1
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Sahray Z, Shocron AN, Uwayid R, Diesendruck CE, Suss ME. Extreme Monovalent Ion Selectivity Via Capacitive Ion Exchange. Water Res 2023; 246:120684. [PMID: 37864883 DOI: 10.1016/j.watres.2023.120684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 09/06/2023] [Accepted: 09/28/2023] [Indexed: 10/23/2023]
Abstract
Capacitive deionization (CDI) is an emerging technology applied to brackish water desalination and ion selective separations. A typical CDI cell consists of two microporous carbon electrodes, where ions are stored in charged micropore via electrosorption into electric double layers. For typical feed waters containing mixtures of several cations and anions, some of which are polluting, models are needed to guide cell design for a target separation, given the complex electrosorption dynamics of each species. An emerging application for CDI is brackish water treatment for direct agricultural use, for which it is often important to selectively electrosorb monovalent Na+ cations over divalent Ca2+ and Mg2+ cations. Recently, it was demonstrated that utilizing constant-voltage CDI cell charging with sulfonated cathodes and short charging times enabled monovalent-selective separations. Here, we utilize a one-dimensional transient CDI model for a flow-through electrode CDI cell to elucidate the mechanisms enabling such separations. We report the discovery that an asymmetric CDI cell with a chemically functionalized cathode induces electric charges in the pristine anode at 0 V cell voltage, which has important implications for monovalent cation selectivity. Leveraging our mechanistic understanding, with our model we uncover a novel operational regime we term "capacitive ion exchange", where the concentration of one ion species increases while competing species concentration decreases. This regime enables resin-less exchange of monovalent cations for divalent cations, with chemical-free electrical regeneration.
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Affiliation(s)
- Zohar Sahray
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Amit N Shocron
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Rana Uwayid
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Charles E Diesendruck
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel; Grand Technion Energy Program, Technion - Israel Institute of Technology, Haifa, Israel
| | - Matthew E Suss
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel; Grand Technion Energy Program, Technion - Israel Institute of Technology, Haifa, Israel; Wolfson Department of Chemical Engineering, Technion - Israel Institute of Technology, Haifa, Israel.
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2
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Alfisi D, Shocron AN, Gloukhovski R, Vermaas DA, Suss ME. Resistance Breakdown of a Membraneless Hydrogen-Bromine Redox Flow Battery. ACS Sustain Chem Eng 2022; 10:12985-12992. [PMID: 36213389 PMCID: PMC9533695 DOI: 10.1021/acssuschemeng.2c02169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 08/31/2022] [Indexed: 06/16/2023]
Abstract
A key bottleneck to society's transition to renewable energy is the lack of cost-effective energy storage systems. Hydrogen-bromine redox flow batteries are seen as a promising solution, due to the use of low-cost reactants and highly conductive electrolytes, but market penetration is prevented due to high capital costs, for example due to costly membranes to prevent bromine crossover. Membraneless hydrogen-bromine cells relying on colaminar flows have thus been investigated, showing high power density nearing 1 W/cm2. However, no detailed breakdown of resistance losses has been performed to-date, a knowledge gap which impedes further progress. Here, we characterize such a battery, showing the main sources of loss are the porous cathode, due to both Faradaic and Ohmic losses, followed by Ohmic losses in the electrolyte channel, with all other sources relatively minor contributors. We further develop and fit analytical expressions for the impedance of porous electrodes in high power density electrochemical cells to impedance measurements from our battery, which enabled the detailed cell resistance breakdown and determination of important electrode parameters such as volumetric exchange current density and specific capacitance. The insights developed here will enable improved engineering designs to unlock exceptionally high-power density membraneless flow batteries.
