1
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Liu N, Yuan J, Zhang X, Ren Y, Yu F, Ma J. 3D grape string-like heterostructures enable high-efficiency sodium ion capture in Ti 3C 2T x MXene/fungi-derived carbon nanoribbon hybrids. MATERIALS HORIZONS 2024; 11:1223-1233. [PMID: 38126361 DOI: 10.1039/d3mh01028g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
2D transition metal carbides and carbonitrides (MXenes) have emerged as promising electrode materials for electrochemistry ion capture but always suffer from severe layer-restacking and irreversible oxidation that restrains their electrochemical performance. Here we design a dual strategy of microstructure tailoring and heterostructure construction to synthesize a unique 3D grape string-like heterostructure consisting of Ti3C2Tx MXene hollow microspheres wrapped by fungi-derived N-doping carbon nanoribbons (denoted as GMNC). The 3D grape string-like heterostructure effectively avoids the aggregation of Ti3C2Tx MXene sheets and enhances the stability of MXenes, providing abundant active sites for ion capture, and an interconnected conductive bionic nanofiber network for high-rate electron transport. In consequence, GMNC achieves a superior adsorption capacity for sodium ions (Na+) in capacitive deionization (CDI) (162.37 mg gNaCl-1) with an ultra-high instantaneous adsorption rate (30.52 mg g-1 min-1) at an applied voltage of 1.6 V and satisfactory cycle stability over 100 cycles, which is a strong performer among the state-of-the-art values for MXene-based CDI electrodes. In addition, in situ electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) measurement combined with density functional theory (DFT) reveals the mechanisms of the Na+ capture process in the GMNC heterostructure. This work opens a new avenue for designing high-performance MXenes with a 3D hierarchical heterostructure for advanced electrochemical applications.
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Affiliation(s)
- Ningning Liu
- Research Center for Environmental Functional Materials, State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, P. R. China.
| | - Jianhua Yuan
- Research Center for Environmental Functional Materials, State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, P. R. China.
| | - Xiaochen Zhang
- Research Center for Environmental Functional Materials, State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, P. R. China.
| | - Yifan Ren
- Research Center for Environmental Functional Materials, State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, P. R. China.
| | - Fei Yu
- College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, P. R. China
| | - Jie Ma
- Research Center for Environmental Functional Materials, State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, P. R. China.
- School of Civil Engineering, Kashi University, Kashi 844000, China
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2
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He Y, Gao T, Gong A, Liang P. Sustained Phosphorus Removal and Enrichment through Off-Flow Desorption in a Reservoir of Membrane Capacitive Deionization. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:3031-3040. [PMID: 38299499 DOI: 10.1021/acs.est.3c08291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2024]
Abstract
In this study, we used a membrane capacitive deionization device with a reservoir (R-MCDI) to enrich phosphorus (P) from synthetic wastewater. This R-MCDI had two small-volume electrode chambers, and most of the electrolyte was contained in the reservoir, which was circulated along the electrode chambers. Compared with conventional MCDI, R-MCDI exhibited a phosphate removal rate of 0.052 μmol/(cm2·min), approximately double that of MCDI. This was attributed to R-MCDI's utilization of OH- alternative adsorption to remove phosphate from the influent. Noticing that around 73.9% of the removed phosphate was stored in the electrolyte in R-MCDI, we proposed a novel off-flow desorption operation to enrich the removed phosphate in the reservoir. Exciting results from the multicycle experiment (∼8 h) of R-MCDI showed that the PO43--P concentration in the reservoir increased all the way from the initial 152 mg/L to the final 361 mg/L, with the increase in the P charge efficiency from 5.5 to 22.9% and the decrease in the energy consumption from 28.2 to 6.8 kW h/kg P. The P recovery performance of R-MCDI was evaluated by viewing other similar studies, which revealed that R-MCDI in this study achieved superior P enrichment with low energy consumption and that the off-flow desorption proposed here considerably simplified the operation and enabled continuous P enrichment.
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Affiliation(s)
- Yunfei He
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Tie Gao
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Ao Gong
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Peng Liang
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
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3
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He Z, Li Y, Wang Y, Miller CJ, Fletcher J, Lian B, Waite TD. Insufficient desorption of ions in constant-current membrane capacitive deionization (MCDI): Problems and solutions. WATER RESEARCH 2023; 242:120273. [PMID: 37393810 DOI: 10.1016/j.watres.2023.120273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Revised: 06/20/2023] [Accepted: 06/25/2023] [Indexed: 07/04/2023]
Abstract
Membrane capacitive deionization (MCDI) is a water desalination technology that involves the removal of charged ions from water under an electric field. While constant-current MCDI coupled with stopped-flow during ion discharge is expected to exhibit high water recovery and good performance stability, previous studies have typically been undertaken using NaCl solutions only with limited investigation of MCDI performance using multi-electrolyte solutions. In the present work, the desalination performance of MCDI was evaluated using feed solutions with different levels of hardness. The increase of hardness resulted in the degradation of desalination performance with the desalination time (Δtd), total removed charge, water recovery (WR) and productivity decreasing by 20.5%, 21.8%, 3.8% and 3.2%, respectively. A more serious degradation of WR and productivity would be caused if Δtd decreases further. Analysis of the voltage profiles and effluent ion concentrations reveal that the insufficient desorption of divalent ions at constant-current discharge to 0 V was the principal reason for the degradation of performance. The Δtd and WR can be improved by discharging the cell using a lower current but the productivity decreased by 15.7% on decreasing the discharging current from 161 to 107 mA. Discharging the cell to a negative potential was shown to be a better option with the Δtd, total removed charge, WR and productivity increasing by 27.4%, 23.9%, 3.6% and 5.3%, respectively, when the cell was discharged to a minimum voltage of - 0.3 V. Use of such a method should be feasible for operation of full scale MCDI plants and would be expected to lead to better regeneration of the electrode, improved desalination performance and, potentially, a significant reduction in the need for use of clean-in-place procedures.
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Affiliation(s)
- Zhizhao He
- UNSW Centre for Transformational Environmental Technologies, Yixing, Jiangsu Province 214206, P. R. China; School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Yingnan Li
- UNSW Centre for Transformational Environmental Technologies, Yixing, Jiangsu Province 214206, P. R. China; School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Yuan Wang
- UNSW Centre for Transformational Environmental Technologies, Yixing, Jiangsu Province 214206, P. R. China; School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Christopher J Miller
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - John Fletcher
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney 2052, Australia
| | - Boyue Lian
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - T David Waite
- UNSW Centre for Transformational Environmental Technologies, Yixing, Jiangsu Province 214206, P. R. China; School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
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4
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Cañas Kurz EE, Hellriegel U, Hdoufane A, Benaceur I, Anane M, Jaiti F, El-Abbassi A, Hoinkis J. Comparison of Pilot-Scale Capacitive Deionization (MCDI) and Low-Pressure Reverse Osmosis (LPRO) for PV-Powered Brackish Water Desalination in Morocco for Irrigation of Argan Trees. MEMBRANES 2023; 13:668. [PMID: 37505034 PMCID: PMC10384803 DOI: 10.3390/membranes13070668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 06/27/2023] [Accepted: 07/09/2023] [Indexed: 07/29/2023]
Abstract
The use of saline water resources in agriculture is becoming a common practice in semi-arid and arid regions such as the Mediterranean. In the SmaCuMed project, the desalination of brackish groundwater (TDS = 2.8 g/L) for the irrigation of Argan trees in Essaouira, Morocco, to 2 g/L and 1 g/L (33% and 66% salt removal, respectively) using low-pressure reverse osmosis (LPRO) (p < 6 bar) and membrane capacitive deionization (MCDI) was tested at pilot scale. MCDI showed 40-70% lower specific energy consumption (SEC) and 10-20% higher water recovery; however, the throughput of LPRO (2.9 m3/h) was up to 1.5 times higher than that of MCDI. In addition, both technologies were successfully powered by PV solar energy with total water costs ranging from EUR 0.82 to EUR 1.34 per m3. In addition, the water quality in terms of sodium adsorption ratio was slightly higher with LPRO resulting in higher concentrations of Ca2+ and Mg2+, due to blending with feed water. In order to evaluate both technologies, additional criteria such as investment and specific water costs, operability and brine disposal have to be considered.
