. This review presents recent applications of plasma technology in proton exchange membrane fuel cells across four key dimensions: cathodes, anodes, proton exchange membranes, and process enhancement, including the preparation and treatment of noble metal catalysts, non‐noble metal catalysts, non‐metal catalysts, and polymer membranes. Furthermore, critical issues of plasma technology applied in PEMFCs were also discussed.

Unlocking synergies of Mg(OH)2 and rice husk silica as dual additives for tailored pore properties, selectivity, and antifouling performances of PES membrane

This research investigates the synergistic impact of incorporating Mg(OH)2 and rice husk silica additives during membrane fabrication to enhance both selectivity and resistance to fouling. The main objective is to harness the enhanced hydrophilicity provided by both additives to elevate membrane characteristics and performance, while also addressing the individual limitations of each additive when used separately. The introduction of Mg(OH)2 and silica is performed on the polyethersulfone (PES) membrane via blending method. The findings of the research show that combination of Mg(OH)2 and silica as additive result in exceptional attributes of the PES membrane, in comparison to membranes modified with each additive separately. This membrane demonstrates outstanding characteristics, including a remarkable porosity of 60.7 %, and exceptional antifouling capability, as evidenced by an impressive Flux Recovery Ratio (FRR) of 84.7 %, thereby enhancing its practical utility. These collective findings underscore the remarkable potential of combining Mg(OH)2 and rice husk silica as beneficial hybrid additives for membrane fabrication. The synergistic approach holds great promise for enhancing membrane properties and overcoming constraints associated with the individual application of each additive.

A Comprehensive Study on the Effect of Plasticizers on the Characteristics of Polymer Inclusion Membranes (PIMs): Exploring Butyl Stearate as a Promising Alternative.

This study investigated the influence of various plasticizers commonly used in the manufacture of polymer inclusion membranes (PIMs), such as 2-nitrophenyl octyl ether (NPOE), phthalates, adipates, and sebacates on the mechanical, thermal, and transport properties of membranes. Additionally, butyl stearate (BTS), chosen for its non-toxic nature compared to phthalates and its cost-effectiveness relative to adipates and sebacates, was evaluated as a plasticizer in PIMs for the first time. All plasticizers were incorporated in PIMs made of either cellulose triacetate (CTA) or poly(vinyl chloride) (PVC) as the base polymers and the task-specific ionic liquid trioctylmethylammonium thiosalicylate (TOMATS) as the carrier. The plasticizers were found to significantly affect the characteristics of membrane hydrophilicity, mechanical flexibility, and thermal stability. Transport experiments using Hg(II) as a model target ion revealed that, for CTA-based PIMs, the plasticizer did not significantly affect transport efficiency. However, for PVC-based PIMs, BTS exhibited better efficiency when compared to NPOE. These findings highlight the potential of BTS as an attractive alternative to currently used plasticizers in PVC-based PIM formulations.

Tuning membrane properties to control supersaturation of antisolvent crystallization

The crystal morphology influences the properties of organic compounds, especially in pharmaceutics such as the dissolution and absorption of drugs in the human cells. In antisolvent crystallization, the crystal size and shape are tied to the degree of mixing and dosage of antisolvent, which could be controlled using membranes with specific morphology/surface properties. Little is known though on the relationship between membrane characteristics, antisolvent mass transfer and crystal properties. Flat sheet polyvinylidene fluoride (PVDF) membranes were prepared using non-solvent induced phase separation, to illustrate the impact of membrane characteristics on the resulting crystal size distribution (CSD) obtained using membrane-assisted antisolvent crystallization (MAAC). The crystallization of glycine was taken as case study. We showed the antisolvent transmembrane flux increased when the membrane thickness decreased, or when the hydrophobicity or the porosity increased. After MAAC operation, membranes had no significant change in surface functional groups, hydrophobicity nor structure. The best-performing membrane was found to have 119° hydrophobicity, 89.4 % porosity and 140 μm thickness, reaching high reproducibility of CSD corresponding to stable transmembrane fluxes throughout 180 min of operation. The capacity of MAAC to consistently produce a narrow CSD at optimum membrane characteristics makes this technology very competitive with conventional crystallization processes.