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Affiliation(s)
- Daniel Alfisi
- 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
| | - Robert Gloukhovski
- Faculty
of Mechanical Engineering, Technion—Israel
Institute of Technology, Haifa 3200003, Israel
| | - David A. Vermaas
- Department
of Chemical Engineering, Delft University
of Technology, Delft 2628, The Netherlands
| | - 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
- Grand
Technion Energy Program, Technion—Israel
Institute of Technology, Haifa 3200003, Israel
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3
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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4
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Uwayid R, Guyes EN, Shocron AN, Gilron J, Elimelech M, Suss ME. Perfect divalent cation selectivity with capacitive deionization. Water Res 2022; 210:117959. [PMID: 34942526 DOI: 10.1016/j.watres.2021.117959] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 12/07/2021] [Accepted: 12/09/2021] [Indexed: 06/14/2023]
Abstract
Capacitive deionization (CDI) is an emerging membraneless water desalination technology based on storing ions in charged electrodes by electrosorption. Due to unique selectivity mechanisms, CDI has been investigated towards ion-selective separations such as water softening, nutrient recovery, and production of irrigation water. Especially promising is the use of activated microporous carbon electrodes due to their low cost and wide availability at commercial scales. We show here, both theoretically and experimentally, that sulfonated activated carbon electrodes enable the first demonstration of perfect divalent cation selectivity in CDI, where we define "perfect" as significant removal of the divalent cation with zero removal of the competing monovalent cation. For example, for a feedwater of 15 mM NaCl and 3 mM CaCl2, and charging from 0.4 V to 1.2 V, we show our cell can remove 127 μmol per gram carbon of divalent Ca2+, while slightly expelling competing monovalent Na+ (-13.2 μmol/g). This separation can be achieved with excellent efficiency, as we show both theoretically and experimentally a calcium charge efficiency above unity, and an experimental energy consumption of less than 0.1 kWh/m3. We further demonstrate a low-infrastructure technique to measure cation selectivity, using ion-selective electrodes and the extended Onsager-Fuoss model.
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Affiliation(s)
- Rana Uwayid
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Eric N Guyes
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Amit N Shocron
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Jack Gilron
- The Jacob Blaustein Institutes for Desert Research, Zuckerberg Institute for Water Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, Israel
| | - Menachem Elimelech
- Department of Chemical and Environmental Engineering, Yale University, New Haven, United States
| | - Matthew E Suss
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel; Wolfson Department of Chemical Engineering, Technion - Israel Institute of Technology, Haifa, Israel; Grand Technion Energy Program, Technion - Israel Institute of Technology, Haifa, Israel.
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5
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Abstract
Sustainably-produced hydrogen is currently intensively investigated as an energy carrier to replace fossil fuels. We here characterize an emerging electrochemical cell termed a desalination fuel cell (DFC) that can continuously generate electricity and desalinate water while using hydrogen and oxygen gases as inputs. We investigated two operational modes, a near-neutral pH operation with H2, O2, and feedwater inputs (H2|O2), and a pH-gradient mode with H2, O2, feedwater, acid, and base inputs (H2 + B|O2 + A). We show that our cell can desalinate water with 30 g/L of salt content to near-zero salt concentration, while generating an enormous amount of electricity of up to 8.6 kW h per m3 of treated water when operated in the pH-gradient mode and up to about 1 kW h per m3 for the near-neutral mode. We quantify the thermodynamic energy efficiency of our device in both operational modes, showing that significantly higher efficiency is achievable in the pH-gradient mode, with up to 95.6%. Further, we present results elucidating the key bottlenecks in the DFC process, showing that the cell current and voltage are limited in the near-neutral pH operation due to a lack of H+ to serve as a reactant, and further reinforce the deleterious effect of halide poisoning on the cathode Pt catalyst and cell open circuit voltage. Such findings demonstrate that new fuel cell catalyst materials, tailored for environments associated with water treatment, can unlock yet-improved performance.
