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

doi:10.1021/acsestwater.3c00741

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 journal › Article › peer-review

6 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 language	English
Pages (from-to)	2390-2402
Number of pages	13
Journal	ACS ES and T Water
Volume	4
Issue number	6
DOIs	https://doi.org/10.1021/acsestwater.3c00741
State	Published - Jun 14 2024

Funding

This work was supported by the National Alliance for Water Innovation (NAWI) through funding from the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office under Funding Opportunity Announcement DE-FOA-0001905. SEM, TEM, EDS, and XRD characterization was performed at the Center for Nanophase Materials Science (CNMS), Oak Ridge National Laboratory. CNMS is a DOE Office of Science User Facility. The authors are grateful to WaterTectonics for providing flow-through EC reactors.

Keywords

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

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10.1021/acsestwater.3c00741

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

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.",

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AU - Jang, Gyoung Gug

AU - Castillo, Cesar

AU - Dutta, Swapnamoy

AU - Su, Yi Feng

AU - Jun, Jiheon

AU - Keum, Jong K.

AU - Kim, Kyungho

AU - Chellam, Shankararaman

AU - Tsouris, Costas

PY - 2024/6/14

Y1 - 2024/6/14

N2 - 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.

AB - 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.

KW - EC Faradaic efficiency

KW - EC fouling

KW - EC long-term performance

KW - Fe electrocoagulation

KW - polarity reversal

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

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