Search Results (927)

This study introduces a novel hybrid model for an electromembrane stack, unifying an equivalent electrical circuit model incorporating specific resistance ($R_M,R_s$) and capacitance ($C_{gs},C_{dl}$) parameters with an empirical fouling model in a single framework. The model simplifies the traditional approach by serially connecting N ($N=10$) ion exchange membranes (anionic PC-SA and cationic PC-SK) and is validated using $NaCl$ and $N{a}_{2}S{O}_4$ solutions in comparison with laboratory tests using various voltage signals, including direct current and electrically pulsed reversal operations at frequencies of 2000 and 4000 Hz. The model specifically accounts for the chemical stratification of the cell unit into bulk solution, diffusion, and Stern layers. We also included a calibration method using correction factors (${\alpha }_i$) to fine-tune the electrical current signals induced by voltage stimulation. The empirical component of the model uses experimental data to simulate membrane fouling, ensuring consistency with laboratory-scale desalination processes performed under pulsed reversal operations and achieving a prediction error of less than 10%. In addition, a comparative analysis was used to assess the increase in electrical resistance due to fouling. By integrating electronic and empirical electrochemical data, this hybrid model opens the way to the construction of simple, practical, and reliable models that complement theoretical approaches, signifying an advance for a variety of electromembrane-based technologies. Full article

Smart agriculture technology is rapidly spreading for its economic benefits and increase in farming efficiency. The management of agricultural activities is fulfilled by a network of connected devices and sensors, using wireless technologies and software to exchange data over the Internet. The electromagnetic fields (EMFs) these systems use increase the background level in farmlands, and the crop plants are exposed to unusual levels of unnatural, polarized, coherent, and variable EM radiation. This combination determines EMF influence on plants. Many studies found effects at different levels of organization—molecular, organismal, and even ecosystem levels—but the underlying mechanisms are still not well understood. In this review paper, we attempted to clarify possible mechanisms on the very basic molecular level involved in the realization of biological effects, discussing the interaction of EMFs with water molecules in living systems, from their effects on biologically significant molecules, membranes, ion channels, and ion transport, oxidative processes in cells, and photosynthesis to the effects on plant growth and development. In conclusion, we discuss the obstacles to defining the conditions for the manifestation of beneficial or adverse effects and setting exposure limits. Full article

Rapid industrialization has generated large volumes of acidic wastewater that, without adequate treatment, pose serious environmental and public health risks. Traditional remediation processes, such as chemical neutralization, ion-exchange, and membrane filtration, are effective but costly, energy-intensive, and generate toxic secondary waste. In contrast, acidophilic microalgae offer a sustainable, cost-effective, and eco-friendly alternative. Algae rely on their cellular structure and metabolism to adsorb, absorb, bioaccumulate, and transform toxic metals while simultaneously neutralizing wastewater with minimal secondary waste production. Although acidophilic algae tolerate highly toxic and low pH conditions, their growth rate and biomass productivity, key drivers of algae-based bioremediation, are often compromised under such conditions. Thus, identifying robust species and evolving strains to thrive in these wastewaters without compromising productivity will facilitate adoption of algae-based bioremediation on a large scale. Integrating algal wastewater remediation with biofuel and biofertilizer production can contribute to the circular economy. In this review, we synthesize mechanisms employed by acidophilic algal strains when exposed to acidic and metal-enriched environments to remediate wastewater. We highlight recent studies applying these strains to acidic wastewater remediation and biogas upgrading and discuss current biotechnological tools aimed at enhancing strain performance for future use in commercial systems. Full article

This review highlights the growing relevance of ion-exchange nanofibrous membranes (IEX-NFMs) in membrane chromatography (MC) for protein purification, emphasising their structural advantages such as high porosity, tunable surface functionality, and low-pressure drops. While the adsorption of IEX-NFMs in MC is expanding due to their potential for high throughput and rapid mass transfer, a critical limitation remains: the precise binding capacity of these membranes is not well understood. Traditional experimental methods to evaluate protein–membrane interactions and optimise binding capacities are labour-intensive, time-consuming, and costly. Therefore, this review underscores the importance of computational modelling as a viable predictive approach to guide membrane design and performance prediction. Yet major obstacles persist, including the challenge of accurate representation of the complex and often irregular pore structures, as well as limited and/or oversimplified adsorption models. Along with molecular-scale simulations such as molecular dynamics (MD) simulations and quantum simulations, meso-scale simulations can provide insight into protein–fibre and protein–protein interactions under varying physicochemical conditions for larger time scales and lower computational burden. These tools can help identify key parameters such as binding accessibility, ionic strength effects, and surface charge density, which are essential for the rational design and performance prediction of IEX-NFMs. Moreover, integrating simulations with experimental validation can accelerate optimisation process while reducing cost. This technical review sets the foundation for a computationally driven design framework for multifunctional IEX-NFMs, supporting their use in next-generation chromatographic separations and broadening their applications in bioprocessing and analytical biotechnology. Full article

