Inhibition of Microbiologically Influenced Corrosion of Mild Steel and Stainless Steel 316 by an Organic Inhibitor

Abstract

Microbiologically influenced corrosion (MIC) is a serious problem that continues to plague many industrial systems. In this study, a method to prevent MIC by the use of an azole-type organic compound on the metal substrates was studied. Inhibition of MIC of mild steel and stainless steel 316 by 2-Methylbenzimidazole (MBI) in seawater with sulphate-reducing bacteria (SRB) was investigated using electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). MBI was shown to be an effective inhibitor in controlling MIC by two strains of sulphate-reducing bacteria: Desulfovibrio desulfuricans, and a local marine isolate. EIS analysis shows an increase in charge transfer resistance for both mild steel and stainless steel 316 after the addition of MBI in the aqueous solution. AFM analyses show a decrease in the surface roughness and pit depth after the addition of MBI. Of the two bacterial strains, it is found that MBI is more effective in the inhibition of corrosion by D. desulfuricans. At a concentration of 1mM, MBI shows a higher MIC inhibition effect on stainless steel 316 (corrosion inhibition 99.5%) than on the mild steel (corrosion inhibition 59.4%). These results indicate that MBI shows potential application in the inhibition of MIC of metal substrates.