Accelerated anaerobic corrosion of electroactive sulfate-reducing bacteria by electrochemical impedance spectroscopy and chronoamperometry

Many microbial species can use cathodes as electron donors for metabolism. This direct electron transfer (DET) pathway has rarely been proposed in biocorrosion processes. DET from Q235 carbon steel to the sulfate-reducing bacteria (SRB) Desulfovibrio caledoniensis and its effect on the corrosion behavior of carbon steel were investigated in the present study. Electroactive SRB biofilm was found to play a key role in the ennoblement of the corrosion potential (Ecorr) and in the acceleration of the corrosion rate, indicating that SRB mainly affected the cathodic reaction of low carbon steel corrosion. In addition, SRB biofilm obtained electrons from carbon steel electrode polarized at − 0.74 V. These findings present new evidence for DET between SRB biofilm and carbon steels.

► We studied electrochemical characteristics of Q235 carbon steel in medium with and without SRB cells.
► Addition of the SRB metabolic product without SRB cell induced a sharply decrease of corrosion potential.
► Corrosion potential of Q235 carbon steel increased about 150 mV in presence of SRB biofilm.
► SRB biofilm mainly accelerated cathodic reaction of carbon steel corrosion.
► SRB biofilm could obtain electrons directly from – 0.74 V polarized carbon steel electrode.