Cathodic Polarization Effect on MIC by SRB

Cathodic polarization of a metallic surface in contact with sulfate-reducing bacteria (SRB) has been reported as a technique for corrosion control when the potential reaches values above -950 mV vs CSE; nevertheless, it has been determined that in populations where this type of bacteria prevails the problem of microbiologically influenced corrosion (MIC) is not controlled adequately. The objective of this study was to evaluate the severity of the attack of a pure SRB strain on a cathodically polarized iron surface using diverse electrochemical techniques and attack morphology. To do this, an experimental design was structured that consisted of several experiments using the electrochemical hydrogen permeation technique of Devanathan and Stachurski to study the effect of a pure strain of Desulfovibrio desulfuricans subspecies Desulfuricans ATCC 7757 on a pure iron sheet polarized at -1000mV vs SCE (-1070 mV vs CSE) during different exposure times of 3, 6, 9, 12, 15, 18, 21, 24, 48 and 72 hours. The results obtained demonstrated that a polarization of -1000mV vs SCE is not sufficient to counteract bacterial growth at the sessile level or the corrosive process influenced by this bacteria and the morphology of the metal after each experiment reflected an increasingly severe corrosive attack over time.