The eutrophication of seawater is not only harmful to the environment, but also influence microbes' proliferation and then influence biocorrosion of marine engineering materials to a great extent. This study investigated the microbiologically influenced corrosion (MIC) of Cu immersed in the Desulfovibrio vulgaris (a sulfate reducing bacterium) medium with four defined nutritional degrees: total nutrition, P lacking, N lacking, and P&N lacking. When D. vulgaris was cultured in more nutritional medium, more H2S was generated and more serious corrosion of Cu occurred. The concentration of H2S corresponding to the medium with total nutrition was as high as 4.9 × 104(±913.0) ppm. The weight loss of Cu in medium with total nutrition increased by at least 50% compared with other nutritional conditions. The depth of pitting pits on Cu increased obviously with more abundant nutrient elements N and P. The electrochemical tests supported the weight loss and also showed that an obvious passivation zone was formed on the anodic polarization curve. This indicated that a protective film was formed on the surface of Cu against uniform corrosion. The analyses of thermodynamics and experiment data indicated that metabolite MIC (M-MIC) account for the Cu corrosion by D. vulgaris.
Keywords: Biofilm; Cu corrosion; Localized corrosion; Microbiologically influenced corrosion; Passivation; SRB.
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