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![Basic cell architecture of multichannel membrane CDI (MC-MCDI) using channels and ion exchange membranes: (A) Conceptual scheme, (B) frame components, and (C) exploded view of cell assembly (Reprinted with permission from Reference [32]).](publication/338697339/figure/fig2/AS:859992915705856@1582049697561/Basic-cell-architecture-of-multichannel-membrane-CDI-MC-MCDI-using-channels-and-ion.png)
Basic cell architecture of multichannel membrane CDI (MC-MCDI) using channels and ion exchange membranes: (A) Conceptual scheme, (B) frame components, and (C) exploded view of cell assembly (Reprinted with permission from Reference [32]).
Source publication
Capacitive deionization (CDI) has gained a lot of attention as a promising water desalination technology. Among several CDI architectures, multichannel membrane CDI (MC-MCDI) has recently emerged as one of the most innovative systems to enhance the ion removal capacity. The principal feature of MC-MCDI is the independently controllable electrode ch...
Contexts in source publication
Context 1
... overcome the limitations of static-and flow-electrode CDI, a unique cell architecture, known as MC-MCDI, has recently been designed ( Figure 5). The MC-MCDI cell consists of the middle and the side channels as the feed and electrode channels, respectively. ...
Context 2
... MC-MCDI cell consists of the middle and the side channels as the feed and electrode channels, respectively. The two channels were separated by a pair of anion and cation exchange membranes (AEM and CEM) ( Figure 5A). In the side channels, porous carbon electrodes are attached to current collectors made of titanium mesh. ...
Context 3
... the side channels, porous carbon electrodes are attached to current collectors made of titanium mesh. The side of the current collector is coated with rubber to press on the ion exchange membrane and seal the middle and the side channels ( Figure 5B,C). As such, both the feed stream and electrolyte can be independently controlled, providing a favorable environment for the formation of the EDL. ...
Context 4
... Enhanced desalination performance MC-MCDI involves an advantageous configuration of the membrane CDI ( Figure 5A). For example, the major benefits of membrane CDI are the enhancement of charge efficiency and salt removal capacity because the added membranes block co-ion repulsion, which causes the undesirable current during the charging step. ...
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A capacitive deionization cell designed with symmetric activated carbon electrodes was demonstrated to be able to successfully reduce wastewater Pb²⁺concentrations to below the 5 ppm statuary limited for discharge into public sewers. The investigation found that the removal efficiency shows a maximum of 98% with an initial Pb²⁺concentration of 100...
Citations
... CDI systems can store energy while simultaneously desalinating water during charging. However, CDI is limited by the relatively narrow range of cell voltage in aqueous media, which restricts the ion removal capacity due to the limited choices of suitable electrodes [69]. ...
Freshwater scarcity and water pollution pose significant global challenges, greatly impacting human well‐being. To address these issues, water quality monitoring plays a crucial role as a preventive measure in various water security initiatives worldwide. However, many traditional testing methods suffer from drawbacks such as low accuracy, limited mobility, and high operational costs. Fortunately, the emergence of microfluidic technology offers a promising avenue for the development of highly sensitive, portable, and cost‐effective water quality monitoring devices. In this study, a comprehensive review of recent advancements in microfluidic technology for water quality monitoring, water desalination, and water purification is provided. The potential for future developments in this field is highlighted, empowering researchers to create innovative water monitoring kits and optimize existing techniques. By harnessing the capabilities of microfluidics, the accuracy, portability, and affordability of water quality monitoring can be enhanced, ultimately addressing the global water challenges we face.
... Electrostatic forces facilitate the attraction or repulsion of ions, aiding in their separation. The application of an electric potential across the membrane allows for the selective transport of ions, thus contributing to the removal of charged contaminants [12]. ...
... The desalination performance of CDI-based technologies is inextricably linked to the operating circumstances of the device, including the operation mode (current or voltage constant mode), flow rate, and composition of the feed stream, in addition to the cell characteristics [79]. Because of this, the performance of these technologies has been represented in a variety of various ways, such as removal efficiency and rate and salt adsorption capacity, as well as charge efficiency and energy consumption (Equations (8)-(13)) [80][81][82]. The salt removal efficiency, often known as SRE, is denoted by the formula of Equation (6) [80][81][82][83]. ...
