Electrokinetic desalination of brackish water and associated challenges in the water and energy nexus

Pan, Shu-Yuan; Snyder, Seth W.; Lin, Yupo J.; Chiang, Pen‐Chi

doi:10.1039/c7ew00550d

Cited by 39 publications

(31 citation statements)

References 165 publications

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“…For this separation, we propose a feed concentration of 20 mM NaCl because it is in the middle of the salinity range where CDI is expected to industrially relevant. [29][30][31] We chose a ∆c of 5 mM and a water recovery of 50% because both of these are reasonably attainable in a research lab setting. It would be more relevant to examine a 15 mM removal from a 20 mM feed at a WR of 75% or higher, but this requires significantly more engineering to achieve.…”

Section: Example Standardized Separation For CDI Researchmentioning

confidence: 99%

Performance metrics for the objective assessment of capacitive deionization systems

Hawks

Ramachandran

Porada³

et al. 2019

Water Research

218

193

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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/m 3 ) and throughput productivity (L/h/m 2 ) 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 testing condition of removing 5 mM from a 20 mM NaCl feed solution at 50% water recovery for CDI research. Using this 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 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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Section: Example Standardized Separation For CDI Researchmentioning

confidence: 99%

Performance metrics for the objective assessment of capacitive deionization systems

Hawks

Ramachandran

Porada³

et al. 2019

Water Research

218

193

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“…The sustainable and reliant supply of sufficient water and energy to a growing population with increasing demand are major challenges humanity is facing, which calls for improved and new technologies. [1][2][3][4] A growing research field profiting from these challenges are flow-electrodes, which find potential application in the fields of cles can form percolating networks, which conduct electrons upon contact with the electrode or current collector and, thus, function as an electrode extension. Such flow-electrodes may be applied to support faradaic reactions, as required for electrosynthesis [8], batteries (e.g.…”

Section: Introduction Motivation and Objectivesmentioning

confidence: 99%

“…[12,13] It is based on the concept of capacitive deionization (CDI), which attracted increasing interest in the recent years due to its energy efficiency, the possibility of energy recovery and the potential application in selective ion removal and recovery of various ionic species. [4,[14][15][16][17][18] CDI uses an electrical field, which leads to the migration of ions towards the oppositely charged electrodes and finally the adsorption of ions in the electrical double layer (EDL) at the electrode surface. The desalination step can be compared to the charging of a capacitor, which enables an energy recovery during the regeneration.…”

Section: Introduction Motivation and Objectivesmentioning

confidence: 99%

Unraveling charge transport in carbon flow-electrodes: Performance prediction for desalination applications

Rommerskirchen

Kalde

Linnartz

et al. 2019

Carbon

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Carbon based flow-electrodes are an increasing research field and find potential application in water treatment processes as well as energy conversion and storage. Flow-electrodes usually consist of a pumpable carbon slurry made of carbon particles suspended in a liquid electrolyte solution. One application for flowelectrodes is flow-electrode capacitive deionization (FCDI), which is a membrane-based, electrically-driven desalination method using mostly activated carbon as active material. In contrast to capacitive deionization (CDI) systems based on static electrodes, the use of flow-electrodes enables a continuous operation and the treatment of high salinity solutions. However, it was observed that the performance of FCDI processes heavily relies on the activated carbon quality. The process performance results from a wide range of parameters, including the activated carbon sample characteristics, which are usually not sufficiently covered and predicted by standard carbon analyses. With this article, we establish a foundation for applying electrochemical impedance spectroscopy (EIS) as predictive characterization method for flow-electrode materials. This includes the investigation of influencing system parameters and carbon characteristics, and the development of an equivalent circuit model. Finally, we demonstrate the possibility to predict and match the desalination performance of flow-electrodes based on different activated carbon types using EIS.

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“…By integrating membrane‐based processes, resources in seawater reverse osmosis (SWRO) brine, specifically NaCl, can be recovered as valuable chemical commodities (i.e., NaOH and HCl) . To produce NaOH and HCl, the SWRO brine can first be pretreated through nanofiltration (NF), selective electrodialysis (SED), or electrodialysis (ED); and, subsequently, it can be processed by electrodialysis with bipolar membranes (BMED) into the products of interest (Figure ) .…”

Section: Membrane‐based Pretreatment Processes For Brine Valorizationmentioning

confidence: 99%

“…Similar to ED, SED is driven by an applied electrical force, which allows for the transport of the ions through charge‐selective membranes; however, it can also separate the monovalent and divalent ions in the brine. An SED system is typically composed of an anode, a cathode, anion‐exchange membranes (AEMs), cation‐exchange membranes (CEMs), and monovalent selective‐to‐anion (MVA) membranes (Figure ) . The ions experience an electrical force resulting from the potential difference between the anode and cathode, causing the anions to move toward the anode while the cations move toward the cathode.…”

Section: Membrane‐based Pretreatment Processes For Brine Valorizationmentioning

confidence: 99%

Integrated Valorization of Desalination Brine through NaOH Recovery: Opportunities and Challenges

et al. 2019

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The rising use of seawater desalination for fresh water production is driving a parallel rise in the discharge of high‐salinity brine into the ocean. Better utilization of this brine would have a positive impact on the energy use, cost, and environmental footprint of desalination. Furthermore, intermittent renewable energy can easily power the brine utilization and, for reverse osmosis technology, the entire desalination plant. One pathway toward these goals is to convert the otherwise discharged brine into useful chemicals; waste could be transformed into sodium hydroxide or caustic soda (NaOH) and hydrochloric acid (HCl). In this Minireview, we discuss opportunities and challenges for integrated valorization of desalination brine through NaOH and HCl recovery.

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Electrokinetic desalination of brackish water and associated challenges in the water and energy nexus

Abstract: This article presents the challenges and opportunities of electrokinetic desalination for brackish water and its recent development and prospective.

Cited by 39 publications

References 165 publications

Performance metrics for the objective assessment of capacitive deionization systems

Performance metrics for the objective assessment of capacitive deionization systems

Unraveling charge transport in carbon flow-electrodes: Performance prediction for desalination applications

Integrated Valorization of Desalination Brine through NaOH Recovery: Opportunities and Challenges

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