Electrodialysis Research Articles

Intensifying transition metal ion removal and recovery from acidic wastewater via electrodialysis (ED) -based process.

Intensifying transition metal ion removal and recovery from acidic wastewater via electrodialysis (ED) -based process.

Performance evaluation of desalination of synthetic brackish water in a three-cell electrodialysis system

ABSTRACT The deficiency of potable water is a critical concern in numerous areas of India, especially in coastal regions where excessive groundwater extraction has resulted in salinity intrusion. The desalination of brackish water offers a viable method for generating sweet potable water. The present research focuses on designing and fabricating a three-cell electrodialysis (ED) chamber to assess its efficacy in removing chloride ions (Cl⁻). The ED chamber utilizes graphite electrodes as both anode and cathode, with ion transport enabled by selective membranes within an electric field. Synthetic saline water with initial Cl⁻ concentrations of 4730, 4750, and 5300 mg/L was processed in three batches, utilizing a maximum current of 4 A and voltage of 30 V provided by a DC power supply. During a 3-hour batch operation, the Cl⁻ removal efficiency initially attained 88%, achieving a maximum removal of 95% as the batch continued. The Cl⁻ concentration was reduced to 230 mg/L, complying with the potable water standards of IS-10500 of 2012. The influence of current and voltage on removal efficiency was also examined. The results illustrate the efficacy of ED technology in brackish water desalination and advance the creation of sustainable water treatment solutions.

Insights into 1-butyl-3-methylimidazolium hydrogen sulfate recovery from wastewater by electrodialysis with heterogeneous ion-exchange membranes

Due to the negative impact of ionic liquids (ILs) on the environment and their high cost, it is very important to examine their recovery and recycling methods. Thus, in this study, research on 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO4) recovery from wastewater by electrodialysis (ED) is presented. The influence of the initial [Bmim]HSO4 concentration, the voltage, and the linear flow velocity on the effective [Bmim]HSO4 recovery was examined. To assess the effectiveness of the proposed method, factors such as IL percentage recovery, degree of concentration, electric current efficiency, and energy consumption were determined. It was found that as the initial concentration of [Bmim]HSO4 in the feed solution increased from 0.01 to 0.2 M, the [Bmim]HSO4 recovery efficiency increased. A 2.3-fold concentration of the [Bmim]HSO4 in the concentrate solution with a recovery of 98.8%, a current efficiency of 67.3%, and energy consumption of 28 kWh/m3 was achieved for ED of a 0.2 M [Bmim]HSO4 solution using heterogeneous ion-exchange membranes. Additionally, the voltage and linear flow velocity affected the [Bmim]HSO4 recovery. The highest ED efficiency for the recovery and concentration of [Bmim]HSO4 was obtained at an applied potential of 4 V, a 2 cm/s linear flow velocity, and 0.2 M IL in the feed solution.

Selective Na+/K+ separation from greenhouse wastewater concentrate streams using Donnan dialysis for sustainable water and nutrient recovery.

Selective Na+/K+ separation from greenhouse wastewater concentrate streams using Donnan dialysis for sustainable water and nutrient recovery.

Concentration of High-Salinity Brine Using Single-Stage Membrane Capacitive Deionization.

Concentrating saline water is essential for zero liquid discharge (ZLD) of wastewater. However, prevailing membrane-based technologies, such as reverse osmosis (RO) and electrodialysis (ED), can hardly handle high concentration differences (ΔC) in a single stage, where multi-stage operation is needed, which increases the operational difficulties and energy input. However, membrane capacitive deionization (MCDI) is theoretically applicable to high ΔC. This study explored the feasibility of employing an MCDI in brine concentrating and proposed several regulating measures on the electrode's porosity, electrical quantity for charging-discharging, and desorption conditions. Based on the determination of salt and water fluxes, these measures were confirmed to mitigate water transfer across the membrane, thereby facilitating salt transportation for brine concentrating. To address the mass imbalance between adsorbed and desorbed, a novel pre-charge strategy was designed, which enabled successful MCDI continuous operation over 50 cycles. A concentration difference of 161 g/L NaCl was achieved per single stage, which is the highest reported result among RO, ED, and MCDI studies. The concentrating rate was as high as 38.4 g/(m2·h) with a comparative energy consumption at RO and ED. This study demonstrated that MCDI is an optional technology for the future application of brine concentrating in ZLD facilities.

