Application Of Electrodialysis Research Articles

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.

Scaling behavior of cation exchange membrane induced by Ca2+ during the electrodialysis for enriching lithium-containing solutions

Membrane fouling, particularly Ca2+-induced scaling on cation exchange membranes (CEM), hinders the application of electrodialysis in lithium extraction. This study investigated the fouling mechanisms of Ca2+ coexisting with Cl− and SO42− on sulfonated CEM, using CaCl2 and CaSO4 solution as the targeted foulants. The conductivity, pH, turbidity, particle size distribution, chemical composition and morphology of the membrane surface were monitored to verify the evolution of the bulk solution and the membrane during the Ca2+-induced fouling. Online detection of conductivity and pH revealed distinct trends in fouling solutions containing Ca2+-Cl- and Ca2+-SO42-. Noticeable changes in turbidity and particle distribution were observed in the concentrated chamber of the highly saturated Ca2+-SO42- solution, whereas the concentrated chamber of the Ca2+-Cl- solution showed turbidity and particle size distribution similar to the initial values. SEM showed that there are different morphologies of scaling crystals in the two types of solution. These fundamental differences are the root cause of the distinct fouling mechanisms between the Ca2+-Cl- solution and Ca2+-SO42- solution. To further investigate the fouling mechanisms, the electrochemical impedance spectroscopy (EIS) was employed to differentiate the impedance of the electric double layer and diffusion layer, providing insights into the characteristics of the CEM-solution interfaces fouled by different lithium-containing solutions. Additionally, adsorption experiments, quartz crystal microbalance with dissipation (QCM-D) and computational simulations (COMSOL, DFT) were conducted to provide detailed insights into the effects of fouling solutions on the properties of the desalted solution, the probability of crystal precipitation, and particularly the interaction between Ca2+ and the functional sites on the CEM. Finally, the Ca2+-induced scaling mechanism of CEM for enriching the lithium-containing solutions with and without SO42− was proposed, elucidating the synergistic effects of Ca2+-induced crystallization in the bulk solution and Ca2+ adsorption on the CEM surface. The research results could offer theoretical guidance for developing pollution control strategies.

Application of Electrodialysis to Production of High-Purity Perrhenic Acid

Application of Electrodialysis to Production of High-Purity Perrhenic Acid

Utilizing Advanced Bipolar Membranes in Next Generation Electrodialysis Systems

Bipolar membranes (BPMs) have experienced a renaissance, owing to their proposed use in membrane electrode assembly (MEA) systems. MEA systems encompass technologies such as fuel cells and electrolyzers, where the BPM allows for fine pH control at the electrodes and helps to prevent ion-crossover that may lead to lower system efficiencies and fouling of the system. The exploration of MEA systems has significantly expanded our fundamental understanding of BPM functionality and limits, setting the stage for future advancements in BPM applications.Beyond MEA systems, BPMs have been seen in a wide array of technologies such as CO2 sequestration systems, electrodialysis, brine remediation, organic acid/base production, and more. These applications all present unique stressor to the BPM that prevent the direct translation of advanced, MEA optimized BPM to these non-MEA systems. Initial investigations into transferring advanced BPM to non-MEA applications have found issues with membrane delamination at scale and a need for system specific catalyst optimization. However, the fundamentals learned from MEA systems translate well and can be used to inform advancements of BPM in these non-MEA systems. Here we present initial findings and proposed solutions for durability issues when optimizing advanced BPM for application in BPM electrodialysis.

