Limitations of charge efficiency in capacitive deionization processes III: The behavior of surface oxidized activated carbon electrodes

Avraham, Eran; Noked, Malachi; Bouhadana, Yaniv; Soffer, Abraham; Aurbach, Doron

doi:10.1016/j.electacta.2010.08.056

Cited by 99 publications

(71 citation statements)

References 13 publications

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“…r c = c eq t charge [4] r σ = σ eq t charge [5] where r σ is equal to I (t) if the cell is charged at constant voltage. The water recovery Wr is defined as the ratio of the volume of treated freshwater to the total volume of the influent water:…”

Section: Methodsmentioning

confidence: 99%

“…1 Due to its simplicity and reliability, capacitive deionization (CDI) has attracted a growing interest for water desalination. [1][2][3][4][5][6][7] Capacitive deionization utilizes highly porous electrodes to remove charged ions in water by electrosorption ( Figure 1). During charging, an electric voltage is applied and ions are driven to oppositely charged electrodes by electrostatic force and entrapped at the electrode-water interface by the formation of an electric double layer (EDL).…”

mentioning

confidence: 99%

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Energy Consumption and Recovery in Capacitive Deionization Using Nanoporous Activated Carbon Electrodes

Han

Karthikeyan

Gregory

2015

J. Electrochem. Soc.

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Capacitive deionization (CDI) is an emerging desalination technology which utilizes porous electrodes to remove ions in water by electrosorption. Similar to electric capacitors, energy is stored and released during charging and discharging cycles, respectively. In this study, a nanoporous activated carbon coupled flow-through CDI device was used to evaluate energy consumption and recovery under various operational conditions by charging and discharging the cell at a constant current, respectively. Results indicated that the charging/discharging current, salt concentration and water flow rate were major factors impacting electrosorption and energy consumption, by changing the structure of the electrical double layer (EDL) and how ion transport occurs between the interface and bulk solution. A porosity-based EDL theory was applied to explain the experimental observations. Between 30 and 45% of the energy consumed during charging could be recovered depending on operational conditions, although thermodynamically more than 98% of the total energy should be recoverable. Results indicated that overpotential and faradaic reactions induced irreversible energy are the major reasons for gaps in observed energy losses. Energy consumption for reducing the salinity of brackish water from 32.7 to 5.5 mM by our device could be as low as 0.85 kWh/m 3 under most optimized conditions (dependent on materials used and cell configuration). The energy consumption can be dramatically reduced by employing more electron-conductive and Faradaic-resistant electrode materials. Increasing demand for freshwater is driving the need for energyefficient and cost-effective technologies to generate potable water from unconventional sources such as brackish water.1 Due to its simplicity and reliability, capacitive deionization (CDI) has attracted a growing interest for water desalination.1-7 Capacitive deionization utilizes highly porous electrodes to remove charged ions in water by electrosorption (Figure 1). During charging, an electric voltage is applied and ions are driven to oppositely charged electrodes by electrostatic force and entrapped at the electrode-water interface by the formation of an electric double layer (EDL). After removing the ions, the electric voltage is removed or reversed to discharge and regenerate the electrodes. Ions return to solution and the concentrated brine is discarded. Desalination is realized by means of consecutive charging/discharging cycles to separate influent water into freshwater and brine (concentrate) streams.Energy consumption is a major factor driving the synthesis of new CDI electrode materials. Energy-efficient CDI devices are required for up-scaling the process and for broader adoption of this technology for potable or agricultural water treatment. An important feature of CDI is that part of the energy consumed during charging can be recovered during discharging, a process similar to charge/discharge in electric capacitors.6,8 CDI could become more cost competitive compared with well-established desa...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Energy Consumption and Recovery in Capacitive Deionization Using Nanoporous Activated Carbon Electrodes

Han

Karthikeyan

Gregory

2015

J. Electrochem. Soc.

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“…Desalination of water by CDI can be operated in two modes related to the flow of solution in the cell: 'flow-by' [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33], in which the solution flows in parallel to, between the electrodes and 'flowthrough' [34][35][36][37][38][39][40][41], in which the solution flows in perpendicular to, through the electrodes. Using the flow-through regime, the solution has to flow through macro-porous electrodes.…”

Section: Introductionmentioning

confidence: 99%

Long term stability of capacitive de-ionization processes for water desalination: The challenge of positive electrodes corrosion

Cohen

Avraham

Bouhadana

et al. 2013

Electrochimica Acta

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252

166

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“…A second important and related discussion in the CDI-literature is the possible role of chemical effects, such as pseudo-capacitance, oxygen reduction, and chemical surface charge, with chemical charge related to the point of zero charge of the carbon [23,25,27]. Of course, these chemical phenomena are well-known to exist in carbon electrodes and must also play a role in CDI.…”

Section: Introductionmentioning

confidence: 99%

Effect of electrode thickness variation on operation of capacitive deionization

Porada

Bryjak

Wal

et al. 2012

Electrochimica Acta

173

117

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Limitations of charge efficiency in capacitive deionization processes III: The behavior of surface oxidized activated carbon electrodes

Cited by 99 publications

References 13 publications

Energy Consumption and Recovery in Capacitive Deionization Using Nanoporous Activated Carbon Electrodes

Energy Consumption and Recovery in Capacitive Deionization Using Nanoporous Activated Carbon Electrodes

Long term stability of capacitive de-ionization processes for water desalination: The challenge of positive electrodes corrosion

Effect of electrode thickness variation on operation of capacitive deionization

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