Inhibition of corrosion of copper by 5‐mercapto‐3‐p‐nitrophenyl‐1,2,4‐triazole in aqueous environment

Abstract

The inhibitor 5‐mercapto‐3‐p‐nitrophenyl‐1‐2‐4‐triazole has 92.75 per cent inhibition efficiency in controlling corrosion of copper in neutral aqueous environment, containing 300 ppm Cl‐, a situation where the chloride concentration of the cooling water system will usually be not greater than 300 ppm. A discussion of mechanistic aspects of corrosion inhibition is based, in a holistic way, on the results obtained from the classical weight loss method, potentiostatic polarisation study, AC‐impedance study, UV‐visible absorption study and different surface examination techniques like FTIR, XRD and ESCA. The protective film is found to be of unimolecular thickness and to consist of Cu (I) – inhibitor complex cuprous chloride, CuCl or CuCl2‐ complex ion or both and no oxide of copper on the surface.