Assessing the impact of electron-donating-substituted chalcones on inhibition of mild steel corrosion in HCl solution: Experimental results and molecular-level insights

Material corrosion is one of the outstanding challenging problems in the industry, and it strongly influences refining and petrochemical plants lifetime. Therefore, prevention of the corrosion of different metals and alloys is imperative in the viewpoint of industrial safety and productivity. For this purpose, the application of suitable corrosion inhibitors is one of the most applicable solutions. The present paper focuses on the anticorrosive properties of three biologically active chalcones, namely (E)-2-(4-(3-(2,5 dimethoxyphenyl)acryloyl) phenoxy)acetic acid (AA-3), 2-(4-(3-(4-methoxyphenyl)propanoyl)phenoxy)acetic acid (AA-2) and (E)-2-(4-(3-(p-tolyl)acryloyl)phenoxy)acetic acid (AA-1) for mild steel in hydrochloric acid at temperature range 303−333 K. The corrosion inhibition performances of chalcones were evaluated by electrochemical tests, gravimetrical method, SEM, molecular orbital theory and molecular dynamics (MD) simulations. Results show that at the concentration of 5 × 10−3 molL-1, chalcone derivatives show high corrosion inhibition activities. All compounds are found to act via adsorption at the metal/solution interface, and their adsorption follows Langmuir isotherm model. Electrochemical tests indicate that the three chalcones act as mixed-type inhibitors. The thermodynamic data of adsorption were determined and discussed. Density Functional Theory (DFT) and MD simulations were used to assess the active sites of adsorption of the three inhibitors and their interaction with the iron surface, respectively. Scanning electron microscope (SEM) was used to analyze the surface morphological changes that chalcones induce in the corroded mild steel. The comparison of experimental results with theoretical data indicates that methoxy functional groups have a considerable influence on the anticorrosive properties of tested chalcones.