... Because of this, the performance of these technologies has been represented in a variety of various ways, such as removal efficiency and rate and salt adsorption capacity, as well as charge efficiency and energy consumption (Equations (8)-(13)) [80][81][82]. The salt removal efficiency, often known as SRE, is denoted by the formula of Equation (6) [80][81][82][83]. The salt removal efficiency, often known as SRE [84], is defined as follows: where C o and C F are the starting and final feed water salt concentrations in mg/L. ...
... The number of ions that were eliminated may be calculated by comparing the levels of conductivity at the beginning and the end of the process. While batch mode has the benefit of it being easier to operate and analyse the data, a single pass is more reflective of industrial MCDI due to the fact that the feed is not continually recycled, and the effluent is collected [81]. ...
Another technique for desalination, known as membrane capacitive deionization (MCDI), has been investigated as an alternative. This approach has the potential to lower the voltage that is required, in addition to improving the ability to renew the electrodes. In this study, the desalination effectiveness of capacitive deionization (CDI) was compared to that of MCDI, employing newly produced cellulose acetate ion exchange membranes (IEMs), which were utilized for the very first time in MCDI. As expected, the salt adsorption and charge efficiency of MCDI were shown to be higher than those of CDI. Despite this, the unique electrosorption behavior of the former reveals that ion transport via the IEMs is a crucial rate-controlling step in the desalination process. We monitored the concentration of salt in the CDI and MCDI effluent streams, but we also evaluated the pH of the effluent stream in each of these systems and investigated the factors that may have caused these shifts. The significant change in pH that takes place during one adsorption and desorption cycle in CDI (pH range: 2.3–11.6) may cause problems in feed water that already contains components that are prone to scaling. In the case of MCDI, the fall in pH was only slightly more noticeable. Based on these findings, it appears that CDI and MCDI are promising new desalination techniques that has the potential to be more ecologically friendly and efficient than conventional methods of desalination. MCDI has some advantages over CDI in its higher salt removal efficiency, faster regeneration, and longer lifetime, but it is also more expensive and complex. The best choice for a particular application will depend on the specific requirements.
... Jeyong Yoon is the leader of the Water Environment and Energy Lab of SNU (South Korea), who has been actively working on electrochemical technologies for environmental applications developing a very fruitful career. As commented before, he has extensively collaborated with Lee J. in electrochemical ion separation (EIONS) technologies and has participated on 6 review papers about the use of capacitive and charge-transfer materials for electrochemical water treatments [76,102,[214][215][216][217]. In the case of Choonsoo Kim, he is the head of the Environmental Electrochemistry Lab in Kongju National University (South Korea) and has also been involved in a research collaboration with Yoon J. and Lee J. Kim, C. has also made significant contributions to the field, specially using the multichannel deionization system [216,[218][219][220]. ...
... As commented before, he has extensively collaborated with Lee J. in electrochemical ion separation (EIONS) technologies and has participated on 6 review papers about the use of capacitive and charge-transfer materials for electrochemical water treatments [76,102,[214][215][216][217]. In the case of Choonsoo Kim, he is the head of the Environmental Electrochemistry Lab in Kongju National University (South Korea) and has also been involved in a research collaboration with Yoon J. and Lee J. Kim, C. has also made significant contributions to the field, specially using the multichannel deionization system [216,[218][219][220]. The multichannel desalination battery (MC-DB) introduced the idea of using a highly concentrated solution between the electrodes and the brackish water to be treated, just separated by ion exchange membranes. ...
... In past years, only a few review papers on the MCDI process (Hassanvand et al. 2017;Folaranmi et al. 2020;Kim et al. 2020b;Ali et al. 2021;Pawlowski 2020;Yang et al. 2020) are available (schematically shown in Fig. 3). The objective of this present review is to summarize the current progress of the MCDI system on desalination and water treatment. ...
The increasing scarcity of fresh water due to rapid population growth and the establishment of new industries every single day has motivated researchers to use efficient technologies for the removal of dissolved salts from water. Various methods of salt removal and wastewater treatment have been established in last decades; however, membrane capacitive deionization has gained much attention due to its low energy consumption and low process costs in water treatment applications. The progress of membrane capacitive deionization for desalination and water treatments is systematically presented in this review. This review includes significant input on the membrane capacitive deionization progress, the current status of membrane capacitive deionization in the removal of salts and different pollutants, and a comparative discussion on various membranes and electrodes used in membrane capacitive deionization reported so far. It also highlights a summary and future scope in the area of membrane capacitive deionization. Based on the literature available and a review of the membrane capacitive deionization process, it could be a more effective and promising process for desalination and water purification.