Cationic surfactants from the group of quaternary ammonium compounds (QACs) are widely used in disinfectants, cosmetics, and household and industrial products. Their strong antimicrobial activity and chemical stability make them valuable in applications but also highly persistent and toxic when released into aquatic environments. This problem has become increasingly relevant during and after the COVID-19 pandemic, when global use of QAC-based disinfectants increased drastically, resulting in their frequent detection in municipal, hospital, and industrial effluents. The concentrations of QACs reported in wastewater range from trace levels to several mg/L, often reaching inhibitory thresholds for biological treatment processes. Although surfactants are not listed in any current European directive, the revised Directive (EU) 2024/1440 classifies micropollutants as a priority group, imposing stricter environmental quality standards and mandatory monitoring requirements. Within this regulatory framework, QACs are recognized as compounds of emerging concern, and their effective removal from wastewater has become a critical challenge. This review summarizes the current knowledge on conventional treatment technologies (coagulation, adsorption, ion exchange, advanced oxidation, and biological processes) and membrane-based methods (ultrafiltration, nanofiltration, reverse osmosis, forward osmosis, and hybrid systems) for the removal of cationic surfactants from water and wastewater. Mechanisms of separation, performance, and operational limitations are discussed. Full article

Membrane electrolytes play a critical role in energy conversion devices. The development of stable, efficient membrane electrolytes is urgent and demands paramount attention for the successful commercialization of fuel cells. Chitosan, a naturally occurring material, and silica particles were used as precursors for organic–inorganic membrane polymers. The silica nanoparticles were prepared by the sol–gel and Stober methods and characterized using various techniques, including XRD, FTIR, etc. The silica-incorporated membranes show improved properties, with the sulfur-functionalized membranes having optimal proton conductivity, ion-exchange capacity, and tensile strength of 0.0238 S/cm, 2.86 meq/g, and 7.3 MPa, respectively. It also showed the lowest methanol permeability. This was clear proof that membrane functionalization has a positive impact on tuning the properties of electrolyte membranes and should be further explored in membrane development. Full article

Hydrogen energy is a pivotal alternative to lithium-ion batteries for low-altitude aircraft, offering a pathway to sustainable aviation with its zero emissions and high energy density. Nevertheless, its broader application is hindered by challenges in storage, safety, and performance under extreme conditions such as low pressure and low temperature at high altitudes. This paper systematically evaluates various hydrogen power technologies—including water-cooled and air-cooled proton exchange membrane fuel cells (PEMFCs) as well as hydrogen turbines—highlighting their respective advantages, limitations, and suitability for different aircraft types. Among these, water-cooled PEMFCs are identified as the most viable option for manned low-altitude aircraft due to their balanced performance in power density and startup capability. In contrast, air-cooled PEMFCs demonstrate distinct cost-effectiveness for lightweight drones, while hydrogen turbines show promise for long-range regional transport. Furthermore, we analyze current progress in integrating PEMFCs into aircraft platforms and discuss persistent challenges in system compatibility and environmental adaptation. Finally, potential future development directions for PEMFC applications in low-altitude aviation are outlined. Full article

Scorpion venom toxins are important peptides being studied for their clinical significance. These peptides act by binding to ion channels in the membrane of nerve cells, causing the symptoms associated with scorpion stings (scorpionism). They principally affect the function of voltage-gated sodium channels (Nav) and are valuable for studying ion channels. Scorpions from the Buthidae family contain toxins that affect sodium channels and have a high affinity for mammalian channels. In this study, two sodium toxins isolated from the venom of the scorpion Centruroides hirsutipalpus, a member of the Buthidae family, were identified as belonging to the beta-type subfamily. These toxins were purified from whole venom using molecular exclusion, cationic-exchange, and reverse-phase chromatography techniques. Their molecular masses were determined using mass spectrometry, while their amino acid sequences were obtained by Edman degradation. A comparative analysis revealed that the sequences are identical to ChiNaBet60 and ChiNaBet50 toxins (now named Chirp7 and Chirp9, respectively) previously identified in the venom gland transcriptomics from C. hirsutipalpus. Furthermore, toxicity studies showed that these toxins were lethal to mammals. Electrophysiological analysis revealed that these peptides act as sodium channel–modulating toxins. In addition, interaction assays with antibodies were performed to analyze the structural determinants governing the binding mechanism. Full article

