Characterization Of Membranes Research Articles

On the directionality of membrane coupled Helmholtz resonators under open air conditions.

Controlling the absorption and diffusion of sound in the audible range constitutes an exciting field of research. Acoustic absorbers and diffusers perform extraordinarily well at high frequencies with sizes comparable to the wavelength of the working frequency. Conversely, efficient low-frequency attenuators demand large volumes leading to unpractical sizes, and there is now interest in determining whether the size of the resonator can be reduced while not compromising - or perhaps even decreasing - the working frequency. One viable approach is through the use of metamaterials to enable the control of device dynamics such that heavy sub-wavelength attenuation can be efficiently realised. To achieve this goal, the theoretical (including a mathematical model and the use of finite element analysis) and experimental characterisation of 3D-printed membrane-coupled Helmholtz resonator (HR) acoustic metamaterials (AMMs) is explored. The results reveal good agreement between theory and experiments, and show that membrane-coupled HR AMMs feature heavy sub-wavelength acoustic attenuation (λ/55) while also showcasing directional responses under open air conditions. These features are explained by the interplay between resonator size, membrane characteristics, and the presence of two acoustic ports. It is anticipated that, together with recent advances on smart AMMs, these systems will foster new progress in the development of dynamic AMMs for wideband attenuation.

Membranes fouling propensity of PSF/GO hollow fiber mixed matrix membranes for water treatment ultrafiltration application.

The study investigated the fouling propensity of polysulfone (PSF) hollow fiber (HF) mixed matrix membranes modified with 1.0 wt.% graphene oxide (GO). Using scanning electron microscopy (SEM), atomic force microscopy (AFM), water contact angle (WCA), and mechanical assessments, the structural characteristics of both untreated and GO-modified PSF HF membranes were examined. Filtration experiments included pure water and model contaminants such as bovine serum albumin (BSA), humic acid (HA), E. coli, and oil-in-water emulsion. The GO-modified membranes demonstrated a significant enhancement in antifouling performance, recovering over 90% of their initial pure water flux with HA and oil, indicating high resistance to irreversible fouling. Additionally, the GO-modified membranes showed superior oil separation efficiency. However, fouling parameters for BSA were similar for both membrane types, suggesting that GO does not significantly affect membrane-BSA interactions. Both types of membranes displayed high retention capabilities for E. coli, with no noticeable improvement due to GO addition. This study highlights the potential of GO-modified PSF HF membranes in enhancing antifouling performance and oil separation efficiency.

Cell inspired delivery system equipped with natural membrane structures in applications for rescuing ischemic stroke.

Ischemic stroke (IS), accounting for 87 % of stroke incidences, constitutes a paramount health challenge owing to neurological impairments and irreversible tissue damage arising from cerebral ischemia. Chief among therapeutic obstacles are the restrictive penetration of the blood-brain barrier (BBB) and insufficient targeting precision, hindering the accumulation of drugs in ischemic brain areas. Motivated by the remarkable capabilities of natural membrane-based delivery vehicles in achieving targeted delivery and traversing the BBB, thanks to their biocompatible architecture and bioactive components, numerous membrane-engineered systems such as cells, cell membranes and extracellular vesicles have emerged as promising platforms to augment IS treatment efficacy with the help of nanotechnology. This review consolidates the primary pathological manifestations following IS, elucidates the unique functionalities of natural membrane drug delivery systems (DDSs) with nanotechnology, as well as delineates the structural characteristics of various natural membranes alongside rational design strategies employed. The review illuminates both the potential and challenges encountered when employing natural membrane DDSs in IS drug therapy, offering fresh perspectives and insights for devising efficacious and practical delivery systems tailored to IS intervention.

Biomimetic Dual‐Driven Heterojunction Nanomotors for Targeted Catalytic Immunotherapy of Glioblastoma

