Effect of Exposure Time on Corrosion Behavior of Carbon Steel in Presence of Shewanella RCRI7 Bacteria

The time-dependent effect of Shewanella RCRI7 on the corrosion behavior of carbon steel was investigated using the potentiodynamic polarization and weight loss methods. The potentiodynamic polarization results revealed that the corrosion rate of carbon steel in the presence and absence of the bacteria was 1.04 and 0.27 mpy, respectively, during a 2–3 h period. The same result was obtained over a 20-day period by weight loss measurements. This trend changed after ~ 20 days as the corrosion rate of carbon steel in the presence of the bacteria was up to about twice that in their absence. It can be deduced that the exposure time changed (either inhibited or enhanced) the effect of Shewanella RCRI7 on the corrosion process. In the 1–20-day period, the biofilm formed by Shewanella RCRI7 protected the carbon steel surface. After 20 days, the corrosion rate in the electrolyte containing the bacteria was enhanced by crack formation and the appearance of discontinuities in the structure of the biofilm.