Understanding Corrosion Inhibition of C38 Steel in HCl Media by Omeprazole: Insights for Experimental and Computational Studies

The influence of omeprazole on C38 steel corrosion in HCl solutions (1, 3, 5 M) was evaluated by weight loss and electrochemical techniques. Density-functional theory (DFT) and molecular dynamic (MD) simulations were also used. The weight loss experiment shows that the maximum inhibition efficiency achieved a value of 98.36% in the presence of 5 × 10−3 M of omeprazole in molar HCl. Polarization measurements revealed that the inhibitor acted as a mixed type. Impedance spectroscopy measurements illustrated that the resistance to charge transfer increased with the addition of omeprazole concentration in 1, 3 and 5 M of HCl. The SEM micrographs demonstrated applicable protection of the C38 surface after the addition of 5 × 10−3 M of omeprazole for all three studied HCl test solutions. The DFT and MD simulations were used to explain the effect of the molecular structure on the corrosion inhibition efficiency and to simulate the adsorption of omeprazole on C38 surface. The corrosion rates were related to generalized pH expressed by Strehlow acidity function.