AbstractThe existence of the blood–brain barrier (BBB) and the characteristics of the immunosuppressive microenvironment in glioblastoma (GBM) present significant challenges for targeted GBM therapy. To address this, a biomimetic hybrid cell membrane‐modified dual‐driven heterojunction nanomotor (HM@MnO2‐AuNR‐SiO2) is proposed for targeted GBM treatment. These nanomotors are designed to bypass the BBB and target glioma regions by mimicking the surface characteristics of GBM and macrophage membranes. More importantly, the MnO2‐AuNR‐SiO2 heterojunction structure enables dual‐driven propulsion through near‐infrared‐II (NIR‐II) light and oxygen bubbles, allowing effective treatment at deep tumor sites. Meanwhile, the plasmonic AuNR‐MnO2 heterostructure facilitates the separation of electron–hole pairs and generates reactive oxygen species (ROS), inducing immunogenic tumor cell death under NIR‐II laser irradiation. Furthermore, MnO2 in the tumor microenvironment reacts to release Mn2+ ions, activating the cGAS‐STING pathway and enhancing antitumor immunity. In vitro and in vivo experiments demonstrate that these dual‐driven biomimetic nanomotors achieve active targeting and deep tumor infiltration, promoting M1 macrophage polarization, dendritic cell maturation, and effector T‐cell activation, thereby enhancing GBM catalysis and immunotherapy through ROS production and STING pathway activation.

A control-oriented comprehensive model of PEM electrolyzer considering double-layer capacitance

The modeling of electrochemical and thermal characteristics of proton exchange membrane (PEM) electrolyzer is significant in the hydrogen production process. However, the calculation of electrode impedance and double-layer capacitance during operation is not accurate enough currently, and the electrothermal coupling characteristics of hydrogen production devices are not fully considered. In this paper, the multi-stage equivalent circuit of the PEM electrolyzer is designed using electrochemical impedance spectroscopy (EIS) and the time-constant fitting method. In addition, according to the temperature control system of the actual hydrogen production device, the electro-thermal model of the PEM electrolyzer is established, in which the fuzzy PID control is used to maintain the temperature stability. Moreover, the electrical characteristics and temperature characteristics are simulated in different time scales. Finally, compared to the existing models, the proposed model is more accurate, and it indicates that the proposed model has better accuracy against the existing models.

Physiopathological Aspects of Synovial Fluid and Membrane in Psoriatic Arthritis

Background: Psoriatic arthritis (PsA) is a chronic inflammatory arthropathy characterized by a variety of clinical manifestations, mainly affecting joints and entheses, but also skin, nails, the eye, and the intestine. Objectives: In this review, we describe the essential characteristics of both synovial membranes and synovial fluid (SF) in PsA. Similarly to other inflammatory arthritis, the histological peculiarities in PsA synovitis are lining hyperplasia, neoangiogenesis, and sublining infiltration by immune cells and inflammatory mediators. Synovial effusions are frequent in PsA patients and SF analysis allows us to determine the pathological process occurring in the joint. Routine examinations help clinicians in defining the inflammatory status and possibly the detection of specific cell subsets. In addition, pathogenic crystals including monosodium urate and calcium pyrophosphate may be found in PsA SF. Conclusions: SF represents a potential substrate to identify the biomarkers that are useful to predict disease progression and response to medications in PsA patients, thus guiding the choice of appropriate and tailored pharmacological treatment.

Fabrication and adsorption characteristics of cuprammonium cellulose-based membranes for removing anionic and cationic dyes

A cotton linter-based source was used to form conjugate electrospun membranes composed of cuprammonium cellulose, polyethylene oxide, and polyacrylonitrile for the removal of the anionic and cationic dyes from aqueous media. The highest removal efficiencies of 94 %, 89.9 %, 87.4 % were achieved for the anionic dyes Congo red (CR), Metanil yellow (MY), and Methyl orange (MO), respectively, and less so on the cationic dyes Crystal violet (CV), and Rhodamine B (RB) were 55.8 % and 15.1 %, respectively. The pseudo-second-order model effectively described the adsorption kinetics for both types of dyes. The composite membrane exhibited adsorption behaviors following the Dubinin-Radushkevich (D-R) isothermal model. Thermodynamics study suggests that the adsorption process was spontaneous except for the RB dye. The activation energy values of CR, MY, MO, CV, and RB dyes were 27.65, 21.17, 11.50, 10.47, and 71.12 kJ/mol, respectively, confirming the physisorption phenomenon for CR, MY, MO, and CV dyes, while chemisorption occurs for RB dyes. This study investigates the potential of a conjugate electrospun membranes as a reusable adsorbent for dye removal. The effects of solution pH, temperature, and dye concentration on adsorption performance were systematically evaluated. The conjugate electrospun membrane efficiency declined by only 10 % after undergoing five adsorption/desorption cycles.

