Corrosion behavior of steel Q235 co-influenced by Thiobacillus thiooxidans and Bacillus

Surface analysis methods, a mass loss method, and electrochemical tests were employed to investigate the corrosion behavior of steel Q235 under the synergistic effect of Thiobacillus thiooxidans (T. t) and Bacillus. Scanning electronic microscopy (SEM) results reveal that a densest biofilm was formed in the mixed bacteria culture; The surface of the sample immersed in the mixed culture appeared circular corrosion poles which much different from the ones in the single-bacteria cultures. Mass loss method results indicate that the corrosion rate in the (T. t)-Bacillus system was between the single-bacteria system. Electrochemical impedance spectroscopy (EIS) show that there were two time constants existed in the T. t-Bacillus system after 2 d immersion, the corrosion resistance of the film performed as initially enhanced then weakened.