Enhancement of exogenous riboflavin on microbiologically influenced corrosion of nickel by electroactive Desulfovibrio vulgaris biofilm

Abstract

Abstract Riboflavin, a soluble redox mediator for electron transfer, is involved in various redox processes in biogeochemical systems. This work gives some insights into the MIC mechanism of pure nickel (Ni) caused by Desulfovibrio vulgaris. Compared with pure copper (Cu) metabolite (M)-MIC, Ni MIC by D. vulgaris exhibits distinctly different corrosion behavior. 20 ppm (w/w) riboflavin dramatically enhances the corrosion rate of Ni (59% increase in weight loss), while it has no impact on Cu MIC. Furthermore, headspace H2 detection reveals that neither proton nor H2S corrosion occurs in Ni MIC (Cu MIC caused by biogenic H2S produces large amounts of H2, whereas Ni MIC does not). The thermodynamic analysis and experimental results indicate that Ni D. vulgaris MIC is caused by trapping extracellular electrons from Ni oxidation for energy, which belongs to extracellular electron transfer (EET)-MIC.