Investigating the performance of direct contact membrane distillation for liquid desiccant regeneration and freshwater production: A CFD-based study

Liquid desiccant air conditioning (LDAC) systems offer a promising solution for enhancing indoor thermal comfort, air quality, humidity control, and energy efficiency. This study focuses on the critical aspect of regenerating liquid desiccants in LDAC systems, which has the potential to enhance system efficiency and performance significantly. Using computational fluid dynamics (CFD) to model direct contact membrane distillation (DCMD) for liquid desiccant regeneration and freshwater production, this research paves the way for improving the performance of LDAC systems. The DCMD process, which involves mass transfer across a membrane driven by a temperature gradient between the permeate and feed channels, is a key area of exploration in this study. The findings of this study have significant implications for the design and operation of LDAC systems. The impact of feed inlet velocity and temperature on vapor flux for liquid desiccant regeneration is substantial, with increasing the feed inlet temperature leading to a fourfold increase in water vapor flux. Similarly, increasing the feed inlet velocity boosts flux due to enhanced convective heat transfer. Membrane characteristics, such as porosity and thickness, are key determinants of system performance. These findings underscore the importance of optimizing these parameters for efficient liquid desiccant regeneration and freshwater production in LDAC systems, thereby enhancing their overall performance and energy efficiency. Finally, a mathematical model for water vapor flux was developed to investigate water vapor flux as a function of key factors such as inlet temperature, velocity, liquid desiccant concentration, and membrane characteristics.

Recovery of Low-concentration Waste Acid by Electrodialysis: Modelling and Validation

In light of the operational principles of Electrodialysis (ED), it is anticipated that this technology would significantly contribute to the recovery of waste acids through selective separation and subsequent proton concentration. However, the imperfect proton leakage characteristics of anion exchange membranes (AEMs) not only detrimentally affect the efficacy of ED-based acid recovery systems but also present considerable challenges for modeling endeavors. This study introduces a model based on the Nernst-Plank Equation at the cell pair scale, aimed at predicting ED performance. The model incorporates an empirical expression that links operational parameters, such as acid concentration and the concentration ratio between the concentrate and dilute compartments, to the permselectivities of AEMs in terms of anion transport numbers. Furthermore, both numerical and experimental analyses are performed to evaluate energy consumption across various operating conditions. The simulation outcomes derived from the proposed model exhibit a strong correlation with experimental data concerning acid transport (where the acid concentration increases from 0.25 M to 1.1 M through a two-stage concentration process), water migration (which demonstrates a nearly linear increase over time with applied currents, specifically a 15% increase under low-current conditions and a 100% increase under high-current conditions), and energy consumption. It is hoped that this model will aid in the design and optimization of ED-based acid reclamation processes, thereby enhancing their practical applications.

Geometric flow control in lateral flow assays: Macroscopic two-phase modeling

Lateral flow assays (LFAs) are widely employed in a diverse range of applications, including clinical diagnostics, pharmaceutical research, forensics, biotechnology, agriculture, food safety, and environmental analysis. A pivotal component of LFAs is the porous polymeric membrane, which facilitates the capillary-driven movement of fluids, known as “imbibition,” in which a wetting fluid displaces a non-wetting fluid within the pore space of the membrane. This study presents a multi-scale modeling framework designed to investigate the imbibition process within LFAs. The framework integrates microscopic membrane characteristics into a macroscopic two-phase flow model, allowing the simulation of imbibition in membranes with different micro-scale properties and macro-scale profiles. The validity of the model was established through comparative analysis with documented case studies, a macro-scale single-phase flow model, and experimental observations, demonstrating its accuracy in simulating the imbibition process. The study also examines imbibition in various geometric configurations, including bifurcated (Y-shaped) and multi-branch geometries commonly found in multiplexed LFAs. The influence of geometric features such as length ratio, width ratio, branching angle, bifurcation point location, and asymmetry on fluid transport is investigated. Results indicate that membranes with larger branching angles exhibit slower imbibition. In addition, the influence of membrane type on macroscopic flow patterns is evaluated, showing that membranes with lower permeability require longer imbibition times. The insights gained from this research support a data-driven strategy for manipulating wetting behavior within LFAs. This approach can be leveraged to optimize the performance of LFAs and increase their effectiveness in various applications.

