Electrochemical studies of the biocorrosion of mild steel in the presence and absence of sulfate reducing bacteria (SRB) grown in lactate/sulfate and lactate/nitrate aqueous media were performed. Open circuit potential measurements revealed a displacement of the potential in the noble direction in both media. However, regular oscillations in the potential were observed only in the lactate/sulfate medium. SEM micrographs showned pits clearly distributed over the surface of the steel samples exposed to SRB cultures in both media, with small size and more uniform pits in the lactate/sulfate media, in agreement with the open circuit potential data. Cyclic voltammetry clearly shows that the SRBs grown in the lactate/sulfate medium lead to high dissolution rates in the transpassive region with the formation of Fe(III) species.
biocorrosion; sulfate-reducing bacteria (SRB); mild steel; electrochemical data
