Corrosion Inhibition of Iron in Acid Solutions by Biological Siderophores

Four siderophores isolated from bacteria have been studied as possible corrosion inhibitors for iron in deareated 1 N . These compounds are aerobactin, enterobactin, parabactin, and rhodotorulic acid. Polarization measurements and ac impedance studies show that all four compounds are inhibitors, with the order of effectiveness being rhodotorulic acid < aerobactin < enterobactin < parabactin. X‐ray photoelectron spectroscopy surface analysis with one of the siderophores, rhodotorulic acid, shows that it chemisorbs at the interface. Enterobactin and parabactin are the most effective corrosion inhibitors of the four because they have the optimum combination of relatively high values of and the largest molecular cross‐sectional areas.