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Affiliation(s)
- Shada Abu Khalla
- The Nancy and Stephen Grand Technion Energy Program, Technion-Israel Institute of Technology, Haifa 3200003, Israel
- Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Imri Atlas
- Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel
- Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Shawn Litster
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Matthew E Suss
- The Nancy and Stephen Grand Technion Energy Program, Technion-Israel Institute of Technology, Haifa 3200003, Israel
- 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
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6
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7
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Yang F, He Y, Rosentsvit L, Suss ME, Zhang X, Gao T, Liang P. Flow-electrode capacitive deionization: A review and new perspectives. Water Res 2021; 200:117222. [PMID: 34029869 DOI: 10.1016/j.watres.2021.117222] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 04/30/2021] [Accepted: 05/03/2021] [Indexed: 06/12/2023]
Abstract
Flow-electrode capacitive deionization (FCDI), as a novel electro-driven desalination technology, has attracted growing exploration towards brackish water treatment, hypersaline water treatment, and selective resource recovery in recent years. As a flow-electrode-based electrochemical technology, FCDI has similarities with several other electrochemical technologies such as electrochemical flow capacitors and semi-solid fuel cells, whose performance are closely coupled with the characteristics of the flow-electrodes. In this review, we sort out the potentially parallel mechanisms of electrosorption and electrodialysis in the FCDI desalination process, and make clear the importance of the flowable capacitive electrodes. We then adopt an equivalent circuit model to distinguish the resistances to ion transport and electron transport within the electrodes, and clarify the importance of electronic conductivity on the system performance based on a series of electrochemical tests. Furthermore, we discuss the effects of electrode selection and flow circulation patterns on system performance (energy consumption, salt removal rate), review the current treatment targets and system performance, and then provide an outlook on the research directions in the field to support further applications of FCDI.
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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
| | - Yunfei He
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Leon Rosentsvit
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, 32000, Israel
| | - Matthew E Suss
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, 32000, Israel; Faculty of Chemical Engineering, Technion - Israel Institute of Technology, Haifa, 32000, Israel.
| | - Xiaori Zhang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Tie Gao
- 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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8
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Amit L, Naar D, Gloukhovski R, la O' GJ, Suss ME. A Single-Flow Battery with Multiphase Flow. ChemSusChem 2021; 14:1068-1073. [PMID: 33225585 DOI: 10.1002/cssc.202002135] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 11/09/2020] [Indexed: 06/11/2023]
Abstract
Widespread adoption of redox flow batteries (RFBs) for renewable energy storage is inhibited by a relatively high cost of storage. This is due largely to typical RFBs requiring two flows, two external tanks, and expensive ion-exchange membranes. Here, we propose a potentially inexpensive Zn-Br2 RFB which is membraneless and requires only a single flow. The flow is an emulsion consisting of a continuous, Br2 -poor aqueous phase and a dispersed, Br2 -rich polybromide phase, pumped through the channel separating anode and cathode. With our prototype cell, we explore the effect of polybromide-phase volume fraction and Br2 concentration on cell performance and plating efficiencies. We demonstrate high discharge currents of up to 270 mA/cm2 , plating efficiencies up to 88 %, and dendriteless plating up to the highest Zn loading investigated of 250 mAh/cm2 . We provide mechanistic insights into cell behavior and elucidate paths towards unlocking ultra-low-cost single-flow RFBs with multiphase flow.
