Seawater desalination by over-potential membrane capacitive deionization: Opportunities and hurdles

Tang, Kexin; Kim, Yong-ha; Chang, Junjun; Mayes, Richard T.; Gabitto, Jorge; Yiacoumi, Sotira; Tsouris, Costas

doi:10.1016/j.cej.2018.09.121

Cited by 89 publications

(38 citation statements)

References 49 publications

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“…[8,27,28] Adding permselective ion-exchange membranes (IEMs) to separate electrodes from the saline water can effectively ameliorate the above-mentioned problems. [21,29,30] Depending on their permselectivity, IEMs can block co-ion expulsion, resulting in an enhancement in salt removal capacity and charge efficiency. [26,30] IEMs can also effectively inhibit the oxidation of anodic carbon electrodes, thereby improving the stability of CDI long-term desalination.…”

Section: Carbon Electrodes For CDImentioning

confidence: 99%

“…[30] Another example using an overpotential (2.4 V) obtained a value up to 64.7 mg g −1 in 500 × 10 −3 m NaCl solution. [29] IEMs has also been demonstrated as effective in prolonging the lifetime of electrodes by alleviating oxidation of anodic carbon electrodes. [31,66] In addition to CDI with static electrodes, the development of flow-electrode CDI (Figure 3b) even can enable continuous desalination.…”

Section: Cell Architecturesmentioning

confidence: 99%

“…[ 21 ] Due to the permselectivity of IEMs, co‐ion expulsion can be effectively suppressed, leading to increased flux of counterions to reach electroneutrality, with the end result that fewer ions remain in the stream and the desalination performance is significantly improved. [ 26,30 ] Some studies have explored the possibility of MCDI for high salinity streams, [ 29,30,71 ] such as applying a reversed‐voltage during discharge step, resulting in a salt removal capacity of 26 mg g −1 in 600 × 10 −3 m NaCl solution. [ 30 ] Another example using an over‐potential (2.4 V) obtained a value up to 64.7 mg g −1 in 500 × 10 −3 m NaCl solution.…”

Section: Fundamentals Of Faradaic Electrode Materials In CDImentioning

confidence: 99%

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Faradaic Electrodes Open a New Era for Capacitive Deionization

et al. 2020

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Capacitive deionization (CDI) is an emerging desalination technology for effective removal of ionic species from aqueous solutions. Compared to conventional CDI, which is based on carbon electrodes and struggles with high salinity streams due to a limited salt removal capacity by ion electrosorption and excessive co-ion expulsion, the emerging Faradaic electrodes provide unique opportunities to upgrade the CDI performance, i.e., achieving much higher salt removal capacities and energy-efficient desalination for high salinity streams, due to the Faradaic reaction for ion capture. This article presents a comprehensive overview on the current developments of Faradaic electrode materials for CDI. Here, the fundamentals of Faradaic electrode-based CDI are first introduced in detail, including novel CDI cell architectures, key CDI performance metrics, ion capture mechanisms, and the design principles of Faradaic electrode materials. Three main categories of Faradaic electrode materials are summarized and discussed regarding their crystal structure, physicochemical characteristics, and desalination performance. In particular, the ion capture mechanisms in Faradaic electrode materials are highlighted to obtain a better understanding of the CDI process. Moreover, novel tailored applications, including selective ion removal and contaminant removal, are specifically introduced. Finally, the remaining challenges and research directions are also outlined to provide guidelines for future research.

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Section: Carbon Electrodes For CDImentioning

confidence: 99%

Section: Cell Architecturesmentioning

confidence: 99%

Section: Fundamentals Of Faradaic Electrode Materials In CDImentioning

confidence: 99%

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Faradaic Electrodes Open a New Era for Capacitive Deionization

et al. 2020

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“…While these processes have evolved, there are still some obstacles. For instance, there are key issues for reverse osmosis (RO) membrane fouling and scaling and also other problems where high energy consumption is needed in thermal desalination [6]. erefore, an effective, energy-efficient alternative to traditional processes for desalination of seawater must be created.…”

Section: Introductionmentioning

confidence: 99%

“…Currently, advances in NF membranes were developed for removal of monovalent ions from the surface water, underground water, brackish water, and seawater [7,9]. e NF was used as a first stage before the RO process, and this leads to many benefits like higher monovalent ion rejection, accomplished higher RO design flux and recovery in water desalination plants, and increase in membrane lifetime [6]. However, NF membranes still need to discover new materials in order to improve a high selectivity for monovalent ions.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Evaluation of Evaporated Casting MWCNT/Chitosan Composite Membranes for Water Desalination

