Membrane Resistance Research Articles

Electrochemical Characterization and Simulation of Ion Transport in Anion Exchange Membranes for Water Treatment Applications

This study presents a comprehensive electrochemical characterization and simulation of anion exchange membranes (AEMs) for water treatment applications, focusing on ion transport behavior. Experimental techniques, including chronopotentiometry, current–voltage (I–V) curve measurements, and electrochemical impedance spectroscopy (EIS), were employed to investigate the kinetics and dynamics of ion transport at the membrane interface. The results were validated and further explored through finite element method (FEM) simulations using COMSOL Multiphysics. The study revealed key insights into the role of membrane resistance, ion diffusion, and capacitive effects on overall membrane performance. Parametric analyses of electrolyte layer thickness, bulk solution concentration, and membrane porosity provided guidelines for optimizing membrane design. The findings highlight the importance of considering these factors in enhancing the efficiency and applicability of AEMs in water treatment processes. Future work will focus on refining simulation models and exploring advanced materials to further improve membrane performance.

Mechanically Enhanced, Environmentally Stable, and Bioinspired Charge-Gradient Hydrogel Membranes for Efficient Ion Gradient Power Generation and Linear Self-Powered Sensing.

The soft hydrogel power source is an interesting example of generating electricity from clean energy. However, ion-selective hydrogel membranes in the systems are often limited by low ion selectivity, high membrane resistance, insufficient mass transfer, and ion concentration polarization, resulting in a generally low power output. Inspired by the unique structure of the electric ray's electric organ, a vertically stacked hydrogel artificial electric organ is proposed, aiming to increase the output current to a greater extent. By constructing the charge gradient in ultrathin ion-selective hydrogel membranes, ion transport is accelerated while mitigating the ion concentration polarization. A single hydrogel artificial electric organ achieves high outputs of ≈290mV and ≈1.46mA cm-2 with rechargeability, surpassing similar devices. Density functional theory further reveals that the energy barrier of ion transport in charge-gradient membranes is lower than that in nongradient membranes. More impressively, the device can still be applied as a linear self-powered pressure sensor for monitoring human activities after the ion gradient is completely dissipated. This study elucidates the key role of the structure and design of ion-selective membranes in the artificial gel power generation system, providing new insights into the further development and multifunctional application of flexible gel power source.

Fire-retardant and thermally conductive polyacrylonitrile-based separators enabling the safety of lithium-ion batteries.

Fire-retardant and thermally conductive polyacrylonitrile-based separators enabling the safety of lithium-ion batteries.

Nitrogen‐Doped Carbon Quantum Dot as Novel Nano Additive to Improve Performance and Fouling Resistance of Forward Osmosis Thin Film Nanocomposite Membranes

ABSTRACTForward osmosis (FO) is considered a strong and energy‐efficient desalination method. The thin film composite (TFC) membranes are widely used in the FO process. In this study, nitrogen‐doped carbon quantum dot (NCQD) was synthesized from citric acid (CA) and m‐phenylene diamine (MPD) as carbon and amine precursors, respectively, by a one‐step hydrothermal method. It was characterized completely by FT‐IR, XRD, UV–visible spectroscopy, DLS, and TEM analysis. Then, NCQD was incorporated in the polyamide (PA) layer to synthesize novel thin film nanocomposite (TFN) membranes. All membranes were analyzed by FT‐IR, WCA, AFM, and FE‐SEM. The TFN‐NCQD membrane, optimized with a concentration of 2000 ppm NCQD, exhibited outstanding FO performance, achieving a 70% increase in water flux compared to the pristine TFC. This membrane attained a peak water flux of 20.4 LMH, a reverse salt flux of 2.1 gMH, and showcased the best selectivity, with values as low as 0.10 g/L among the others. The strong interaction between amine functional groups of NCQD with both MPD and TMC during interfacial polymerization resulted in excellent adhesion and compatibility between the nanofiller and PA, increasing the lifespan of TFN membranes. Moreover, the novel TFN‐NCQD2 membrane showed better fouling behavior than pristine TFC, a 22% improvement when sodium alginate solution (600 ppm) was used as a foulant model.

