Reverse Electrodialysis Research Articles

Harnessing salinity gradient energy: Pushing forward in water reclamation via on-site reverse electrodialysis technology

Effluents from urban wastewater treatment plants (UWWTPs) discharged into water bodies such as the sea or ocean, offer a potential source of renewable energy through the salinity gradient (SGE) between seawater and treated water. The European project Life-3E: Environment-Energy-Economy aims to demonstrate an innovative process integrating renewable energy production with water reclamation. Using reverse electrodialysis (RED) technology, SGE can power tertiary wastewater treatment processes in coastal UWWTPs, offsetting energy costs associated with water regeneration and reuse.This study pioneers a pilot-scale RED system with a 20.125 m2 membrane area at a coastal UWWTP in Comillas, Spain. The initial tests with synthetic solutions in the up-scaled RED module have reached a peak power density of 1.39 W/m2. Under real environmental conditions, using natural seawater and treated water at ambient temperatures (289 ± 0.5 K), the system achieved a peak power density of 0.95 W/m2, outperforming previous setups in stability and efficiency.The results show competitive energy metrics, with an energy efficiency of 1.9 W/m2·m³LC and up to 38.2 Wh/m³LC generated. The treated water, with an inlet conductivity to the RED stack of <1 mS/cm, exits the pilot with a conductivity of around 4 mS/cm (measured under a load of 2A and a flow rate of 500 L/h), maintaining the quality standards for urban reuse.This study demonstrates the effective integration of RED technology into water reclamation stages, creating a self-sustained energy loop and enhancing the efficiency in water management. By harnessing blue energy and supporting sustainable water reuse, this research contributes to the global shift toward a circular water economy and critical sustainability goals.

A Review on Various Techniques for Boron Recovery: Focusing on Efficiency, Sustainability, Scalability, and Cost-Effectiveness

Boron is a critical element extensively used across various industries—such as glass manufacturing, ceramics, agriculture, detergents, nuclear energy, and aerospace—due to its unique chemical and physical properties. However, its widespread industrial use has raised significant environmental concerns, particularly its accumulation in aquatic systems, posing risks to biodiversity, plant life, and human health. This review examines the impacts of boron pollution on aquatic organisms, plants, and humans, highlighting the necessity for effective recovery strategies. We provide a comprehensive analysis of boron recovery techniques—such as reverse osmosis, electrodialysis, nanofiltration, adsorption, membrane distillation, and leaching—focusing on their efficiency, sustainability, scalability, and cost-effectiveness. The evaluation compares each method’s operational parameters, environmental impact, and economic feasibility. While methods like reverse osmosis and electrodialysis offer high removal efficiencies, they are often limited by operational costs and environmental drawbacks. Alternative methods like adsorption and nanofiltration present more sustainable and cost-effective options but may require optimization for large-scale applications. This review underscores the need for advanced, economically viable, and sustainable boron recovery technologies to mitigate environmental risks and comply with regulatory standards.

Effect of channel roughness on the particle diffusion and permeability of carbon nanotubes in reverse electrodialysis process applying molecular dynamics simulation

Innovative technology and methods are crucial for making pure and refreshing water. Two main methods are present to delete soluble salts from water: membrane processes and thermal processes. A beneficial membrane technique is reverse electrodialysis. This research used molecular dynamics (MD) simulation to investigate how channel roughness affected particle diffusion and permeability in carbon nanotubes (CNTs) via the reverse electrodialysis process. The results indicate that adding roughness in the CNT duct increased the force between the primary fluid and the duct. Using an armchair-edged CNT structure maximized the electric current in the sample. Furthermore, the roughness increased the intensity of force in the channel, which was due to gravity, leading to a decrease in the mobility of fluid particles. Additionally, several broken hydrogen bonds inside the simulation box increased from 116 to 128 in the duct sample with roughness.