Technologies Available for Treatment of Saline Water for Livestock Drinking: A Review

Water is an essential nutrient required for physiological and metabolic processes in livestock. However, in many arid and semi-arid regions, freshwater resources are scarce, and saline or brackish water becomes the only available source. Consumption of saline water can adversely affect livestock productivity and health. Desalination offers a solution by converting saline water into potable quality. This review explores the technologies available for desalination of saline water for livestock drinking, encompassing thermal, membrane-based, chemical, and renewable energy-assisted systems. Reverse osmosis (RO), electrodialysis (ED), multi-stage flash distillation (MSF), vapor compression distillation (VCD), and freeze desalination are examined in detail. Additionally, solar desalination and its potential for decentralized livestock farms is discussed. The review concludes by emphasizing the need for technology selection based on water quality, energy availability, scale of operation, and economic viability.

Coupling electrodialysis with microbial electrosynthesis enables high-rate, high-titer, and cost-effective acetate production from CO2.

Coupling electrodialysis with microbial electrosynthesis enables high-rate, high-titer, and cost-effective acetate production from CO2.

The Enrichment of Acetic Acid Using an Integrated Reverse Osmosis-Electrodialysis Process.

In this study, the integrated process of reverse osmosis (RO) and electrodialysis (ED) is developed to concentrate the dilute solution of acetic acid (HAc). The key parameters, such as RO pressure, ED voltage, and ED volume ratio, were systematically evaluated and the operation conditions of the processes were optimized. Under an operating pressure of 5 MPa, RO can enrich low-concentration HAc from 1.5 wt.% to 6.5% wt.% and the energy consumption is 0.37 kW·h·kg-1. Next, RO-concentrated water was used as the ED feed and the first ED with a volume ratio of the concentrated to dilute chamber of 1:4 was carried out under the conditions of a flow rate of 30 L/h and an operating voltage of 12 V; the HAc concentration reached 12.50 wt.%. The second ED with a volume ratio of 1:5 made the final HAc concentration reach 19.02 wt.%. This study shows that using RO-concentrated water instead of initial water for the ED process can reduce water energy consumption and cost markedly, and the RO-ED integrated process can efficiently pre-enrich low-concentration HAc aqueous solution, and the enriched HAc concentration meets the requirements for the further distillation of HAc.

Contribution of the transmembrane electric potential to the set voltage in a single-anion exchange membrane electrodialysis-cell and the role of solution conditions.

Contribution of the transmembrane electric potential to the set voltage in a single-anion exchange membrane electrodialysis-cell and the role of solution conditions.

Combining Novel Membrane Technologies for Sustainable Nutrient Recovery from Digestate: Effect of Solid Content

Nutrient recovery from anaerobic digestate has gained increasing importance in recent years due to its potential to reduce resource dependency and to close nutrient cycles. The aim of this work is to evaluate the influence of a previous solid–liquid separation phase on nutrient recovery efficiency using two innovative membrane technologies, namely, gas-permeable membranes (GPM) and electrodialytic (ED) processes, applied individually or in combination. The obtained results were compared with those obtained through the centrifugation of the raw digestate and direct chemical precipitation followed by centrifugation in terms of the efficiency in the recovery of N (nitrogen) and P (phosphorous). A total of nine scenarios of digestate processing were compared. GPM technology allowed for the recovery of 65% of the N content in the raw digestate (41.5 g total solids (TS) kg−1) and 67% of N in the liquid fraction (28.0 g TS kg−1), without any significant difference between the two scenarios. However, the results revealed significant differences in the P recovery with ED from the raw digestate (15%) and the liquid fraction (34%), suggesting that phosphorous extraction can be improved by the application of a prior solid–liquid phase. The recovery of N with the GPM technology also enhanced the further recovery of total P with the ED processes. Furthermore, the combination of these technologies allowed for the recovery of N- and P-rich solutions, which were used to precipitate secondary struvite with an efficiency of up to 85%. This research provides a practical framework for sustainable nutrient management, advancing solutions for resource efficiency and environmental stewardship.

The Potential of Electrodialysis with Mediating Solution (EDM) for Eliminating Alkaline Scaling: Experimental Validation and Mechanistic Elucidation.