Class II (three-layer system) phenomenological model based on limiting current density and dynamic chelation chemistry for separation of rare earth elements using electrodialysis

This paper presents an in-depth investigation into the optimization of rare earth element (REE) separation through electrodialysis, leveraging a newly developed Class II phenomenological model. This study explores the pivotal roles of the HEDTA/Nd molar ratio and pH of feed solution on enhancing the separation efficiency of neodymium (Nd) and praseodymium (Pr) from lanthanum (La) and cerium (Ce). By integrating expanded Nernst-Planck equations and the concept of limiting current density, the model offers a sophisticated understanding of ion transport dynamics and the impacts of concentration polarization. Experimental validation confirms the model’s predictive accuracy, demonstrating its practical applicability for industrial-scale operations. The research delineates how operational parameters such as chelating agent concentration and pH critically influence the purity and yield of separated REEs. The dynamic nature of chelation chemistry is also examined, highlighting its evolution during the electrodialysis process and its effect on the system’s overall performance. Key findings illustrate that lower HEDTA/Nd molar ratios significantly enhance the purity of Nd + Pr by minimizing the chelation of La and Ce, thus facilitating their migration to the concentrate compartment. Conversely, higher ratios maximize yield by retaining more Nd + Pr in the feed compartment. This dual approach allows for optimized separation based on specific industrial requirements. The outcomes of this study not only advance the field of REE separation but also provide a framework for further research into more efficient and sustainable extraction methods. The developed model and its validation represent a step forward in the practical application of electrodialysis in REE processing, offering substantial benefits for the critical materials sector.

Towards Sustainable Lithium-Ion Battery Recycling: Advancements in Circular Hydrometallurgy

The growing demand for lithium-ion batteries (LIBs) has led to significant environmental and resource challenges, such as the toxicity of LIBs’ waste, which pose severe environmental and health risks, and the criticality of some of their components. Efficient recycling processes are essential to mitigate these issues, promoting the recovery of valuable materials and reducing environmental pollution. This review explores the application of electrodialysis in the process of recycling LIBs to contribute to the principles of circular hydrometallurgy. The article is structured to provide a comprehensive understanding of the topic, starting with an overview of the environmental and resource challenges associated with manufacturing LIBs. Then the current recycling processes are presented, focusing on hydrometallurgical methods. The concept of circular hydrometallurgy is introduced, emphasizing sustainable resource recovery. The electrodialysis technique is described in this context, highlighting its integration into the process of recycling LIBs to separate and recover valuable metals. Finally, the article addresses the challenges and limitations of the electrodialysis technique, such as energy consumption and system optimization, and identifies areas for future research and development. Through this analysis, the review aimed to contribute to advancing the development of more sustainable and efficient LIB recycling technologies, ensuring a safer and more environmentally friendly approach to the management of batteries’ lifecycle.

Materials descriptors for advanced water dissociation catalysts in bipolar membranes.

The voltage penalty driving water dissociation (WD) at high current density is a major obstacle in the commercialization of bipolar membrane (BPM) technology for energy devices. Here we show that three materials descriptors, that is, electrical conductivity, microscopic surface area and (nominal) surface-hydroxyl coverage, effectively control the kinetics of WD in BPMs. Using these descriptors and optimizing mass loading, we design new earth-abundant WD catalysts based on nanoparticle SnO2 synthesized at low temperature with high conductivity and hydroxyl coverage. These catalysts exhibit exceptional performance in a BPM electrolyser with low WD overvoltage (ηwd) of 100 ± 20 mV at 1.0 A cm-2. The new catalyst works equivalently well with hydrocarbon proton-exchange layers as it does with fluorocarbon-based Nafion, thus providing pathways to commercializing advanced BPMs for a broad array of electrolysis, fuel-cell and electrodialysis applications.

Improving ammonia nitrogen removal and recovery by BMED stack optimization: The effect of ion exchange membrane thickness

