Density functional treatment and electro analytical measurements of liquid phase interaction of 2-ethylbenzimidazole (EBI) and ethyl (2-ethylbenzimidazolyl) acetate (EEBA) on mild steel in hydrochloric acid

DFT calculations on the liquid phase interaction and corrosion inhibition properties of 2-ethylbenzimidazole (EBI) and its derivative ethyl (2-ethylbenzimidazolyl)acetate (EEBA) on mild steel in hydrochloric acid (0.5, 5 and 1.5 M) at three different temperatures (303, 308 and 313 K) have been studied using EIS, polarization, adsorption measurements and computational calculations. Results show that EBI and EEBA act as effective inhibitors for the corrosion of mild steel in hydrochloric acid media. Polarization studies showed that both the inhibitors behave as mixed type inhibitors with respect to the electrode reactions. EEBA offers better inhibition efficiency than EBI. The inhibition efficiency found to decrease with increase in temperature in either of the cases. The mechanism involves adsorption phenomenon and in the case of EEBA, the adsorption obeyed Langmuir adsorption isotherm. For EBI, the adsorption obeyed Langmuir adsorption isotherm except for 313 K in 1.5 M HCl, for which the best fit adsorption isotherm was Temkin adsorption isotherm. (C) 2016 Elsevier B.V. All rights reserved.