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Affiliation(s)
- Lihi Amit
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Danny Naar
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Robert Gloukhovski
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | | | - Matthew E Suss
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
- Grand Technion Energy Program, Technion - Israel Institute of Technology, Haifa, Israel
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9
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Ma J, Zhang C, Yang F, Zhang X, Suss ME, Huang X, Liang P. Carbon Black Flow Electrode Enhanced Electrochemical Desalination Using Single-Cycle Operation. Environ Sci Technol 2020; 54:1177-1185. [PMID: 31829572 DOI: 10.1021/acs.est.9b04823] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Flow-electrode electrochemical desalination (FEED) processes (e.g., flow-electrode capacitive deionization), which use flowable carbon particles as the electrodes, have attracted increasing attention, holding the promise for continuous desalination and high desalting efficiency. While it is generally believed that carbon particles with abundant microporous and large specific capacitances (e.g., activated carbon, AC) should be ideal candidates for FEED electrodes, we provide evidence to the contrary, showing that highly conductive electrodes with low specific surface area can outperform microporous AC-based electrodes. This study revealed that FEED using solely high surface area AC particles (∼2000 m2 g-1, specific capacitance of ∼44 F g-1, average salt adsorption rate of ∼0.15 μmol cm-2 min-1) was vastly outperformed by electrodes based solely on low-surface area carbon black (CB, ∼70 m2 g-1, ∼0.5 F g-1, ∼0.75 μmol cm-2 min-1). Electrochemical impedance spectroscopy results suggest that the electrode formed by CB particles led to more effective electronic charge percolation, likely contributing to the improved desalination performance. In addition, we propose and demonstrate a novel operation mode, termed single cycle (SC), which greatly simplified the FEED cell configuration and enabled simultaneous charging and discharging. Using SC mode with CB flow electrodes delivered an increased average salt removal rate relative to the more traditional short-circuited closed cycle (SCC) mode, achieving up to 1.13 μmol cm-2 min-1. Further investigations demonstrate that up to 50% of energy input would be avoided when using CB flow electrodes operated under SC mode as compared to that of AC flow electrodes operated under SCC mode. In summary, the FEED process presented in this study provided an innovative and promising approach toward high-efficient and low-cost brackish water desalination.
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Affiliation(s)
- Junjun Ma
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment , Tsinghua University , Beijing 100084 , PR China
| | - Changyong Zhang
- UNSW Water Research Centre, School of Civil and Environmental Engineering , University of New South Wales , Sydney NSW 2052 , Australia
| | - Fan Yang
- 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
| | - Matthew E Suss
- Faculty of Mechanical Engineering Technoin , Israel Institute of Technology , Haifa 3200 , Israel
| | - 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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10
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Abstract
Capacitive deionization (CDI) is an emerging water treatment technology often applied to brackish water desalination and water softening. Typical CDI cells consist of two microporous carbon electrodes sandwiching a dielectric separator, and desalt feedwater flowing through the cell by storing ions in electric double layers (EDLs) within charged micropores. CDI cells have demonstrated size-based ion selectivity wherein smaller hydrated ions are preferentially electrosorbed over larger hydrated ions. We demonstrate that such size-based selectivity can be substantially enhanced through the addition of chemical charge to micropores via surface functionalization. We develop a micropore EDL theory that includes both finite ion size effects and micropore chemical charge, which predicts such enhancements and elucidates that they result from denser counterion packing in micropores. With our experimental CDI cell, we desalted an electrolyte consisting of equimolar potassium (K+) and lithium (Li+) ions. We show that use of a surface-functionalized (oxidized) cathode significantly increased the electrosorption ratio of smaller K+ to larger Li+ compared to a cell with a pristine cathode, for example, from ∼1 to 1.84 for a charging voltage of 0.4 V. Our model predicts yet-higher electrosorption ratios are attainable, but our experimental cell suffered from significant cathode chemical charge degradation at applied voltages of ∼1 V.
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11
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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 Res 2019; 152:126-137. [PMID: 30665159 DOI: 10.1016/j.watres.2018.10.074] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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12
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Abstract
A broad variety of materials, ranging from composites and heat transfer nano-fluids to electrochemical energy storage electrodes, widely employ cylindrical particles of various aspect ratios, such as carbon nanotubes. These particles are generally excellent conductors of heat and electricity and when dispersed in a continuous medium influence dramatically the transport properties of the heterogeneous material by forming a percolating network. Numerous theories exist to predict key parameters such as particle concentration at the percolation threshold and transport properties at concentrations beyond the threshold. The microstructure formed by connecting particles in the material is an important determinant toward such parameters but often requires complex numerical models to resolve. In this paper, we present an analytical, probabilistic model capturing the microstructure of a system of randomly positioned, soft-core, cylindrical particles with a finite aspect ratio, valid at arbitrary particle concentration. Our analytical framework allows for the calculation of the particle contact number distribution and percolation probability of the particle system. We show that our analytical model is more accurate than excluded volume theory for predicting the percolation threshold for spherocylinders of finite aspect ratios, and agrees well with the corresponding numerical results. Our theory describes the percolating network topology above the percolation threshold and can serve as the foundation for analytical composition-structure-property relationships for heterogeneous materials with conducting cylindrical particles.
