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Zhu Y, Lian B, Wang Y, Miller C, Bales C, Fletcher J, Yao L, Waite TD. Machine learning modelling of a membrane capacitive deionization (MCDI) system for prediction of long-term system performance and optimization of process control parameters in remote brackish water desalination. WATER RESEARCH 2022; 227:119349. [PMID: 36402097 DOI: 10.1016/j.watres.2022.119349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 10/22/2022] [Accepted: 11/08/2022] [Indexed: 06/16/2023]
Abstract
Membrane Capacitive Deionization (MCDI) is a promising electrochemical technique for water desalination. Previous studies have confirrmed the effectiveness of MCDI in removing contaminants from brackish groundwaters, especially in remote areas where electricity is scarce. However, as with other water treatment technologies, performance deterioration of the MCDI system still occurs, hindering the stability of long-term operation. Herein, a machine learning (ML) modelling framework and various ML models were developed to (i) investigate the performance deterioration due particularly to insufficient charging/discharging of the electrode caused by accumulation of ions and electrode scaling and (ii) optimise MCDI operating parameters such that the impacts of these deleterious effects on unit performance were minimized. The ML models developed in this work exhibited a prediction accuracy of cycle time with average mean absolute percentage error (MAPE) values of 16.82% and 16.09% after 30-fold cross validation for Random Forest (RF) and Multilayer Perceptron (MLP) models respectively. The pre-trained ML model predicted different declining trends of water production for two different operating conditions and provided corresponding recommendations on frequencies of chemical cleaning. A case study on the adjustment of operating parameters using the results suggested by the optimization ML model was conducted. The model validation results showed that the overall water production and water recovery of the system using the cycle-based optimized process control parameters (SCN 1) exceeds the MCDI system performance under three fixed parameter settings that were used at each stage of SCN 1 by 1.78% to 4.48% and 2.95% to 9.46%, respectively. Permutation-based and Shapley additive explanation (SHAP) coefficients were also employed for variable importance (VIMP) analysis to uncover the "black-box" nature of the ML models and to better understand the various features' contributions to overall MCDI system performance.
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Affiliation(s)
- Yunyi Zhu
- UNSW Centre for Transformational Environmental Technologies (CTET), Yixing, Jiangsu, China; Water Research Centre, School of Civil and Environmental Engineering, UNSW Sydney, Australia
| | - Boyue Lian
- Water Research Centre, School of Civil and Environmental Engineering, UNSW Sydney, Australia
| | - Yuan Wang
- UNSW Centre for Transformational Environmental Technologies (CTET), Yixing, Jiangsu, China; Water Research Centre, School of Civil and Environmental Engineering, UNSW Sydney, Australia
| | - Christopher Miller
- Water Research Centre, School of Civil and Environmental Engineering, UNSW Sydney, Australia
| | - Clare Bales
- Water Research Centre, School of Civil and Environmental Engineering, UNSW Sydney, Australia
| | - John Fletcher
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Australia
| | - Lina Yao
- School of Computer Science and Engineering, UNSW Sydney, Australia
| | - T David Waite
- UNSW Centre for Transformational Environmental Technologies (CTET), Yixing, Jiangsu, China; Water Research Centre, School of Civil and Environmental Engineering, UNSW Sydney, Australia.
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SONG X, FANG D, HUO S, SONG X, HE M, ZHANG W, LI K. Exceptional capacitive deionization desalination performance of hollow bowl-like carbon derived from MOFs in brackish water. Sep Purif Technol 2021. [DOI: 10.1016/j.seppur.2021.119550] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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3
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Luo L, He Q, Ma Z, Yi D, Chen Y, Ma J. In situ potential measurement in a flow-electrode CDI for energy consumption estimation and system optimization. WATER RESEARCH 2021; 203:117522. [PMID: 34384947 DOI: 10.1016/j.watres.2021.117522] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/28/2021] [Accepted: 08/02/2021] [Indexed: 06/13/2023]
Abstract
Flow electrode capacitive deionization (FCDI) is a promising electrochemical technique for brackish water desalination; however, there are challenges in estimating the distribution of resistance and energy consumption inside a FCDI system, which hinders the optimization of the rate-limiting compartment. In this study, energy consumption of each FCDI component (e.g., flow electrodes, membranes and desalination chamber) was firstly described by using in situ potential measurement (ISPM). Results of this study showed that the energy consumption (EC) of the flow electrodes dominated under most conditions. While an increase in the carbon black content in the flow electrodes could improve the energy efficiency of the electrode component, consideration should be given to the contribution of ion exchange membranes (IEMs) and the desalination chamber to the EC. Based on the above analysis, system optimization was carried out by introducing IEMs with relatively low resistance and/or packing the desalination chamber with titanium meshes. Results showed that the voltage-driven desalination capability was increased by 39.3% with the EC reduced by 17.5% compared to the control, which overcame the tradeoff between the kinetic and energetic efficiencies. Overall, the present work facilitates our understanding of the potential drops across an FCDI system and provides insight to the optimization of system design and operation.