Bipolar membrane electrodialysis (BMED) has emerged as an efficient and promising technology for the removal and recovery of ammonia nitrogen. Despite its potential, the optimization of BMED systems for enhanced performance and energy efficiency remains a critical challenge, particularly in the context of varying ion exchange membrane (IEM) thicknesses. Membranes with a thickness of < 80 µm have low resistance and are mainly used for processes requiring low energy consumption. Membranes with a thickness of 80–250 µm have moderate resistance and high ion selectivity and are widely used for electrodialysis applications. Membranes with a thickness of > 250 µm have higher ion selectivity than commercial membranes with a thickness of 80–250 µm and are suitable for processes that demand high purity. This study investigates the effect of IEM thickness ranging from 16–400 µm on BMED performance for ammonia nitrogen removal and recovery, and energy consumption. The BMED configuration comprising five cell triplets consisting of a cation exchange membrane, bipolar membrane, and anion exchange membrane was employed. The thickness of IEMs was divided into three categories: 16–17 µm (PCEM/ PAEM), 100–150 µm (CD100/AD100, InnoSep-C/InnoSep-A), and 380–400 µm (MC-3470/MA-3475). In membranes with a thickness of 100–150 µm, the ammonia nitrogen removal was exceptionally high at 99.2 %, with a recovery of 98.7 % (CD100/AD100: 100 µm) at a current density of 80 mA/cm2, and the system exhibited low specific energy consumption (SEC) of 8.87 kWh/kg-N (InnoSep-C/InnoSep-A: 150 µm) at a current density of 20 mA/cm2. However, when using the thinnest IEMs (PCEM: 16 µm, PAEM: 17 µm), an increase in total ammonia nitrogen loss (10.21–22.01 %) led to a reduction in ammonia nitrogen recovery. Conversely, when using the thickest IEMs (MC-3470: 380 µm, MA-3475: 400 µm), the SEC was extremely high (30.98–126.67 kWh/kg-N), making them unsuitable for the BMED process for ammonia nitrogen removal and recovery. Based on these experimental results, it is suggested to use an optimal thickness of IEM within the range of 80–250 µm in the BMED systems to achieve a balanced performance, maximizing ammonia nitrogen removal and recovery while minimizing the SEC. Consequently, the present study provides a comprehensive understanding of the effects of the IEM thicknesses on the BMED systems and could offer a practical perspective for optimizing the BMED stack with respect to improving the removal and recovery rate of ammonia nitrogen and reducing the energy consumption.

Application of bipolar membrane electrodialysis for acidification of skim milk. A comprehensive study on process performance and effects on ion-exchange membranes

Bipolar membrane electrodialysis (EDBM) can be applied for the electro-acidification of skim milk (SM) using a water-splitting effect. A new method of SM acidification gives opportunities and perspectives to the development of alternative and novel products in the dairy industry. The present study assessed the effect of temperatures from 5 °C to 30 °C of EDBM on the electro-acidification of SM in terms of the mineral composition of the side streams. The mechanisms of ion transport during electro-acidification by bipolar membranes (BMs) coupled with cation-exchange membranes (CMs) were investigated. The results showed that the pH of the SM was decreased by ∼14.3% through the proton ions generated due to a water-splitting reaction in the bipolar interface region. Since the BMs and CMs are suspected to change their properties at different temperatures in the high protein solution, their properties and characteristics were investigated. The EDBM performance parameters were calculated. Furthermore, performance efficiency coefficients of the EDBM process as mass flux (J), capacity (CF), specific energy consumption (E) and the current efficiency (η) were calculated.

Bifunctional Crosslinker Enables Antifouling PVA-Based Anion Exchange Membranes with Enhanced Dimensional Stability for Electrodialysis Applications

Bifunctional Crosslinker Enables Antifouling PVA-Based Anion Exchange Membranes with Enhanced Dimensional Stability for Electrodialysis Applications

