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Title: Seawater desalination by over-potential membrane capacitive deionization: Opportunities and hurdles

Abstract

The salt removal capacity ( SRC) of the carbon electrodes in membrane capacitive deionization (MCDI) is limited by the applied potential (<1.6 V). Thus, enhancement of the SRC is essential before applying MCDI to seawater desalination. This study aims at developing a novel MCDI system for seawater desalination by applying over-potential (OP) to enhance ion-adsorption capacity and kinetics, and by reversing the polarity (RP) of electrodes to improve ion-desorption kinetics (hereafter named OP-MCDI-RP) for seawater desalination. At 2.4 V, the OP-MCDI system with mesoporous carbon demonstrated a SRC value of 64.7 mg g –1 when desalting 0.5 M NaCl solution, while the OP-CDI system could only remove 8.2 mg g –1 under identical conditions. Similarly, an OP-MCDI cell using carbon aerogel demonstrated a greater SRC value of 43.4 mg g –1 in comparison with 12.5 mg g –1 achieved in OP-CDI. These results indicate that the OP-MCDI system can directly desalt high salinity water regardless of the electrode material. In contrast to the OP-MCDI system, the OP-MCDI-RP system yields a higher regeneration efficiency by applying a reversed low-voltage. It is shown that, under appropriate operating conditions, the OP-MCDI-RP system reduced the electrical conductivity of a seawater sample of 37 practicalmore » salinity units by 99.9%, suggesting that the OP-MCDI-RP system can be employed for seawater desalination. In conclusion, due to the dramatic increase in energy demand and insufficient long-term stability caused by high potential and high salt concentration, however, the OP-MCDI-RP process should be further investigated for potential practical applications.« less

Authors:
ORCiD logo [1];  [2];  [3]; ORCiD logo [4];  [5];  [6]; ORCiD logo [7]
  1. Georgia Inst. of Technology, Atlanta, GA (United States); Tianjin Univ., Tianjin (People's Republic of China); Chinese Academy of Sciences (CAS), Beijing (China)
  2. Georgia Inst. of Technology, Atlanta, GA (United States); Louisiana State Univ., Baton Rouge, LA (United States)
  3. Chinese Academy of Sciences (CAS), Beijing (China)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Prairie View A&M Univ., Prairie View, TX (United States)
  6. Georgia Inst. of Technology, Atlanta, GA (United States)
  7. Georgia Inst. of Technology, Atlanta, GA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1488696
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Chemical Engineering Journal
Additional Journal Information:
Journal Volume: 357; Journal Issue: C; Journal ID: ISSN 1385-8947
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Membrane capacitive deionization; Over-potential; Seawater desalination; Mesoporous carbon; Carbon aerogel

Citation Formats

Tang, Kexin, Kim, Yong-ha, Chang, Junjun, Mayes, Richard T., Gabitto, Jorge, Yiacoumi, Sotira Z., and Tsouris, Costas. Seawater desalination by over-potential membrane capacitive deionization: Opportunities and hurdles. United States: N. p., 2018. Web. doi:10.1016/j.cej.2018.09.121.
Tang, Kexin, Kim, Yong-ha, Chang, Junjun, Mayes, Richard T., Gabitto, Jorge, Yiacoumi, Sotira Z., & Tsouris, Costas. Seawater desalination by over-potential membrane capacitive deionization: Opportunities and hurdles. United States. doi:10.1016/j.cej.2018.09.121.
Tang, Kexin, Kim, Yong-ha, Chang, Junjun, Mayes, Richard T., Gabitto, Jorge, Yiacoumi, Sotira Z., and Tsouris, Costas. Mon . "Seawater desalination by over-potential membrane capacitive deionization: Opportunities and hurdles". United States. doi:10.1016/j.cej.2018.09.121. https://www.osti.gov/servlets/purl/1488696.
@article{osti_1488696,
title = {Seawater desalination by over-potential membrane capacitive deionization: Opportunities and hurdles},
author = {Tang, Kexin and Kim, Yong-ha and Chang, Junjun and Mayes, Richard T. and Gabitto, Jorge and Yiacoumi, Sotira Z. and Tsouris, Costas},
abstractNote = {The salt removal capacity (SRC) of the carbon electrodes in membrane capacitive deionization (MCDI) is limited by the applied potential (<1.6 V). Thus, enhancement of the SRC is essential before applying MCDI to seawater desalination. This study aims at developing a novel MCDI system for seawater desalination by applying over-potential (OP) to enhance ion-adsorption capacity and kinetics, and by reversing the polarity (RP) of electrodes to improve ion-desorption kinetics (hereafter named OP-MCDI-RP) for seawater desalination. At 2.4 V, the OP-MCDI system with mesoporous carbon demonstrated a SRC value of 64.7 mg g–1 when desalting 0.5 M NaCl solution, while the OP-CDI system could only remove 8.2 mg g–1 under identical conditions. Similarly, an OP-MCDI cell using carbon aerogel demonstrated a greater SRC value of 43.4 mg g–1 in comparison with 12.5 mg g–1 achieved in OP-CDI. These results indicate that the OP-MCDI system can directly desalt high salinity water regardless of the electrode material. In contrast to the OP-MCDI system, the OP-MCDI-RP system yields a higher regeneration efficiency by applying a reversed low-voltage. It is shown that, under appropriate operating conditions, the OP-MCDI-RP system reduced the electrical conductivity of a seawater sample of 37 practical salinity units by 99.9%, suggesting that the OP-MCDI-RP system can be employed for seawater desalination. In conclusion, due to the dramatic increase in energy demand and insufficient long-term stability caused by high potential and high salt concentration, however, the OP-MCDI-RP process should be further investigated for potential practical applications.},
doi = {10.1016/j.cej.2018.09.121},
journal = {Chemical Engineering Journal},
number = C,
volume = 357,
place = {United States},
year = {2018},
month = {9}
}

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