Green Synthesis of Nanocomposite Membranes for Sustainable Water Filtration

In order to tackle the worldwide problems of water pollution and shortage, this work explores the green synthesis of nanocomposite membranes for sustainable water filtering. Graphene oxide, cellulose nanocrystals, and silver nanoparticles were used as nanofillers in the fabrication of nanocomposite membranes, which were made using renewable polymer matrix (PES, PVDF, PAN). By including different polymer matrices and nanofillers, the composition analysis demonstrated the adaptability of nanocomposite membrane manufacturing, enabling the customization of membrane characteristics. Improved membrane shape and structural integrity were shown to result from the homogeneous dispersion of nanofillers inside the polymer matrix, according to characterization tests. Nanocomposite membranes demonstrated high flux rates and rejection rates for different pollutants, confirming their excellent performance in filtration experiments. The membranes’ improved fouling resistance also increased their service life and decreased the frequency of maintenance needs. Supporting the eco-friendliness of nanocomposite membrane production, an environmental impact evaluation found that it used less energy and generated less trash than traditional techniques. All things considered, nanocomposite membranes have shown great promise as long-term water treatment solutions due to their superior performance, durability, and environmental friendliness, as well as their effective production and characterisation. More study is needed to perfect membrane characteristics and solve the remaining problems that prevent their broad use in water treatment systems.

Molecular simulation of [P8883][Tf2N] ionic liquid decorated silica in 6FDA-ODA based mixed matrix membrane for enhanced CO2/CH4 separation.

Mixed-matrix membranes (MMMs) have been reported to have considerable scope in gas separation applications because of their merged inherent strength of a durable polymer matrix and the exceptional performance capabilities of inorganic fillers. The selection of comparatively suitable polymers with fillers that can match each other and boost interfacial compatibility while ensuring uniform dispersion of filler within the polymer is still intensively demanding and is challenging at the experimental scale. Ionic liquids (ILs) are effective in promoting better dispersion and compatibility, leading to improved separation performance. A computational molecular simulation approach is employed in current work to design a hybrid membrane having Trioctapropyl phosphonium bis(trifluoromethylsulfonyl)imide [P8883][Tf2N] IL decorated silica as a filler and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride-4,4'-oxydianiline (6FDA-ODA) polymer for carbon dioxide (CO2) separation from methane (CH4). Thermophysical and gas transport properties under pure and mixed gas condition (30, 50, and 70% CO2/CH4) within the MMMs with varying filler loadings (5, 10, and 15 wt% IL-silica) are examined via Grand Canonical Monte Carlo (GCMC) and Molecular Dynamics (MD) simulations. Membrane characteristics like glass transition temperature (T g), Fractional Free Volume (v f), X-Ray Diffraction (XRD), solubility, diffusivity, permeability, and selectivity for neat and IL-silica filled 6FDA-ODA are computed. The results show that the T g of the composite membrane with 5 wt% IL-silica is found to be considerably higher (with 305 °C) than that of the pure 6FDA-ODA polymer having 298 °C. A higher T g value highlights the effective dispersion and higher adhesion between the filler and polymer membrane. Additionally, CO2 permeability for 5 wt% IL-silica/6FDA-ODA MMM is significantly improved, measuring 319.0 barrer while maintaining a CO2/CH4 selectivity of 16.2. These values are 89% and 56% respectively, greater than the corresponding values of neat 6FDA-ODA membrane. Published data from the literature review is used to validate the findings and guarantee their reliability. The obtained results exhibited an error in the range of 0.7-9%. Hence, it is concluded from the study that molecular simulation can be used to design IL decorated silica incorporated within 6FDA-ODA matrix, which is able to boost the interfacial compatibility, with elevated CO2/CH4 selectivity and CO2 permeability.

Design of polybenzimidazolium membranes for use in vanadium redox flow batteries.

In recent years, polybenzimidazole (PBI) membranes have been proposed for vanadium redox flow batteries (VRFBs) as an alternative to perfluoroalkylsulfonic acid membranes such as Nafion™. Despite their excellent capacity retention, PBI membranes tend to suffer from a low ionic conductivity. The formation of a polybenzimidazolium through an N-alkylation of the benzimidazole core is shown to improve the ionic conductivity of the membrane, with this class of materials having found uses in alkaline fuel cell and water electrolysis systems. However, much less is known about their incorporation into a VRFB. This article describes the use of hexamethyl-p-terphenyl polybenzimidazolium (HMT-PMBI) membranes for a vanadium redox flow battery, with the membrane characteristics in acidic media being related to their performance in a single-cell VRFB setup. A change of the degree of methylation from 56 to 65, 75, and 89% leads to an increase in ionic conductivity, correlated with an increased fraction of free water in the ionomer. The corresponding increase in cell performance is, however, accompanied by a drop in capacity retention. The membrane with a degree of methylation of 65% shows balanced properties, with a 5% higher efficiency and a two times improved capacity retention compared to Nafion™ NR212 over 200 charge-discharge cycles at 200 mA cm-2.