Electrodialysis for Removal of Impurities in Silver Electrowinning

In this work, we investigate the potential of electrodialysis to separate copper from silver electrowinning solution. We further explore and discuss optimization of the electrodialysis process design.Ag is in a high global demand, driven mainly by its use in electronics, jewelry and as investment. The recycling potential for Ag is large and will increase in the coming years due to Ag usage in solar panels. One route of recycling Ag from End-of-life products is batch-electrowinning. In preparation, the products are melted and reshaped into scrape plates which are anodically dissolved in nitric acid solution. Typically, silver is found in alloys with less noble metals like copper, zinc, and iron. While silver is deposited on the stainless-steel cathode surface, the impurities accumulate in the electrolyte. To maintain a high purity of the recycled silver, the contaminated nitric acid solution must be replaced regularly. We investigate the potential of implementing a continues electrodialysis stage parallel to the electrowinning bath to remove copper and other divalent cations from the solution.In electrodialysis, anion- and cations-exchange membranes are stacked alternatingly between two electrodes. When a current is drawn, the cations move towards the cathode, passing the cation-exchange membrane and vice versa for the anions. Since the membranes are selective for either anions or cations, they strongly retard the passage of the opposite ion. Therefore, cations and anions are accumulated in every second compartment, while every other chamber is desalinated. By using monovalent-selective ion-exchange membranes, separation between monovalent (f. ex., Ag+) and multivalent ions (f. ex., Cu2+, Zn2+, Fe2+, Fe3+) can be achieved [1].If the concentration of impurities can be held at a constant level, the nitric acid solution can be recycled continuously rather than replaced as a batch. The only consumable required by the process is electricity. We evaluate the viability of the process and investigate the influence of pH on the process efficiency.We determined the optimal operating current for separating Cu2+ from Ag+ in an equimolar concentration of 10 mM by doing amperodynamic sweeps and recording current-voltage curves. We then tested the desalination performance of an electrodialysis stack with different commercially available anion-/cation-exchange membrane pairs. The single membrane area was 36 cm2, and 9 membranes were used in total (five anion-exchange membranes and four monovalent-selective cation-exchange membranes). The Cu2+ and Ag+ concentrations in the diluate and concentrate compartments were determined by atomic mass spectrometry, and the membranes were analyzed with scanning electrode microscopy to detect adsorbed silver. Since scaling and fouling are dominant drawbacks in industrial applications of electrodialysis, we studied the influence of pH on the adsorption of silver in the membrane.Commercial monovalent-selective cation-exchange membranes by Neosepta showed high selectivity for silver over copper. The limiting current density was 10.4 A/m2 for neutral 10 mM AgNO3 solution at a flow rate of 100 mL/min and increased by almost 10 times when we adjusted the pH to 1 using nitric acid. In neutral solution, silver was recovered to almost 100 % after two hours of electrodialysis at 10 mA, while copper leakage was 7.5 %. At pH 1, silver recovery and copper leakage were 83 % and 9 %, respectively, after two hours electrodialysis at 100 mA. Consequently, the percentage silver adsorbed in the membranes were close to 0 % in neutral solution and 17 % at pH 1. The work input was significantly higher at pH 1 due to electric current consumed by mass transport of protons. As a next step, we investigate the long-term effect on the membranes with regards to Ag and Cu adsorption, which could be stabilizing at a certain concentration of Ag and Cu or increasing over time.We conclude that electrodialysis is a promising technology for removal of impurities in Ag electrowinning from End-of-life products, justifying large room for future research on development of membranes and operational design.[1] Zimmermann, P., Tekinalp, Ö., Deng, L., Forsberg, K., Wilhelmsen, Ø., Burheim, O. (2020). Electrodialysis in Hydrometallurgical Processes. In: Azimi, G., Forsberg, K., Ouchi, T., Kim, H., Alam, S., Baba, A. (eds) Rare Metal Technology 2020. The Minerals, Metals & Materials Series. Springer, Cham.

Polyaniline encapsulated sulphonated graphene oxide based cation exchange membrane for electrodialytic separation of mono- and bi-valent ions