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Affiliation(s)
- Edgardo E Cañas Kurz
- Center of Applied Research, Karlsruhe University of Applied Sciences, 76133 Karlsruhe, Germany
| | - Ulrich Hellriegel
- Center of Applied Research, Karlsruhe University of Applied Sciences, 76133 Karlsruhe, Germany
| | - Abdelkarim Hdoufane
- Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech 40010, Morocco
| | - Ibtissame Benaceur
- Faculty of Sciences and Technologies Errachidia, Moulay Ismail University, Errachidia 52000, Morocco
| | - Makram Anane
- Centre de Recherches et des Technologies des Eaux, Soliman 8020, Tunisia
| | - Fatima Jaiti
- Faculty of Sciences and Technologies Errachidia, Moulay Ismail University, Errachidia 52000, Morocco
| | | | - Jan Hoinkis
- Center of Applied Research, Karlsruhe University of Applied Sciences, 76133 Karlsruhe, Germany
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5
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Nordstrand J, Zuili L, Dutta J. Fully 3D Modeling of Electrochemical Deionization. ACS OMEGA 2023; 8:2607-2617. [PMID: 36687060 PMCID: PMC9850726 DOI: 10.1021/acsomega.2c07133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 12/20/2022] [Indexed: 06/17/2023]
Abstract
Electrochemical deionization devices are crucial for meeting global freshwater demands. One such is capacitive deionization (CDI), which is an emerging technology especially suited for brackish water desalination. In this work, we extend an electrolytic capacitor (ELC) model that exploits the similarities between CDI systems and supercapacitor/battery systems. Compared to the previous work, we introduce new implementational strategies for enhanced stability, a more detailed method of describing charge efficiency, layered integration of leakage reactions, and theory extensions to new material and operational conditions. Thanks to the stability and flexibility the approach brings, the current work can present the first fully coupled and spatiotemporal three-dimensional (3D) CDI model. We hope that this can pave the way toward generalized and full-scale modeling of CDI units under varying conditions. A 3D model can be beneficial for investigating asymmetric CDI device structures, and the work investigates a flow-through device structure with inlet and outlet pipes at the center and corners, respectively. The results show that dead (low-flow) areas can reduce desalination rates while also raising the total leakage. However, the ionic flux in this device is still enough under normal operating conditions to ensure reasonable performance. In conclusion, researchers will now have some flexibility in designing device structures that are not perfectly symmetric (real-life case), and hence we share the model files to facilitate future research with 3D modeling of these electrochemical deionization devices.
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6
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Nordstrand J, Dutta J. Ohmic charging in capacitive deionization: Efficient water desalination using capacitive spacers. NANO SELECT 2023. [DOI: 10.1002/nano.202200233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- Johan Nordstrand
- Functional Materials Applied Physics Department School of Engineering Sciences KTH Royal Institute of Technology AlbaNova universitetscentrum Stockholm Sweden
| | - Joydeep Dutta
- Functional Materials Applied Physics Department School of Engineering Sciences KTH Royal Institute of Technology AlbaNova universitetscentrum Stockholm Sweden
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7
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Theory of bipolar connections in capacitive deionization and principles of structural design. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.141066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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8
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El-Deen AG, El-kholly HK, Ali MEM, Ibrahim HS, Zahran M, Helal M, Choi JH. Polystyrene sulfonate coated activated graphene aerogel for boosting desalination performance using capacitive deionization. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.121760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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9
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Alkhadra M, Su X, Suss ME, Tian H, Guyes EN, Shocron AN, Conforti KM, de Souza JP, Kim N, Tedesco M, Khoiruddin K, Wenten IG, Santiago JG, Hatton TA, Bazant MZ. Electrochemical Methods for Water Purification, Ion Separations, and Energy Conversion. Chem Rev 2022; 122:13547-13635. [PMID: 35904408 PMCID: PMC9413246 DOI: 10.1021/acs.chemrev.1c00396] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
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.
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Affiliation(s)
- Mohammad
A. Alkhadra
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
| | - Xiao Su
- Department
of Chemical and Biomolecular Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Matthew E. Suss
- Faculty
of Mechanical Engineering, Technion—Israel
Institute of Technology, Haifa 3200003, Israel,Wolfson
Department of Chemical Engineering, Technion—Israel
Institute of Technology, Haifa 3200003, Israel,Nancy
and Stephen Grand Technion Energy Program, Technion—Israel Institute of Technology, Haifa 3200003, Israel
| | - Huanhuan Tian
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
| | - Eric N. Guyes
- Faculty
of Mechanical Engineering, Technion—Israel
Institute of Technology, Haifa 3200003, Israel
| | - Amit N. Shocron
- Faculty
of Mechanical Engineering, Technion—Israel
Institute of Technology, Haifa 3200003, Israel
| | - Kameron M. Conforti
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
| | - J. Pedro de Souza
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
| | - Nayeong Kim
- Department
of Chemical and Biomolecular Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Michele Tedesco
- European
Centre of Excellence for Sustainable Water Technology, Wetsus, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
| | - Khoiruddin Khoiruddin
- Department
of Chemical Engineering, Institut Teknologi
Bandung, Jl. Ganesha no. 10, Bandung, 40132, Indonesia,Research
Center for Nanosciences and Nanotechnology, Institut Teknologi Bandung, Jl. Ganesha no. 10, Bandung 40132, Indonesia
| | - I Gede Wenten
- Department
of Chemical Engineering, Institut Teknologi
Bandung, Jl. Ganesha no. 10, Bandung, 40132, Indonesia,Research
Center for Nanosciences and Nanotechnology, Institut Teknologi Bandung, Jl. Ganesha no. 10, Bandung 40132, Indonesia
| | - Juan G. Santiago
- Department
of Mechanical Engineering, Stanford University, Stanford, California 94305, United States
| | - T. Alan Hatton
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
| | - Martin Z. Bazant
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States,Department
of Mathematics, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States,
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10
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Knowledge and Technology Used in Capacitive Deionization of Water. MEMBRANES 2022; 12:membranes12050459. [PMID: 35629785 PMCID: PMC9143758 DOI: 10.3390/membranes12050459] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/13/2022] [Accepted: 04/14/2022] [Indexed: 02/01/2023]
Abstract
The demand for water and energy in today’s developing world is enormous and has become the key to the progress of societies. Many methods have been developed to desalinate water, but energy and environmental constraints have slowed or stopped the growth of many. Capacitive Deionization (CDI) is a very new method that uses porous carbon electrodes with significant potential for low energy desalination. This process is known as deionization by applying a very low voltage of 1.2 volts and removing charged ions and molecules. Using capacitive principles in this method, the absorption phenomenon is facilitated, which is known as capacitive deionization. In the capacitive deionization method, unlike other methods in which water is separated from salt, in this technology, salt, which is a smaller part of this compound, is separated from water and salt solution, which in turn causes less energy consumption. With the advancement of science and the introduction of new porous materials, the use of this method of deionization has increased greatly. Due to the limitations of other methods of desalination, this method has been very popular among researchers and the water desalination industry and needs more scientific research to become more commercial.
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Pan Z, An J, Wang P, Fan X, Shen T, Xu R, Song Y, Song C. Novel strategy to enhance the desalination performance of flow-electrode capacitive deionization process via the assistance of electro-catalytic water splitting. Sep Purif Technol 2021. [DOI: 10.1016/j.seppur.2021.119753] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Nordstrand J, Dutta J. A new automated model brings stability to finite‐element simulations of capacitive deionization. NANO SELECT 2021. [DOI: 10.1002/nano.202100270] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Johan Nordstrand
- Functional Materials, Applied Physics Department, School of Engineering Sciences KTH Royal Institute of Technology AlbaNova universitetscentrum Stockholm 106 91 Sweden
| | - Joydeep Dutta
- Functional Materials, Applied Physics Department, School of Engineering Sciences KTH Royal Institute of Technology AlbaNova universitetscentrum Stockholm 106 91 Sweden
- Center of Nanotechnology King Abdulaziz University Jeddah 21589 Saudi Arabia
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13
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Abstract
Several harmful or valuable ionic species present in seawater, brackish water, and wastewater are amphoteric, weak acids or weak bases, and, thus, their properties depend on local water pH. Effective removal of these species can be challenging for conventional membrane technologies, necessitating chemical dosing of the feedwater to adjust pH. A prominent example is boron, which is considered toxic in high concentrations and often requires additional membrane passes to remove during seawater desalination. Capacitive deionization (CDI) is an emerging membraneless technique for water treatment and desalination, based on electrosorption of salt ions into charging microporous electrodes. CDI cells show strong internally generated pH variations during operation, and, thus, CDI can potentially remove pH-dependent species without chemical dosing. However, development of this technique is inhibited by the complexities inherent to the coupling of pH dynamics and ion properties in a charging CDI cell. Here, we present a theoretical framework predicting the electrosorption of pH-dependent species in flow-through electrode CDI cells. We demonstrate that such a model enables insight into factors affecting species electrosorption and conclude that important design rules for such systems are highly counterintuitive. For example, we show both theoretically and experimentally that for boron removal, the anode should be placed upstream and the cathode downstream, an electrode order that runs counter to the accepted wisdom in the CDI field. Overall, we show that to achieve target separations relying on coupled, complex phenomena, such as in the removal of amphoteric species, a theoretical CDI model is essential.
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14
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He Z, Liu S, Lian B, Fletcher J, Bales C, Wang Y, Waite TD. Optimization of constant-current operation in membrane capacitive deionization (MCDI) using variable discharging operations. WATER RESEARCH 2021; 204:117646. [PMID: 34543974 DOI: 10.1016/j.watres.2021.117646] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 08/16/2021] [Accepted: 09/03/2021] [Indexed: 06/13/2023]
Abstract
Membrane capacitive deionization (MCDI) is an emerging electric field-driven technology for brackish water desalination involving the removal of charged ions from saline source waters. While the desalination performance of MCDI under different operational modes has been widely investigated, most studies have concentrated on different charging conditions without considering discharging conditions. In this study, we investigate the effects of different discharging conditions on the desalination performance of MCDI electrode. Our study demonstrates that low-current discharge (1.0 mA/cm2) can increase salt removal by 20% and decrease volumetric energy consumption by 40% by improving electrode regeneration and increasing energy recovery, respectively, while high-current discharge (3.0 mA/cm2) can improve productivity by 70% at the expense of electrode regeneration and energy recovery. Whether discharging electrodes at the low current or high current is optimal depends on a trade-off between productivity and energy consumption. We also reveal that stopped flow discharge (85%) can achieve higher water recovery than continuous flow discharge (35-59%). However, stopped flow discharge caused a 20-30% decrease in concentration reduction and a 25-50% increase in molar energy consumption, possibly due to the higher ion concentration in the macropores at the end of discharging step. These results reveal that an optimal discharging operation should be obtained from achieving a balance among productivity, water recovery and energy consumption by varying discharging current and flow rate.