Fouling phenomena are among the main issues in membrane processes, worsening unit performance and membrane properties. So far, few modelling approaches have been proposed to predict colloidal fouling in electromembrane-based technologies. This work presents an original simulation platform that couples computational fluid dynamics (CFD) simulations with electrodialysis (ED) and colloidal fouling models to investigate the impact of colloidal deposition at the channel and unit scales of ED systems. Fluid dynamics, salt transport and fouling layer growth were all addressed. The model was calibrated and validated with colloidal fouling data from the literature. The regions more susceptible to fouling growth were identified. Polarization phenomena, as well as the increase in pressure losses and electrical resistance over time, were evaluated. Full article

The design of the chemical structure of ion-conductive membranes is critical to enhance proton/vanadium ion selectivity and the performance of vanadium redox flow batteries (VRFBs). Herein, camphorsulfonic acid is proposed as a novel proton-conductive group and grafted on polybenzimidazole (PBICa). The pendant sulfonic acid group on the end of the grafted side chains is flexible to promote the aggregation of ionic clusters at even a relatively low ion-exchange capacity (IEC) of 2.14 mmol g⁻¹. The formation of these high-quality clusters underscores the remarkable efficacy of this structural strategy in driving nanoscale phase separation, which is a prerequisite for creating efficient proton-conducting pathways. The bulky and non-coplanar architecture of the camphorsulfonic acid group helps to increase the proportion of free volume compared with the conventional sulfonated polybenzimidazole, which not only promotes water uptake to facilitate proton transport but also exerts a sieving effect to effectively block vanadium ion permeation. The well-formed ionic clusters, together with the expanded free volume architecture, endow the membrane with both high proton conductivity (30.5 mS cm⁻¹) and low vanadium ion permeability (0.15 × 10⁻⁷ cm² s⁻¹), achieving excellent proton/vanadium ion selectivity of 9.85 × 10⁹ mS s cm⁻³, which is about 5.6-fold that of a Nafion 212 membrane. Operating at 200 mA cm⁻², the PBICa-based VRFB achieves an energy efficiency of 78.4% and a discharge capacity decay rate of 0.32% per cycle, outperforming the Nafion 212-based battery (EE of 76.9%, capacity decay of 0.79% per cycle). Full article

Hybrid membranes are promising alternatives for various applications, combining a continuous polymer phase with a dispersed filler phase to achieve synergistic functional benefits. The ideal fillers should possess well-defined structures and unique properties for multi-functionality, as well as being sourced from renewable, biodegradable materials for sustainability purposes. This study explored the potential of using cellulose-based renewable materials as fillers for hybrid polymer electrolyte membranes (PEMs) in fuel cells. Cellulose whiskers (CWs), known for their high crystallinity and elastic modulus, were effectively synthesized via optimized sequential alkali treatment and acid hydrolysis. Subsequent functionalization with citric acid was performed to enhance their reinforcing properties and overall performance. Initial characterization using ATR-FTIR and XRD confirmed the CWs’ structural composition, high crystallinity, and the presence of reactive groups (sulfate and hydroxyl). The functionalization process introduced new carbonyl groups (C=O), which was verified by ATR-FTIR, while maintaining high hydrophilicity. Morphological analysis revealed that the crosslinked CWs created a denser and more compact microstructure within the membrane, leading to a significant enhancement in mechanical strength. The modifications to the cellulose whiskers not only improved structural integrity but also boosted the membrane’s ion exchange capacity (IEC) and proton conductivity compared to membranes with unmodified CWs. Initial experiments demonstrated CWs’ compatibility as a filler in a polysulfone (PSU) matrix, forming hybrid membranes suitable for fuel cell applications. Full article

