The Effect of the Chemical Structure of Benzopyridine and Benzimidazole on their Corrosion Inhibiting Action of Ordinary Steel in Acidic Medium

We present in this work the study of the protective effect of Benzopyridine (BP) and Benzimidazole (BZ) on the corrosion of ordinary steel in 1 M HCl. This study was carried out using gravimetric methods, potentiodynamic and electrochemical impedance measurements. The effect of structural molecule on their inhibition efficiency has been reported with a view to establishing a relationship between inhibitor efficiency and molecular structure. Both compounds inhibit the corrosion of ordinary steel to different degrees. It has been found that the molecule which comprises a pyridinum group has a higher inhibition efficiency than that of the compound which has an imidazole group, which indicate that the order of efficiency of these compounds in solution and the extent of their tendency to adsorb on ordinary steel surface is as follows: BP>BZ. The synergistic study between the studied inhibitors and potassium iodide shows that we can improve the inhibitory efficiency of our inhibitors and that these compounds act in combined forms by a competitive adsorption. The theoretical calculation by the density function theory (DFT) method confirms the experimental results.