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Affiliation(s)
- Zhizhao He
- UNSW Centre for Transformational Environmental Technologies, Yixing, Jiangsu 214206, PR China; School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
| | - Shuai Liu
- UNSW Centre for Transformational Environmental Technologies, Yixing, Jiangsu 214206, PR China.
| | - Boyue Lian
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
| | - John Fletcher
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney 2052, Australia.
| | - Clare Bales
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
| | - Yuan Wang
- UNSW Centre for Transformational Environmental Technologies, Yixing, Jiangsu 214206, PR China; School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
| | - T David Waite
- UNSW Centre for Transformational Environmental Technologies, Yixing, Jiangsu 214206, PR China; School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
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15
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He C, Lian B, Ma J, Zhang C, Wang Y, Mo H, Waite TD. Scale-up and Modelling of Flow-electrode CDI Using Tubular Electrodes. WATER RESEARCH 2021; 203:117498. [PMID: 34371229 DOI: 10.1016/j.watres.2021.117498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/09/2021] [Accepted: 07/27/2021] [Indexed: 06/13/2023]
Abstract
A novel design for a flow-electrode capacitive deionization (FCDI) system consisting of tubular electrodes in a shell and tube heat exchanger configuration is proposed. Each electrode consists of a metallic mesh current collector along the inner circumference of a tubular ion-exchange membrane. This tubular FCDI design is suitable for scale-up as it consists of easily manufactured components which can be assembled in an array. An apparatus with 4 tubular electrodes with a large effective area (202.3 cm2) was constructed and shown to provide a high net salt (NaCl) removal rate (0.15 mg s-1 at 1.2 V applied voltage and ∼2000 mg L-1 influent total dissolved solids concentration). A computational fluid dynamics (CFD) model incorporating ion migration and transport mechanisms was developed to simulate the ion concentration and electrical potential profiles in the water channel. The results of CFD modelling highlighted the need to maximize regions of both high potential gradient and high hydraulic flow in order to achieve optimal salt removal. In brief, this study presents a new design approach for FCDI scale-up and provides a computational tool for optimization of this design and future innovative FCDI designs.
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Affiliation(s)
- Calvin He
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Boyue Lian
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Jinxing Ma
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Changyong Zhang
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Yuan Wang
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Hengliang Mo
- Beijing Origin Water Membrane Technology Company Limited, Huairou, Beijing, 101400, P. R. China
| | - T David Waite
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
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16
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Wang G, Yan T, Shen J, Zhang J, Zhang D. Capacitive Removal of Fluoride Ions via Creating Multiple Capture Sites in a Modulatory Heterostructure. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:11979-11986. [PMID: 34427438 DOI: 10.1021/acs.est.1c03228] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Fluoride pollution has become a major concern because of its adverse effects on human health. However, the removal capacity of defluorination agents in traditional methods is far from satisfactory. Herein, capacitive removal of F- ions via creating multiple capture sites in a modulatory heterostructure has been originally demonstrated. The heterostructure of uniformly dispersed Al2O3 coating on hollow porous nitrogen-doped carbon frameworks was precisely synthesized by atomic layer deposition. An exceptional F- ion removal efficiency at 1.2 V (95.8 and 92.9% in 5 and 10 mg/L F- solutions, respectively) could be finally achieved, with a good regeneration ability after 20 consecutive defluorination cycles. Furthermore, we investigated the removal mechanisms of F- ions by in situ Raman, in situ X-ray diffraction, and ex situ X-ray photoelectron spectroscopy measurements. The promotional removal capacity was realized by the multiple capture sites of the reversible conversion of Al-F species and the insertion of F- ions into the carbon skeleton. This work offers an important new pathway and deep understanding for efficient removal of F- ions from wastewater.
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Affiliation(s)
- Guizhi Wang
- International Joint Laboratory of Catalytic Chemistry, Department of Chemistry, Research Center of Nano Science and Technology, College of Sciences, State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Shanghai University, No.99 Shangda Road, Shanghai 200444, China
| | - Tingting Yan
- International Joint Laboratory of Catalytic Chemistry, Department of Chemistry, Research Center of Nano Science and Technology, College of Sciences, State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Shanghai University, No.99 Shangda Road, Shanghai 200444, China
| | - Junjie Shen
- Department of Chemical Engineering, University of Bath, Bath BA2 7AY, U.K
| | - Jianping Zhang
- International Joint Laboratory of Catalytic Chemistry, Department of Chemistry, Research Center of Nano Science and Technology, College of Sciences, State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Shanghai University, No.99 Shangda Road, Shanghai 200444, China
| | - Dengsong Zhang
- International Joint Laboratory of Catalytic Chemistry, Department of Chemistry, Research Center of Nano Science and Technology, College of Sciences, State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Shanghai University, No.99 Shangda Road, Shanghai 200444, China
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17
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Partial Desalination of Saline Groundwater: Comparison of Nanofiltration, Reverse Osmosis and Membrane Capacitive Deionisation. MEMBRANES 2021; 11:membranes11020126. [PMID: 33673190 PMCID: PMC7917583 DOI: 10.3390/membranes11020126] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/31/2021] [Accepted: 02/03/2021] [Indexed: 11/17/2022]
Abstract
Saline groundwater (SGW) is an alternative water resource. However, the concentration of sodium, chloride, sulphate, and nitrate in SGW usually exceeds the recommended guideline values for drinking water and irrigation. In this study, the partial desalination performance of three different concentrated SGWs were examined by pressure-driven membrane desalination technologies: nanofiltration (NF), brackish water reverse osmosis (BWRO), and seawater reverse osmosis (SWRO); in addition to one electrochemical-driven desalination technology: membrane capacitive deionisation (MCDI). The desalination performance was evaluated using the specific energy consumption (SEC) and water recovery, determined by experiments and simulations. The experimental results of this study show that the SEC for the desalination of SGW with a total dissolved solid (TDS) concentration of 1 g/L by MCDI and NF is similar and ranges between 0.2–0.4 kWh/m3 achieving a water recovery value of 35–70%. The lowest SECs for the desalination of SGW with a TDS concentration ≥2 g/L were determined by the use of BWRO and SWRO with 0.4–2.9 kWh/m3 for a water recovery of 40–66%. Even though the MCDI technique cannot compete with pressure-driven membrane desalination technologies at higher raw water salinities, this technology shows a high selectivity for nitrate and a high potential for flexible desalination applications.
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Exploring the Function of Ion-Exchange Membrane in Membrane Capacitive Deionization via a Fully Coupled Two-Dimensional Process Model. Processes (Basel) 2020. [DOI: 10.3390/pr8101312] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
In the arid west, the freshwater supply of many communities is limited, leading to increased interest in tapping brackish water resources. Although reverse osmosis is the most common technology to upgrade saline waters, there is also interest in developing and improving alternative technologies. Here we focus on membrane capacitive deionization (MCDI), which has attracted broad attention as a portable and energy-efficient desalination technology. In this study, a fully coupled two-dimensional MCDI process model capable of capturing transient ion transport and adsorption behaviors was developed to explore the function of the ion-exchange membrane (IEM) and detect MCDI influencing factors via sensitivity analysis. The IEM enhanced desalination by improving the counter-ions’ flux and increased adsorption in electrodes by encouraging retention of ions in electrode macropores. An optimized cycle time was proposed with maximal salt removal efficiency. The usage of the IEM, high applied voltage, and low flow rate were discovered to enhance this maximal salt removal efficiency. IEM properties including water uptake volume fraction, membrane thickness, and fixed charge density had a marginal impact on cycle time and salt removal efficiency within certain limits, while increasing cell length and electrode thickness and decreasing channel thickness and dispersivity significantly improved overall performance.
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19
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Toledo-Carrillo E, Zhang X, Laxman K, Dutta J. Asymmetric electrode capacitive deionization for energy efficient desalination. Electrochim Acta 2020. [DOI: 10.1016/j.electacta.2020.136939] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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20
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Pan SY, Haddad AZ, Kumar A, Wang SW. Brackish water desalination using reverse osmosis and capacitive deionization at the water-energy nexus. WATER RESEARCH 2020; 183:116064. [PMID: 32745671 DOI: 10.1016/j.watres.2020.116064] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 05/30/2020] [Accepted: 06/14/2020] [Indexed: 06/11/2023]
Abstract
In this article, we present a critical review of the reported performance of reverse osmosis (RO) and capacitive deionization (CDI) for brackish water (salinity < 5.0 g/L) desalination from the aspects of engineering, energy, economy and environment. We first illustrate the criteria and the key performance indicators to evaluate the performance of brackish water desalination. We then systematically summarize technological information of RO and CDI, focusing on the effect of key parameters on desalination performance, as well as energy-water efficiency, economic costs and environmental impacts (including carbon footprint). We provide in-depth discussion on the interconnectivity between desalination and energy, and the trade-off between kinetics and energetics for RO and CDI as critical factors for comparison. We also critique the results of technical-economic assessment for RO and CDI plants in the context of large-scale deployment, with focus on lifetime-oriented consideration to total costs, balance between energy efficiency and clean water production, and pretreatment/post-treatment requirements. Finally, we illustrate the challenges and opportunities for future brackish water desalination, including hybridization for energy-efficient brackish water desalination, co-removal of specific components in brackish water, and sustainable brine management with innovative utilization. Our study reveals that both RO and CDI should play important roles in water reclamation and resource recovery from brackish water, especially for inland cities or rural regions.