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Affiliation(s)
- Anatoly Golovnev
- Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - Matthew E Suss
- Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
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13
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Shocron AN, Suss ME. The effect of surface transport on water desalination by porous electrodes undergoing capacitive charging. J Phys Condens Matter 2017; 29:084003. [PMID: 28092627 DOI: 10.1088/1361-648x/29/8/084003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Capacitive deionization (CDI) is a technology in which water is desalinated by ion electrosorption into the electric double layers (EDLs) of charging porous electrodes. In recent years significant advances have been made in modeling the charge and salt dynamics in a CDI cell, but the possible effect of surface transport within diffuse EDLs on these dynamics has not been investigated. We here present theory which includes surface transport in describing the dynamics of a charging CDI cell. Through our numerical solution to the presented models, the possible effect of surface transport on the CDI process is elucidated. While at some model conditions surface transport enhances the rate of CDI cell charging, counter-intuitively this additional transport pathway is found to slow down cell charging at other model conditions.
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Affiliation(s)
- Amit N Shocron
- Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
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14
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Mutha HK, Lu Y, Stein IY, Cho HJ, Suss ME, Laoui T, Thompson CV, Wardle BL, Wang EN. Porosimetry and packing morphology of vertically aligned carbon nanotube arrays via impedance spectroscopy. Nanotechnology 2017; 28:05LT01. [PMID: 28033120 DOI: 10.1088/1361-6528/aa53aa] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Vertically aligned one-dimensional nanostructure arrays are promising in many applications such as electrochemical systems, solar cells, and electronics, taking advantage of high surface area per unit volume, nanometer length scale packing, and alignment leading to high conductivity. However, many devices need to optimize arrays for device performance by selecting an appropriate morphology. Developing a simple, non-invasive tool for understanding the role of pore volume distribution and interspacing would aid in the optimization of nanostructure morphologies in electrodes. In this work, we combined electrochemical impedance spectroscopy (EIS) with capacitance measurements and porous electrode theory to conduct in situ porosimetry of vertically aligned carbon nanotube (VA-CNT) forests non-destructively. We utilized the EIS measurements with a pore size distribution model to quantify the average and dispersion of inter-CNT spacing (Γ), stochastically, in carpets that were mechanically densified from [Formula: see text] tubes cm-2 to [Formula: see text] tubes cm-2. Our analysis predicts that the inter-CNT spacing ranges from over 100 ± 50 nm in sparse carpets to sub 10 ± 5 nm in packed carpets. Our results suggest that waviness of CNTs leads to variations in the inter-CNT spacing, which can be significant in sparse carpets. This methodology can be used to predict the performance of many nanostructured devices, including supercapacitors, batteries, solar cells, and semiconductor electronics.
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Affiliation(s)
- Heena K Mutha
- Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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15
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Guyes EN, Simanovski A, Suss ME. Several orders of magnitude increase in the hydraulic permeability of flow-through capacitive deionization electrodes via laser perforations. RSC Adv 2017. [DOI: 10.1039/c7ra00459a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Laser perforation of a flow channel array in flow-through CDI electrodes dramatically increases electrode permeability while desalination performance is maintained.
