Surface chemistry and corrosion behaviour of 304 stainless steel in simulated seawater containing inorganic sulphide and sulphate-reducing bacteria

• The sulphidization of passive film by inorganic and biogenic sulphide was studied.
• Rapid sulphidization of passive films by the biogenic sulphide was observed.
• Different corrosion behaviours by inorganic and biogenic sulphides were determined.
• Biogenic sulphide was more aggressive toward steels than its inorganic counterpart.

Although many studies have been carried out regarding the role of sulphide anions in promoting microbial corrosion of various metal substrates, very little is known about the differences between inorganic sulphide and biogenically-derived sulphide by sulphate-reducing bacteria (SRB) and what the reasons for differing corrosion behaviour between the two types of sulphide may be towards common metals. In this study, various electrochemical and surface analytical techniques were employed to study the effect of the inorganic and biogenic sulphide (active SRB present) on the surface chemistry and corrosion behaviour of 304 stainless steels in a simulated seawater-based modified Baar’s (SSMB) medium. Clear differences in the surface chemistry of the sulphurised passive film by inorganic and biogenic sulphide (active SRB present) were quantified by X-ray photoelectron spectroscopy (XPS). The transformation of metal sulphides in abiotic and biotic sulphide solutions with the exposure time was correlated with different corrosion behaviour of 304 stainless steels.

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