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Affiliation(s)
- Shu-Yuan Pan
- Department of Bioenvironmental Systems Engineering, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei City, 10617, Taiwan, ROC.
| | - Andrew Z Haddad
- Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Arkadeep Kumar
- Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Sheng-Wei Wang
- Department of Water Resources and Environmental Engineering, Tamkang University, New Taipei City, 251301, Taiwan, ROC
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21
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Wang L, Zhang C, He C, Waite TD, Lin S. Equivalent film-electrode model for flow-electrode capacitive deionization: Experimental validation and performance analysis. WATER RESEARCH 2020; 181:115917. [PMID: 32505888 DOI: 10.1016/j.watres.2020.115917] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 04/26/2020] [Accepted: 05/03/2020] [Indexed: 06/11/2023]
Abstract
Flow electrode capacitive deionization (FCDI) is a promising configuration for capacitive deionization due to its capability of continuous operation and achieving a relatively large salinity reduction. Due to the complexity of the multi-phase flow involved in FCDI, modeling FCDI system performance has been a challenge with no predictive FCDI model thus far developed. In this study, we developed an equivalent film-electrode (EFE) model for FCDI in which the flow electrodes are approximated as moving film electrodes that behave in a manner similar to conveyor belts. The EFE-FCDI model is validated using results from a series of FCDI experiments and then applied to elucidate the spatial variations of the key properties of the FCDI system and to resolve the contributions of different aspects of the system to energy consumption. The impact of activated carbon loading in the flow electrode and the feed and effluent target concentrations on the overall FCDI performance are also discussed based on model simulation. In summary, the EFE-FCDI model enhances our understanding of the system-level behavior of FCDI systems and can be employed for optimizing FCDI design and operation.
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Affiliation(s)
- Li Wang
- Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN, 37235-1831, USA
| | - Changyong Zhang
- UNSW Water Research Centre, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales, 2052, Australia
| | - Calvin He
- UNSW Water Research Centre, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales, 2052, Australia
| | - T David Waite
- UNSW Water Research Centre, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, New South Wales, 2052, Australia
| | - Shihong Lin
- Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN, 37235-1831, USA; Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, 37235-1604, USA.
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22
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Wang G, Yan T, Zhang J, Shi L, Zhang D. Trace-Fe-Enhanced Capacitive Deionization of Saline Water by Boosting Electron Transfer of Electro-Adsorption Sites. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:8411-8419. [PMID: 32453947 DOI: 10.1021/acs.est.0c01518] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Capacitive deionization (CDI) is a promising water purification technology. However, the current ion adsorption capacity of CDI electrode materials is still an issue, which cannot meet the rapid demand of clean water from saline water. Herein, trace-Fe-enhanced removal of ions from saline water via CDI is presented. The ion adsorption capacity of CDI electrodes is up to 36.25 mg g-1 in a 500 mg L-1 NaCl media at 1.2 V together with stable regeneration property. In situ Raman and ex situ XPS measurements unravel the removal mechanism of ions from saline water, and the reinforced adsorption of ions is due to the introduction of trace Fe boosting electron transfer of electro-adsorption sites during the CDI process. This work presents a promising solution to highly efficient capacitive deionization for saline water.
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Affiliation(s)
- Guizhi Wang
- State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Research Center of Nano Science and Technology, Department of Chemistry, College of Sciences, Shanghai University, Shanghai, 200444, People's Republic of China
| | - Tingting Yan
- State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Research Center of Nano Science and Technology, Department of Chemistry, College of Sciences, Shanghai University, Shanghai, 200444, People's Republic of China
| | - Jianping Zhang
- State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Research Center of Nano Science and Technology, Department of Chemistry, College of Sciences, Shanghai University, Shanghai, 200444, People's Republic of China
| | - Liyi Shi
- State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Research Center of Nano Science and Technology, Department of Chemistry, College of Sciences, Shanghai University, Shanghai, 200444, People's Republic of China
| | - Dengsong Zhang
- State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Research Center of Nano Science and Technology, Department of Chemistry, College of Sciences, Shanghai University, Shanghai, 200444, People's Republic of China
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23
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Hierarchical porous carbon derived from activated biochar as an eco-friendly electrode for the electrosorption of inorganic ions. Sep Purif Technol 2020. [DOI: 10.1016/j.seppur.2020.116813] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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24
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Basis and Prospects of Combining Electroadsorption Modeling Approaches for Capacitive Deionization. PHYSICS 2020. [DOI: 10.3390/physics2020016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Electrically driven adsorption, electroadsorption, is at the core of technologies for water desalination, energy production, and energy storage using electrolytic capacitors. Modeling can be crucial for understanding and optimizing these devices, and hence different approaches have been taken to develop multiple models, which have been applied to explain capacitive deionization (CDI) device performances for water desalination. Herein, we first discuss the underlying physics of electroadsorption and explain the fundamental similarities between the suggested models. Three CDI models, namely, the more widely used modified Donnan (mD) model, the Randles circuit model, and the recently proposed dynamic Langmuir (DL) model, are compared in terms of modeling approaches. Crucially, the common physical foundation of the models allows them to be improved by incorporating elements and simulation tools from the other models. As a proof of concept, the performance of the Randles circuit is significantly improved by incorporating a modeling element from the mD model and an implementation tool from the DL model (charge-dependent capacitance and system identification, respectively). These principles are accurately validated using data from reports in the literature showing significant prospects in combining modeling elements and tools to properly describe the results obtained in these experiments.
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25
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Wang L, Liang Y, Zhang L. Enhancing Performance of Capacitive Deionization with Polyelectrolyte-Infiltrated Electrodes: Theory and Experimental Validation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:5874-5883. [PMID: 32216292 DOI: 10.1021/acs.est.9b07692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The energy efficiency of capacitive deionization (CDI) with porous carbon electrodes is limited by the high ionic resistance of the macropores in the electrodes. In this study, we demonstrate a facile approach to improve the energy efficiency by filling the macropores with ion-conductive polyelectrolytes, which is termed polyelectrolyte-infiltrated CDI (pie-CDI or πCDI). In πCDI, the filled polyelectrolyte effectively turns the macropores into a charged ion-selective layer and thus increases the conductivity of macropores. We show experimentally that πCDI can save up to half of the energy consumption compared to membrane CDI, achieving identical desalination during the charging step. The energy consumption can be even lower if the process is operated at a smaller average salt adsorption rate. Further energy breakdown analysis based on a theoretical model confirms that the improved energy efficiency is largely attributed to the increased conductivity in the macropores.
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Affiliation(s)
- Li Wang
- Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, Tennessee 37235-1831, United States
| | - Yuanzhe Liang
- Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, Tennessee 37235-1831, United States
| | - Li Zhang
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
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26
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27
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Salamat Y, Hidrovo CH. Significance of the micropores electro-sorption resistance in capacitive deionization systems. WATER RESEARCH 2020; 169:115286. [PMID: 31734390 DOI: 10.1016/j.watres.2019.115286] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 10/12/2019] [Accepted: 11/05/2019] [Indexed: 06/10/2023]
Abstract
Capacitive Deionization (CDI) is an emerging technology representing a potential alternative to the common, energy-intensive desalination methods for low salinity water streams. In CDI an electrical field is applied to separate ionic species from aqueous solutions and electro-adsorb them into a highly porous material. CDI is a complex multi-scale system which requires robust mathematical models to closely describe its performance. Here, a dynamic two-dimensional model is developed coupling the diffusion and advection of the species in the bulk solution with their diffusion and electro-sorption in the porous electrodes. In this model, the adsorption/desorption resistance between the micropores and macropores along with variable non-electrostatic attractive forces in the micropores are also incorporated. The proposed theory is validated against experiments using a circular CDI cell operating under various conditions, where different transport mechanisms are limiting the total ion removal process. Performance of the CDI systems is also evaluated using inclusive figures of merit. The obtained results accentuate the significant effect of the rate-limited transfer of the ionic species from the macropores into the micropores, especially in systems subject to severe ion starvation, where neglecting this electro-sorption resistance leads to up to 50% and 210% overestimation of the energy efficiency and overall desalination performance, respectively. Furthermore, although the commonly used transport theory describing CDI fails to capture the dynamics of the systems at low initial concentration and high adsorption capacity by assuming fast electro-sorption without any resistance, the presented theory closely models the transport mechanisms in such systems. Moreover, we experimentally and numerically demonstrate a trade-off between the energetic and desalination performance in systems with low and high mass Péclet number.
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Affiliation(s)
- Yasamin Salamat
- Mechanical and Industrial Engineering Department, Northeastern University, 334 Snell Engineering Center, 360 Huntington Ave, Boston, MA, 02115, USA
| | - Carlos H Hidrovo
- Mechanical and Industrial Engineering Department, Northeastern University, 334 Snell Engineering Center, 360 Huntington Ave, Boston, MA, 02115, USA.