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Affiliation(s)
- Liang Luo
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400044, PR China.; National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing 400044, PR China
| | - Qiang He
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400044, PR China.; National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing 400044, PR China
| | - Zixin Ma
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400044, PR China.; National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing 400044, PR China
| | - Duo Yi
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400044, PR China.; National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing 400044, PR China
| | - Yi Chen
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400044, PR China.; National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing 400044, PR China..
| | - Jinxing Ma
- Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou, 510006, PR China.
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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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Shi L, Newcomer E, Son M, Pothanamkandathil V, Gorski CA, Galal A, Logan BE. Metal-Ion Depletion Impacts the Stability and Performance of Battery Electrode Deionization over Multiple Cycles. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:5412-5421. [PMID: 33784453 DOI: 10.1021/acs.est.0c08629] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Prussian blue hexacyanoferrate (HCF) materials, such as copper hexacyanoferrate (CuHCF) and nickel hexacyanoferrate (NiHCF), can produce higher salt removal capacities than purely capacitive materials when used as electrode materials during electrochemical water deionization due to cation intercalation into the HCF structure. One factor limiting the application of HCF materials is their decay in deionization performance over multiple cycles. By examining the performance of CuHCF and NiHCF electrodes at three different pH values (2.5, 6.3, and 10.2) in multiple-cycle deionization tests, losses in capacity (up to 73% for CuHCF and 39% for NiHCF) were shown to be tied to different redox-active centers through analysis of dissolution of electrode metals. Both copper and iron functioned as active centers for Na+ removal in CuHCF, while iron was mainly the active center in NiHCF. This interaction of Na+ and active centers was demonstrated by correlating the decrease in performance to the concentration of these metal ions in the effluent solutions collected over multiple cycles at different pHs (up to 0.86 ± 0.14 mg/L for iron and 0.42 ± 0.17 mg/L for copper in CuHCF and 0.38 ± 0.05 mg/L for iron in NiHCF). Both materials were more stable (<11% decay for CuHCF and no decay for NiHCF) when the appropriate metal salt (copper or nickel) was added to the feed solutions to inhibit electrode dissolution. At a pH of 2.5, there was an increased competition between protons and Na+ ions, which decreased the Na+ removal amount and lowered the thermodynamic energy efficiency for deionization for both electrode materials. Therefore, while an acidic pH provided the most stable performance, a circumneutral pH would be useful to produce a better balance between performance and longevity.
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Affiliation(s)
- Le Shi
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Evan Newcomer
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Moon Son
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Vineeth Pothanamkandathil
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Christopher A Gorski
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Ahmed Galal
- Chemistry Department, Faculty of Science, Cairo University, Giza 12613, Egypt
| | - Bruce E Logan
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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Zhang C, Ma J, Wu L, Sun J, Wang L, Li T, Waite TD. Flow Electrode Capacitive Deionization (FCDI): Recent Developments, Environmental Applications, and Future Perspectives. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:4243-4267. [PMID: 33724803 DOI: 10.1021/acs.est.0c06552] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
With the increasing severity of global water scarcity, a myriad of scientific activities is directed toward advancing brackish water desalination and wastewater remediation technologies. Flow-electrode capacitive deionization (FCDI), a newly developed electrochemically driven ion removal approach combining ion-exchange membranes and flowable particle electrodes, has been actively explored over the past seven years, driven by the possibility of energy-efficient, sustainable, and fully continuous production of high-quality fresh water, as well as flexible management of the particle electrodes and concentrate stream. Here, we provide a comprehensive overview of current advances of this interesting technology with particular attention given to FCDI principles, designs (including cell architecture and electrode and separator options), operational modes (including approaches to management of the flowable electrodes), characterizations and modeling, and environmental applications (including water desalination, resource recovery, and contaminant abatement). Furthermore, we introduce the definitions and performance metrics that should be used so that fair assessments and comparisons can be made between different systems and separation conditions. We then highlight the most pressing challenges (i.e., operation and capital cost, scale-up, and commercialization) in the full-scale application of this technology. We conclude this state-of-the-art review by considering the overall outlook of the technology and discussing areas requiring particular attention in the future.
