Electrochemical assessment of imidazole derivatives as corrosion inhibitors for mild steel in 3.5 NaCl solution

The corrosion inhibition efficiency of benzimidazole, 2-methylbenzimidazole and 2- aminobenzimidazole for mild steel immersed in 3.5 NaCl solution was investigated by electrochemical impedance spectroscopy EIS at concentration range from 10-5 to 10-2 M of imidazoles and temperature range from 30 to 50°C. In addition, DC polarization was examined to determine inhibition mechanism at concentration range from 10-5 to 10-2 M of the imidazole derivatives. Double layer capacitance and charge transfer resistance were extracted from EIS plots after fitting with an appropriate circuit. Surface coverage was calculated based on capacitance and resistance of the corroding cell. It was found that increase of inhibitor concentration and temperature results in increase and decrease of surface coverage respectively. The results showed that these compounds have limited corrosion inhibition. The adsorption of these compounds on the steel surface obeys Temkin isotherm.