Alkaline scaling in the cathode chambers of conventional electrodialysis (ED) stacks presents significant challenges when desalinating solutions containing divalent cations. This scaling, resulting from the combined effects of water electrolysis and the migration of divalent cations from the feedwater into the catholyte, further extends from the cathode chamber to the surfaces of both the cation exchange membrane (CEM) and the anion exchange membrane (AEM) in the adjacent dilute chamber. This study aims to mitigate alkaline scaling, without pretreatment or antiscalant dosing, by optimizing the ED stack design to restrict divalent cation transport toward the cathode. We evaluated three ED stack configurations, each forming the cathode chamber with a distinct ion transport control mechanism: (1) a monovalent selective cation exchange membrane (SCEM), (2) a bipolar membrane (BPM), and (3) a mediating solution chamber adjacent to the cathode chamber (EDM). Our results indicated that stacks employing the SCEM or BPM partially restricted divalent cation migration but remained vulnerable to scaling under higher feed salinities, due to weakened Donnan exclusion within the SCEM, and strong internal ion polarization at the BPM interface. In contrast, the EDM stack exhibited superior antiscaling performance by combining strong Donnan exclusion through an AEM with ionic buffering in the mediating solution chamber, effectively blocking cation transport and eliminating conditions conducive to scaling. Additionally, the EDM stack maintained low electrical resistance and high operational stability, making it a simple, efficient, and cost-effective solution for scaling mitigation in ED systems.

Automatic Salt Removal for Drip Irrigation System Using IoT

Sustainable agriculture relies on effective irrigation management, but salt buildup in drip systems reduces efficiency and harms crops. The research introduces an automatic salt removal method using an Internet of Things (IoT)-based intelligent irrigation system. Excess salts are removed before they enter the drip lines using electrodialysis (ED) and capacitive deionization (CDI). The quality of water is measured by sensors (TDS, EC, Flow, and Pressure), while activities are regulated by an Arduino microcontroller. Monitoring and control in real-time are facilitated through a dashboard that is cloud hosted. An automatic flushing mechanism enhances durability by preventing clogging. Through the reduction of salinity by 65%, the system improved water distribution and crop health. Harvesting solar electricity enhances sustainability through reduced reliance on conventional energy. For agriculture, the process maximizes water usage, minimizes maintenance, and enhances soil condition. Key Words: Sustainable agriculture, automatic salt removal technique, electrodialysis, capacitive deionization, Arduino microcontroller.

Photo‐Electrodialysis for Brackish Water Desalination: A Life Cycle Sustainability Assessment from Experimental Insights

Enhancing the sustainability of freshwater generation through electrodialysis (ED) can be achieved by integrating this process with readily available solar energy. Photo‐ED consists of adding a photoactive coating on one of the electrodes to facilitate ion transport when exposed to light. In this study, an experimental and life cycle assessment investigation has been conducted on a conventional ED and photo‐ED system to desalinate brackish water. The energy requirements for photo‐ED and conventional ED are found to be 4.31 and 4.57 kWh m−3, respectively. Most of the life cycle impact assessment results for photo‐ED desalination are found to be lower than conventional ED at 1.47 kg CO2 eq m−3, 8.36 × 10−4 kg PM2.5 eq m−3, 0.01 m3 m−3, 5.24 × 10−6 kg P m−3, 2.69 × 10−3 kg SO2 eq m−3, and 0.37 kg 1,4 DB eq m−3 for the climate change (CC), fine particulate matter formation (FPMF), freshwater consumption (FWC), freshwater eutrophication (FWE), terrestrial acidification (TA), and terrestrial ecotoxicity (TE) impact categ, respectively. A sensitivity analysis is also conducted to observe how various electricity inputs and lifetimes of the components affect the selected environmental impacts.

Unravelling the potential of combined electrodialysis/electrocoagulation for boosted dye removal and membrane anti-fouling activity.

Membrane fouling is the major technology issue facing the wide application of electrodialysis (ED) for water purification in real world cases. The fouling of membrane in ED leads to reduce the removal rate, increase inmembrane damage, and it requires continuous costly maintenance. Herein, a successful dual process combining ED and electrocoagulation (EC) was designed to combat anionic membrane (AMX) fouling and to boost organic dye pollutant (methyl orange, (MO)) removal efficiency. Electrodialysis-electrocoagulation (ED-EC) was constructed via the use of cheap aluminum anode. In such a combined system, coagulation synergistically accumulates and eliminates MO species, and meanwhile, the separation of mineral (Na+ and Cl-) occurs by ED mechanism. A performance comparison between single ED and ED-EC demonstrates technological, economic, and efficiency benefits of combined ED-EC process as compared to single ED. The MO removal rate was improved from 20.72 to 96.92%, the electrical resistance of the ED cell (EREDC) was reduced by 40%, and the amount of Cl- ions transferred was boosted by twice. Membrane surface characterization proved that AMX membrane fouling was very intense in single ED due to MO fixation and accumulation on the membrane pores, which in turn makes the process unable to function effectively and continuously. On the contrary, ED-EC exhibits excellent mass transfer and boosted continuous removal without any observed increase in the electrical resistance of the dual cell. To further understand synergistic performance of dual ED-EC, experiments were carried out under different operating conditions including variation in current density, variation in MO concentration, and changes in pH and NaCl electrolyte dose. Highest efficiency using dual system was recorded at pH close to neutral, while the removal at alkaline or acidic solutions. The final sludge obtained after the treatment was characterized via SEM-EDS, XRD, and FTIR techniques. Overall, this study proves the correlation between ED and EC to build a dual process allowing highly efficiency and continuous processing which are the crucial factors that arewanted at real-world application.

