P26-2 : Electrolysis of corroded iron FeS2 suppresses anaerobic microbial corrosion promoted by Desulfovibrio vulgaris
It was estimated that 20 to 30 percent of all corrosion on pipelines is ascribed to microbial causes mainly by sulfate-reducing bacteria (SRB). To suppress the microbial corrosion, excess amount of antibiotics are practically used despite of large expense and their toxicity to environment. Recently we have found that iron surface at potential more negative than –0.5 V (vs. standard hydrogen electrode) suppresses the corrosion caused by SRB in environmental microbe flora. However, mechanisms to inactivate the SRB have remained unclear. Here we study the mechanism for potential tuning to suppress the microbial corrosion using an isolated model SRB strain, Desulfovibrio vulgaris. Potential tuning at –0.5 V decreased corrosion current caused by D. vulgaris more than 90 %. Spectroscopic and chromatographic analysis on the corrosion products showed the potential posing at –0.5 V drove an electrolysis of FeS2, resulted in the production of HS–, suggesting that the corrosion is suppressed by deactivating SRB with the sudden increase of HS– concentration at the iron surface.
keywords:Microbially influenced corrosion,Sulfate-reducing bacteria,Electrochemistry,Electrochemical protection,X-ray Photoelectron Spectroscopy