The performance of a graphene oxide thin film composite membrane for sweet whey ultrafiltration

Membranes manufactured from graphene oxide (GO) have received significant attention for desalination and nanofiltration applications due to their exceptional mechanical strength, chemical stability and high selectivity. However, the performance of GO membranes in food processing applications is less well understood. In this work, the performance of a GO membrane, advertised as being of 1 kDa molecular weight cutoff, is compared to that of two commercial polymeric membranes of different molecular weight cut-off (advertised as 10 kDa and 1 kDa) for the ultrafiltration of sweet whey from the dairy industry. At bench scale, the GO membrane had comparable rejection for both total solids and protein to the 10 kDa polymeric membrane, but with more than double the flux, provided by a much lower intrinsic membrane resistance. Analysis of the membrane fouling process suggested that the GO membrane fouled more slowly than the 1 kDa polymeric membrane, but the fouling process was not significantly different to that reported in the literature for polymeric membranes in this application. Pilot scale trials conducted using a commercial spiral wound module of 1.2 m2 area of the GO membrane confirmed that the membrane retained a higher flux. This flux was, however, reduced from the bench scale value.

Current Direction Regulates Ion Transport Across Layer-by-Layer One-Side-Coated Ion-Exchange Membranes in Electrodialysis.

Polyelectrolyte multilayer (PEM) modified membranes can attain selective ion separations in electrodialysis with several potential applications, such as sustainable brine management. To understand the ion transport across PEM-coated membranes, we coated six different commercial cation-exchange membranes (CEMs) with PEM via the layer-by-layer technique. Coating one side of the membrane with a PEM leads to an asymmetric current-voltage response in case of solutions containing Mg2+ and Ca2+ ions. When the coating faces the counterion transport direction (FT), the coated membrane reaches a limiting current density which does not occur if the applied current is reversed. We investigated these phenomena via several electrochemical techniques. After coating, the total membrane resistance increases significantly at solutions of Mg2+ or Ca2+ (relative to the bare membrane resistance). Furthermore, the transport characteristics of the PEM coating are highly influenced by the base membrane resistance and fixed-charge density. Regarding the counterion type, the resistance of the coated membrane increases in the same order as the bare membrane: K+ < Na+< Ca2+ < Mg2+. The higher the bare membrane resistance is, the higher the PEM resistance is. The co-ion valency (i.e., monovalent Cl- or divalent SO42-) had limited to insignificant effects on the current-voltage response of the coated membranes. Therefore, dielectric exclusion is insignificant for these coated membranes at the tested concentrations, i.e., 0.25 M SO42-. Lastly, we employed an ion transport model to explain the observed effect of the current direction on the current-voltage response and analyze the effective properties of the PEM coating.

Effect of &lt;i&gt;Enterococcus faecium&lt;/i&gt; strain 18 on fungi of the genus &lt;i&gt;Candida&lt;/i&gt;

Introduction. Enterococcus spp. which are representatives of the intestinal normal microbiota, play an important role in ensuring colonization resistance of mucous membranes, producing antimicrobial compounds, and therefore are widely used as the basis of probiotic drugs. In the last decade, infections caused by Candida fungi have become a serious clinical problem. In this regard, it is relevant to evaluate the probiotic characteristics of the E. faecium strain 18 and study its antifungal activity. The aim is to investigate the effect of the E. faecium strain 18 on the growth and mature biofilm of Candida spp., as well as to characterize its agregation and coagregation abilities. Materials and methods. The effect on fungal growth was determined by the dynamics of the optical density of broth cultures; the effect of enterococcus supernatant on formed biofilms was studied in sterile polystyrene 96-well plates. The probiotic potential of E. faecium strain 18 was assessed by its ability to autoagregate and coagregate interaction with 20 strains of Candida of different species — C. albicans, C. krusei, C. kefir, C. glabrata. The scanning electron microscopy was used to obtain images. Results. The inhibitory effect of the supernatant of E. faecium strain 18 has been shown to affect the growth of Candida of all studied species, as well as their mature biofilms. The level of inhibition of the growth of formed biofilms in non-albicans species was 58.6–72.9% and 51.4% for C. albicans. The autoagregation rates of E. faecium strain 18 were 57.6% after 2 hours of incubation and 60.4% after 5 hours. E. faecium strain 18 demonstrated different levels of coagregation with the studied species of Candida, with the index values observed after 5 hours of cultivation being higher in non-albicans species, and the maximum value recorded for C. glabrata (85.6%). Conclusion. The experimental data obtained allow us to consider the studied strain as the basis for a probiotic that has an anti-candidiasis effect.

