The corrosion behavior and mechanism of carbon steel induced by extracellular polymeric substances of iron-oxidizing bacteria

In this work, the corrosion behavior and mechanism of carbon steel induced by extracellular polymeric substances (EPS) extracted from an iron-oxidizing bacterium culture were studied using surface analysis and electrochemical measurements in 3.5 wt% NaCl solutions. Results of electrochemical measurements showed that 7 day-old EPS at 240 mg L−1 inhibited the corrosion of carbon steel, especially after the EPS solution was heat treated to deactivate the enzymes in the EPS. However, 7 day-old EPS at much higher and much lower concentrations accelerated corrosion. Furthermore, 14 day-old EPS and 28 day-old EPS at 240 mg L−1 also accelerated corrosion.