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Affiliation(s)
- Changyong Zhang
- 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
| | - Lei Wu
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Jingyi Sun
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Li Wang
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States
| | - Tianyu Li
- 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
- Shanghai Institute of Pollution Control and Ecological Safety, Tongji University, Shanghai 200092, P. R. China
- UNSW Centre for Transformational Environmental Technologies, Yixing, Jiangsu Province 214206, P. R. China
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Liu Y, Deng YY, Zhang Q, Liu H. Overview of recent developments of resource recovery from wastewater via electrochemistry-based technologies. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 757:143901. [PMID: 33310303 DOI: 10.1016/j.scitotenv.2020.143901] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 11/05/2020] [Accepted: 11/17/2020] [Indexed: 06/12/2023]
Abstract
As the rapid increase of the worldwide population, recovering valuable resources from wastewater have attracted more and more attention by governments and academia. Electrochemical technologies have been extensively investigated over the past three decades to purify wastewater. However, the application of these technologies for resource recovery from wastewater has just attracted limited attention. In this review, the recent (2010-2020) electrochemical technologies for resource recovery from wastewater are summarized and discussed for the first time. Fundamentals of typical electrochemical technologies are firstly summarized and analyzed, followed by the specific examples of electrochemical resource recovery technologies for different purposes. Based on the fundamentals of electrochemical reactions and without the addition of chemical agents, metallic ions, nutrients, sulfur, hydrogen and chemical compounds can be effectively recovered by means of electrochemical reduction, electrochemical induced precipitation, electrochemical stripping, electrochemical oxidation and membrane-based electrochemical processes, etc. Pros and cons of each electrochemical technology in practical applications are discussed and analyzed. Single-step electrochemical process seems ineffectively to recover valuable resources from the wastewater with complicated constituents. Multiple-step processes or integrated with biological and membrane-based technologies are essential to improve the performance and purity of products. Consequently, this review attempts to offer in-depth insights into the developments of next-generation of electrochemical technologies to minimize energy consumption, boost recovery efficiency and realize the commercial application.
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Affiliation(s)
- Yuan Liu
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Key Laboratory of Reservoir Aquatic Environment, Chinese Academy of Sciences, Chongqing 400714, China.
| | - Ying-Ying Deng
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Key Laboratory of Reservoir Aquatic Environment, Chinese Academy of Sciences, Chongqing 400714, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qi Zhang
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Key Laboratory of Reservoir Aquatic Environment, Chinese Academy of Sciences, Chongqing 400714, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hong Liu
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Key Laboratory of Reservoir Aquatic Environment, Chinese Academy of Sciences, Chongqing 400714, China
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Son M, Cho KH, Jeong K, Park J. Membrane and Electrochemical Processes for Water Desalination: A Short Perspective and the Role of Nanotechnology. MEMBRANES 2020; 10:E280. [PMID: 33053773 PMCID: PMC7600412 DOI: 10.3390/membranes10100280] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/07/2020] [Accepted: 10/09/2020] [Indexed: 11/16/2022]
Abstract
In the past few decades, membrane-based processes have become mainstream in water desalination because of their relatively high water flux, salt rejection, and reasonable operating cost over thermal-based desalination processes. The energy consumption of the membrane process has been continuously lowered (from >10 kWh m-3 to ~3 kWh m-3) over the past decades but remains higher than the theoretical minimum value (~0.8 kWh m-3) for seawater desalination. Thus, the high energy consumption of membrane processes has led to the development of alternative processes, such as the electrochemical, that use relatively less energy. Decades of research have revealed that the low energy consumption of the electrochemical process is closely coupled with a relatively low extent of desalination. Recent studies indicate that electrochemical process must overcome efficiency rather than energy consumption hurdles. This short perspective aims to provide platforms to compare the energy efficiency of the representative membrane and electrochemical processes based on the working principle of each process. Future water desalination methods and the potential role of nanotechnology as an efficient tool to overcome current limitations are also discussed.