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28
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Tan C, He C, Fletcher J, Waite TD. Energy recovery in pilot scale membrane CDI treatment of brackish waters. WATER RESEARCH 2020; 168:115146. [PMID: 31627136 DOI: 10.1016/j.watres.2019.115146] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/15/2019] [Accepted: 09/30/2019] [Indexed: 06/10/2023]
Abstract
An energy recovery technique using a high-current bi-directional dc-dc converter for membrane capacitive de-ionization (mCDI) of brackish waters is described and it's performance assessed in a pilot-scale prototype. The energy recovery system is shown to reduce the energy consumption of the pilot-scale mCDI unit, powered by photovoltaics and with battery storage, by between 30 and 40%. Use of a stopped flow process also enables water recovery of up to 87%. The contributions to energy consumption in the system are quantified with the insights gained from this analysis enabling the selection of an optimum voltage range for desorption termination that maximizes the daily recovered energy. The experimental results demonstrate that energy usage by the mCDI process of lower than 0.4 kWh/m3 is achievable with almost 40% of the energy supplied by the batteries recovered.
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Affiliation(s)
- Cheng Tan
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia.
| | - Calvin He
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, 2052, Australia.
| | - John Fletcher
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia.
| | - T David Waite
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, 2052, Australia.
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29
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Moreno D, Hatzell MC. Constant chemical potential cycles for capacitive deionization. Phys Chem Chem Phys 2019; 21:24512-24517. [PMID: 31663088 DOI: 10.1039/c9cp05032a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The primary energy consuming operations which occur within a Capacitive Deionization (CDI) cell, are the ion removal (electrosorption), ion concentrating (electrodesorption), and solution switching processes. In theory the maximum system performance for a CDI system arises when solution switching occurs while maintaining a fixed number of ions (N), and when electrosorption/desorption occurs while maintaining a fixed chemical potential (μ). These fixed state variable based operations are analogous to the Carnot cycle, where heat transfer occurs at constant temperature and compression and expansion occur while maintaining constant entropy. In reality, maintaining a constant number of ions during switching is not practically feasible, thus here we investigate two alternative cycles where switching instead occurs while maintaining constant charge or voltage. Unlike constant number of ions, maintaining charge and voltage constant is feasible using a potentiostat. These theoretical cycles were chosen as they are analogues or ideal-like (Stirling and Ericsson) cycles, which are also practically feasible. The thermodynamic analysis reveals that these alternative cycles provide an avenue to approach the theoretical limit with low saline feed water; however, they are not capable of approximating ideal operations at elevated feed-water concentrations.
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Affiliation(s)
- Daniel Moreno
- Georgia Institute of Technology, 771 Ferst Drive NW, Love Bldg - Room 316, Atlanta, GA 30332, USA.
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30
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Han J, Yan T, Shen J, Shi L, Zhang J, Zhang D. Capacitive Deionization of Saline Water by Using MoS 2-Graphene Hybrid Electrodes with High Volumetric Adsorption Capacity. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:12668-12676. [PMID: 31532191 DOI: 10.1021/acs.est.9b04274] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Capacitive deionization (CDI) has received wide attention as an emerging water treatment technology because of its low energy consumption, low cost, and high efficiency. However, the conventional carbon electrode materials for CDI have low densities, which occupy large volumes and are disadvantageous for use in limited space (e.g., in household or on offshore platforms). In order to miniaturize the CDI device, it is quite urgent to develop high volumetric adsorption capacity (VAC) electrode materials. To overcome this issue, we rationally designed and originally developed high VAC MoS2-graphene hybrid electrodes for CDI. It is interesting that MoS2-graphene hybrid electrode has a much higher NaCl VAC of 14.3 mg/cm3 with a gravimetric adsorption capacity of 19.4 mg/g. It has been demonstrated that the adsorption capacity is significantly enhanced because of the rapid ion transport of MoS2 and high electrical conductivity of graphene. In situ Raman spectra and high-angle annular dark-field scanning transmission electron microscopy tests demonstrated a favorable Faradaic reaction, which was crucial to enhancing the NaCl VAC of the MoS2-graphene hybrid electrode. This work opens a new avenue for miniaturizing future CDI devices.
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Affiliation(s)
- Jinlong Han
- Department of Chemistry, College of Sciences, State Key Laboratory of Advanced Special Steel, Research Center of Nano Science and Technology, School of Materials Science and Engineering , Shanghai University , Shanghai 200444 , PR China
| | - Tingting Yan
- Department of Chemistry, College of Sciences, State Key Laboratory of Advanced Special Steel, Research Center of Nano Science and Technology, School of Materials Science and Engineering , Shanghai University , Shanghai 200444 , PR China
| | - Junjie Shen
- Department of Chemical Engineering , University of Bath , Bath BA2 7AY , U.K
| | - Liyi Shi
- Department of Chemistry, College of Sciences, State Key Laboratory of Advanced Special Steel, Research Center of Nano Science and Technology, School of Materials Science and Engineering , Shanghai University , Shanghai 200444 , PR China
| | - Jianping Zhang
- Department of Chemistry, College of Sciences, State Key Laboratory of Advanced Special Steel, Research Center of Nano Science and Technology, School of Materials Science and Engineering , Shanghai University , Shanghai 200444 , PR China
| | - Dengsong Zhang
- Department of Chemistry, College of Sciences, State Key Laboratory of Advanced Special Steel, Research Center of Nano Science and Technology, School of Materials Science and Engineering , Shanghai University , Shanghai 200444 , PR China
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31
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Mubita TM, Dykstra JE, Biesheuvel PM, van der Wal A, Porada S. Selective adsorption of nitrate over chloride in microporous carbons. WATER RESEARCH 2019; 164:114885. [PMID: 31426005 DOI: 10.1016/j.watres.2019.114885] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 07/04/2019] [Accepted: 07/18/2019] [Indexed: 05/05/2023]
Abstract
Activated carbon is the most common electrode material used in electrosorption processes such as water desalination with capacitive deionization (CDI). CDI is a cyclic process to remove ions from aqueous solutions by transferring charge from one electrode to another. When multiple salts are present in a solution, the removal of each ionic species can be different, resulting in selective ion separations. This ion selectivity is the result of combined effects, such as differences in the hydrated size and valence of the ions. In the present work, we study ion selectivity from salt mixtures with two different monovalent ions, chloride and nitrate. We run adsorption experiment in microporous carbons (i.e., without applying a voltage), as well as electrosorption experiments (i.e., based on applying a voltage between two carbon electrodes). Our results show that i) during adsorption and electrosorption, activated carbon removes much more nitrate than chloride; ii) at equilibrium, ion selectivity does not depend strongly on the composition of the water, but does depend on charging voltage in CDI; and iii) during electrosorption, ion selectivity is time-dependent. We modify the amphoteric Donnan model by including an additional affinity of nitrate to carbon. We find good agreement between our experimental results and the theory. Both show very high selectivity towards nitrate over chloride, [Formula: see text] ∼10, when no voltage is applied, or when the voltage is low. The selectivity gradually decreases with increasing charging voltage to [Formula: see text] ∼6 at Vch = 1.2 V. Despite this decrease, the affinity-effect for nitrate continues to play an important role also at a high voltage. In general, we can conclude that our work provides new insights in the importance of carbon-ion interactions for electrochemical water desalination.
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Affiliation(s)
- T M Mubita
- Department of Environmental Technology, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, the Netherlands; Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, the Netherlands
| | - J E Dykstra
- Department of Environmental Technology, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, the Netherlands.
| | - P M Biesheuvel
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, the Netherlands
| | - A van der Wal
- Department of Environmental Technology, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, the Netherlands; Evides Water Company, Schaardijk 150, 3063 NH Rotterdam, the Netherlands
| | - S Porada
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, the Netherlands; Soft Matter, Fluidics and Interfaces Group, Faculty of Science and Technology, University of Twente, Meander ME 314, 7500 AE Enschede, the Netherlands
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32
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Yang F, Ma J, Zhang X, Huang X, Liang P. Decreased charge transport distance by titanium mesh-membrane assembly for flow-electrode capacitive deionization with high desalination performance. WATER RESEARCH 2019; 164:114904. [PMID: 31382149 DOI: 10.1016/j.watres.2019.114904] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 07/17/2019] [Accepted: 07/22/2019] [Indexed: 06/10/2023]
Abstract
This study employed a titanium mesh-membrane assembly (MMA) as the current collector in flow-electrode capacitive deionization (FCDI) device (designated as M-FCDI), and obtained a much reduced charge transport distance as compared to traditional FCDI with plate-shaped current collectors located far from the exchange membrane. The average salt removal rate of M-FCDI was greatly improved by 76% under 10 wt% carbon content than the control experiment with graphite plate as current collector, and the charge efficiency remained over 75% even under low carbon loading. This improvement was attributed to the reduced resistance as revealed by electrochemical impedance spectroscopy tests. Further investigation on FCDI's performance with different specifications of titanium meshes showed that the implementation of MMA could provide a larger effective electron transfer area, which would lead to better desalting performance.
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Affiliation(s)
- Fan Yang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, PR China
| | - Junjun Ma
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, PR China
| | - Xudong Zhang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, PR China
| | - Xia Huang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, PR China.
| | - Peng Liang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, PR China.
