Active Control of Irreversible Faradic Reactions to Enhance the Performance of Reverse Electrodialysis for Energy Production from Salinity Gradients

Yoontaek Oh, Ji Hyung Han, Hanki Kim, Namjo Jeong, David A. Vermaas, Jin Soo Park, Soryong Chae

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Irreversible faradic reactions in reverse electrodialysis (RED) are an emerging concern for scale-up, reducing the overall performance of RED and producing environmentally harmful chemical species. Capacitive RED (CRED) has the potential to generate electricity without the necessity of irreversible faradic reactions. However, there is a critical knowledge gap in the fundamental understanding of the effects of operational stack voltages of CRED on irreversible faradic reactions and the performance of CRED. This study aims to develop an active control strategy to avoid irreversible faradic reactions and pH change in CRED, focusing on the effects of a stack voltage (0.9-5.0 V) on irreversible faradic reactions and power generation. Results show that increasing the initial output voltage of CRED by increasing a stack voltage has an insignificant impact on irreversible faradic reactions, regardless of the stack voltage applied, but a cutoff output voltage of CRED is mainly responsible for controlling irreversible faradic reactions. The CRED system with eliminating irreversible faradic reactions achieved a maximum power density (1.6 W m-2) from synthetic seawater (0.513 M NaCl) and freshwater (0.004 M NaCl). This work suggests that the control of irreversible faradic reactions in CRED can provide stable power generation using salinity gradients in large-scale operations.

Original languageEnglish
Pages (from-to)11388-11396
JournalEnvironmental Science and Technology
Volume55
Issue number16
DOIs
Publication statusPublished - 2021

Bibliographical note

Accepted Author Manuscript

Keywords

  • capacitive reverse electrodialysis
  • irreversible faradic reactions
  • pH change
  • power generation
  • salinity gradients
  • stack voltage

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