Physicochemical, Electrochemical, and Theoretical Study of Three Synthesized Organic Inhibitors for 316L Stainless Steel in HCl

This work deals with the synthesis and physicochemical, electrochemical characterization of three organic compounds, and then the study of their inhibitory efficiency against corrosion phenomenon of 316L stainless steel in hydrochloric acid solution medium. The structure of the as-prepared organic compounds was confirmed by FT-IR, 1H, and 13C NMR spectroscopy analyses. In parallel, electrochemical methods, impedance spectroscopy, and potentiodynamic polarization were of great interest to determine the inhibitive efficiency. In fact, the corrosion current density of 316L stainless steel without inhibitor is 76.60 μA/cm2, and a significant decrease in the corrosion current densities was observed after the addition of the organic molecules, where an increase of 87% in terms of the inhibition efficiency was noted particularly with the Amine 3. Moreover, scanning electron microscopy images brought out the presence of the organic protective layer. In addition, following the concentration effect has shown that the phenomenon of stability and high inhibition efficiency could be reached even at small concentrations around of 10–5 M. The Langmuir isotherm was used to feature the adsorption on sample surface. Furthermore, in order to demonstrate the protective effect of organic compounds against 316L stainless steel corrosion, theoretical studies based on two different methods (density functional theory and molecular dynamic) were applied. Accordingly, the performed results through the different approaches are in good agreement with each other and provide a general insight into the phenomenon studied.