Organic Corrosion Inhibitors for Aluminum in Perchloric Acid

Substituted N-arylpyrroles containing carbaldehyde groups on a pyrrole ring and their inhibitive effects on the corrosion of aluminum (Al) in perchloric acid (HClO4) were investigated. Electrochemical measurements showed the organic compounds examined had good inhibiting properties at 40°C. The high inhibition effect of the N-aryl-2,5-dimethylpyrroles containing carbaldehyde groups on a pyrrole ring on corrosion of Al in acid media was explained on the basis of the electronic structure of the molecule and by the condensation characteristic of the carbaldehydes. Investigation of the influence of substitution type (–F,–Cl, – NH2) on the inhibiting characteristics of examined organic compounds showed the best inhibiting effect was from substituted N-arylpyrrole with fluorine in the ortho position of the phenyl ring.