Reverse electrodialysis (RED) is a relatively recent technology for renewable energy harvesting from the interaction of river and seawater. This paper revisits the thermodynamic equilibrium governing the ionic transport processes through ion-exchange membranes (IEMs) under RED conditions and theoretically derives approximate analytical expressions for the ionic concentrations at the inner boundaries of a permeable membrane with well-stirred baths. The equation for the Donnan ion partitioning at the membrane–solution interface, which is based on the equality of the electrochemical potential in the two phases, is analysed for binary salts with symmetric (1:1) and asymmetric (2:1) electrolytes, by considering bathing solutions with the equivalent concentrations 0.02 M in the dilute bath, and 0.5, 1, and 1.5 M in the concentrate one. Simple approximate analytical expressions exhibiting the evolution with the membrane fixed-charge concentration of the counter-ionic concentrations at the inner boundaries of the membrane, the concentration gradients inside the membrane, the total Donnan electric potential, and the ionic partitioning coefficients have been derived. The approximate generalised expressions for a general z₁:z₂ binary electrolyte are also presented for the first time. Full article

Ionomers are promising materials because ionic interactions and their reversible clustering provide sensitivity to stimuli and facilitate energy dissipation, polymer miscibility, and ion transport. The existence of a wide variety of interacting ionic groups and their associated macromolecular structures provides the basis for considering the supramolecular organization of ionic polymeric materials as a factor determining the emergence of specific properties. The main structural elements of ionomers are ionic clusters, and the properties of ionomers are determined by their sizes and size distribution. Ionomers are attractive for use in composites, actuators, coatings, dyed textiles, adhesives, shape-memory and self-healing materials, water purification membranes, and ion-exchange membranes for fuel cells and batteries. This paper presents a review of the macromolecular structure and supramolecular organization of ionomers and their properties, depending on the basis of their ionic functionalization. The ionic functions of ionomers are determined primarily by the type of ion (cations or anions) that serves as the basis for their functionalization. Ionomers containing both anionic and cationic pendant ions are considered, with attention given to the influence of the nature of the counterions used on the properties of ionomers. Full article

Thorium occupies a unique position in the global energy agenda, being simultaneously considered a promising nuclear fuel and an ecological risk factor. Its fuel cycle (Th-232 → U-233) offers significant advantages over uranium, including reduced waste, improved resistance to burnup, and lower proliferation risks, while molten salt reactor designs demonstrate potential to reduce electricity costs and consume transuranic elements from spent nuclear fuel. At the same time, the geochemical mobility of Th⁴⁺ ions, prone to forming soluble and colloidal species, increases the likelihood of their migration into soils and waters, with subsequent accumulation in biota and induction of radiotoxic effects. This study applied a comprehensive review of thorium’s energy potential and environmental risks, analyzing advances in reactor technology alongside mitigation methods such as coagulation, membrane separation, ion exchange, and adsorption with natural and modified sorbents. The findings emphasize that thorium’s strategic role in sustainable nuclear power is inseparable from the development of reliable safeguards to protect ecosystems. We conclude that a dual approach—integrating innovative reactor engineering with effective environmental countermeasures—will be essential for safe deployment of thorium technologies, ensuring their contribution to clean energy generation while minimizing ecological impacts. Full article

Hydrogen-rich water (HRW) has attracted significant attention for its physiological and therapeutic potential, driving efforts to develop a green and direct production approach. In particular, if solar energy could be utilized to power the process and the power-generation and water-production modules could be integrated into a single device, it would greatly enhance portability and user convenience, making it an ideal solution for personalized healthcare and outdoor applications. We demonstrate solar-assisted proton exchange membrane (PEM) electrolysis using symmetric IrO₂ electrodes at both cathode and anode to directly generate HRW. The symmetric design simplifies manufacturing, mitigates lifetime mismatch and metal-ion cross-contamination. IrO₂ films were electrodeposited on stainless steel substrates and annealed at 400–700 °C. When coupled with a 100 cm² Si solar cell, the electrode annealed at 550 °C—featuring ~6 nm IrO₂ nanocrystals embedded in an amorphous matrix—exhibited the highest hydrogen production rate. At an applied voltage of 4 V, this 550 °C-annealed IrO₂ electrode produced approximately 1800 μmol h⁻¹ of H₂, corresponding to about 44 mL h⁻¹ of H₂ at 25 °C and 1 atm. Corrosion tests show the HRW is less aggressive to iron than DI, RO, and tap water, suggesting better compatibility with metallic components. During water splitting, the oxidation–reduction potential (ORP) rapidly decreases to <−300 mV within 0–10 min and then stabilizes, with the 550 °C–annealed electrode exhibiting the lowest ORP. Upon air exposure, the ORP increases by ~200 mV over 45–70 min yet remains reductive for >120 min, indicating persistent dissolved H₂ and sustained performance. Overall, the symmetric IrO₂ architecture provides a green, stable, and direct route to HRW production. Full article