Biofilm-forming bacteria can protect mild (unalloyed) steel from corrosion. Mild steel coupons incubated with Rhodoccocus sp. strain C125 and Pseudomonas putida mt2 in an aerobic phosphate-buffered medium containing benzoate as carbon and energy source, underwent a surface reaction leading to the formation of a corrosion-inhibiting vivianite layer [Fe3(PO4)2]. Electrochemical potential (E) measurements allowed us to follow the buildup of the vivianite cover. The presence of sufficient metabolically active bacteria at the steel surface resulted in an E decrease to -510 mV, the potential of free iron, and a continuous release of ferrous iron. Part of the dissolved iron precipitated as vivianite in a compact layer of two to three microns in thickness. This layer prevented corrosion of mild steel for over two weeks, even in a highly corrosive medium. A concentration of 20 mM phosphate in the medium was found to be a prerequisite for the formation of the vivianite layer.
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Research Article| October 01 2001
Corrosion protection by anaerobiosis
Water Sci Technol (2001) 44 (8): 103–106.
H.P. Volkland, H. Harms, O. Wanner, A.J.B. Zehnder; Corrosion protection by anaerobiosis. Water Sci Technol 1 October 2001; 44 (8): 103–106. doi: https://doi.org/10.2166/wst.2001.0475
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