Corrosion protection of mild steel in hydrochloric acid up to 313 K using propyl benzimidazole: Electroanalytical, adsorption and quantum chemical studies

The inhibition efficiency of propyl benzimidazole for mild steel in hydrochloric acid in three different concentrations at 303, 308 & 313 K have been studied by polarization, electrochemical impedance spectroscopy, adsorption, surface studies and basic computational calculations. The inhibition efficiencies and the global chemical reactivity relate to total energy, EHOMO, ELUMO and gap energy (ΔE). Propyl benzimidazole interact with mild steel surface through adsorption and the process of adsorption follow Langmuir isotherm model. The inhibition efficiency increases with concentration and reaches maximum at 150 ppm. The increase in temperature have an inverse relationship with protection efficiency. The corrosion inhibition efficiencies and the global chemical reactivity relate to total energy, EHOMO, ELUMO and gap energy (ΔE). Keywords: Propyl benzimidazole, Corrosion inhibition, Mils steel, EIS, Computational technique