Performance assessment by experimental and Theoretical approaches of newly synthetized benzyl amide derivatives as corrosion inhibitors for carbon steel in 1.0 M hydrochloric acid environment

Abstract

• The anticorrosion effect of two inhibitors on C-steel in 1 M HCl was studied. • The polarization results show that (HBEDA) and (HBDETA) are mixed-type inhibitors. • The impedance data suggest the adsorption of the inhibitors on C-steel surface. • The Langmuir adsorption isotherm governs the adsorption mechanism. • QC and MC show that hetero atoms serve as active sites to facilitate adsorption. As part of the efforts made by many researchers to evaluate a lot of chemical compounds as inhibitors for carbon steel corrosion, this research focuses on novel two compounds of benzamide derivatives. The investigated compounds namely N, N -bis (p-hydroxybenzoyl) ethylenediamine (HBEDA) and N, N -bis (p-hydroxybenzoyl) Diethylenetriamine (HBDETA), were formulated then characterized using FTIR, 1 HNMR, and elemental analysis to elucidate the structures chemically. Theoretical and experimental (electrochemical and morphology) studies made clear that (HBEDA) and (HBDETA) improve carbon steel (C-steel) inhibition efficiency in 1 M hydrochloric acid as concentrations increase (25, 50, 100, 150, 200, 250 ppm). The benzamide derivatives acted as interface corrosion inhibitors in an electrochemical impedance spectroscope (EIS) experiment, and they acted as mixed type corrosion inhibitors in a polarization test. They yielded best efficiency gains of 95.8 percent for HBEDA and 99.6 percent for HBDETA. Information collected from the EIS technique was studied in order to represent the corrosion inhibition procedure using an equivalent circuit (EC). The elevated K ads values and negative ΔG ads (-28.71, −28.79 kJ/mol) values of the two compounds (understudy) revealed that they were strongly and spontaneously adsorbed at C-steel/electrolyte connections respectively, and the adsorption isotherm of Langmuir fitted widely with the empirical data. The Surface examination (morphology) of metal employing energy dispersive X-ray (EDX) and scanning electron microscope (SEM) evaluations confirmed the adsorption of (HBEDA) and (HBDETA) on the substrate (C-steel).