Investigation of a Pharmaceutically Active Compound Omeprazole as Inhibitor for Corrosion of Mild Steel in H2SO4 Solution

Inhibition performance of omeprazole for mild steel in 0.1M H2SO4 solution has been investigated through different approaches including potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), weight loss, scanning electron microscope (SEM) experiments and theoretical calculations. The experimental results reveal that omeprazole is an effective inhibitor with a maximum achievable inhibition efficiency of 98.5%, and the adsorption of omeprazole on the mild steel surface is found to obey the Langmuir adsorption isotherm. Polarization curves illustrate that omeprazole acts as a mixed-type inhibitor, and EIS demonstrates that an adsorption film of the inhibitor is formed on mild steel surface. Moreover, quantum chemical calculations and the molecular dynamics (MD) simulation are also performed to gain the further insight of the inhibition mechanism of omeprazole on steel corrosion, which show that the possible adsorption centers of the omeprazole molecule are benzene ring, benzimidazole ring, sulphinyl and the nitrogen atom of the hexaheterocyclic.