Alsuhybani

Alshahrani

Haidyrah

2020

Journal of Chemistry

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Fresh water scarcity and pollution turn out to be a most serious issue throughout the world due to the rapid population growth. The application of nanomaterials (NMs) for the removal of pollutants from water has attracted significant attention. The nanofiltration membrane was fabricated through the evaporative casting (EC) method using multiwalled carbon nanotubes (MWCNT) and chitosan (CHIT) as the surfactant to enable water purification. The developed EC membrane properties were characterized in mechanical, surface charging (zeta potential), surface morphology, and hydrophobicity properties. Results demonstrated that incorporation of MWCNT and the biopolymers (chitosan) resulted in suitable developments in mechanical properties of the membrane. For example, the membrane has shown values for tensile strength (28 ± 1 MPa), elongation (10.2 ± 1.2%), Young’s modulus (1.2 ± 0.1 GPa), and toughness of (1.9 ± 0.2 J/g). When more significant changes were investigated on the surface morphology of the EC membrane, it was observed that the pores on the surface morphology of the EC membrane decreased as the evaporative casting method was used. Moreover, the permeability of the membrane towards water, inorganic salts, and pH effect on salt rejections was studied using the NF/RO system. These established nanocomposite membranes signify the promising candidates for fresh water desalination and elimination of organic impurities.

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Understanding the Enhanced Capacitive Desalination Performance of Spherical ZnCo₂O₄ Electrode

2021

Adv Materials Inter

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Nevertheless, they suffer from the issues such as high input energy cost and secondary environmental contamination. On the contrary, the capacitive deionization (CDI) has been a promising desalination method associating with the different advantages, i.e., high desalination capacity, low capital cost, and environment friendly. [15,16] In a representative CDI process triggered by direct potential, the anions and cations in the brine separately move to the anode and the cathode, and then be adsorbed. To achieve the recycling, the adsorbed ions are expelled from the electrode by a reverse voltage being applied. Previous studies have recognized that the desalination performance of CDI is greatly determined by the electrode. According to the classic electrical double layer theory, the electrodes' material should own high specific surface area and admirable conductivity since the former one provides the space to accommodate salty ions while the latter one governs the ions and electron diffusions during the desalination. [17,18] However, there is a limitation on desalination capacity enabled by this manner that the specific surface area of electrode is finite.In recent years, researchers proposed to use the Faraday reaction instead physical adsorption to increase the desalting capacity of CDI. [19] Due to this reason, the electrodes' material with high Faraday reactivity has attracted the enormous attentions including transition metal oxides (TMO). [20,21] Benefiting from the enhanced synergistic effect, the bimetallic TMO possesses the improved properties over single-metallic TMO, i.e., conductivity, reactive sites, and stability. [22][23][24] For example, the electrical conductivity of NiCo 2 O 4 is at least 100 times higher than that of either Ni-or Co-oxides. [25] Further, it is worth noting that the bimetallic oxides, i.e., MCo 2 O 4 where M represents the metal atom with two valence state such as Ni, Fe, Mn, Zn, etc., have unique spinel structure. In terms of the MCo 2 O 4 spinel structure, the regular tetrahedral and octahedral position is occupied by the divalent M 2+ and Co 3+ , respectively. In application to sodium ions battery, the electrochemically active M and Co are separated from their original positions under the action of potential. [26,27] As a result, the sodium ions from electrolyte would combine with O to form Na-O bond, leading to storage of energy. Among all MCo 2 O 4 candidates, the spinel ZnCo 2 O 4 (ZCO) has been extensively employed for many

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Seawater desalination by over-potential membrane capacitive deionization: Opportunities and hurdles

Cited by 89 publications

References 49 publications

Faradaic Electrodes Open a New Era for Capacitive Deionization

Faradaic Electrodes Open a New Era for Capacitive Deionization

Synthesis, Characterization, and Evaluation of Evaporated Casting MWCNT/Chitosan Composite Membranes for Water Desalination

Understanding the Enhanced Capacitive Desalination Performance of Spherical ZnCo₂O₄ Electrode

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Seawater desalination by over-potential membrane capacitive deionization: Opportunities and hurdles

Cited by 89 publications

References 49 publications

Faradaic Electrodes Open a New Era for Capacitive Deionization

Faradaic Electrodes Open a New Era for Capacitive Deionization

Synthesis, Characterization, and Evaluation of Evaporated Casting MWCNT/Chitosan Composite Membranes for Water Desalination

Understanding the Enhanced Capacitive Desalination Performance of Spherical ZnCo2O4 Electrode

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Understanding the Enhanced Capacitive Desalination Performance of Spherical ZnCo₂O₄ Electrode