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33
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Fritz PA, Boom R, Schroen K. Polyelectrolyte-activated carbon composite electrodes for inverted membrane capacitive deionization (iMCDI). Sep Purif Technol 2019. [DOI: 10.1016/j.seppur.2019.03.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Wang L, Lin S. Theoretical framework for designing a desalination plant based on membrane capacitive deionization. WATER RESEARCH 2019; 158:359-369. [PMID: 31055016 DOI: 10.1016/j.watres.2019.03.076] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 02/26/2019] [Accepted: 03/05/2019] [Indexed: 06/09/2023]
Abstract
Despite significant progress made in multiple aspects of capacitive deionization (CDI), a rational framework is in need for optimizing the design and operation of a large desalination system based on CDI. In this work, we develop a theoretical framework for guiding the design of a desalination plant based on CDI with ion exchange membranes (i.e. membrane CDI, or MCDI). This framework is established by identifying (1) the practical design constraints, (2) the inter-relationships between different design and operating parameters, (3) a set of independent variables, and (4) the key performance metrics. The proposed design framework reduces the degrees of freedom of the system and facilitates more focused and systematic analysis of the overall performance of an MCDI-based desalination plant. Careful analysis using the proposed design framework suggests the presence of an optimal tradeoff curve that comprises all the possible optima of design and operating conditions with which an MCDI-based desalination plant is the most cost-effective. We also show that the typical practice of using equal flowrates for charging and discharge yields very good performance compared to the optima, as long as water recovery is not too high. Finally, we also briefly explain the implication of this framework on cost-based optimization of the design and operation of an MCDI-based desalination plant.
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Affiliation(s)
- Li Wang
- Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN, 37235-1831, USA
| | - Shihong Lin
- Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN, 37235-1831, USA; Department of Chemical and Bimolecular Engineering, Vanderbilt University, Nashville, TN, 37235-1831, USA.
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Choi JH, Yoon DJ. A stable operation method for membrane capacitive deionization systems without electrode reactions at high cell potentials. WATER RESEARCH 2019; 157:167-174. [PMID: 30953851 DOI: 10.1016/j.watres.2019.03.083] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 02/24/2019] [Accepted: 03/27/2019] [Indexed: 06/09/2023]
Abstract
A method for operating membrane capacitive deionization (MCDI) systems without electrode reactions at a high cell potential was studied. The charge supplied to the cell was controlled to suppress Faradaic reactions. The maximum allowable charge (MAC) that can be supplied to a carbon electrode without electrode reactions was measured to be 58 C/g. Adsorption experiments were conducted while supplying a charge of 55 C/g (95% of the MAC value) in constant-current (CC) and constant-voltage (CV) mode. The cell potential increased to 1.42 V in CC (1.43-4.29 mA/cm2) mode, but the concentration and pH of the effluent were kept constant. In addition, the effluent pH was stable in CV (1.25-2.0 V) mode. The salt adsorption capacities and charge efficiencies were approximately 15.5 mg/g and 92%, respectively, regardless of the current densities and cell potentials applied to the cell. With increasing cell potential, the concentration polarization in the feed stream was intensified, resulting in an increase in cell resistance. It was thought that electrode reactions did not occur at a high cell potential because of the high voltage drop due to the cell resistance. The higher the cell potential (or current density) is, the faster the desalination rate in MCDI operation. It is expected that this operation method applying the MAC concept will contribute to the stable operation of MCDI systems and an improvement in desalination performance.
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Affiliation(s)
- Jae-Hwan Choi
- Department of Chemical Engineering, Kongju National University, 1223-24 Cheonan-daero, Seobuk-gu, Cheonan, Chungnam, 31080, South Korea.
| | - Duck-Jin Yoon
- Department of Chemical Engineering, Kongju National University, 1223-24 Cheonan-daero, Seobuk-gu, Cheonan, Chungnam, 31080, South Korea
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36
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Wang L, Lin S. Mechanism of Selective Ion Removal in Membrane Capacitive Deionization for Water Softening. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:5797-5804. [PMID: 31013430 DOI: 10.1021/acs.est.9b00655] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Capacitive deionization (CDI) is an emerging technology capable of selective removal of ions from water. While many studies have reported chemically tailored electrodes for selective ion removal, the selective removal of divalent cations (i.e., hardness) over monovalent cations can simply be achieved using membrane CDI (MCDI) equipped with ion exchange membranes (IEMs). In this study, we use both experimental and modeling approaches to systematically investigate the selective removal of Ca2+ over Na+. Specifically, the impacts of current density, hydraulic retention time, and feed composition on the selectivity of Ca2+ over Na+ were investigated. The results from our study suggest a universal correlation between the ratio of molar fluxes and the ratio of spacer channel ion concentrations, regardless of operating conditions and feed composition. Our analysis also reveals inherent and universal trade-off relationships between selectivity and the Ca2+ removal rate and between selectivity and the degree of Ca2+ removal. This fundamental understanding of the mechanism of selective ion removal in MCDI can also be applied to flow-electrode CDI processes that employ IEMs.
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Affiliation(s)
- Li Wang
- Department of Civil and Environmental Engineering , Vanderbilt University , Nashville , Tennessee 37235-1831 , United States
| | - Shihong Lin
- Department of Civil and Environmental Engineering , Vanderbilt University , Nashville , Tennessee 37235-1831 , United States
- Department of Chemical and Biomolecular Engineering , Vanderbilt University , Nashville , Tennessee 37235-1604 , United States
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37
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Wang L, Dykstra JE, Lin S. Energy Efficiency of Capacitive Deionization. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:3366-3378. [PMID: 30802038 DOI: 10.1021/acs.est.8b04858] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Capacitive deionization (CDI) as a class of electrochemical desalination has attracted fast-growing research interest in recent years. A significant part of this growing interest is arguably attributable to the premise that CDI is energy efficient and has the potential to outcompete other conventional desalination technologies. In this review, systematic evaluation of literature data reveals that while the absolute energy consumption of CDI is in general low, most existing CDI systems achieve limited energy efficiency from a thermodynamic perspective. We also analyze the causes for the relatively low energy efficiency and discuss factors that may lead to enhanced energy efficiency for CDI.
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Affiliation(s)
- Li Wang
- Department of Civil and Environmental Engineering , Vanderbilt University , Nashville , Tennessee 37235-1831 , United States
| | - J E Dykstra
- Department of Environmental Technology , Wageningen University , Bornse Weilanden 9 , 6708 WG Wageningen , The Netherlands
| | - Shihong Lin
- Department of Civil and Environmental Engineering , Vanderbilt University , Nashville , Tennessee 37235-1831 , United States
- Department of Chemical and Biomolecular Engineering , Vanderbilt University , Nashville , Tennessee 37235-1604 , United States
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38
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Selective removal of nitrate ion using a novel activated carbon composite carbon electrode in capacitive deionization. Sep Purif Technol 2019. [DOI: 10.1016/j.seppur.2018.11.081] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Hawks SA, Ramachandran A, Porada S, Campbell PG, Suss ME, Biesheuvel PM, Santiago JG, Stadermann M. Performance metrics for the objective assessment of capacitive deionization systems. WATER RESEARCH 2019; 152:126-137. [PMID: 30665159 DOI: 10.1016/j.watres.2018.10.074] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 10/25/2018] [Accepted: 10/28/2018] [Indexed: 06/09/2023]
Abstract
In the growing field of capacitive deionization (CDI), a number of performance metrics have emerged to describe the desalination process. Unfortunately, the separation conditions under which these metrics are measured are often not specified, resulting in optimal performance at minimal removal. Here we outline a system of performance metrics and reporting conditions that resolves this issue. Our proposed system is based on volumetric energy consumption (Wh/m3) and throughput productivity (L/h/m2) reported for a specific average concentration reduction, water recovery, and feed salinity. To facilitate and rationalize comparisons between devices, materials, and operation modes, we propose a nominal standard separation of removing 5 mM from a 20 mM NaCl feed solution at 50% water recovery. We propose this particular separation as a standard, but emphasize that the rationale presented here applies irrespective of separation details. Using our proposed separation, we compare the desalination performance of a flow-through electrode (fte-CDI) cell and a flow between membrane (fb-MCDI) device, showing how significantly different systems can be compared in terms of generally desirable desalination characteristics. In general, we find that performance analysis must be considered carefully so to not allow for ambiguous separation conditions or the maximization of one metric at the expense of another. Additionally, for context and clarity, we discuss a number of important underlying performance indicators and cell characteristics that are not performance measures in and of themselves but can be examined to better understand differences in performance.
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Affiliation(s)
- Steven A Hawks
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA, United States
| | - Ashwin Ramachandran
- Department of Aeronautics & Astronautics, Stanford University, Stanford, CA, 94305, United States
| | - Slawomir Porada
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA, Leeuwarden, The Netherlands; Soft Matter, Fluidics and Interfaces Group, Faculty of Science and Technology, University of Twente, Meander ME 314, 7500 AE, Enschede, the Netherlands
| | - Patrick G Campbell
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA, United States
| | - Matthew E Suss
- Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - P M Biesheuvel
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA, Leeuwarden, The Netherlands
| | - Juan G Santiago
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, United States
| | - Michael Stadermann
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA, United States.