Graphical abstract
... 819 As a result, the deionization system exhibited an increase of 131% in the average rate of salt removal compared to the same system in the absence of H 2 Q. 819 Kim et al. used redox species as an additional means for salt removal in the multichannel redox system (see Figure 25d). 939 In this system, the redox reaction between Fe(CN 6 ) 3− and Fe(CN 6 ) 4− further remove ions from the feed to maintain bulk electroneutrality in the electrolyte, 936 and the redox species are continuously regenerated as the redox couple circulates the electrodes. Overall, the desalination performance of this system (with a capacity of 67.8 mg g −1 ) was improved by more than a factor of three compared to the same system in the absence of the redox species (with a capacity of 20.0 mg g −1 ). ...
... 795 For example, Nordstrand et al. recently designed a parallel arrangement of cells with symmetrically distributed flows to maintain a low pressure drop across the system. 648 Another challenge during scale up of CDI is to make the process continuous, which has been the focus of FCDI 8 0 9 , 8 2 5 , 8 2 6 , 1 2 2 5 and multichannel MCDI 936,955,1226,1227 systems. The latter enables continuous production of both fresh and brine streams by periodically switching the products of the middle and side channels. ...
Agricultural development, extensive industrialization, and rapid growth of the global population have inadvertently been accompanied by environmental pollution. Water pollution is exacerbated by the decreasing ability of traditional treatment methods to comply with tightening environmental standards. This review provides a comprehensive description of the principles and applications of electrochemical methods for water purification, ion separations, and energy conversion. Electrochemical methods have attractive features such as compact size, chemical selectivity, broad applicability, and reduced generation of secondary waste. Perhaps the greatest advantage of electrochemical methods, however, is that they remove contaminants directly from the water, while other technologies extract the water from the contaminants, which enables efficient removal of trace pollutants. The review begins with an overview of conventional electrochemical methods, which drive chemical or physical transformations via Faradaic reactions at electrodes, and proceeds to a detailed examination of the two primary mechanisms by which contaminants are separated in nondestructive electrochemical processes, namely electrokinetics and electrosorption. In these sections, special attention is given to emerging methods, such as shock electrodialysis and Faradaic electrosorption. Given the importance of generating clean, renewable energy, which may sometimes be combined with water purification, the review also discusses inverse methods of electrochemical energy conversion based on reverse electrosorption, electrowetting, and electrokinetic phenomena. The review concludes with a discussion of technology comparisons, remaining challenges, and potential innovations for the field such as process intensification and technoeconomic optimization.
... This implied that a higher ratio of salt ions was adsorbed per unit charge at this highest mass loading of Tp-TGI, indicating a reduction in undesirable phenomena such as co-ion expulsion and faradaic reactions in the MCDI cell [44]. Further, the ASAR [45] and ENAS are important parameters that give insight into the kinetics and energy consumption of the MCDI process. The ASAR of the Tp-TGI series of membranes increased with increasing iCON loading, demonstrating that a greater number of salt ions can be removed in a given time period. ...
Membrane capacitive deionization (MCDI) is a promising technique to achieve desalination of low-salinity water resources. The primary requirements for developing and designing materials for MCDI applications are large surface area, high wettability to water, high conductivity, and efficient ion-transport pathways. Herein, we synthesized ionic covalent organic nanosheets (iCONs) containing guanidinium units that carry a positive charge. A series of quaternized polybenzimidazole (QPBI)/iCON ([email protected]) nanocomposite membranes was fabricated using solution casting. The surface, thermal, wettability, and electrochemical properties of the [email protected] nanocomposite membranes were evaluated. The [email protected] anion-exchange membranes achieved a salt adsorption capacity as high as 15.6 mg g⁻¹ and charge efficiency of up to 90%, which are 50% and 20% higher than those of the pristine QPBI membrane, respectively. The performance improvement was attributed to the increased ion-exchange capacity (2.4 mmol g⁻¹), reduced area resistance (5.4 Ω cm²), and enhanced hydrophilicity (water uptake = 32%) of the [email protected] nanocomposite membranes. This was due to the additional quaternary ammonium groups and conductive ion transport networks donated by the iCON materials. The excellent desalination performance of the [email protected] nanocomposite membranes demonstrated their potential for use in MCDI applications and alternative electromembrane processes.