Advanced Wastewater Treatment: Synergistic Integration of Reverse Electrodialysis with Electrochemical Degradation Driven by Low-Grade Heat

The reverse electrodialysis heat engine (REDHE) represents a transformative innovation that converts low-grade thermal energy into salinity gradient energy (SGE). This crucial form of energy powers reverse electrodialysis (RED) reactors, significantly changing wastewater treatment paradigms. This comprehensive review explores the forefront of this emerging field, offering a critical synthesis of key discoveries and theoretical foundations. This review begins with a summary of various oxidation degradation methods, including cathodic and anodic degradation processes, that can be integrated with RED technology. The degradation principles and characteristics of different RED wastewater treatment systems are also discussed. Then, this review examines the impact of several key operational parameters, degradation circulation modes, and multi-stage series systems on wastewater degradation performance and energy conversion efficiency in RED reactors. The analysis highlights the economic feasibility of using SGE derived from low-grade heat to power RED technology for wastewater treatment, offering the dual benefits of waste heat recovery and effective wastewater processing.

A Novel Hydrogen Production System Based On Multistage Reverse Electrodialysis

Salinity gradient energy can be converted into hydrogen energy through the system combining multi-stage reverse electrodialysis (MSRED) with polymer electrolyte membrane water electrolysis. However, the relevant performance of the system has never been investigated. In this paper, the influence of relevant parameters of MSRED on the performance of the system was analyzed theoretically through a reliable mathematical model. The results showed that increasing the flow velocity of solutions will cause remarkable decrease in the energy recovery of the system, although the total output power and hydrogen production rate of the system increase correspondingly. Besides, thickening compartments of the high concentration solution is effective to reduce the energy consumption for pump with a small augment in the total output power and hydrogen production rate of the system, while the energy recovery of the system is still dropping slowly.

Effect of external force on the dispersion of particles and permeability of substances via carbon nanotubes in reverse electrodialysis using molecular dynamics simulation

BackgroundUsing novel technologies and solutions is crucial for producing clean water. There are different ways to remove dissolved salts from water. MethodsThis study aimed to analyze the effect of an external force (EF) on the morphology of channels, the dispersion of particles, and the permeability of substances via carbon nanotubes in reverse electrodialysis. It was done using a computer simulation that studied the movement of molecules. This research aimed to study the effect of EF on the dispersion of particles and permeability of substances via carbon nanotubes using a reverse electrodialysis approach. The results show that increasing the EF from 0.0001 to 0.0005 eV/Å increased the electric current and fluid flow intensity from 5.31 e/ns and 211.31 atom/ns to 5.62 e/ns and 263.01 atom/ns. Moreover, the density decreased from 4.83 to 4.66 atom/nm3. Furthermore, the number of broken hydrogen bonds increased from 116 to 166. Significant findingsBy understanding the effect of EF on particle movement and material passage through carbon nanotubes, researchers can optimize the design of reverse electrodialysis systems to enhance their performance. This can lead to more effective and cost-efficient water treatment solutions, crucial for producing clean water.

Deep learning-assisted prediction and profiled membrane microstructure inverse design for reverse electrodialysis

Compared to traditional inter-membrane spacers, profiled ion exchange membranes significantly improve the energy harvesting performance of reverse electrodialysis (RED). Here computational fluid dynamics is employed to generate data regarding the flow and mass transfer characteristics and performance index under different profiled membrane microstructures. Data-driven deep learning models are constructed for microstructure shape generation, physics field prediction, and performance forecasting. Results show that the microstructure shape generation via the Bezier generative adversarial network, the physical field prediction via conditional generative adversarial network for the velocity field and the performance prediction via multi-layer perceptron for power number and Sherwood number achieves satisfied accuracy, respectively. The gradient descent algorithm is utilized to optimize the microstructure shape achieving higher mass transfer performance and lower pump power consumption. Compared to the traditional straight ridge channel, the optimized microstructure channel exhibits a reduction of 18.85 % in the power number and an increase of 41.00 % in the Sherwood number, rendering significantly boosted performance.

