ABSTRACT
The inhibition effect of imidazole derivatives 4-methyl-2-propyl-1H-benzimidazole-6-carboxylic acid (MPBI) and 1,4'-Dimethyl-2'-propyl-1H,3'H-2,5'-dibenzimidazole (DPBI) against mild steel corrosion in 1 N HCl solutions were evaluated using conventional weight loss, potentiodynamic polarization, linear polarization and electrochemical impedance spectroscopy. The weight loss results showed that both are excellent corrosion inhibitors, electrochemical polarizations data revealed the mixed mode of inhibition and the results of electrochemical impedance spectroscopy have shown that the change in the impedance parameters, charge transfer resistance and double layer capacitance, with the change in concentration of the inhibitor is due to the adsorption of the molecule leading to the formation of a protective layer on the surface of mild steel. The inhibition action of these compounds was, assumed to occur via adsorption on the steel surface through the active centres contained of the molecule.