The Role of Cation Exchange Membrane Characteristics in CO2 Electrolysis to CO Using Acid Anolyte

Cation exchange membranes are considered a suitable option for zero-gap CO2 electrolysis due to their potential to avoid carbonation and improve carbon efficiency. However, the use of acidic anolytes remains an issue due to high hydrogen production. This study investigates Nafion® membranes (111, 112, 115, 211, and 212) with different thicknesses produced by extrusion or solution-cast processes in a zero-gap cell with an acidic anolyte containing K2SO4. Faradaic efficiencies for CO production (FECO) are higher with thinner membranes, regardless of the manufacturing process, reaching FECO around 75% at 50 mA cm⁻². Additionally, membranes with similar thicknesses (∼50.8 µm) but produced in different ways displayed flow field carbonation after 3 hours of electrolysis at 30°C and 50 mA cm⁻². Linear sweep voltammetry (LSV) in full and half-cell configurations shows limiting diffusion current (iL) relative to proton transport for all the employed membranes, no matter the thickness. In contrast, the iL for Nafion® 115, the thicker membrane, is suppressed, indicating that proton depletion is fast and the electrode surface alkalinization primarily results from water reduction in this case. A mechanistic analysis was performed to explain the behavior of the limiting currents in the cell with Ar- and CO2-feed, indicating that CO2 reduction aids in the consumption of H+ provided by the membrane, increasing the local pH at less negative potentials. Overall, thinner membranes exhibited higher values of FECO and energy efficiency for CO (EE%CO). However, solution-cast membranes are more prone to provide K+, leading to better performance than those prepared by extrusion.

Dynamic response characteristics of proton exchange membrane fuel cell during transient loading: An experiment study

The dynamic performance of Proton Exchange Membrane Fuel Cell (PEMFC) is crucial for safe and efficient operation and remains a major barrier to commercialization. In this paper the dynamic response characteristics of PEMFC under serpentine flow field (SFF) and parallel flow field (PFF) are discussed. The effects of current loading, operating pressures, anode and cathode stoichiometric ratios, as well as operating temperatures on the dynamic response characteristics of PEMFC are systematically studied through experimental methods. Furthermore, the principle and mitigation strategies for voltage undershoot are investigated. It shows that lower current density, higher back pressure and higher temperature are benefit to alleviate voltage undershoot. Compared with the SFF, the Second-stage time delay of PFF is shortened by 9.2 s, the VU is decreased by 17.27 mV, and the energy loss is reduced by 0.71%. Moreover, Pearson correlation coefficient is proposed to evaluate the correlation between index and PEMFC performance.

Reversible MOF-Based mixed matrix membranes for SO2/N2 separation: A photo-responsive approach

Fuel consumption for industrial development, SO2 gas emissions are increasing year by year and have become a focal point of air pollution. Membrane separation method photo-responsive materials and MOFs have attracted more and more attention in a variety of fields. This is because the membrane separation method uses less energy and is an uncomplicated process; MOFs have superior gas adsorption capabilities; and the photo-responsive materials are controllable. In this study, mixed matrix membranes are prepared using Uio-66-NH2 and photo-responsive materials CE-Azo-Uio-66 as fillers and Pebax as base membranes. By improving the dissolution-diffusion mechanism for SO2 gas molecules, SO2/N2 gas separation is accomplished. More channels for the mass transport of SO2 gas through the membrane can be created by MOFs increased porosity and larger specific surface area. Secondly, the SO2 adsorption and dissolution-diffusion mechanism of the mixed matrix membrane are strengthened by the grafted SO2 affinity groups on the MOF. Moreover, Pebax/CE-Azo-Uio-66 membranes is not only significantly more permeation selective than Pebax/Uio-66-NH2 membranes, but also shows photo-responsive characteristic. The SO2 permeability and selectivity of Pebax/CE-Azo-Uio-66 mixed matrix membranes at CE-Azo-Uio-66 content of 20 % are increased by 191 % and 179 %, respectively, compared to pure Pebax membranes. It is also found that the SO2 permeability and SO2/N2 selectivity of the membranes show regularly reversible changes at the UV–Vis photoconversion conditions of Pebax/CE-Azo-Uio-66-20 % membranes, indicating the photo-responsive characteristics of mixed matrix membranes that include Azo groups. The SO2 permeability of the Pebax/CE-Azo-Uio-66 membrane is increased by 1300 Barrer and the SO2/N2 selectivity is increased by 350 when the light source is changed from UV to Vis light, achieving a controlled separation of SO2/N2. Besides, the addition of MOF particles significantly enhances the mechanical properties and stability of the membrane.

