The effect of <i>Bacillus cereus</i> and SRB on corrosion character of Q355 carbon steel and their synergistic mechanism

Purpose This study aims to explore the dynamic mechanism through which Bacillus cereus mitigates the corrosion of Q355 carbon steel caused by sulfate-reducing bacteria (SRB) in simulated seawater. Design/methodology/approach Coupon experiments, Electrochemical Analysis, Super Depth-of-Field Microscopy, X-ray Diffraction, X-ray photoelectron spectroscopy and Fluorescence Microscopy are used to investigate the dynamic mechanism of Bacillus cereus in mitigating corrosion. Findings A “competition – transformation – reconstruction” synergy is found. Bacillus cereus suppresses SRB abundance and forms a dynamic pH equilibrium (about 6.78). It inhibits the S2 produced by SRB and forms FOOH-NH4 complexes. These complexes co-deposit with extracellular polymers of Bacillus cereus and other corrosion byproducts to form a three-dimensional isolation barrier, resisting corrosive ions and achieving corrosion inhibition. Originality/value This study reveals the unique dynamic mechanism of Bacillus cereus in mitigating the corrosion of Q355 carbon steel caused by SRB in simulated seawater, providing a thinking of corrosion control in marine environments.