Selecting Electrode Materials and Sequence for Electrochemical Removal of Chlorinated Ethenes in Groundwater

Bente Højlund Hyldegaard*, Lisbeth M. Ottosen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Chlorinated ethene contaminations are a widespread environmental hazard and a threat to drinking water supplies. Electrochemical methods for in situ degradation of the chlorinated ethenes in the plume are under development. In laboratory, complete electrochemical removal of chlorinated ethenes in undivided flow-through reactors is reported when using palladized iron (Fe) cathodes (C) and cast Fe anodes (A). The cost of the electrodes depends on the Fe purity. In this study, 99.95%, 99.8% and 98+% palladized Fe cathodes, and 99.8% Fe and cast Fe anodes were investigated. The surfaces of the palladized Fe electrodes were examined by scanning electron microscopy. Deposition of palladium by electroless plating onto the Fe surfaces was uneven and disconnected. The less pure the Fe material, the higher the degree of oxide coverage of the cathode’s surface during electroless plating. Electrochemical application via Fe electrodes installed in a flow-through reactor of field-extracted groundwater and sandy sediment was studied for three-electrode configurations of A–A–C and C–C–A. The anodes of 99.8% Fe and cast Fe demonstrated different corrosion patterns; uniform corrosion and graphitization, respectively. Corrosion products clogged the sandy matrix. The corrosion product compositions differed between the A–A–C and C–C–A electrode configurations. The groundwater pH of 7.35 ± 0.05 changed downgradient to the electrochemical zone to 9.5 and 6.2 for the A–A–C and C–C–A reactors, respectively. The response of the hydrogeochemical settings to the established redox zones showed that the C–C–A electrode configuration was less intrusive to the surrounding environment. [Figure not available: see fulltext.].
Original languageEnglish
Article number290
JournalWater, Air, and Soil Pollution
Volume231
Issue number6
Number of pages15
ISSN0049-6979
DOIs
Publication statusPublished - 2020

Keywords

  • Electrochemistry
  • Electrode material
  • Electrode sequence
  • Corrosion
  • Precipitation
  • Hydrogeochemistry

Cite this