Tosyl-hydrazine, 4-nitrobenzoyl-hydrazine and terephthalyl-hydrazine as inhibitors for the corrosion of copper and aluminium in sulphiric acid

Abstract

The effect of tosyl-hydrazine (THy), 4-nitrobenzoyl-hydrazine (4-NBHy) and terephthalyl-hydrazine (terephthalyl-Hy) on the corrosion of copper and aluminium in sulphuric acid has been investigated. The inhibitive efficiency ranking of these compounds from both weight loss and polarization measurements was found to be terephthalyl-Hy > Thy > 4-NBHy for Cu and THy > 4-NBHy for Al. Both THy and 4-NBHy were found to be much less efficient as inhibitors for the corrosion of aluminium when compared to the corrosion of copper in sulphuric acid. The inhibitors acted cathodically both in the case of copper and aluminium, by merely blocking the cathodic reaction sites in the former and by altering the course of the mechanism of corrosion in the latter. The relative inhibitive efficiency of these compounds has been explained on the basis of structure dependent electron donor properties of the inhibitors and the nature of the metal-inhibitor interaction at the surface.