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Affiliation(s)
- Eric N. Guyes
- Faculty of Mechanical Engineering
- Technion – Israel Institute of Technology
- Haifa 32000
- Israel
| | - Anastasia Simanovski
- Faculty of Mechanical Engineering
- Technion – Israel Institute of Technology
- Haifa 32000
- Israel
| | - Matthew E. Suss
- Faculty of Mechanical Engineering
- Technion – Israel Institute of Technology
- Haifa 32000
- Israel
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16
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Srimuk P, Zeiger M, Jäckel N, Tolosa A, Krüner B, Fleischmann S, Grobelsek I, Aslan M, Shvartsev B, Suss ME, Presser V. Enhanced performance stability of carbon/titania hybrid electrodes during capacitive deionization of oxygen saturated saline water. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2016.12.060] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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17
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Rubin S, Suss ME, Biesheuvel PM, Bercovici M. Induced-Charge Capacitive Deionization: The Electrokinetic Response of a Porous Particle to an External Electric Field. Phys Rev Lett 2016; 117:234502. [PMID: 27982655 DOI: 10.1103/physrevlett.117.234502] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Indexed: 06/06/2023]
Abstract
We demonstrate the phenomenon of induced-charge capacitive deionization that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electric field. The external electric field induces an electric dipole in the porous particle, leading to its capacitive charging by both cations and anions at opposite poles. This regime is characterized by a long charging time, which results in significant changes in salt concentration in the electrically neutral bulk, on the scale of the particle. We qualitatively demonstrate the effect of advection on the spatiotemporal concentration field, which, through diffusiophoresis, may introduce corrections to the electrophoretic mobility of such particles.
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Affiliation(s)
- S Rubin
- Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - M E Suss
- Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - P M Biesheuvel
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
| | - M Bercovici
- Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel
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18
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Cohen H, Eli SE, Jõgi M, Suss ME. Suspension Electrodes Combining Slurries and Upflow Fluidized Beds. ChemSusChem 2016; 9:3045-3048. [PMID: 27763726 DOI: 10.1002/cssc.201601008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 08/28/2016] [Indexed: 06/06/2023]
Abstract
Carbon-based suspension electrodes are currently intensively investigated for emerging electrochemical systems, such as flow batteries, flow capacitors, and capacitive deionization cells. The main limitation of such electrodes is their low electric conductivity, which is typically orders of magnitude lower than that of traditional static carbon electrodes. Two main categories of suspension electrodes exist: 1) slurry electrodes where particles are not significantly affected by gravity, and 2) fluidized bed electrodes where particles are affected by gravity. We introduce a novel category that we term "combined" suspension electrodes, which combine dilute slurries and dense fluidized beds. We present experimental measurements of the electrochemical impedance and electric conductivity of two combined electrodes. For one set of materials, the measured electric conductivity of the combined electrode is at least an order of magnitude above the fluidized bed and slurry components alone, demonstrating that a synergetic effect can be achieved when adding dilute slurry to dense fluidized bed. For a second set of materials, results show that the combined electrode conductivity is lower than the slurry component alone, a counter-intuitive result, demonstrating that increasing electrode carbon loading does not always enhance the electric conductivity.
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Affiliation(s)
- Hagai Cohen
- Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - Shaked Ein Eli
- Department of Physics, Technion-Israel Institute of Technology, Haifa, Israel
| | - Morten Jõgi
- Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - Matthew E Suss
- Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
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19
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Suss ME, Biesheuvel PM, Baumann TF, Stadermann M, Santiago JG. In situ spatially and temporally resolved measurements of salt concentration between charging porous electrodes for desalination by capacitive deionization. Environ Sci Technol 2014; 48:2008-2015. [PMID: 24433022 DOI: 10.1021/es403682n] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Capacitive deionization (CDI) is an emerging water desalination technique. In CDI, pairs of porous electrode capacitors are electrically charged to remove salt from brackish water present between the electrodes. We here present a novel experimental technique allowing measurement of spatially and temporally resolved salt concentration between the CDI electrodes. Our technique measures the local fluorescence intensity of a neutrally charged fluorescent probe which is collisionally quenched by chloride ions. To our knowledge, our system is the first to measure in situ and spatially resolved chloride concentration in a laboratory CDI cell. We here demonstrate good agreement between our dynamic measurements of salt concentration in a charging, millimeter-scale CDI system to the results of a modified Donnan porous electrode transport model. Further, we utilize our dynamic measurements to demonstrate that salt removal between our charging CDI electrodes occurs on a longer time scale than the capacitive charging time scales of our CDI cell. Compared to typical measurements of CDI system performance (namely, measurements of outflow ionic conductivity), our technique can enable more advanced and better-controlled studies of ion transport in CDI systems, which can potentially catalyze future performance improvements.