... Furthermore, the potential of MCDI as a technology for a specific purpose such as selective removal of ions has been attracted [9][10][11]. The ion removal performance of MCDI has been enhanced with the introduction of various electrode materials such as functionalized carbon electrodes [12][13][14][15], intercalating materials [16][17][18][19], and integrating with redox materials [20][21][22][23][24][25]. The modification of cell construction [26][27][28][29], and optimization of the operation method [30][31][32][33] have also enhanced the performance of MCDI. ...
In the practical implementation of capacitive deionization (CDI), membrane CDI with a bipolar electrode (bipolar MCDI) is emerging as one of the alternative CDI platforms due to its favorable cell configuration for scale-up and low current originating from the serial connection of electrodes. Nevertheless, one obstacle to practical use is that there are few studies about the energy recovery process for the high energy efficiency of bipolar MCDI, requiring further research. Therefore, in this study, we propose a bipolar MCDI process with energy recovery and assess its potential by analysis of a lab-scale module with a single stack and nine stacks of the bipolar electrode (i.e., 2.4 V and 12 V system, respectively) and a pilot-scale module with 250 stacks (i.e., 300 V system). As a result, the energy consumption of the bipolar MCDI systems was reduced by 43% and 41% in the lab-scale modules with 2.4 V and 12 V systems, respectively, via energy recovery. Furthermore, the energy recovery led to a 40% reduction in the energy consumption of bipolar MCDI, even in the pilot-scale modules of the 300 V system. The results suggest that energy recovery in bipolar MCDI can be one of the essential processes and it has a strong potential for implementation in real industrial and environmental applications.
... (14.12)À(14.17)] (Ha, Lee, & Yoon, 2021;Kim, Lee, & Kim, 2020;. The salt removal efficiency (SRE) is given as: ...
... An important aspect in the development of the CDI was the incorporation of IEMs into the process, resulting in the MCDI. This technological advance has made it possible to block and repel co-ions, thus improving charge efficiency and desalination capacity, in addition to increasing the stability of the system due to the reduction of parallel reactions such as carbon oxidation and oxygen reduction (Kim et al., 2020). Moreover, IEMs act as protective shields of electrodes against foulants (Pawlowski, Huertas, Galinha, Crespo, & Velizarov, 2020); so, fouling ends up occurring in IEMs similarly to other electromembrane processes, as in ED, for example (Hassanvand, Chen, Webley, & Kentish, 2019;Wang, Bai, & Zhang, 2020). ...
The electromembrane process is a designation to describe technologies grounded on ion migration through ion-exchange membranes using the electrical potential gradient as the driving force. In this field, the main processes are electrodialysis, electrodialysis reversal, electrodialysis with the bipolar membrane, electrodeionization, and membrane-capacitive deionization. This chapter presents the operational principles, the transport equations, particularities, applications, and limitations for these electromembrane processes. Their competitiveness, compared to other technologies, depends on a series of conditions such as the quality of the water or wastewater to be treated, the degree of treatment desired, space and energy available for installing the treatment plant, as well as installation and operating costs. Nowadays, electromembrane processes are also applied for product purification and recovery in many industries. However, most uses are due to electro-membrane processes bringing together clean technologies able to change polluted water in drinking water and convert wastewater into a source of reuse water, thus allowing materials recovery.. Thus electromembrane technologies may be chosen as closing-loop methods for zero-discharge processes.
... In the same manner as a capacitor, energy can be partially recovered during the electrode regeneration step [56][57][58]. The energy consumption in the CDI process strongly depends on the salt concentration of the feed water because CDI desalinates ions by electrosorption [59]. Thus, it has been suggested that CDI is more energy-efficient than RO for brackish water desalination when the feed salinity is lower than 3.5 g/L, and the product water salinity is 1 g/L [60]. ...
Due to advances in desalination technology, desalination has been considered as a practical method to meet the increasing global fresh water demand. This paper explores the status of the desalination industry and research work in South Korea. Desalination plant designs, statistics, and the roadmap for desalination research were analyzed. To reduce energy consumption in desalination, seawater reverse osmosis (SWRO) has been intensively investigated. Recently, alternative desalination technologies, including forward osmosis, pressure-retarded osmosis, membrane distillation, capacitive deionization, renewable-energy-powered desalination, and desalination batteries have also been actively studied. Related major consortium-based desalination research projects and their pilot plants suggest insights into lowering the energy consumption of desalination and mitigation of the environmental impact of SWRO brine as well. Finally, considerations concerning further development are suggested based on the current status of desalination technology in South Korea.