Polyaniline encapsulated sulphonated graphene oxide (SGO-PANI) was prepared by ion exchange process. The SGO-PANI was incorporated in sulphonated poly(ether ether ketone) (SPEEK) matrix to fabricate the mono-valent selective cation exchange membrane. The structural morphology of SGO-PANI was studied by FTIR, XPS, SEM and XRD spectra. Resultant SPEEK@SGO-PANI membrane exhibited excellent stabilities and physicochemical and electrochemical properties suitable for electrodialysis (ED) applications. Encapsulation of strong acid with a weak base seems to improve electrostatic repulsion between membrane surfaces and of bi-valent ions, which are responsible for significant flux reduction. Chronopotentiometric and current–voltage responses of SPEEK@SGO-PANI membrane confirmed its ion-conducting nature along with 3.32 mA cm−2 limiting current density (Ilim). Reported SPEEK@SGO-PANI membrane showed a high electrodialytic flux of Na+ compared to bi-valent ions (Mg2+, Ca2+, and Cd2+). Extremely low energy consumption and high current efficiency (81.18%) at 6.0 V applied voltage for Na+ (0.10 M) revealed the promising nature of the reported membrane. Observed mono-valent ion selectivity aroused due to improved electrostatic repulsion of bi-valent ions with the membrane surface.

On the interaction of electroconvection at a membrane interface with the bulk flow in a spacer-filled feed channel

The operational range of electro-driven processes can be extended by (i) reducing diffusion resistances at the membrane/electrolyte interface using spacers and (ii) by electroconvective mixing of the boundary layer at overlimiting current densities. Although many studies have addressed each of these phenomena separately, the details of the interplay of spacer-engineered hydrodynamics and electroconvection are unexplored. In this study, we establish a methodology of a new membrane cell design and the use of a high-speed microparticle tracking velocimetry setup for direct observation and quantification of the 3D velocity field in a spacer-filled electrodialysis channel under process conditions relevant for real electrodialysis applications, i.e., overlimiting currents and elevated Reynolds. We unravel details of the superposition of electroconvective vortices and forced flow velocity with and without an inserted spacer. Overall, the forced flow flattens the vortex structure of electroconvection at increasing Reynolds numbers. In terms of vortex heights, a spacer with intentional dead zones outperforms a commercial spacer that decreases the boundary layer thickness. This study suggests a counter-intuitive spacer design: to exploit electroconvection, an engineered spacer design for maximum use of electroconvection in the far overlimiting region should aim to create intentional regions of low flow velocity.

Preparation of High-Performance Semihomogeneous Cation Exchange Membranes for Electrodialysis via Solvent-Free Polyethylene Particle-Confined Monomer Polymerization

The inherent two-phase structure of heterogeneous ion exchange membranes leads to defects in high area resistance and powder, which has greatly limited the application in electrodialysis. In this research, we have prepared a series of semihomogeneous cation exchange membranes from polyethylene-polystyrene (PE–PS) resin particles, which were synthesized via monomer absorption and PE particle-confined polymerization. The processing of semihomogeneous cation exchange membranes was conducted via thermoforming the PE–PS resin particles into films and subsequent sulfonation. The influence of the monomer content on water uptake, IEC, membrane area resistance, and electrodialysis performance was studied. The results proved that due to the excellent mechanical and film-forming characteristics of PE, the sulfonated membranes were still endowed with great mechanical properties, and the heating conditions enhanced the monomer absorption in polyethylene particles, which ensured high IEC for excellent electrodialysis performance after sulfonation. It was observed that the semihomogeneous cation exchange membrane (CEM-60) showed the highest NaCl desalination ratio (92.3%) and exhibited higher current efficiency (97.68%) and lowest surface area resistance (1.82 Ω·cm2), which exceeded the commercial cation exchange membrane CAM (6.96 Ω·cm2). These results suggested a promising future of semihomogeneous membranes.

Interplay between Forced Convection and Electroconvection during the Overlimiting Ion Transport through Anion-Exchange Membranes: A Fourier Transform Analysis of Membrane Voltage Drops

Electrodialysis (ED) applications have expanded in recent years and new modes of operation are being investigated. Operation at overlimiting currents involves the phenomenon of electroconvection, which is associated with the generation of vortices. These vortices accelerate the process of solution mixing, making it possible to increase the transport of ions across the membranes. In this work, frequency analysis is applied to investigate the interaction between different parameters on the development of electroconvection near anion-exchange membranes, which would provide a basis for the development of ED systems with favored electroconvection. Chronopotentiometric curves are registered and Fast Fourier Transform analysis is carried out to study the amplitude of the transmembrane voltage oscillations. Diverse behaviors are detected as a function of the level of forced convection and current density. The synergistic combination of forced convection and overlimiting currents leads to an increase in the signal amplitude, which is especially noticeable at frequencies around 0.1 Hz. Fast Fourier Transform analysis allows identifying, for a given system, the conditions that lead to a transition between stable and chaotic electroconvection modes.

