Kinetic properties of the passive film on copper in the presence of sulfate-reducing bacteria

Elina Huttunen-Saarivirta*, E. Ghanbari, F. Mao, Pauliina Rajala, Leena Carpén, D. D. Macdonald

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    20 Citations (Scopus)

    Abstract

    Copper specimens were exposed to Sulfate-Reducing Bacteria (SRB) for 10 months under the conditions corresponding to the final disposal of high-level nuclear waste. In-situ electrochemical impedance spectroscopy (EIS) measurements were carried out to characterize the surface-environment interface after various times of exposure. The EIS results are interpreted in terms of the Point Defect Model (PDM), in order to obtain kinetic information on the formation of the Cu2S passive film. The standard rate constant and the rate constants for the surface reactions revealed that the Cu2S layer is a p-type semiconductor. The diffusion constant for cation vacancies in the barrier layer and the average bulk cation vacancy concentration in the barrier layer were found to be on the orders of 10−13 cm2·s−1 and 1022 cm−3, respectively, i.e., both slightly higher than reported in literature for corresponding electrochemically developed Cu2S layers. The electric field strength was approximately 3·105 Vcm−1 at all measurement points. These results are presented and discussed in this work in the light of storage of high-level nuclear waste.

    Original languageEnglish
    Pages (from-to)C450-C460
    JournalJournal of the Electrochemical Society
    Volume165
    Issue number9
    DOIs
    Publication statusPublished - 1 Jan 2018
    MoE publication typeA1 Journal article-refereed

    Funding

    Posiva Oy is acknowledged for providing OFP-Cu for the experiments and groundwater for the SRB enrichment cultures. The Ministry of Employment and the Economy in Finland is thanked for funding provided through the Public Nuclear Waste Management Program KYT2014 for collecting experimental data. The financial support for the SUBTRIB project from the participating companies and the Finnish Funding Agency for Technology and Innovation (Tekes, through funding decision 865/31/2016) as well as from the Finnish Foundation for Technology Promotion for E.H.-S. enabled her research visit to Berkley, USA and the PDM data optimization work. One of the authors (D.D.M.) also thanks SSM of Sweden for their support of his current research on the corrosion of copper in sulfide-containing geological brines.

    Keywords

    • copper sulfide
    • passive film
    • point defect model

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