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Affiliation(s)
- Matthew E Suss
- Department of Mechanical Engineering, Stanford University , 440 Escondido Mall, Stanford, California 94305, United States
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20
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Worsley MA, Kucheyev SO, Mason HE, Merrill MD, Mayer BP, Lewicki J, Valdez CA, Suss ME, Stadermann M, Pauzauskie PJ, Satcher JH, Biener J, Baumann TF. Mechanically robust 3D graphene macroassembly with high surface area. Chem Commun (Camb) 2012; 48:8428-30. [DOI: 10.1039/c2cc33979j] [Citation(s) in RCA: 208] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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21
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Suss ME, Mani A, Zangle TA, Santiago JG. Electroosmotic pump performance is affected by concentration polarizations of both electrodes and pump. Sens Actuators A Phys 2011; 165:310-315. [PMID: 21516230 PMCID: PMC3079224 DOI: 10.1016/j.sna.2010.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Current methods of optimizing electroosmotic (EO) pump performance include reducing pore diameter and reducing ionic strength of the pumped electrolyte. However, these approaches each increase the fraction of total ionic current carried by diffuse electric double layer (EDL) counterions. When this fraction becomes significant, concentration polarization (CP) effects become important, and traditional EO pump models are no longer valid. We here report on the first simultaneous concentration field measurements, pH visualizations, flow rate, and voltage measurements on such systems. Together, these measurements elucidate key parameters affecting EO pump performance in the CP dominated regime. Concentration field visualizations show propagating CP enrichment and depletion fronts sourced by our pump substrate and traveling at order mm/min velocities through millimeter-scale channels connected serially to our pump. The observed propagation in millimeter-scale channels is not explained by current propagating CP models. Additionally, visualizations show that CP fronts are sourced by and propagate from the electrodes of our system, and then interact with the EO pump-generated CP zones. With pH visualizations, we directly detect that electrolyte properties vary sharply across the anode enrichment front interface. Our observations lead us to hypothesize possible mechanisms for the propagation of both pump- and electrode-sourced CP zones. Lastly, our experiments show the dynamics associated with the interaction of electrode and membrane CP fronts, and we describe the effect of these phenomena on EO pump flow rates and applied voltages under galvanostatic conditions.
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Affiliation(s)
| | | | | | - Juan G. Santiago
- Corresponding author: 440 Escondido Mall, Bldg 530, rm 224, Stanford, CA, 94305, tel: 1-650-723-5689, fax: 1-650-723-7657,
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22
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Persat A, Suss ME, Santiago JG. Basic principles of electrolyte chemistry for microfluidic electrokinetics. Part II: Coupling between ion mobility, electrolysis, and acid-base equilibria. Lab Chip 2009; 9:2454-2469. [PMID: 19680571 DOI: 10.1039/b906468k] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We present elements of electrolyte dynamics and electrochemistry relevant to microfluidic electrokinetics experiments. In Part I of this two-paper series, we presented a review and introduction to the fundamentals of acid-base chemistry. Here, we first summarize the coupling between acid-base equilibrium chemistry and electrophoretic mobilities of electrolytes, at both infinite and finite dilution. We then discuss the effects of electrode reactions on microfluidic electrokinetic experiments and derive a model for pH changes in microchip reservoirs during typical direct-current electrokinetic experiments. We present a model for the potential drop in typical microchip electrophoresis device. The latter includes finite element simulation to estimate the relative effects of channel and reservoir dimensions. Finally, we summarize effects of electrode and electrolyte characteristics on potential drop in microfluidic devices. As a whole, the discussions highlight the importance of the coupling between electromigration and electrophoresis, acid-base equilibria, and electrochemical reactions.
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Affiliation(s)
- Alexandre Persat
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
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