Corrosion of low-carbon steel in sulphuric acid solution in presence of pyrazole—halides mixture

Abstract

The corrosion behaviour of steel (0.05% C) in 0.5 M sulphuric acid solution in the presence of pyrazole—halide mixtures was studied. The increase in surface coverage values in the order of I − > Br − > Cl − seems to indicate that the radii and the electronegativity of halides play an important role in the adsorption process. The inhibition efficiency ( P%) increases with increasing concentration of pyrazole. The addition of halide enhances the inhibition efficiency to a considerable extent. The temperature increases the corrosion rate in the range 30–85°C in the presence and absence of inhibitors. The apparent activation energy is 12.4 kcal/mol. The synergistic effect of pyrazole and halide ions is discussed from the viewpoint of adsorption models. The inhibitive action requires knowledge of inhibitor at the electrode—solution interface.