Suitability of Electrodialysis with Monovalent Selective Anion-Exchange Membranes for Fractionation of Aqueous Mixture Containing Reactive Dye and Mineral Salt.

To fulfil the goals of the circular economy, the treatment of textile wastewater should be focused on the recovery of valuable components. Monovalent anion-selective electrodialysis (MASED) was applied for the separation of reactive dyes from mineral salts. Standard cation-exchange membranes (CM membranes) and monovalent selective anion-exchange membranes (MVA membranes) were used in the electrodialysis (ED) stack. The separation efficiency was evaluated for model solutions of various reactive dyes (varying in molecular weight and chemical reactivity) containing NaCl. In the course of MASED, the mineral salt was successfully removed from the dye solutions with an efficacy of 97.4-99.4%, irrespectively of the composition of the treated solution. The transport of dye molecules through the ion-exchange membranes (IEMs) from diluate to concentrate compartments was irrelevant. Nonetheless, a significant adsorption of dye particles on the membranes was observed. Around 11-40% of the initial dye mass was deposited in the ED stack. Dye adsorption intensity was significantly affected by dye reactivity. This study showed the potential of the MASED process for the separation of the reactive dye from the mineral salt on condition that antifouling membrane properties are improved. The obtained streams (the concentrate rich in mineral salt and the diluate containing the reactive dye) can be reused in the dye-house textile operations; however, some loss of dye mass should be included.

Using γ‐Valerolactone as a Nontoxic Solvent for Fabricating Anion‐Exchange Membrane via Nonsolvent‐Induced Phase Separation

ABSTRACTThe nonsolvent induced phase separation (NIPS) method and its variants have garnered significant attention for the fabrication of ion‐exchange membranes (IEMs) due to several potential advantages, including ease of scalability, reduced material requirements, and enhancements in operational performance. However, the hazards associated with traditional membrane fabrication solvents poses a considerable limitation to the advancement and application of NIPS. This study explores the use of a green solvent, specifically γ‐valerolactone (GVL), for the first time in the preparation of IEMs via the NIPS technique. Initially, fundamental investigations, including thermodynamic and kinetic analyses of the casting solution composed of GVL and chloromethylated polysulfone (CMPS), as well as assessments of membrane morphology and electrochemical properties, are conducted to evaluate the feasibility of IEM production in comparison to the NMP/CMPS system. Additionally, some applied experiments, such as desalination by electrodialysis (ED) and acid recovery via diffusion dialysis (DD), are performed to examine the impacts of casting solution composition on the performances of the resulting membranes. The results from the ED experiments indicate that the membrane produced from a 19 w.% GVL/CMPS solution can achieve a 27% reduction in energy consumption while maintaining a comparable current efficiency to commercial membranes. Furthermore, the DD experiments reveal that this membrane exhibits a H+ dialysis coefficient of m/h and a separation factor of 256, significantly surpassing the performance metrics of commercial membranes. These findings clearly demonstrate that GVL is a viable green solvent for the preparation of polysulfone IEMs with highly competitive performance characteristics.

The Effect of pH on Aniline Removal from Water Using Hydrophobic and Ion-Exchange Membranes

The presence of aniline, a toxic aromatic amine, has been recorded in different industrial wastewaters. This study aims to investigate the transport of charged and neutral aniline species in aqueous solutions through hydrophobic and ion-exchange membranes (IEMs). Hydrophobic polyoctylmethylsiloxane (POMS) and polydimethylsiloxane (PDMS) membranes and cationic (CEMs) and anionic (AEMs) exchange membranes were tested using diffusion cells and electrodialysis (ED). Diffusion experiments showed that neutral aniline removal reached 90% with POMS and 100% with PDMS due to the concentration gradient between feed (pH = 10) and receiving (pH = 3) solutions. For IEMs, neutral aniline exhibited a faster transport than charged species, with neutral-to-charged transport ratios of 6.6:1 for AEMs and 3.2:1 for CEMs, type I. During ED experiments, an external electric potential increased the charged aniline transport, achieving higher initial fluxes (124.7 mmol·m2·h−1 at pH 4) compared to neutral aniline (43.6 and 53.2 mmol·m2·h−1 for AEMs and CEMs, type I). ED also demonstrated that charged aniline can be removed up to 97% using IEMs. These findings demonstrate the effectiveness of hydrophobic and IEMs in removing aniline, providing insights into its transport mechanism, contributing to the optimization of membrane technologies in treating industrial wastewater effluents, and environmental sustainability.

