Benzidine-based Schiff base compounds for employing as corrosion inhibitors for carbon steel in 1.0 M HCl aqueous media by chemical, electrochemical and computational methods

Abstract The inhibiting performance of three benzidine derivatives named Bis (4(dimethylamino)benzylidene)biphenyl-4,4′-diamine (DBB), Bis(4-methoxy benzylidene)biphenyl-4,4′-diamine (MBB) and Bis(4-chlorobenzylidene)biphenyl-4,4′-diamine (CBB) for carbon steel (CS) corrosion in 1.0 M HCl aqueous media was evaluated using weight loss and electrochemical techniques. The affinity of tested compounds towards the steel surface was investigated using Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations. Compounds revealed a good inhibition action in tested medium even at low concentrations and the inhibition efficiency increases with increasing concentration of inhibitors. Polarization curves show that they act as mixed-type inhibitors and their adsorption process obeyed the Langmuir adsorption model. SEM, AFM and EDX studies were used to confirm the presence of the protective film formed on the carbon steel surface by observing the corrosion attack morphologies and elemental composition of the corrosion products, respectively. DFT and MD results complement experimental studies and demonstrate that Schiff base moieties and functional groups are responsible for corrosion inhibitive performances of investigated compounds.