The Synergistic Effect of 2-Chloromethylbenzimidazole and Potassium Iodide on the Corrosion behavior of Mild Steel in Hydrochloric Acid Solution

Abstract

The synergistic effect of 2-chloromethylbenzimidazole (2-CBI) and potassium iodide (KI) for mild steel in 1 M hydrochloric acid solution was investigated by potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that, with the addition of 100 ppm potassium iodide, the inhibition efficiecy (IE) of 100 ppm 2-CBI in 1 M hydrochloric acid had been improved from 91.14% to 96.15%. And synergistic parameter of 100 ppm 2-CBI with different amounts of potassium iodide is always greater than 1. The adsorption of potassium iodide combining with 100 ppm 2-CBI obeys to the Langmuir adsorption isotherm. Thermodynamic adsorption parameters, including ΔG 0 ads , ΔH a and ΔS a of the adsorption of the combinned inhibitor, as well as the E a of the mild steel corrosion in 1 M HCl with the combinned inhibitor, were calculated.