Graphene oxide‐based nanofluidic membranes for reverse electrodialysis that generate electricity from salinity gradients

Graphene oxide‐based nanofluidic membranes for reverse electrodialysis that generate electricity from salinity gradients

Investigating the effect of temperature and concentration on the performance of reverse electrodialysis systems

Reverse electrodialysis (RED) is a membrane-based technology proposed for harvesting electricity from a salinity gradient. In this study, a detailed examination of the effect of temperature and concentration on RED membrane properties is undertaken. Modelling of the co-ion concentration as a function of temperature allows the Donnan potential to be estimated, while membrane resistance and ion diffusivity can be modelled by an Arrhenius relationship with temperature. Membrane resistance is best modelled using a reciprocal relationship with concentration, while permeability and diffusivity show a power law dependence upon concentration. Using these results, the effect of increasing the temperature of the entire RED system is compared to the case where only the temperature of the diluate solution is increased. The model is in good agreement with experimental results across temperatures from 10 to 40 °C. It shows that a comparable increase in gross power density can be achieved when only the temperature of the diluate solution is increased, relative to increasing the temperature of the entire system. However, increasing the temperature also reduces the pumping energy required for each stream. In the present case, this reduction in pumping energy with temperature is more significant than the changes within the stack itself. Thus, an increase in temperature of the entire system from 20 to 40 °C results in a 27 % increase in net power density as compared to an increase of the diluate solution alone. It is thus concluded that increasing the temperature of the entire system (rather than just the diluate stream) provides a pathway to increasing the power density of the system if waste heat is available, promoting its adoption for energy harvesting.

Anti‐Swelling 3D Nanohydrogel for Efficient Osmotic Energy Conversion

AbstractOsmotic energy conversion based on reverse electrodialysis (RED) technology has attracted intense attention. As the key component, the ion‐selective membranes should meet the basic requirements of high power density, high mechanical strength, and easy preparation. Polyelectrolyte hydrogel materials are good candidates, due to their high charge density. However, the severe swelling effect decreases the ion selectivity and mechanical strength. To solve this problem, an anti‐swelling 3D nanohydrogel is demonstrated, which is in situ polymerized in the nanoporous polyimide (PI) membrane, exhibiting ultrahigh power density in osmotic energy conversion. Because of the nano‐confinement of the PI matrix, the swelling ratio of the nanohydrogel decreases to 37.5% from 593.2% of the bulk hydrogel. Meanwhile, the hybrid membrane exhibits excellent mechanical strength (≈89.5 MPa). Under a 500‐fold concentration gradient, the nanohydrogel generates a power density of up to 48.5 W m−2, one order of magnitude higher than that of the bulk hydrogel. The anti‐swelling 3D nanohydrogel introduces a new concept in designing separation membranes for osmotic energy conversion.

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.

Surface functionalized porous MXene (Ti3C2Tx)/Polyethyleneimine membrane for efficient osmotic energy conversion

The development of ion-selective membranes is crucial for achieving efficient osmotic power conversion in reverse electrodialysis system. However, balancing ion selectivity and ion permeability in membranes remains a challenge, limiting improvements in energy conversion efficiency for practical applications. In this study, we develop efficient cation exchange membranes by integrating versatile aromatic hydroxyl groups with MXene nanosheets and polyethyleneimine (PEI) into their lamellar structure. This approach holds promise for achieving non-swelling, high selectivity, and enhanced power density for osmotic energy conversion. The abundance positive surface charge within PEI molecules, combined with the 2D sub-nanochannels of MXene nanosheets, facilitates the biomimetic replication of channel size, chemical groups, and adjustable charge density in the resulting membranes. The fabrication of these membranes is easily achieved through simple hydrothermal, functionalization, and surface-charged techniques, suggesting promising scalability. These membranes exhibit remarkable stability against swelling in aqueous solutions for up to 25 days and demonstrate a high selectivity of 0.95 and a superior output power density of 18.3 W/m2 in artificial river water and seawater.

Bioinspired Homonuclear Diatomic Iron Active Site Regulation for Efficient Antifouling Osmotic Energy Conversion.

