An operando ORP-EIS study of the copper reduction reaction supported by thiourea and chlorides as electrorefining additives

Thomas Marcel Collet, Noel Hallemans, Benny Wouters, Kristof Ramharter, John Lataire, Rik Pintelon, Annick Hubin

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)
63 Downloads (Pure)

Abstract

Additives are used in metal electroreduction processes to obtain a smooth and optimal metal deposit. However, the mechanism with which these additives influence the metal deposition is poorly understood. Operando odd random phase electrochemical impedance spectroscopy (ORP-EIS) experiments have been performed to study the effect of a chloride-thiourea additive mixture on the reduction of copper ions in a sulfuric acid solution. This additive mixture is crucial in the copper electrorefining process. An optimal experimental design and a well-founded methodology is applied to study this complex additive mixture. The ORP-EIS data is studied to analyze non-stationarities and non-linearities and the time-varying impedance is resolved when necessary. Two equivalent circuits are proposed to model the impedance data and the model parameters are linked to physical processes in the system. The use of the time-varying impedance when studying thiourea in a plating process and the use of distributed circuit elements in the EIS model is discussed.
Original languageEnglish
Article number138762
Number of pages12
JournalElectrochimica Acta
Volume389
DOIs
Publication statusPublished - 1 Sep 2021

Bibliographical note

Funding Information:
This research is financially supported by Flanders Innovation and Entrepreneurship (VLAIO grant HBC.2017.0212) and Aurubis Belgium NV.

Publisher Copyright:
© 2021 Elsevier Ltd

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

Keywords

  • Operando ORP-EIS
  • Time-varying impedance
  • Electrorefining
  • Copper reduction
  • Additives

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