Electrochemical Direct Lithium Extraction: A Review of Electrodialysis and Capacitive Deionization Technologies

The rapid expansion of lithium-ion battery (LIB) markets for electric vehicles and renewable energy storage has exponentially increased lithium demand, driving research into sustainable extraction methods. Traditional lithium recovery from brine using evaporation ponds is resource intensive, consuming vast amounts of water and causing severe environmental issues. In response, Direct Lithium Extraction (DLE) technologies have emerged as more efficient, eco-friendly alternatives. This review explores two promising electrochemical DLE methods: Electrodialysis (ED) and Capacitive Deionization (CDI). ED employs ion-exchange membranes (IEMs), such as cation exchange membranes, to selectively transport lithium ions from sources like brine and seawater and achieves high recovery rates. IEMs utilize chemical and structural properties to enhance the selectivity of Li+ over competing ions like Mg2+ and Na+. However, ED faces challenges such as high energy consumption, membrane fouling, and reduced efficiency in ion-rich solutions. CDI uses electrostatic forces to adsorb lithium ions onto electrodes, offering low energy consumption and adaptability to varying lithium concentrations. Advanced variants, such as Membrane Capacitive Deionization (MCDI) and Flow Capacitive Deionization (FCDI), enhance ion selectivity and enable continuous operation. MCDI incorporates IEMs to reduce co-ion interference effects, while FCDI utilizes liquid electrodes to enhance scalability and operational flexibility. Advancements in electrode materials remain crucial to enhance selectivity and efficiency. Validating these methods at the pilot scale is crucial for assessing performance, scalability, and economic feasibility under real-world conditions. Future research should focus on reducing operational costs, developing more durable and selective electrodes, and creating integrated systems to enhance overall efficiency. By addressing these challenges, DLE technologies can provide sustainable solutions for lithium resource management, minimize environmental impact, and support a low-carbon future.

Use of Membrane Techniques for Removal and Recovery of Nutrients from Liquid Fraction of Anaerobic Digestate.

This review focuses on the use of membrane techniques to recover nutrients from the liquid fraction of digestate (LFD) and emphasizes their role in promoting the principles of the circular economy. A range of membrane separation processes are examined, including microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), forward osmosis (FO), membrane distillation (MD) and new tools and techniques such as membrane contactors (MCs) with gas-permeable membranes (GPMs) and electrodialysis (ED). Key aspects that are analyzed include the nutrient concentration efficiency, integration with biological processes and strategies to mitigate challenges such as fouling, high energy requirements and scalability. In addition, innovative hybrid systems and pretreatment techniques are examined for their potential to improve the recovery rates and sustainability. The review also addresses the economic and technical barriers to the full-scale application of these technologies and identifies future research directions, such as improving the membrane materials and reducing the energy consumption. The comprehensive assessment of these processes highlights their contribution to sustainable nutrient management and bio-based fertilizer production.

Lithium Extraction by Electrodialysis: Effect of Co-Occurring Ions for Application in Brine Processing

Lithium (Li) is considered a critical material because of growing Li-ion battery demand and 90% of global production occurring in Australia, Chile, and China. Li-ion (Li+) extraction from brine uses large areas for evaporation and precipitation. Membrane separation can extract lithium with minimal water losses. However, the effect of brine composition on Li+ transport across different commercial membranes in electrodialysis (ED) separations remains a pressing knowledge gap. This study aimed to evaluate co-occurring ion effects (Na+, Mg2+, Ca2+) on ED Li+ extraction using different commercial membranes. Li+ extraction performance was evaluated for varying current densities in binary solutions using a single-stack ED cell comprised of a standard anion exchange membrane and either a standard cation exchange (CEM), monovalent-selective CEM, or nanofiltration (NF) membrane. Li+ selectivities were highest for the monovalent-selective CEM, followed by NF and then standard CEM. Monovalent contaminants remain an extant challenge for Li+ extraction using all membranes tested. Selectivity factors for Li+ over divalent cations reached 6.8 (SLi/Mg) and 56.7 (SLi/Ca) at 2.8 mA cm−2 for the monovalent-selective CEM. These divalent separation factors were achieved without Ca precipitation/fouling; Li+/Mg2+ and Li+/Ca2+ ratios increased from 0.5 in the feed (for both ions) to 5.0 and 3.5 in the permeate.