Membrane-based reverse electrodialysis is globally recognized as a promising technology for harnessing osmotic energy. However, its practical application is greatly restricted by the poor anti-fouling ability of existing membrane materials. Inspired by the structural and functional models of natural cytochrome c oxidases (CcO), the first use of atomically precise homonuclear diatomic iron composites as high-performance osmotic energy conversion membranes with excellent anti-fouling ability is demonstrated. Through rational tuning of the atomic configuration of the diatomic iron sites, the oxidase-like activity can be precisely tailored, leading to the augmentation of ion throughput and anti-fouling capacity. Composite membranes featuring direct Fe-Fe motif configurations embedded within cellulose nanofibers (CNF/Fe-DACs-P) surpass state-of-the-art CNF-based membranes with power densities of ca. 6.7Wm-2 and a 44.5-fold enhancement in antimicrobial performance. Combined, experimental characterization and density functional theory simulations reveal that homonuclear diatomic iron sites with metal-metal interactions can achieve ideally balanced adsorption and desorption of intermediates, thus realizing superior oxidase-like activity, enhanced ionic flux, and excellent antibacterial activity.

Exploration of the Influences of Electrode Materials and Solutions on the Performances of a Reverse Electrodialysis Cell with a Deduced Equation

Exploration of the Influences of Electrode Materials and Solutions on the Performances of a Reverse Electrodialysis Cell with a Deduced Equation

Reverse Osmosis Concentrated Water Treatment Technology Research

With the national “double carbon” goal, energy saving and consumption reduction strategic plan to promote, more and more enterprises will be “zero discharge” of wastewater as the ultimate goal of industrial wastewater. Reverse osmosis (RO) process is the most common way of water treatment process, in the treatment of water treatment and pure water preparation at the same time, will be accompanied by a variety of inorganic and organic pollutants contained in the by-products of concentrated water, these difficult to deal with high salt, complex composition of the reverse osmosis concentration of water, not directly discharged without treatment, not only to make a lot of water in the concentration of water to be a waste of water resources, will be a large extent on the ocean, soil and other natural environments to cause irreversible damage. Reversible damage to the ocean, soil and other natural environments. Therefore, it is of great significance to protect the environment by finding an economical and efficient treatment method for RO concentrated water. For the regeneration of fresh water resources of RO concentrated water, there have been many international reports on the development of zero liquid discharge (ZLD) or near-zero liquid discharge technology, through the membrane technology to reverse osmosis concentrated water concentration, water recycling, reduce the volume of concentrated water, and then based on the thermal technology of concentrated water desalination, evaporation and crystallization process leads to the recovery of water, and at the same time, the process of solid by-products after dehydration, purification, can also produce a considerable amount of water. At the same time, the solid by-products produced in the process can be dehydrated and purified, which can also produce considerable economic value of commodities. Concentrated water concentration process around how to achieve low-cost RO concentrated water concentration process, in the disc tube reverse osmosis (DTRO), electrodialysis (ED), membrane distillation (MD) and forward osmosis (FO) and other new membrane concentration technology field carried out a wide range of research on the concentration of further concentrated water to provide more prospects for application. Solidification crystallization through reasonable crystallization control and solid-liquid separation technology, can achieve effective separation and purification of solutes, for various industries to provide solid products in line with the quality requirements, commonly used evaporation crystallization, cooling crystallization, solvent crystallization, ion exchange methods and other ways. Through the study of reverse osmosis concentrated water concentration treatment, crystallization and solidification of the two important links of the production process plan, summarize the practicality of various technologies and advantages and disadvantages, integration of existing technologies, research suitable for reverse osmosis concentrated water resources utilization of economic technology solutions, optimize the treatment process, and ultimately realize the application of engineering examples, is the direction of the efforts of researchers in recent years.

Continuous Selective Reverse Electrodialysis Process Based on Salt-Lake Brines and Its Thermodynamic Analysis

Continuous Selective Reverse Electrodialysis Process Based on Salt-Lake Brines and Its Thermodynamic Analysis

An Opportunity for Synergizing Desalination by Membrane Distillation Assisted Reverse-Electrodialysis for Water/Energy Recovery.