Evaluation of durability of A201 anion-exchange membranes towards organic solvents

Abstract Electrolysis using solid polymer electrolyte membranes, such as anion-exchange membranes (AEMs), is a promising technology for electrolysis and organic electrosynthesis. Herein, we report that the A201 membrane, a representative AEM widely used in AEM water electrolysis (AEMWE), exhibits remarkable durability in a wide range of organic solvents. The A201 membrane was soaked in various organic solvents for three weeks, and no significant physical changes, such as swelling and dissolution, were observed. AEMWE using A201 membrane soaked with organic solvents was performed with pure water at a current density of 25 mA cm–2, enabling smooth electrolysis with reasonable cell voltage within the 2.2 − 2.7 V range. Water electrolysis was also performed using organic solvents while maintaining a relatively small cell voltage for 4 h. Electrochemical impedance spectroscopy was performed to evaluate the charge transfer resistance, which revealed that the membrane resistance increased with increasing the polarity of the solvents. The A201 membrane exhibits chemical stability and maintains ionic conductivity in the presence of organic solvents, suggesting its potential suitability for applications in organic electrosynthesis. Graphical abstract

Phase angle: a novel application of bioelectrical impedance technology in osteoarthritis screening and diagnosis.

Bioelectrical impedance technology (EBI) offers a non-invasive, cost-effective method for body composition assessment, showing promise in diagnosing and managing musculoskeletal disorders, particularly osteoarthritis (OA). OA is a major global health concern, notably affecting the knee and hip joints. Conventional imaging techniques like X-rays and MRI have limitations in early detection, as they cannot capture microscopic cartilage changes. Phase angle (PhA), an essential EBI parameter, is widely applied in evaluating sarcopenia, tumors, and body fluids, and is increasingly valuable in OA research. PhA reflects cellular health through cell membrane impedance, with studies showing that lower PhA levels correlate with OA severity and predict OA-related degeneration, supporting its role in early screening. Additionally, EBI holds potential for monitoring OA progression and evaluating treatment efficacy. This review summarizes recent advances in OA diagnosis with EBI, focusing on the applications of PhA and other bioimpedance parameters in screening, monitoring, and evaluation. Through systematic analysis, this review provides theoretical support for EBI's clinical use, highlighting its potential in OA prevention, diagnosis, and intervention. With continued technological progress, EBI is poised to become a critical tool in OA management, particularly for early diagnosis and personalized treatment.

High-throughput screening identifies bazedoxifene as a potential therapeutic for dysferlin-deficient limb girdle muscular dystrophy.

Limb-girdle muscular dystrophy R2 (LGMD R2) is a rare genetic disorder characterised by progressive weakness and wasting of proximal muscles. LGMD R2 is caused by the loss of function of dysferlin, a transmembrane protein crucial for plasma membrane repair in skeletal muscles. This study aimed to identify drugs that could improve the localisation and restore the function of an aggregated mutant form of dysferlin (DYSFL1341P). We developed an in vitro high-throughput assay to monitor the expression and reallocation of aggregated mutant dysferlin (DYSFL1341P) in immortalised myoblasts. After screening 2239 clinically approved drugs and bioactive compounds, the ability of the more promising candidates to improve cell survival following hypo-osmotic shock was assessed. Their protective effects were evaluated on immortalised myoblasts carrying other dysferlin mutations and on dysferlin-deficient muscle fibres from Bla/J mice. We identified two compounds, saracatinib and bazedoxifene, that increase dysferlin content in cells carrying the DYSFL1341P mutation. Both drugs improved cell survival and plasma membrane resistance following osmotic shock. Whereas saracatinib acts specifically on misfolded L1341P dysferlin, bazedoxifene shows an additional protective effect on dysferlin KO immortalised myoblasts and mice muscle fibres. Further analysis revealed that bazedoxifene induces autophagy flux, which may enhance the survival of LGMD R2 myofibres. Our drug screening identified saracatinib and bazedoxifene as potential treatments for LGMD R2, especially for patients with the L1341P mutation. The widespread protective effect of bazedoxifene reveals a new avenue toward genotype-independent treatment of LGMD R2 patients.