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40
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Bhat AP, Reale ER, del Cerro M, Smith KC, Cusick RD. Reducing impedance to ionic flux in capacitive deionization with Bi-tortuous activated carbon electrodes coated with asymmetrically charged polyelectrolytes. WATER RESEARCH X 2019; 3:100027. [PMID: 31193985 PMCID: PMC6549939 DOI: 10.1016/j.wroa.2019.100027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 02/22/2019] [Accepted: 02/23/2019] [Indexed: 05/30/2023]
Abstract
Capacitive deionization (CDI) with electric double layers is an electrochemical desalination technology in which porous carbon electrodes are polarized to reversibly store ions. Planar composite CDI electrodes exhibit poor energetic performance due the resistance associated with salt depletion and tortuous diffusion in the macroporous structure. In this work, we investigate the impact of bi-tortuosity on desalination performance by etching macroporous patterns along the length of activated carbon porous electrodes in a flow-by CDI architecture. Capacitive electrodes were also coated with thin asymmetrically charged polyelectrolytes to improve ion-selectivity while maintaining the bitortuous macroporous channels. Under constant current operation, the equivalent circuit resistance in CDI cells operating with bi-tortuous electrodes was approximately 2.2 times less than a control cell with unpatterned electrodes, leading to significant increases in working capacitance (20-22 to 26.7-27.8 F g-1), round-trip efficiency (52-71 to 71-80%), and charge efficiency (33-59 to 35-67%). Improvements in these key performance indicators also translated to enhanced salt adsorption capacity, rate, and most importantly, the thermodynamic efficiency of salt separation (1.0-2.0 to 2.2-4.1%). These findings demonstrate that the use of bi-tortuous electrodes is a novel approach of reducing impedance to ionic flux in CDI.
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Affiliation(s)
- Akash P. Bhat
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Erik R. Reale
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Martina del Cerro
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Kyle C. Smith
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Computational Science and Engineering Program, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Beckman Institute for Advanced Study, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Roland D. Cusick
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
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41
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Song J, Ma J, Zhang C, He C, Waite TD. Implication of Non-electrostatic Contribution to Deionization in Flow-Electrode CDI: Case Study of Nitrate Removal From Contaminated Source Waters. Front Chem 2019; 7:146. [PMID: 30968014 PMCID: PMC6439345 DOI: 10.3389/fchem.2019.00146] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 02/28/2019] [Indexed: 11/13/2022] Open
Abstract
While flow-electrode capacitive deionization (FCDI) operated in short-circuited closed cycle (SCC) mode appears to hold promise for removal of salt from brackish source waters, there has been limited investigation on the removal of other water constituents such as nitrate, fluoride or bromide in combination with salt removal. Of particular concern is the effectiveness of FCDI when ions, such as nitrate, are recognized to non-electrostatically adsorb strongly to activated carbon particles thereby potentially rendering it difficult to regenerate these particles. In this study, SCC FCDI was used to desalt source waters containing nitrate at different concentrations. Results indicate that nitrate can be removed from source waters using FCDI to concentrations <1 mg NO3-N L-1 though a lower quality target such as 10 mg L-1 would be more cost-effective, particularly where the influent nitrate concentration is high (50 mg NO3-N L-1). Although studies of the fate of nitrate in the FCDI system show that physico-chemical adsorption of nitrate to the carbon initially plays a vital role in nitrate removal, the ongoing process of nitrate removal is not significantly affected by this phenomenon with this lack of effect most likely due to the continued formation of electrical double layers enabling capacitive nitrate removal. In contrast to conventional CDI systems, constant voltage mode is shown to be more favorable in maintaining stable effluent quality in SCC FCDI because the decrease in electrical potential that occurs in constant current operation leads to a reduction in the extent of salt removal from the brackish source waters. Through periodic replacement of the electrolyte at a water recovery of 91.4%, we show that the FCDI system can achieve a continuous desalting performance with the effluent NO3-N concentration below 1 mg NO3-N L-1 at low energy consumption (~0.5 kWh m-3) but high productivity.
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Affiliation(s)
- Jingke Song
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, Australia.,College of Environmental Science and Engineering, Tongji University, Shanghai, China.,Shanghai Institute of Pollution Control and Ecological Security, Shanghai, China
| | - Jinxing Ma
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, Australia
| | - Changyong Zhang
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, Australia
| | - Calvin He
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, Australia
| | - T David Waite
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, Australia
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43
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Kim M, Cerro MD, Hand S, Cusick RD. Enhancing capacitive deionization performance with charged structural polysaccharide electrode binders. WATER RESEARCH 2019; 148:388-397. [PMID: 30399553 DOI: 10.1016/j.watres.2018.10.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 09/24/2018] [Accepted: 10/14/2018] [Indexed: 06/08/2023]
Abstract
Capacitive deionization (CDI) performance, as measured by salt adsorption capacity (SAC) and energy normalized adsorption of salt (ENAS), is frequently limited by anion repulsion at the positive electrode. In this work, we investigate the ability to prevent co-ion repulsion by increasing complementary fixed charged within the electrode macropores by binding composite CDI electrodes with the ionically charged structural polysaccharides chitosan and carboxymethyl cellulose. When employing asymmetrically charged electrode binders, co-ion repulsion was prevented, resulting in SAC and ENAS values that were three times greater than composite electrodes bound with polyvinylidene fluoride (PVDF) and similar to CDI electrodes composed of chemically modified carbon. Polysaccharide binders did not modify the charge balance in the carbon micropores but did shift the discharge voltage of maximum adsorption, enabling a shift in operating voltage that prolonged cycle lifetime without a significant loss in performance. The mechanism of improved salt accumulation with polysaccharide binders was explored with a one-dimensional model that integrated CDI and ion-exchange membrane covered (MCDI) sub-units. Model simulations indicate that carbon macropores covered with thin layers of charged polysaccharides increase adsorption by a sequential accumulation and release of salt to depleted uncovered pores.
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Affiliation(s)
- Martin Kim
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, 3217 Newmark Civil Engineering Laboratory, Urbana, IL 61801, USA
| | - Martina Del Cerro
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, 3217 Newmark Civil Engineering Laboratory, Urbana, IL 61801, USA
| | - Steven Hand
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, 3217 Newmark Civil Engineering Laboratory, Urbana, IL 61801, USA
| | - Roland D Cusick
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, 3217 Newmark Civil Engineering Laboratory, Urbana, IL 61801, USA.
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44
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Tan C, He C, Tang W, Kovalsky P, Fletcher J, Waite TD. Integration of photovoltaic energy supply with membrane capacitive deionization (MCDI) for salt removal from brackish waters. WATER RESEARCH 2018; 147:276-286. [PMID: 30317037 DOI: 10.1016/j.watres.2018.09.056] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 09/27/2018] [Accepted: 09/30/2018] [Indexed: 06/08/2023]
Abstract
Capacitive de-ionization (CDI) systems are well-known for their low energy consumption making them suitable for applications powered by renewable energy. In this study, CDI technology is, for the first time, integrated with a suitably-scaled, stand-alone, renewable power system comprising photovoltaic panels and battery storage. Guidelines for designing and sizing such power systems are proposed including determining electrode charging current, PV panels and battery capacity. A 1 kW pilot plant was designed, constructed and operated to verify the proposed guidelines. Using the pilot plant, the total energy consumption of the system has been evaluated with different electrode charging currents and influent flow rates and the relationship between these parameters analyzed. This analysis has enabled the development of practical design guidelines for bulk water treatment with MCDI electrodes. The results of this study show that use of photovoltaic-powered MCDI water treatment, particularly when combined with energy recovery, is competitive against more mature water-treatment technologies for particular applications and at particular locations.
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Affiliation(s)
- Cheng Tan
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW 2052, Australia.
| | - Calvin He
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, 2052, Australia.
| | - Wangwang Tang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha, 410082, China.
| | - Peter Kovalsky
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, 2052, Australia.
| | - John Fletcher
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW 2052, Australia.
| | - T David Waite
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, 2052, Australia.
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45
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Zhang Y, Chen L, Mao S, Sun Z, Song Y, Zhao R. Fabrication of porous graphene electrodes via CO 2 activation for the enhancement of capacitive deionization. J Colloid Interface Sci 2018; 536:252-260. [PMID: 30368097 DOI: 10.1016/j.jcis.2018.10.063] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/18/2018] [Accepted: 10/21/2018] [Indexed: 11/15/2022]
Abstract
Capacitive deionization (CDI) is a simple, cost-efficient and environmentally-friendly method for brackish water desalination. In order to improve the desalination performance, the inner structures of the porous electrodes should provide more space for ion storage and transportation. Therefore, we utilized an efficient method to synthesize porous graphene electrodes based on the technique of pressurized oxidation and CO2 activation. The prepared electrodes were characterized electrochemically by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy, and the desalination performance between different samples was compared as well. These results showed that AGE-30 had the highest electrosorption capacity (6.26 mg/g) among all samples, and this was attributed to its high specific surface area (898 m2/g), high pore volume (1.223 cm3/g), high specific capacitance (56.21F/g), and smaller inner resistance. Thus, the CO2 activation is confirmed to be a useful method for the enhancement of the graphene electrodes for CDI.
