A Thermodynamic Interpretation of Microbiologically Influenced Corrosion

The authors have tabulated bacteria that mediate or facilitate various pairs of half-cell reactions affected by bacteria in otherwise kinetically unfavorable electrochemical cells. Nernst equation plots of these half-cell electrode reactions have been overlaid on the potential-pH Pourbaix diagram for iron, permitting convenient comparisons of the thermodynamic equilibria between corrosion and biomediated half-cell reactions. Correlations emerging from these comparisons support known mechanisms of microbiologically influenced corrosion (MIC) and provide indications of some new ones for iron and carbon steels in reducing conditions.