ENHANCED MECHANICAL AND THERMAL PROPERTIES OF ELECTROSPUN CELLULOSE ACETATE FIBER MEMBRANES INCORPORATING PAHAE NATURAL ZEOLITE

In recent decades, fiber membranes have garnered significant attention and found numerous applications across various fields. This work used the electrospinning method to create fiber membranes with cellulose acetate (CA) as a primary polymer material. The characteristics of the fiber membrane, such as mechanical and thermal properties, were investigated by incorporating Pahae Natural Zeolite (PNZ) microparticles into the CA matrix. The fiber membranes' mechanical properties are improved by adding PNZ to the CA matrix, and the CA/PNZ 10% exhibits the maximum tensile strength of 0.97 MPa and elongation at a break of 4.52%. Meanwhile, incorporating PNZ filler into CA fiber membranes significantly enhances their thermal stability. This improvement is attributed to the formation of hydrogen bonds between CA and PNZ, as evidenced by the increasing residue values with higher PNZ content. Specifically, the residue of pure CA membrane fiber is 13.46%, which increases to 44.06% for CA/PNZ 15% fiber membranes. These favorable thermal and mechanical properties of the fiber membranes indicate the promising potential of CA/PNZ based membranes for filtration applications.

Effect of GM1 concentration change on plasma membrane: molecular dynamics simulation and analysis.

Ganglioside GM1 is a class of glycolipids predominantly located in the nervous system. Comprising a ceramide anchor and an oligosaccharide chain containing sialic acid, GM1 plays a pivotal role in various cellular processes, including signal transduction, cell adhesion, and membrane organization. Moreover, GM1 has been implicated in the pathogenesis of several neurological disorders, such as Parkinson's disease, Alzheimer's disease, and stroke. In this study, by creating a neural cell model membrane simulation system and employing rigorous molecular models, we utilize a coarse-grained molecular dynamics approach to explore the structural and dynamic characteristics of multi-component neuronal plasma membranes at varying GM1 ganglioside concentrations. The simulation results reveal that as GM1 concentration increases, a greater number of hydrogen bonds form between GM1 molecules, resulting in the formation of larger clusters, which leads to reduced membrane fluidity, increased lipid ordering, decreased membrane thickness and surface area and higher levels of GM1 dissociation. Through a meticulous analysis, while considering GM1's structural attributes, we offer valuable insights into the structural and dynamic traits of the cell membrane. This study provides a robust methodology for exploring membrane characteristics and enhances our comprehension of GM1 molecules, serving as a resource for both experimental and computational researchers in this field.

The Application of Three-Dimensional High-Density Electrical Method in Detecting Vertical HDPE Membranes at Landfill Sites

Landfilling is one of the important methods in hazardous waste treatment. In order to prevent the landfill leachate from connecting with external groundwater and prevent leachate from flowing into external polluted water bodies and soil, vertical anti-seepage membranes will be installed along the perimeter of the reservoir area. Given the structural characteristics of vertical HDPE membranes and site conditions, this study proposes the application of three-dimensional high-density electrical resistivity (3D-HDER) tomography for the detection of these membranes. Compared with the traditional resistivity method, the high-density resistivity method can realize automatic switching of electrode device type, electrode spacing and measuring points during the measurement process, thereby improving detection accuracy and work efficiency. By employing 3D-HDER for data collection on vertical HDPE membranes and inverting the subsurface resistivity distribution, the presence of leaks can be inferred based on the distribution of low-resistivity anomalies in the target underground area, thereby facilitating the integrity assessment of the vertical HDPE membranes. This research was applied in a practical investigation at a municipal landfill site in Hunan Province, where field tests were conducted, and the effectiveness of 3D-HDER in detecting vertical HDPE membranes was validated through excavation. The experimental results indicate that: (1) 3DHDER is capable of effectively and accurately locating shallow leaks, and (2) low resistivity anomalies were observed in the vicinity of the leaks.