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Affiliation(s)
- Moon Son
- School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, UNIST-gil 50, Ulsan 44919, Korea; (M.S.); (K.H.C.)
| | - Kyung Hwa Cho
- School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, UNIST-gil 50, Ulsan 44919, Korea; (M.S.); (K.H.C.)
| | - Kwanho Jeong
- School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, UNIST-gil 50, Ulsan 44919, Korea; (M.S.); (K.H.C.)
| | - Jongkwan Park
- School of Civil, Environmental and Chemical Engineering, Changwon National University, Changwon, Gyeongsangnamdo 51140, Korea
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10
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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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Wang R, Lin S. Thermodynamic reversible cycles of electrochemical desalination with intercalation materials in symmetric and asymmetric configurations. J Colloid Interface Sci 2020; 574:152-161. [DOI: 10.1016/j.jcis.2020.04.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/02/2020] [Accepted: 04/07/2020] [Indexed: 01/23/2023]
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12
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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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Zhang C, Wu L, Ma J, Wang M, Sun J, Waite TD. Evaluation of long-term performance of a continuously operated flow-electrode CDI system for salt removal from brackish waters. WATER RESEARCH 2020; 173:115580. [PMID: 32065937 DOI: 10.1016/j.watres.2020.115580] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/31/2020] [Accepted: 02/01/2020] [Indexed: 06/10/2023]
Abstract
While flow-electrode capacitive deionization (FCDI), one of the most popular CDI variants, possesses a number of advantages over conventional fixed-electrode CDI (e.g., large salt adsorption capacity, high flow efficiency and convenient management of the electrodes), challenges remain in constructing and operating an FCDI system such that it can operate continuously. Here we achieve effective continuous removal of salt from a brackish feed stream using flowing carbon electrodes which are regenerated in a closed-loop manner by using our previously introduced integrated FCDI/MF strategy. The performance of the FCDI/MF system is characterized over a two week period of operation with key factors influencing the desalination performance identified. Results show that the FCDI/MF system is capable of continuously desalinating brackish water (∼2 g L-1) to portable levels (<0.5 g L-1) whilst sustaining an extraordinary water recovery rate (∼92%) and relatively low energy consumption (∼0.5 kWh m-3). No obvious deterioration in performance or membrane fouling was observed during the 14-day operation. While the carbon particles used in the flow electrode exhibited only a minor increase in oxygen-containing groups over the 14 days of operation, a significant reduction in particle size was observed, likely as a consequence of the high-frequency collisions and associated friction between particles that occurred in the FCDI/MF system. Further studies regarding flowable electrode optimization, cell configuration design and process modelling are needed in order to realize the scale-up and practical implementation of this emerging technology.
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Affiliation(s)
- Changyong Zhang
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, 2052, Australia.
| | - Lei Wu
- 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.
| | - Min Wang
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, 2052, Australia.
| | - Jingyi Sun
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, 2052, Australia.
| | - T David Waite
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, 2052, Australia; Shanghai Institute of Pollution Control and Ecological Safety, Tongji University, Shanghai, 200092, PR China; UNSW Centre for Transformational Environmental Technologies, Yixing, Jiangsu Province, 214206, PR China.
