Investigation of Inhibition Effect and Determination of Some Quantum Chemical Parameters of an Organic Compound on the Carbon Steel in Sulfuric Acid Medium

Abstract

The inhibition ability of [3-(4-methyl-pyridin-2-y1)-4-oxo-2-phenylimino-thiazolidin-5-ylidene]-acetic acid ethyl ester (MOTAE) on the corrosion behavior of carbon steel in 0.5 M sulfuric acid solution was investigated using weight loss and potentiodynamic polarization techniques. The inhibition efficiencies increased as the concentration of the compound was increased. The calculated inhibition efficiencies from the investigated methods were in good agreement. Potentiodynamic polarization measurements indicate that MOTAE acts as a mixed type inhibitor. The adsorption of inhibitor on the steel surface obeys Langmuir adsorption isotherm. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM)‎ were used to characterize the surface of the alloy. The structure of inhibitor was optimized using three quantum chemical levels. Some quantum chemical parameters as well as Mulliken charge densities for this molecule were computed and discussed.