Analysis of morphology, cytotoxicity, and water content characteristics of freeze-dried amnion membrane from human and bovine

Placenta tissue has biological advantages, including anti-inflammatory, anti-bacterial, anti-fibrotic formation, and immunomodulatory properties. The amnion membrane (AM) is an inner side membrane of the placenta that faces the fetus. The main sources of amnion are humans and animals, with bovine being one of the significant sources. The aim of this study was to analyze the morphology, cytotoxicity, and water content characteristic of freeze‑dried amnion membrane (FD‑AM) from humans and bovines to measure the safety and compatibility of bovine FD-AM as an alternative to human FD-AM. This study is an observational cross-sectional study. Samples were divided into two groups: human FD-AM and bovine FD-AM groups. Both groups were examined for morphology characteristics by scanning electron microscopy (SEM), cytotoxicity by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) analysis, and water content by drying through moisture analyzer device. The morphology characteristics of bovine FD-AM and human FD-AM, as observed through SEM, showed similar results of a smooth, flat surface with no cavity and were well dehydrated. MTT assay analysis on both groups demonstrated cytocompatibility with cell viability exceeding 70% in the control group. However, human FD-AM showed a higher number of viable cells (0.19±0.01) compared to bovine FD-AM (0.12±0.03), with a statistically significant difference (p<0.05). The water content analysis revealed that both groups met the standard, with levels below 10%. While bovine FD-AM (7.19±0.45%) had slightly higher water content than human FD-AM (6.79±1.0%), the difference was not significant (p>0.05). Both human FD-AM and bovine FD-AM showed good results in morphology, cytotoxicity, and water content characteristics and compatibility. In conclusion, bovine FD-AM might be considered as an alternative to human FD-AM.

Microfluidics-Assisted Polymer Vesicle Budding in Emulsion Systems: A Promising Approach for the Preparation and Application of Polymer Vesicles

The challenge of producing polymer vesicles remains difficult, despite numerous attempts to modulate the kinetics of polymer vesicle budding and achieve precise control over the membrane characteristics. An innovative approach that incorporates the use of copolymer-loaded single-emulsion droplets is proposed to address this challenge. This method enables the precise manipulation of micelles and polymer vesicles’ composition, structures and dimensions. The emulsion contracts and forms microspheres when the copolymer concentrations exceed > 0.5 wt%, resulting in the formation of nano polymer vesicles. Conversely, the copolymer spontaneously forms micro polymer vesicles and micelles through vesicle budding at lower concentrations. The spontaneous production of vesicles and micelles can be induced by modifying the copolymer concentration in the emulsion. Our discoveries have a significant impact relative to the development of copolymer membranes and contribute to an enhanced comprehension of the mass manufacturing of polymer vesicles from single emulsions.

Eco-friendly non-fluorinated membranes for renewable energy storage

The European Union is studying the possibility of prohibiting the use of fluorinated-based materials which could limit the use of the most studied and used Nafion and Nafion-like membranes for any applications. Therefore, this study focuses on the preparation and performance evaluation of green, non-fluorinated proton exchange membranes in a chlor-alkali-based reversible electrochemical cell system for renewable energy storage applications. The membranes were prepared by casting and cross-linking of polyvinyl alcohol (PVA) with varying chitosan (CS) concentrations (5–20 wt%), followed by sulfonation using diluted sulfuric acid at room temperature. CS concentrations significantly influenced membrane's physicochemical properties, including ion exchange capacity, ionic conductivity, mechanical strength, and water uptake. Positron annihilation lifetime spectroscopy revealed a correlation between free volume properties and other membrane characteristics. A custom-designed 3D-printed electrochemical cell was developed, capable of operating in reversible mode (both electrolysis and fuel cell modes) with a zero-gap configuration. The PVA/CS (20 wt%) membrane outperformed Nafion, exhibiting a lower voltage (4 V vs. 6 V) in electrolysis mode at 50 mA cm⁻2 and a higher specific power density (2.7 vs. 1.9 mW cm⁻2 mgPt) in fuel cell mode. The obtained results demonstrate that crosslinked PVA/CS non-fluorinated based membranes can be sulfonated using diluted sulfuric acid and work effectively in reversible chlor-alkali electrochemical cells.

Temperature dependence of water and salt transport in concentration gradient batteries: Insight from membrane properties

The performance of concentration gradient batteries (CGBs) based on reverse electrodialysis technology is inevitably influenced by seasonal temperature fluctuations; however, these effects have not been thoroughly investigated. This study explored the temperature dependence of water and salt transport in CGBs using five different membranes over a temperature range of 5–45 °C to elucidate these impacts. The results indicated that the temperature dependence of current efficiency and voltage efficiency in CGBs was respectively controlled by permeation processes (including both water and salt) and membrane resistance. The temperature dependence of mass transfer in these membranes was associated with the characteristics of the species crossing the membrane (such as size) and, more significantly, with membrane properties, including water volume fraction and fixed charge density. Therefore, we proposed that controlling these membrane characteristics can modulate the influence of temperature on mass transfer and CGB performance. This research enhanced our understanding of how temperature affects mass transfer mechanisms in different membranes and provided valuable insights for improving energy conversion in CGBs and other membrane processes.