Networked cellulose-integrated highly permeable TFC polyamide membranes with tailored nanofiltration performance.

Networked cellulose-integrated highly permeable TFC polyamide membranes with tailored nanofiltration performance.

Muscarinic type 1 receptor activated effectors in principal neurons of the rat basolateral amygdala.

The basolateral amygdala (BLA) plays a crucial role in context-specific learning and memory by integrating valence-specific stimuli with internal physiological states. Cholinergic signaling systems modulate neural excitability to influence information processing in the BLA. Muscarinic acetylcholine receptors (mAChRs) are of particular interest because aberrant mAChR signaling in BLA circuits is associated with neuropsychiatric disorders, cognitive impairment, substance use, and age-related cognitive decline. This study evaluates mAChR activation in BLA principal neurons (PNs) in juvenile rat brain slices using whole-cell patch-clamp recordings. We found that carbachol (CCh, a selective mAChR agonist) excites BLA PNs voltage clamped near the resting potential (as indicated by a downward shift in holding current), but produces a biphasic change in membrane resistance, indicating an involvement of multiple effectors. More specifically, we observed that CCh excites BLA PNs by inhibiting the afterhyperpolarization (AHP), by reducing a steady state inhibitory current, and by promoting an afterdepolarization (ADP). We further identify and characterize a CCh-induced and calcium-activated non-selective cation current (ICAN) that underlies the ADP in voltage clamp. Overall, our findings provide new insights into specific effectors modulated by activation of pirenzepine sensitive mAChRs expressed by BLA PNs. We also reveal new details about the time- and voltage-dependence of current carried by the CCh/M1R-activated ICAN like current in BLA PNs, and highlight its ability to promote a suprathreshold ADP capable of generating sustained firing after a brief excitatory stimulus. Improved understanding of these effectors will provide potentially valuable new insights on the wide range of mechanisms through which cholinergic system dysfunction can lead to impaired executive function.

Carvacrol and Streptomycin in Combination Weaken Streptomycin Resistance in Pectobacterium carotovorum subsp. carotovorum

Pectobacterium carotovorum subsp. carotovorum (Pcc) is a major phytopathogen responsible for soft rot in vegetables, affecting various staple crops such as carrots and potatoes. However, the recent emergence of streptomycin-resistant strains of Pcc has compromised the effectiveness of streptomycin for treating disease in agriculture. This study aimed to evaluate the effects of the phenolic compounds carvacrol, streptomycin, and a combination of both on the antibacterial activity, cell membrane integrity, and virulence factors of a streptomycin-resistant strain of Pcc (SP). The results revealed that the minimum inhibitory concentrations (MIC) of carvacrol and streptomycin against the SP strain were 200 μL/L and 50 g/L, respectively. In particular, their combined application had an additive effect on SP (fractional inhibitory concentration index, FICI = 0.625), leading to 2-fold and 8-fold reductions in the concentrations of the combined use of carvacrol and streptomycin, respectively, compared to when used alone. Follow-up control tests using detached Chinese cabbage, potato, and carrot samples showed that the combined treatment significantly alleviates the severity of soft rot disease and inhibits the relative conductivity, motility, and extracellular hydrolase secretion of SP. The scanning electron microscopy and confocal laser scanning microscopy observations further confirmed the disruption of SP’s cell membrane permeability and cell wall integrity after treatment with both carvacrol and streptomycin. Additionally, the transcriptome analysis indicated that their combined use enhanced the suppression of SP by regulating genes associated with its membrane integrity, virulence factors, and resistance mechanisms. In conclusion, applying the phenol–antibiotic combination of carvacrol and streptomycin significantly reduces the streptomycin dose needed against SP and can effectively control soft rot in vegetables prone to it, offering a potential management strategy for controlling SP-induced soft rot during postharvest storage.

