Effect of Chloride Ion Concentration on Corrosion of Q235 Steel in Sulfate-Reducing Bacteria Containing Solution

摘要

The sedimentary water in crude oil storage tanks contains a large amount of chloride ions andmicroorganisms, represented by sulfate-reducing bacteria(SRB), which is the main reason for thecorrosion of tank bottom. In this paper, electrochemical impedance spectroscopy(EIS) and polarizationcurves were used to study the effect of different chloride ion concentration on the corrosion behavior ofQ235 steel in sterile solution and that containing sulphate-reducing bacteria. The results showed that thechloride ion concentration had a significant effect on the corrosion behavior of Q235 steel in SRBcontaining solution. With the increase of the concentration lower than 20 g·L-1, the current density ofQ235 steel in SRB solution was greater than that of the sterile solution for the synergistic effect ofchloride ion and SRB, and the corrosion potential shifted negatively, indicating that the microorganismspromoted the corrosion of Q235 steel. When the chloride ion concentration exceeded 20 g·L-1, thecorrosion rate of Q235 steel decreased with the increase of the concentration. The self-corrosion currentdensity was much smaller than that in the sterile solution, and the corrosion potential shifted positively,revealing that the higher chloride concentration inhibited the growth of sulfate-reducing bacteria.