High-performance and ultra-robust triboelectric nanogenerator based on hBN nanosheets/PVDF composite membranes for wind energy harvesting

Triboelectric nanogenerator (TENG) is a novel energy technology that converts high-entropy mechanical energy from the environment into electrical energy using triboelectrification and electrostatic induction effects. However, the low surface charge density and easy wear of traditional triboelectric materials are bottlenecks for their practical applications. Here, a remarkable triboelectric properties, superior mechanical properties, exceptional wear resistance, and high thermal conductivity hexagonal boron nitride nanosheets (hBNNS)/ polyvinylidene difluoride (PVDF) composite negative triboelectric material is developed. The inclusion of hBNNS as an electron acceptor and nucleating agent not only effectively boosted the surface charge density (711 μC/m2) and mechanical characteristics of the composite membrane, but also the friction coefficient (COF) and thermal conductivity of the 2 wt% hBNNS/PVDF composite membrane decreased by 28.6 % and increased by 22.2 % compared to the PVDF matrix, respectively. The optimized TENG delivers a peak voltage of 434 V, a current of 53 μA, and a power of 4.84 mW. Furthermore, it exhibits exceptional ultra-robust, enabling continuous operation for 72 h at a wind speed of 17.5 m/s while maintaining performance above 90.6 %. Additionally, the TENG is capable of effectively powering a smart hygrothermograph and realizing wireless real-time monitoring, or directly lit up 102 white LEDs in a serial connection. This work addresses the challenges of low output performance and limited lifespan in TENG from a material perspective, providing a valuable reference method for the design of negative triboelectric materials with high surface charge density, good mechanical properties, low COF, and high thermal conductivity.

Effect of colloidal magnetite (Fe3O4) nanoparticles on the electrical characteristics of the azolectin bilayer in a static inhomogeneous magnetic field

This work is devoted to the study of the combined effects of applied magnetic field and MNPs on the electrical characteristics of bilayer lipid membranes. We present results of the study of electrical parameters of azolectin membranes in a static inhomogeneous magnetic field at the one-sided addition of positively charged quasi-spherical superparamagnetic magnetite nanoparticles with a diameter of about 4 nm. The magnet was located at different distances from the membrane, and the magnetic field attracted the nanoparticles to the membrane surface with different strengths. We observed three pronounced effects that depended on the external magnetic field. Firstly, after addition of nanoparticles in a magnetic field, the conductance of the membranes increased. A smooth increase in conductance was accompanied in some cases by the appearance of current jumps, which can be associated with the formation of through pores with a radius of no more than 1 nm. The conductance increased with increasing magnetic field gradient. Secondly, at zero command voltage, a negative current through the membrane was observed. Although our experiments did not allow us to unambiguously determine which particles create this current, we believe that this current is associated with the penetration of particles through the membrane. This effect intensified with increasing magnetic field gradient. Thirdly, we observed a sharp change in the nonlinear dependence of capacitance on voltage associated both with the change in the surface potential of the azolectin membrane and with the effect of MNP binding to the membrane surface on the apparent membrane capacitance.

Research on typical operating conditions of hydrogen production system with off-grid wind power considering the characteristics of proton exchange membrane electrolysis cell

Hydrogen energy, with its abundant reserves, green and low-carbon characteristic, high energy density, diverse sources, and wide applications, is gradually becoming an important carrier in the global energy transformation and development. In this paper, the off-grid wind power hydrogen production system is considered as the research object, and the operating characteristics of a proton exchange membrane (PEM) electrolysis cell, including underload, overload, variable load, and start- stop are analyzed. On this basis, the characteristic extraction of wind power output data after noise reduction is carried out, and then the self-organizing mapping neural network algorithm is used for clustering to extract typical wind power output scenarios and perform weight distribution based on the statistical probability. The trend and fluctuation components are superimposed to generate the typical operating conditions of an off-grid PEM electrolytic hydrogen production system. The historical output data of an actual wind farm are used for the case study, and the results confirm the feasibility of the method proposed in this study for obtaining the typical conditions of off-grid wind power hydrogen production. The results provide a basis for studying the dynamic operation characteristics of PEM electrolytic hydrogen production systems, and the performance degradation mechanism of PEM electrolysis cells under fluctuating inputs.