Effect of marine microorganisms and biofilms on cathodic current

Naoki Washizu, Tadashi Shinohara, Shin Ichi Motoda, Jun'ichi Sakai

    Research output: Contribution to journalArticle

    2 Citations (Scopus)

    Abstract

    In order to explain the mechanism that works in microbiologically influenced enhancement of corrosion rates, cathodic currents were measured on type 329J4L stainless steel exposed to seawater, and a biological analysis on biofilms was conducted. The cathodic current densities measured at 0.1 V vs. SHE were ranging from 0.3 μA/cm2 to 3 μA/cm2, after the specimen had been held at 0.1 V vs. SHE in natural seawater. On the other hand, the cathodic current densities at 0.1 V vs. SHE after the exposure to natural seawater under an open circuit condition, were higher than 1 μA/cm 2 in the early stage of the measurement. However, they fell to values lower than 0.1 μA/cm2 in 12 h. The current densities measured at 0.2 V vs. SHE were approximately 2 μA/cm2 in the initial stages and the final stages of the measurement, after the beforehand exposure to natural seawater at 0.2 V vs. SHE. The current densities measured at 0.2 V vs. SHE after the beforehand exposure to natural seawater under an open circuit condition, were higher than 1 μA/cm2 in the initial stages of the measurement and lower than 0.1 μA/cm2 in the final stages. In the case of measurements at 0.3 V vs. SHE, the average values of cathodic current densities were approximately 0.2 μA/cm2 after the beforehand exposure to natural seawater at 0.3 V vs. SHE, and lower than 0.01 μA/cm 2 after the beforehand exposure to natural seawater in an open circuit state. The cathodic current densities after the exposure to synthetic seawater, were lower than 0.01 μA/cm2 in the cases of measurement at 0.1 V vs. SHE, 0.2 V vs. SHE and 0.3 V vs. SHE. The data on DNA base arrangement detected by the denaturing gradient gel electrophoresis test in a biofilm formed at 0.2 V vs. SHE in natural seawater, was different from the data detected in a biofilm formed under an open circuit condition. It is, therefore, concluded that some specific types of microorganisms selectively attach to steel surfaces under cathodic conditions, and that such microorganisms are the cause of large cathodic currents resulting in high corrosion rates.

    Original languageEnglish
    Pages (from-to)472-479
    Number of pages8
    JournalZairyo to Kankyo/ Corrosion Engineering
    Volume56
    Issue number10
    DOIs
    Publication statusPublished - 2007 Oct

    Keywords

    • Cathodic condition
    • Corrosion rate
    • DNA base arrangement
    • Natural seawater
    • Open circuit condition
    • Type 329J4L

    ASJC Scopus subject areas

    • Energy (miscellaneous)
    • Mechanical Engineering
    • Metals and Alloys

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