Anticorrosive properties of green-synthetized benzylidene derivatives for mild steel in hydrochloric acid: An experimental study combined with DFTB and molecular dynamics simulations

Abstract

Two benzylidene derivatives anisaldehyde-cyanoguanidine imine (CMBG) and p-dimethylaminobenzal dehyde-TRIS imine (DBHP) were prepared according to the 12 Principles of Green Chemistry. They were evaluated as corrosion inhibitors for 1020 mild steel in acidic media (HCl 1 mol L-1) by gravimetric and electrochemical measurements and reached 82 and 92% anticorrosive efficiency, respectively, at 2.20 mmol L-1. A comprehensive theoretical study was carried out using Density-Functional Based Tight Binding (DFTB) and molecular dynamics (MD) simulations. Electrochemical results indicated that inhibitors had a robust inhibitive effect on the corrosion process, significantly increasing the polarization resistance of the working electrode while reducing both cathodic and anodic corrosion reactions. Physical-chemical calculations indicated the formation of a protective multilayer and that physical-chemical adsorption governed the inhibition process. AFM and SEM with EDX analyses depicted a smoother surface in the presence of the organic molecules, pointing to the formation of a protective barrier. DFTB calculations revealed that inhibitor molecules formed covalent bonds with iron atoms, which was confirmed by the Projected Density of States (PDOS) of adsorbed systems. (C) 2022 Elsevier B.V. All rights reserved.