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Patel SK, Qin M, Walker WS, Elimelech M. Energy Efficiency of Electro-Driven Brackish Water Desalination: Electrodialysis Significantly Outperforms Membrane Capacitive Deionization. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:3663-3677. [PMID: 32084313 DOI: 10.1021/acs.est.9b07482] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Electro-driven technologies are viewed as a potential alternative to the current state-of-the-art technology, reverse osmosis, for the desalination of brackish waters. Capacitive deionization (CDI), based on the principle of electrosorption, has been intensively researched under the premise of being energy efficient. However, electrodialysis (ED), despite being a more mature electro-driven technology, has yet to be extensively compared to CDI in terms of energetic performance. In this study, we utilize Nernst-Planck based models for continuous flow ED and constant-current membrane capacitive deionization (MCDI) to systematically evaluate the energy consumption of the two processes. By ensuring equivalently sized ED and MCDI systems-in addition to using the same feed salinity, salt removal, water recovery, and productivity across the two technologies-energy consumption is appropriately compared. We find that ED consumes less energy (has higher energy efficiency) than MCDI for all investigated conditions. Notably, our results indicate that the performance gap between ED and MCDI is substantial for typical brackish water desalination conditions (e.g., 3 g L-1 feed salinity, 0.5 g L-1 product water, 80% water recovery, and 15 L m-2 h-1 productivity), with the energy efficiency of ED often exceeding 30% and being nearly an order of magnitude greater than MCDI. We provide further insights into the inherent limitations of each technology by comparing their respective components of energy consumption, and explain why MCDI is unable to attain the performance of ED, even with ideal and optimized operation.
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Affiliation(s)
- Sohum K Patel
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States
- Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (NEWT), Yale University, New Haven, Connecticut 06520-8286, United States
| | - Mohan Qin
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States
- Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (NEWT), Yale University, New Haven, Connecticut 06520-8286, United States
| | - W Shane Walker
- Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (NEWT), Yale University, New Haven, Connecticut 06520-8286, United States
- Department of Civil Engineering, The University of Texas at El Paso, El Paso, Texas 79968-0513, United States
| | - Menachem Elimelech
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States
- Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (NEWT), Yale University, New Haven, Connecticut 06520-8286, United States
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15
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Liu H, Zhang J, Xu X, Wang Q. A Polyoxometalate‐Based Binder‐Free Capacitive Deionization Electrode for Highly Efficient Sea Water Desalination. Chemistry 2020; 26:4403-4409. [DOI: 10.1002/chem.201905606] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Hang Liu
- Department of Chemistry College of Science Northeastern University Shenyang 110819 P. R. China
| | - Juan Zhang
- Department of Chemistry College of Science Northeastern University Shenyang 110819 P. R. China
| | - Xinxin Xu
- Department of Chemistry College of Science Northeastern University Shenyang 110819 P. R. China
| | - Qiang Wang
- Key Laboratory of Electromagnetic Processing of Materials MOE Northeastern University Shenyang 110819 P. R. China
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16
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Delgado A, Jiménez M, Iglesias G, Ahualli S. Electrical double layers as ion reservoirs: applications to the deionization of solutions. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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17
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Hand S, Guest JS, Cusick RD. Technoeconomic Analysis of Brackish Water Capacitive Deionization: Navigating Tradeoffs between Performance, Lifetime, and Material Costs. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:13353-13363. [PMID: 31657552 DOI: 10.1021/acs.est.9b04347] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Capacitive deionization (CDI), a class of electrochemical separation technologies, has been proposed as an energy-efficient brackish water desalination method. Previous studies have focused on improving capacity and energy consumption through material (e.g., ion-selective membranes [IEMs], charged carbon) and operational modifications, but there has been no analysis that directly links lab-scale experimental performance to capital and operating costs of full-scale water production. In this study, we developed a parameterized process model and technoeconomic analysis framework to project capital and operating costs at the million gallon per day scale based on reported material and operational characteristics for constant current CDI with and without low ($20 m-2)- and high-cost ($100 m-2) IEMs. Using this framework, we conducted global sensitivity and uncertainty analyses for water price across the reported CDI design space. Our results show that the operating constraints of brackish water desalination lead to capital costs 2-14 times greater than operating costs (particularly for MCDI). While MCDI outperforms CDI, IEM prices dictate the threshold at which MCDI is more cost-effective. The high relative capital costs highlight the importance of achieving system lifetimes at 2 years or beyond. Last, we set performance and areal cost benchmarks for material-based CDI performance and lifetime improvements.
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Affiliation(s)
- Steven Hand
- Department of Civil and Environmental Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801-2352 , United States
| | - Jeremy S Guest
- Department of Civil and Environmental Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801-2352 , United States
| | - Roland D Cusick
- Department of Civil and Environmental Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801-2352 , United States
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