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Affiliation(s)
- Yi Zhang
- Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, School of Physics and Materials Science, East China Normal University, 3663 North Zhongshan Road, 200062 Shanghai, China
| | - Ling Chen
- Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, School of Physics and Materials Science, East China Normal University, 3663 North Zhongshan Road, 200062 Shanghai, China
| | - Shudi Mao
- Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, School of Physics and Materials Science, East China Normal University, 3663 North Zhongshan Road, 200062 Shanghai, China
| | - Zhuo Sun
- Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, School of Physics and Materials Science, East China Normal University, 3663 North Zhongshan Road, 200062 Shanghai, China
| | - Yenan Song
- Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, School of Physics and Materials Science, East China Normal University, 3663 North Zhongshan Road, 200062 Shanghai, China.
| | - Ran Zhao
- Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, School of Physics and Materials Science, East China Normal University, 3663 North Zhongshan Road, 200062 Shanghai, China.
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46
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Dykstra JE, Porada S, van der Wal A, Biesheuvel PM. Energy consumption in capacitive deionization - Constant current versus constant voltage operation. WATER RESEARCH 2018; 143:367-375. [PMID: 29986246 DOI: 10.1016/j.watres.2018.06.034] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Revised: 05/24/2018] [Accepted: 06/15/2018] [Indexed: 06/08/2023]
Abstract
In the field of Capacitive Deionization (CDI), it has become a common notion that constant current (CC) operation consumes significantly less energy than constant voltage operation (CV). Arguments in support of this claim are that in CC operation the endpoint voltage is reached only at the end of the charging step, and thus the average cell voltage during charging is lower than the endpoint voltage, and that in CC operation we can recover part of the invested energy during discharge. Though these arguments are correct, in the present work based on experiments and theory, we conclude that in operation of a well-defined CDI cycle, this does not lead, for the case we analyze, to the general conclusion that CC operation is more energy efficient. Instead, we find that without energy recovery there is no difference in energy consumption between CC and CV operation. Including 50% energy recovery, we find that indeed CC is more energy efficient, but also in CV much energy can be recovered. Important in the analysis is to precisely define the desalination objective function, such as that per unit total operational time -including both the charge and discharge steps- a certain desalination quantity and water recovery must be achieved. Another point is that also in CV operation energy recovery is possible by discharge at a non-zero cell voltage. To aid the analysis we present a new method of data representation where energy consumption is plotted against desalination. In addition, we propose that one must analyze the full range of combinations of cycle times, voltages and currents, and only compare the best cycles, to be able to conclude which operational mode is optimal for a given desalination objective. We discuss three methods to make this analysis in a rigorous way, two experimental and one combining experiments and theory. We use the last method and present results of this analysis.
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Affiliation(s)
- J E Dykstra
- Department of Environmental Technology, Wageningen University, the Netherlands; Wetsus, European Centre of Excellence for Sustainable Water Technology, Leeuwarden, the Netherlands.
| | - S Porada
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Leeuwarden, the Netherlands; Soft matter, Fluidics and Interfaces Group, Faculty of Science and Technology, University of Twente, Enschede, the Netherlands
| | - A van der Wal
- Department of Environmental Technology, Wageningen University, the Netherlands; Evides, Rotterdam, the Netherlands
| | - P M Biesheuvel
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Leeuwarden, the Netherlands
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47
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Hemmatifar A, Ramachandran A, Liu K, Oyarzun DI, Bazant MZ, Santiago JG. Thermodynamics of Ion Separation by Electrosorption. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:10196-10204. [PMID: 30141621 DOI: 10.1021/acs.est.8b02959] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present a simple, top-down approach for the calculation of minimum energy consumption of electrosorptive ion separation using variational form of the (Gibbs) free energy. We focus and expand on the case of electrostatic capacitive deionization (CDI). The theoretical framework is independent of details of the double-layer charge distribution and is applicable to any thermodynamically consistent model, such as the Gouy-Chapman-Stern and modified Donnan models. We demonstrate that, under certain assumptions, the minimum required electric work energy is indeed equivalent to the free energy of separation. Using the theory, we define the thermodynamic efficiency of CDI. We show that the thermodynamic efficiency of current experimental CDI systems is currently very low, around 1% for most existing systems. We applied this knowledge and constructed and operated a CDI cell to show that judicious selection of the materials, geometry, and process parameters can lead to a 9% thermodynamic efficiency and 4.6 kT per removed ion energy cost. This relatively high thermodynamic efficiency is, to our knowledge, by far the highest thermodynamic efficiency ever demonstrated for traditional CDI. We hypothesize that efficiency can be further improved by further reduction of CDI cell series resistances and optimization of operational parameters.
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Affiliation(s)
- Ali Hemmatifar
- Department of Mechanical Engineering , Stanford University , Stanford , California 94305 , United States
| | - Ashwin Ramachandran
- Department of Aeronautics & Astronautics , Stanford University , Stanford , California 94305 , United States
| | - Kang Liu
- Department of Mechanical Engineering , Stanford University , Stanford , California 94305 , United States
| | - Diego I Oyarzun
- Department of Mechanical Engineering , Stanford University , Stanford , California 94305 , United States
| | - Martin Z Bazant
- Departments of Chemical Engineering and Mathematics , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Juan G Santiago
- Department of Mechanical Engineering , Stanford University , Stanford , California 94305 , United States
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Legrand L, Schaetzle O, de Kler RCF, Hamelers HVM. Solvent-Free CO 2 Capture Using Membrane Capacitive Deionization. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:9478-9485. [PMID: 29993236 DOI: 10.1021/acs.est.8b00980] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Capture of CO2, originating from both fossil fuels, such as coal combustion, and from renewables, such as biogas, appears to be one of the greatest technological challenges of this century. In this study, we show that membrane capacitive deionization (MCDI) can be used to capture CO2 as bicarbonate and carbonate ions produced from the reaction of CO2 with water. This novel approach allows capturing CO2 at room temperature and atmospheric pressure without the use of chemicals. In this process, the adsorption and desorption of bicarbonate ions from the deionized water solution drive the CO2(g) absorption-desorption from the gas phase. In this work, the effects of the current density and the CO2 partial pressure were studied. We found that between 55 and 75% of the electrical charge of the capacitive electrodes can be directly used to absorb CO2 gas. The energy requirement of such a system was found to be ≈40 kJ mol-1 at 15% CO2 and could be further improved by reducing the ohmic and non-ohmic energy losses of the MCDI cell.
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Affiliation(s)
- L Legrand
- Wetsus, European Centre of Excellence for Sustainable Water Technology , Oostergoweg 7 , 8911 MA Leeuwarden , The Netherlands
- Department of Environmental Technology , Wageningen University , Bornse Weilanden 9 , 6708 WG Wageningen , The Netherlands
| | - O Schaetzle
- Wetsus, European Centre of Excellence for Sustainable Water Technology , Oostergoweg 7 , 8911 MA Leeuwarden , The Netherlands
| | - R C F de Kler
- Wetsus, European Centre of Excellence for Sustainable Water Technology , Oostergoweg 7 , 8911 MA Leeuwarden , The Netherlands
| | - H V M Hamelers
- Wetsus, European Centre of Excellence for Sustainable Water Technology , Oostergoweg 7 , 8911 MA Leeuwarden , The Netherlands
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Hassanvand A, Chen GQ, Webley PA, Kentish SE. A comparison of multicomponent electrosorption in capacitive deionization and membrane capacitive deionization. WATER RESEARCH 2018; 131:100-109. [PMID: 29277078 DOI: 10.1016/j.watres.2017.12.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 11/03/2017] [Accepted: 12/09/2017] [Indexed: 06/07/2023]
Abstract
In this study, the desalination performance of Capacitive Deionization (CDI) and Membrane Capacitive Deionization (MCDI) was studied for a wide range of salt compositions. The comprehensive data collection for monovalent and divalent ions used in this work enabled us to understand better the competitive electrosorption of these ions both with and without ion-exchange membranes (IEMs). As expected, MCDI showed an enhanced salt adsorption and charge efficiency in comparison with CDI. However, the different electrosorption behavior of the former reveals that ion transport through the IEMs is a significant rate-controlling step in the desalination process. A sharper desorption peak is observed for divalent ions in MCDI, which can be attributed to a portion of these ions being temporarily stored within the IEMs, thus they are the first to leave the cell upon discharge. In addition to salt concentration, we monitored the pH of the effluent stream in CDI and MCDI and discuss the potential causes of these fluctuations. The dramatic pH change over one adsorption and desorption cycle in CDI (pH range of 3.5-10.5) can be problematic in a feed water containing components prone to scaling. The pH change, however, was much more limited in the case of MCDI for all salts.
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Affiliation(s)
- Armineh Hassanvand
- School of Chemical and Biomedical Engineering, University of Melbourne, Parkville, VIC 3010, Australia
| | - George Q Chen
- School of Chemical and Biomedical Engineering, University of Melbourne, Parkville, VIC 3010, Australia; The ARC Dairy Innovation Hub, Department of Chemical Engineering, University of Melbourne, Parkville, VIC 3010, Australia
| | - Paul A Webley
- School of Chemical and Biomedical Engineering, University of Melbourne, Parkville, VIC 3010, Australia
| | - Sandra E Kentish
- School of Chemical and Biomedical Engineering, University of Melbourne, Parkville, VIC 3010, Australia; The ARC Dairy Innovation Hub, Department of Chemical Engineering, University of Melbourne, Parkville, VIC 3010, Australia.
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