Inhibitory Action of Benzofuran Derivatives on Mild Steel Corrosion in Hydrochloric Acid Solutions

Abstract

Derivatives of benzofuran ((E)-ethyl-5-(2-phenyldiazenyl) benzofuran-2-carboxylate and ethyl 5-aminobenzofuran-2-carboxylate) were used as corrosion inhibitors for mild steel in hydrochloric acid solution. The inhibition efficiency depended on the concentration and type of the benzofurans. The inhibition efficiency ranged between 75 and 85 % at the highest concentration (25 mM), and between 35 and 40 % at the lowest concentration (5 mM) of inhibitor in 1 M HCl solution. Inhibition efficiency decreased with rise in temperature, this corresponded to surface coverage of the metal by the inhibitor. Potentiodynamic polarization measurements have been carried out at room temperature, which clearly reveal the fact that all investigated inhibitors are of mixed type and they inhibit corrosion of mild steel by blocking the active sites of the metal surface. The results also showed that, the inhibitors were adsorbed on the mild steel surface according to Langmuir adsorption isotherm.