Progress on membrane technology for separating bioactive peptides

Bioactive peptide (BP) is short sequence of amino acids, which can play different biological activities depending on its structural characteristics and amino acid sequence. As health promoters, bioactive peptides (BPs) have attracted more and more attention in recent years. Separation and purification methods of BPs such as pressure-driven and electrically-driven membrane processes were reviewed in this paper. Especially, cell configuration and application of electrodialysis with filtration membrane (EDFM), a new emerging electro-driven membrane technology, in separating anionic and cationic BPs were introduced in detail. It is difficult to separate and purify BPs due to their excellent water solubility as well as uncertain composition and structure. Thus, further development in efficient and economical technologies for the separation and purification of BPs is urgent to improve human health. • Multistage UF process can be used to obtain BPs with high purity and activity. • EDFM is a prospective technology due to its good flexibility and selectivity. • EDFM has potential to large-scale separation of BPs in the future.

Combined Electrodialysis and Electrocoagulation as Treatment for Industrial Wastewater Containing Arsenic and Copper.

In copper smelting processes, acidic effluents are generated that contain inorganic contaminants such as arsenic and copper. Nowadays, the treatment of wastewater is done by physicochemical methods without copper recovery. Electrodialysis is an alternative process that can recover copper. Moreover, when electrocoagulation is applied to remove arsenic from wastewater, a more stable final sludge of less volume is obtained. The present research studies the application of a combined electrodialysis and electrocoagulation process to (1) recover Cu and (2) precipitate and remove arsenic simultaneously in the same batch reactor, using synthetic wastewater that simulates wastewater from a copper smelter. Copper and arsenic could be removed and separated by the electrodialysis part, and the electrocoagulation of arsenic was verified. With electrodialysis, the arsenic and copper removals were 67% and 100%, respectively, while 82% of the arsenic arriving at the electrocoagulation part of the cell could be precipitated and removed by this process. Initial concentrations were around 815 mg L-1 Cu and 7700 mg L-1 As. The optimal current was found to be 1.36 A due to the shorter treatment times necessary to get removal percentages, recovery percentages and energy/removed copper mass ratios in the same ranges as the values achieved with a current of 1.02 A. In summary, the combined process is a promising tool for simultaneous copper recovery and arsenic removal.

Chromium-Modified Heterogeneous Bipolar Membrane: Structure, Characteristics, and Practical Application in Electrodialysis.

The modification of an MB-2 bipolar ion exchange membrane with chromium (III) hydroxide was carried out by a chemical method, namely, by the sequential treatment of the membrane with a solution of chromium (III) salt and alkali. Data on the morphology, phase, and chemical composition of the modified membrane were obtained using scanning electron microscopy and energy-dispersive analysis. In particular, it was shown that the modifier was distributed in a layer 30-50 microns thick at the boundary of the cation- and anion-exchange layers of the bipolar membrane. The electrochemical behavior of the modified membrane in the process of sodium sulfate conversion was studied by measurements of the following characteristics: the current efficiency of the acid and base, the energy consumption of the process, and the degree of contamination of the target products with salt ions. It was shown that the resulting membrane has an alkali and acid yield of 61% and 57%, respectively. This is higher than the same yields for the industrial unmodified MB-2 membrane (38% and 30%). The results of this study demonstrated that the modified samples allowed obtaining a higher yield of acid and base, reducing the content of salt ions in the target products and also reducing the electricity consumption for obtaining a unit of the target product. The concentration dependences of the electrical conductivity of the MK-40 heterogeneous ion-exchange membrane, which is a cation-exchange layer of MB-2, in sodium sulfate solutions before and after its modification with chromium (III) oxide were obtained. A decrease in the specific electrical conductivity of the membrane with the introduction of a modifier was established. A quantitative assessment of the influence of the modifier on the current flow, volume fraction, and spatial orientation of the conductive phases of MK-40 was carried out using an extended three-wire model for the description of the model parameters of ion-exchange materials. When a modifying additive was introduced into MK-40, the fraction of the current passing through the inner solution and the intergel phase decreased. This was due to the substitution of part of the free solution in the pore volume by the modifier. A variant of the practical application of electrodialysis with the chromium-modified bipolar ion-exchange membranes is recommended.

