Heterocyclic Schiff bases as corrosion inhibitors for carbon steel in 1 M HCl solution: hydrodynamic and synergetic effect

Abstract

{(1Z)-2-oxo-N′-phenyl-N-quinolin-8-ylpropanehydrazonamide (H2L-H) and (1Z)-N′-(4-bromophenyl)-2-oxo-N-quinolin-8-ylpropanehydrazonamide (H2L-Br)} have been studied as corrosion inhibitors of carbon steel in 1 M HCl medium by the weight loss method, potentiodynamic polarization, electrochemical impedance spectroscopy EIS, scanning electron microscopy SEM coupled with Energy Dispersion X-Ray Spectroscopy EDS, Atomic Force Microscopy AFM, IR and UV-visible spectroscopy. The inhibition efficacy has been shown to increase with increasing inhibitor concentration. The corrosion of the carbon steel is mainly controlled by a charge transfer process. The temperature effect was evidenced and the thermodynamic parameters were calculated. The adsorption of the inhibitors on the metal surface obeyed the Langmuir adsorption isotherm. The hydrodynamic effect and the synergetic effect have been implemented. Inhibitory efficiency decreases with increasing rotation speed and the used additives adsorb cooperatively to form a protective layer on the metal surface. The results obtained by the experimental measurements and those of the theoretical calculations (DFT and MD simulation) are in good correlation.