Performance Restoration of Iron Electrodes by Polarity Reversal after Long-Term Surface Fouling in Wastewater Electrocoagulation

Gyoung Gug Jang, Cesar Castillo, Swapnamoy Dutta, Yi Feng Su, Jiheon Jun, Jong K. Keum, Kyungho Kim, Shankararaman Chellam, Costas Tsouris

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Iron electrocoagulation (Fe-EC) performance often declines with time, producing lower contaminant removal efficiencies and higher energy requirements due to formation of a fouling layer on the electrodes. Here, we investigate the formation of the fouling layer and the effectiveness of polarity reversal to restore the Fe-EC performance. A thin, porous iron oxide layer initially forms on the anode, thickening into a dense, over 150-μm thick crystalline layer after extended operation. This fouling layer restricts dissolution and diffusion of Fe ions into the bulk solution, thus increasing the anode potential required to maintain a desired electrical current and decreasing Faradaic efficiency. Polarity reversal applied when performance decline is observed effectively removes the fouling layer, thereby restoring Faradaic and contaminant removal efficiencies and decreasing energy consumption. Our findings suggest that gas generation at the cathode surface after polarity reversal causes removal of the fouling layer. This study enhances the current understanding of fouling-layer formation in Fe-EC and offers a practical approach, involving polarity reversal, to maintain electrode reactivity and optimal Fe-EC performance.

Original languageEnglish
Pages (from-to)2390-2402
Number of pages13
JournalACS ES and T Water
Volume4
Issue number6
DOIs
StatePublished - Jun 14 2024

Keywords

  • EC Faradaic efficiency
  • EC fouling
  • EC long-term performance
  • Fe electrocoagulation
  • polarity reversal

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