Nitrate pollution accelerated the microbial corrosion of Fe0: A simulated corrosion verification for understanding marine corrosion phenomenological model.

In the seawater-sediment simulated immersion system, nitrate affected microbial corrosion of steel. The research studied the corrosion processes of Q235 steel influenced by nitrate exposure from aspects such as mineral evolution, environmental microbial cultivation, and interfacial electrochemistry. Nitrate pollution affected the corrosion acceleration (0.11 ± 0.01 mm*y-1, pitmax = 21.11 μm). Severe iron corrosion might not originate from the acidification of the interface microenvironment or the bioactivity of sulfate-reducing bacteria controlled by diffusion of inorganic nitrogen in the rust layer, but rather from the microbial metabolism of nitrate-reducing bacteria. The nitrate-addition had altered the composition of the microbial community attached to the steel surface, with a significant increase in the abundance of Achromobacter. The attached microorganisms regulated the Fe0 oxidation and the NO3- reduction on the Q235 steel surface to increase the pitting corrosion sensitivity and live bacteria number. The effect of nitrate on microbial corrosion of Fe0 in aerobic environment showed different understandings from the proposed corrosion phenomenological model.