Enhancing Silica Scaling Resistance and Perm-Selectivity of Reverse Osmosis Membranes via Increased Charge Density and Suppressed Coordination Capacity.

Silica scaling poses a substantial challenge in the advanced treatment of industrial wastewater by reverse osmosis (RO) membranes, while the existing methods modifying RO membranes to enhance antisilica scaling performance often compromise water permeance. Herein, we fabricated a sulfonated RO membrane (SLRO) using sodium lignosulfonate as a comonomer, achieving an enhanced charge density and reduced coordination capacity. SLRO exhibited superior antisilica scaling performance, reducing scaling rates by ∼145, ∼166, and ∼157% under acidic, neutral, and alkaline conditions compared to the control. Reduced density gradient analysis confirmed that sulfonic acid groups (-SO3H) on the SLRO surface increased the repulsion of silicic acid. Moreover, the SLRO demonstrated reductions of ∼112, ∼137, and ∼133% in cation-mediated silica scaling rates under the same conditions, attributed to the weaker coordination between -SO3H and cations, which diminished the cation-bridging effect. Furthermore, SLRO membranes exhibited high pure water permeance (3.3 L m-2 h-1 bar-1) and NaCl rejection (99.2%), with a water/NaCl selectivity (7.8 bar-1) three times greater than that of the control (2.6 bar-1), primarily attributed to increased surface roughness and reduced apparent thickness of the PA layer. Our work provides a robust strategy for fabricating silica scaling-resistant RO membranes with improved perm-selectivity.

Organic-Inorganic Modification of PVDF Membranes by PDA@ZnO and PDA@MgO Nanoparticles for Enhanced Performance of Organic Dye Wastewater Treatment.

Polyvinylidene fluoride (PVDF) membranes represent a potential technology for the in-depth treatment of organic dye-containing wastewater. Nevertheless, the intractable membrane fouling and the limited versatility have significantly constrained its applications. Herein, through the nonsolvent-induced phase inversion method, we have successfully fabricated the PDA@MgO/PVDF and PDA@ZnO/PVDF membranes, which are modified by the synergistic action of MgO or ZnO nanoparticles with polydopamine (PDA), respectively. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), as well as the analyses of pore structure, contact angle, and surface free energy, were utilized to characterize the hybrid membranes. The results demonstrate that the modification of PDA@MgO and PDA@ZnO can enhance the hydrophilicity, pure flux, dye rejection, and pollution resistance of PVDF membranes. The enhanced hydrophilicity of the modified membranes results from the increase in surface free energy and its polar component term. Comparatively, the PDA@ZnO/PVDF membrane exhibits a smaller contact angle (69°) and a higher pure water flux (378.63 L/m2·h·bar), whereas the PDA@MgO/PVDF membrane possesses greater mechanical strength and better antifouling performance. The PDA@MgO/PVDF membrane can achieve a rejection rate of 94.6% for disperse deep blue 79, and the flux recovery rate can reach approximately 82%. This research offers novel insights into the application of PVDF membranes for the treatment of organic dye-containing wastewater.

In-situ air bubble for efficient membrane scaling cleaning with a catalytic nanofiber membrane in membrane distillation

In-situ air bubble for efficient membrane scaling cleaning with a catalytic nanofiber membrane in membrane distillation

Study on the insulation resistance of proton exchange membrane fuel cell stacks

Study on the insulation resistance of proton exchange membrane fuel cell stacks

Thermal treatment effects on separation performance and plasticization resistance of polyimide and PIM-1 membranes

Thermal treatment effects on separation performance and plasticization resistance of polyimide and PIM-1 membranes

A novel approach for enhancing the abrasion resistance of disc ceramic membranes by surface-patterning technology

A novel approach for enhancing the abrasion resistance of disc ceramic membranes by surface-patterning technology

Potential roles of quorum quenching in microbial aggregates during wastewater treatment.

Potential roles of quorum quenching in microbial aggregates during wastewater treatment.