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Merging Ion Concentration Polarization between Juxtaposed Ion Exchange Membranes to Block the Propagation of the Polarization Zone
Published on: February 23, 2017
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Perfect divalent cation selectivity with capacitive deionization.
Rana Uwayid1, Eric N Guyes1, Amit N Shocron1
1Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel.
Water Research
|December 23, 2021
Summary
Sulfonated activated carbon electrodes achieve perfect divalent cation selectivity in capacitive deionization (CDI), a promising water treatment technology. This breakthrough enables efficient water softening and nutrient recovery with minimal energy consumption.
Area of Science:
- Materials Science
- Electrochemistry
- Environmental Engineering
Background:
- Capacitive deionization (CDI) is a membraneless technology for water desalination and ion separation.
- Activated carbon electrodes are cost-effective and widely available for CDI applications.
- Existing CDI methods show limited selectivity for specific ion types.
Purpose of the Study:
- To demonstrate perfect divalent cation selectivity in capacitive deionization using novel electrode materials.
- To investigate the theoretical and experimental performance of sulfonated activated carbon electrodes for ion separation.
- To develop a low-infrastructure method for measuring cation selectivity in CDI.
Main Methods:
- Fabrication and characterization of sulfonated activated carbon electrodes.
- Theoretical modeling and experimental testing of CDI cells with mixed salt solutions (NaCl and CaCl2).
- Measurement of ion removal using ion-selective electrodes and the extended Onsager-Fuoss model.
Main Results:
- Achieved perfect divalent cation (Ca2+) selectivity, removing 127 μmol/g Ca2+ while expelling monovalent Na+ (-13.2 μmol/g).
- Demonstrated calcium charge efficiency above unity, indicating highly effective ion removal.
- Attained low experimental energy consumption below 0.1 kWh/m3 for the separation process.
Conclusions:
- Sulfonated activated carbon electrodes represent a significant advancement in CDI selectivity for divalent cations.
- The developed CDI system offers efficient and energy-saving water treatment solutions.
- The low-infrastructure selectivity measurement technique is valuable for CDI research and development.
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