Hydrogen Permeation Characteristics of Pd-Cu Membrane in Plasma Membrane Reactor

Hydrogen Permeation Characteristics of Pd-Cu Membrane in Plasma Membrane Reactor

ПЕРВАПОРАЦИОННОЕ РАЗДЕЛЕНИЕ ВОДНО-СПИРТОВЫХ СМЕСЕЙ НА ПОЛИУРЕТАНОВЫХ МЕМБРАНАХ НА ОСНОВЕ АМИНОЭФИРОВ БОРНОЙ И ОРТОФОСФОРНОЙ КИСЛОТ: ЭКСПЕРИМЕНТ И МОДЕЛИРОВАНИЕ

In this work, the separation characteristics of a selective layer of pervaporation membranes made of polyurethanes based on amino esters of orthophosphoric acid (AEPA) and amino esters of boric acid (AEBA) were studied during the dehydration of azeotropic water-alcohol mixtures. Polymer compositions of polyurethanes based on various compositions of AEPA and AEBA were studied in order to identify the best options. For polyurethane based on AEPA, moles of orthophosphoric acid influenced the composition of the polymer composition; for polyurethane based on AEBA, the effect of modifiers (bulk adducts of diphenylolpropane diglycidyl ether and copper chloride) was measured. A technology has been developed for the production of polymer pervaporation membranes with a selective layer of restrictive polyurethanes. Experimental studies on the pervaporation dehydration of isopropanol/water and ethanol/water mixtures in various alcohol concentrations (50-99 wt%) and various feedstock temperatures are presented. Obtains permeate flux and separation factor results for membrane confinement when separating confinement mixtures. It has been determined that an increase in the moles of orthophosphoric acid in the composition of the polymer composition AEPA and the use of modifiers in the synthesis of the polymer composition AEBA improve the separation characteristics of pervaporation membranes. It was revealed that when the process temperature increases by 20 °C, the permeate flow through the membrane increases, for example, for polyurethane based on AEPA-5-PEG, the value increases by 2 times, with a practically unchanged separation coefficient. Based on the pervaporation separation index data, promising polymer compositions were selected. The results of the data obtained are compared with the studies of other authors; the membranes we use have high values of permeate flux and separation coefficient, which are consistent with the values for any membranes from the open literature. Based on the concept of dissolution-diffusion, the process of pervaporation of isopropanol/water and ethanol/water mixtures through polymer membranes was simulated. The given calculation system is cyclic, and the results of calculating the permeate flow and separation coefficient using this model are in good agreement with the experimental data obtained.

Mathematical modeling of the magnetic field in the vicinity of narrow capillaries

A mathematical model of the magnetic field, which is generated by negative charges located on the outer side of the red blood cell (RBC) membrane, has been constructed. When modeling, the geometric (area, volume) and physical (speed, number of revolutions per second, charge, number of charges on the membrane) characteristics of a red blood cell in a narrow capillary are taken into account. Computer calculations made it possible to find the magnetic field strength near a single RBC rolling along a narrow capillary. Calculations were also carried out to determine the magnetic field strength in the vicinity of a capillary through which several RBCs move. The dependence of the maximum magnetic field strength on the distances between RBCs (hematocrit) was found. In particular, it is shown that at distances from the capillary equal to 8 capillary diameters, the maximum magnetic field intensity changes on average by 1.3 times with an increase in hematocrit by 1.5 times (from 12.27% to 18.25%).

Layer-by-layer membranes for vanadium redox flow battery

Layer-by-layer (LbL) is a widely utilized method for enhancing the selectivity, efficiency, and long-term stability of ion exchange membranes (IEMs) in various applications. This technique involves the deposition of charged thin films on IEM surface through electrostatic interactions using polycations and polyanions. The simplicity and straightforwardness of the LbL modification technique make it a preferred choice due to its reduced preparation steps and time. This method is found to be suitable for preparation of IEMs with excellent vanadium barrier properties for vanadium redox flow battery (VRFB), a battery that is highly sought to promote renewable energy to the grid level. The objective of this article provides an overview for progress in the development of IEMs for VRFB using LbL method. This includes not only description of the basics of the LbL method and its pros and cons but also factors affecting membrane functions and stability. The current applications of various LbL prepared membranes in VRFB and the challenges to their performance are pointed out. The research future directions to enhance membranes characteristics are discussed. Overall, this short review offers valuable insights into the exploration of LbL techniques for the preparation of highly selective, efficient, and stable membranes for VRFB applications.