Hydrazine and substituted hydrazines as corrosion inhibitors for lead in acetic acid

Abstract

The effect of hydrazine (Hy) and substituted hydrazines (phenyl hydrazine (PHy ), 2,4-dinitrophenyl hydrazine (2,4-DNPHy), 4-nitrobenzoyl hydrazine (4-NBHy), and tosyl hydrazine (THy)) on the corrosion of lead in acetic acid has been investigated. The inhibitive efficiency ranking of these compounds from both weight loss and polarisation measurements was found to be THy ≥ 4-NBHy » Hy > PHy > 2,4-DNPHy. The drift of free corrosion potential to more noble values and the increase in anodic overpotential without any change in Tafel slope in the presence of inhibitors suggest that the inhibitors retard the corrosion process by blocking anodic reaction sites. The relative inhibitive efficiency of these compounds is explained on the basis of structure dependent electron donor properties.