Potential application of hybrid reverse electrodialysis (RED)-forward osmosis (FO) system to fertilizer-producing industrial plant for efficient water reuse

This study presents an experimental investigation and a parametric analysis of the applicability of agricultural fertigation and power generation using a reverse electrodialysis-forward osmosis (RED-FO) hybrid system, with a water stream discharged from a fertilizer-producing plant. The results of this study demonstrated the possibility of achieving high salinity power generation from the RED system utilizing high-salinity brine and low-salinity ammonia solution that simulates reverse osmosis (RO) brine and wastewater streams released by the fertilizer-producing industry. The feasibility of stream dilution for fertigation application is demonstrated when the resulting moderately saline RED effluent is introduced into the FO process as a draw solution. The effect of external load addition, flow velocities variation, and concentration changes of the working solutions on the overall stack internal resistance and, thereby, RED performance was evaluated. As such, the lowest internal resistance converged to a threshold value of 4.03 Ω, giving the highest gross power density of 2.17 W/m2 when a flow velocity of 1.18 cm/s, 10 Ω external load, and 0.015 M (NH4)2SO4/1 M NaCl solution pair were utilized. In addition, the effect of the number of ion exchange membrane pairs and wastewater stream recycling was studied and optimized to amplify the osmotically generated power. As a result, the most consistent power generation was achieved when using 20 pairs of membrane cells in a single-pass flow mode operation. The applicability of the RED effluent to a subsequent FO system as a draw solution (DS) was investigated, showing a dilution rate (17 %) and a conductivity (1–2 mS/cm of DS) suitable for agricultural fertigation applications.

Comparison of the Electrodialysis Performance in Tartrate Stabilization of a Red Wine Using Aliphatic and Aromatic Commercial and Modified Ion-Exchange Membranes.

The application of electrodialysis for tartrate stabilization and reagent-free acidity correction of wine and juices is attracting increasing interest. New aliphatic membranes CJMC-3 and CJMA-3 and aromatic membranes CSE and ASE were tested to determine their suitability for use in these electrodialysis processes and to evaluate the fouling of these membranes by wine components for a short (6-8 h) operating time. Using IR spectroscopy, optical indication and measurement of surface contact angles, the chemical composition of the studied membranes, as well as some details about their fouling by wine components, was clarified. The current-voltage charsacteristics, conductivity and water-splitting capacity of the membranes before and after electrodialysis were analyzed. We found that in the case of cation-exchange membranes, complexes of anthocyanins with metal ions penetrate into the bulk (CJMC-3) or are localized on the surface (CSE), depending on the degree of crosslinking of the polymer matrix. Adsorption of wine components by the surface of anion-exchange membranes CJMA-3 and ASE causes an increase in water splitting. Despite fouling under identical conditions of electrodialysis, membrane pair CJMC-3 and CJMA-3 provided 18 ± 1 tartrate recovery with 31 · 10-3 energy consumption, whereas CSE and ASE provided 20 ± 1% tartrate recovery with an energy consumption of 28 · 10-3 Wh, in addition to reducing the conductivity of wine by 20 ± 1%. The casting of aliphatic polyelectrolyte films on the surface of aromatic membranes reduces fouling with a relatively small increase in energy consumption and approximately the same degree of tartrate recovery compared to pristine CSE and ASE.