The influence of iron-binding ligands in the corrosion of carbon steel driven by iron-reducing bacteria

Abstract

AbstractIron reducing bacteria (IRB) are thought to accelerate the corrosion of steel by removing the Fe(III)-oxide passivating layer through iron respiration. We investigated the effect of the iron-binding ligands oxalate, malonate, and succinate on the corrosion of carbon steel driven by the IRB Shewanella oneidensis. These dicarboxylates were found to accelerate the corrosion of carbon steel driven by IRB up to 2.6 times more than the abiotic experiment without dicarboxylates. Iron dissolution was enhanced by dicarboxylates, and this influenced the ability of planktonic cells to engage in iron respiration. The strong iron-binding ligands oxalate and malonate supported iron reduction by planktonic cells, whereas in the experiments with succinate or without dicarboxylate, a direct contact mechanism with the solid Fe(III)-oxide was observed. Faster microbial respiration rates were found in experiments with succinate than with oxalate or malonate, suggesting a competition for iron between the microbial cells and the strong iron-binding ligands.