Capacitive deionization on-chip as a method for microfluidic sample preparation

Roelofs, Susan Helena; Kim, Bumjoo; Eijkel, Jan C.T.; Han, Jongyoon; Berg, Albert van den; Odijk, Mathieu

doi:10.1039/c4lc01410c

Cited by 18 publications

(20 citation statements)

References 31 publications

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“…As discussed earlier, however, electrogenerated Cl 2 is not stable in solution but reacts to yield ions [Eq. (5)]. This counteracts the slight IDZ formed by the transient presence of Cl 2 and, ultimately, results in an increase in solution conductivity near the trailing edge of the anode (axial position 25 μm).…”

Section: Numerical Simulationsmentioning

confidence: 99%

“…The electrochemical reaction was modeled as a flux, and the chemical reaction of Cl 2 in solution [Eq. (5)] was modeled using reaction rate constants. HOCl dissociation was not included in the model [Eq.…”

Section: Numerical Simulationsmentioning

confidence: 99%

“…Several methods have recently been reported for manipulating the trajectory of ions in microfluidic devices, [1][2][3][4][5] and in some cases these methods have been applied to the desalination of salt water. [6][7][8][9][10] With regard to the latter, the approach that has received the most attention relies on the presence of an ion depletion zone (IDZ).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Chloride Oxidation on Local Electric Fields in Microelectrochemical Systems

2019

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We recently reported that electrochemical oxidation of Cl− to neutral Cl2 decreases solution conductivity, thereby yielding a local electric field gradient. Here, we report detailed experimental results and simulations indicating that the situation is more complex than we originally thought. The key new findings are twofold. First, once generated, Cl2 rapidly reacts with water to form ionic species that increase, rather than decrease, solution conductivity near the anode. Second, the electrochemical potential gradient measured in the vicinity of the anode during Cl− oxidation is dominated by differences in the chemical potential, rather than the electrical potential, of the solution. These findings clarify the electrochemical and chemical processes previously reported to enable desalination via faradaic Cl− oxidation.

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Section: Numerical Simulationsmentioning

confidence: 99%

Section: Numerical Simulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Chloride Oxidation on Local Electric Fields in Microelectrochemical Systems

2019

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“…The storage capacity of the system is proportional to the effective surface area of the electrodes and the potential applied across the electrodes. 57 A two-electrode configuration to desalinate droplets was suggested by Dak and coworkers. At the same time co-ions are repelled from the electrodes, which results in an efficiency loss.…”

Section: Capacitive Deionizationmentioning

confidence: 99%

Microfluidic desalination techniques and their potential applications

2015

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In this review we discuss recent developments in the emerging research field of miniaturized desalination. Traditionally desalination is performed to convert salt water into potable water and research is focused on improving performance of large-scale desalination plants. Microfluidic desalination offers several new opportunities in comparison to macro-scale desalination, such as providing a platform to increase fundamental knowledge of ion transport on the nano- and microfluidic scale and new microfluidic sample preparation methods. This approach has also lead to the development of new desalination techniques, based on micro/nanofluidic ion-transport phenomena, which are potential candidates for up-scaling to (portable) drinking water devices. This review assesses microfluidic desalination techniques on their applications and is meant to contribute to further implementation of microfluidic desalination techniques in the lab-on-chip community.

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“…6 A key property of CDI is the potential for energy efficient separation when using relatively dilute electrolyte solutions (i.e., where the molecules of water outnumber by roughly three or more orders of magnitude the number of ions). 7 Despite CDI's many benets, a fundamental limitation to the usable cell voltage range is the narrow electrochemical stability window of water.…”

mentioning

confidence: 99%

Capacitive deionization in organic solutions: case study using propylene carbonate

et al. 2016

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Capacitive deionization (CDI) is an emerging technology for the energy-efficient removal of dissolved ions from aqueous solutions. Expanding this technology to non-aqueous media, we present an experimental characterization of a pair of porous carbon electrodes towards electrosorption of dissolved ions in propylene carbonate. We demonstrate that application of CDI technology for treatment of an organic solution with an electrochemical stability window beyond 1.2 V allows for a higher salt removal capacity and higher charge efficiency as compared to CDI applied for treatment of aqueous electrolytes. Further, we show that using conductivity measurements of the stream emerging from the CDI cell combined with an equilibrium electric double-layer structure model, we can gain insights into charge compensation mechanisms and ion distribution in carbon nanopores.Electrosorption is a process whereby ionic electrolyte species are electrostatically conned near to charged solid-liquid interfaces, enabling fast energy storage and recovery via electric double-layer capacitors (or supercapacitors)1 and water desalination via capacitive deionization (CDI).2 In such applications, a pair of porous carbon electrodes (or stacks thereof) is charged, and ions are electrosorbed onto the pore surfaces, residing in electric double-layers (EDLs). One important difference between supercapacitors and CDI is the operation at very different ionic strength: CDI is employed at low concentrations, typically in the range of 100 mM or lower, while supercapacitors operate at 1 M or higher (depending on the electrolyte system).3 Also, while the eld of CDI has been focused almost entirely on the study and application of water desalination (ion removal from aqueous electrolytes), 4 supercapacitors can store energy with aqueous electrolytes, organic electrolytes, and solvent-free systems based on ionic liquids.While it is well known that CDI can separate a feed water stream into potable water and a separate brine stream, recently, CDI has been investigated as a promising tool for other separations in aqueous solutions, including between ionic species with different valencies, 5 and in separations for microuidic sample purication.6 A key property of CDI is the potential for energy efficient separation when using relatively dilute electrolyte solutions (i.e., where the molecules of water outnumber by roughly three or more orders of magnitude the number of ions). 7 Despite CDI's many benets, a fundamental limitation to the usable cell voltage range is the narrow electrochemical stability window of water.4 As a consequence, the maximum voltage in typical CDI systems does not exceed 1.2 to 1.4 V.4,8 At electric potentials above this level, water decomposition occurs at the electrodes via water electrolysis, which acts as a parasitic energy loss and a source of unwanted gas generation. Thus, the maximum NaCl adsorption capacity for CDI systems based on capacitive electrodes remains limited to roughly 20 mg NaCl g carbon À1 , when normalized by the mass ...

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Capacitive deionization on-chip as a method for microfluidic sample preparation

Cited by 18 publications

References 31 publications

Effect of Chloride Oxidation on Local Electric Fields in Microelectrochemical Systems

Effect of Chloride Oxidation on Local Electric Fields in Microelectrochemical Systems

Microfluidic desalination techniques and their potential applications

Capacitive deionization in organic solutions: case study using propylene carbonate

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