Industry, agriculture, and a growing population all have a major impact on the scarcity of clean-water. Desalinating or purifying contaminated water for human use is crucial. The combination of thermal membrane systems can outperform conventional desalination with the help of synergistic management of the water-energy nexus. High energy requirement for desalination is a key challenge for desalination cost and its commercial feasibility. The solution to these problems requires the intermarriage of multidisciplinary approaches such as electrochemistry, chemical, environmental, polymer, and materials science and engineering. The most feasible method for producing high-quality freshwater with a reduced carbon footprint is demanding incorporation of industrial low-grade heat with membrane distillation (MD). More precisely, by using a reverse electrodialysis (RED) setup that is integrated with MD, salinity gradient energy (SGE) may be extracted from highly salinized MD retentate. Integrating MD-RED can significantly increase energy productivity without raising costs. This review provides a comprehensive summary of the prospects, unresolved issues, and developments in this cutting-edge field. In addition, we summarize the distinct physicochemical characteristics of the membranes employed in MD and RED, together with the approaches for integrating them to facilitate effective water recovery and energy conversion from salt gradients and freshwater.

Underpinning the Role of Nanofiltration and Other Desalination Technologies for Water Remediation and Brine Valorization: Mechanism and Challenges for Waste‐to‐Wealth Approach

Desalination brine can negatively impact the marine environment in several ways, although there are ongoing discussions regarding the severity and magnitude of environmental effects. A fascinating strategy to lessen any adverse effects is to undertake resource recovery from the brine, which also has the potential for additional revenue generation. More recently, the increasing demand for secure and less geographically restricted sources of precious or rare earth minerals, integrated with growing awareness of waste management and environmental sustainability, is driving the development of economically viable technologies to recover valuable materials from waste streams. This article provides an overview of different methods and technologies, including reverse osmosis (RO), electrodialysis (ED), and distillation, that can be used to recover precious materials, including Li, Mg, Na, and Rb and valuable blends from various waste sources and thus create a more sustainable and circular economy. The mechanisms are discussed in detail, including electrochemical processes (electrolysis, ED, and capacitive deionization), thermal desalination (multistage flash distillation and membrane distillation), pressure‐driven desalination (RO and nanofiltration), and microbial desalination cells. Challenges associated with recovering precious materials from waste streams, such as fouling, scaling, and environmental impact, along with further research directions and potential applications of desalination technologies, are also addressed.

Water trapping inside anion exchange membranes during practical reverse electrodialysis applications

The power output of reverse electrodialysis (RED), an important renewable energy technology, can be improved using high-salinity feed solutions. Herein, a RED stack of ultrathin ion exchange membranes was operated continuously for 10 days using reverse osmosis brine (~0.9 M NaClequivalent) and underground water (~0.01 M NaClequivalent). The net power and net energy efficiency were initially 1.8 W m−2cell pair and 40.8%, respectively, and then decreased gradually, as did the generated current and stack resistance. This deterioration was caused not by conventional membrane fouling but by trapped water inside the polymer matrix of the anion exchange membrane, especially near the cathode. The high salinity gradient and ultrathin membranes caused a flux imbalance between co-ion transport and osmotic water permeation. Further, bulk mass transfer was enhanced inside the RED stack to maintain electroneutrality. Therefore, combinations of membranes with high water permeability and permselectivity may be required to achieve stable RED operation.

Modular Customized Biomimetic Nanofluidic Diode for Tunable Asymmetric Ion Transport.

Artificial ion diodes, inspired by biological ion channels, have made significant contributions to the fields of physics, chemistry, and biology. However, constructing asymmetric sub-nanofluidic membranes that simultaneously meet the requirements of easy fabrication, high ion transport efficiency, and tunable ion transport remains a challenge. Here, a direct and flexible in situ staged host-guest self-assembly strategy is employed to fabricate ion diode membranes capable of achieving zonal regulation. Coupling the interfacial polymerization process with a host-guest assembly strategy, it is possible to easily manipulate the type, order, thickness, and charge density of each module by introducing two oppositely charged modules in stages. This method enables the tuning of ion transport behavior over a wide range salinity, as well as responsive to varying pH levels. To verify the potential of controllable diode membranes for application, two ion diode membranes with different ion selectivity and high charge density are coupled in a reverse electrodialysis device. This resulted in an output power density of 63.7W m-2 at 50-fold NaCl concentration gradient, which is 12 times higher than commercial standards. This approach shows potential for expanding the variety of materials that are appropriate for microelectronic power generation devices, desalination, and biosensing.