Triazoles As Inhibitors of Corrosion of Mild Steel In Acids

Abstract

A study of the inhibition efficiency of triazoles on the corrosion of mild steel in hydrochloric, sulphuric, nitric and phosphoric acids indicates that it is possible to obtain an efficiency of greater than 95% by using benzotriazole of appropriate concentration. At comparative concentrations, the inhibition efficiency obtained with benzotriazole is much greater than that obtained with triazole or amino triazole. The concentration of benzotriazole needed to obtain a high degree of efficiency increases with increase in concentration of acid.Polarisation measurements indicate that benzotriazole increases both the anodic and cathodic polarisation. However, on anodic polarisation, a potential of unpolarisability is observed indicating a change in the kinetics of metal dissolution.Measurements of differential double layer capacity in hydrochloric acid with and without benzotriazole indicate that the surface coverage is complete at a concentration of 2 mM.