The effect of sodium benzoate on microbial corrosion of steel in seawater

摘要

It is known that the addition of some biocides could prevent the microbial corrosion of steel by Sulphate Reducing Bacteria (SRB). Sodium benzoate, which is known as a food preservative and also as an anodic inhibitor of steel corrosion, might be a candidate of microbial corrosion control agent. Some mild steel specimens were immersed in natural sea water containing SRB, with and without addition of inhibitor, during certain time intervals. Weight loss measurements indicated that SRB has increased the steel corrosion rate in sea water and Na-benzoate is insufficiently effective inhibitor. The X - ray diffraction analysis showed that the corrosion products consist principally of Fe_3O_4, FeS and FeSO_4.4H_2O, which performed the passivity of the steel specimen. Microscopic observation proved that Na-benzoate is an effective pitting inhibitor. Bacterial count using the MPN method, however, showed that the population growth of SRB was unaffected by Na-benzoate except for low bacteria concentration in the short time immersions.