The influence of N-heterocyclics on corrosion inhibition and hydrogen permeation through mild steel in acidic solutions

The influence of N‐heterocyclics, viz. imidazole (IA), benzimidazole (BIA) and 2‐methyl imidazole (MIA) on the corrosion and hydrogen permeation through mild steel in 1 N H2SO4 and in 1N HC1 has been studied using weight loss and various corrosion monitoring techniques. Imidazole and benzimidazole inhibit the corrosion of mild steel in both the acidic solutions, but methyl imidazole accelerates the corrosion. They behave as cathodic inhibitors by influencing the cathodic polarization reaction. Except methyl imidazole, the other two compounds reduce the hydrogen permeation current in both the acids. The adsorption of these compounds on the mild steel surface from both the acids obeys Temkin’s adsorption isotherm. Trends in the increase of charge transfer resistance and decrease of capacitance values also show the adsorption of inhibitors on the metal surface.