Solvent-free synthesis and corrosion inhibition performance of Ethyl 2-(1,2,3,6-tetrahydro-6-oxo-2-thioxopyrimidin-4-yl)ethanoate on carbon steel in pickling acids: Experimental, quantum chemical and Monte Carlo simulation studies
By El-Lateef, Hany M. Abd; Abdallah, Zeinab A.; Ahmed, Mohamed S. Mohamed
Published in Journal of Molecular Liquids
2019
Abstract
Ethyl 2-(1,2,3,6-tetrahydro-6-oxo-2-thioxopyrimidin-4-yl)ethanoate (EOTPE) was synthesized by a facile and cost-effective method. The structure confirmation of the synthesized EOTPE was performed by different spectroscopic methods. The corrosion inhibition action of EOTPE in pickling acids (1.0 N HCl and1.0 N H2SO4) at different temperatures (30–60 °C) was tested by various surface and corrosion methods, including open circuit potential (EOCP-t), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX). The inhibition capacity of EOTPE was found to 92.1% and 97.0% in the case of H2SO4 and HCl, respectively at the optimum dose of 1 × 10−3 M. The PDP method demonstrated that EOTPE compound acted as a mixed-type inhibitor in both studied acids. Moreover, adsorption of EOTPE inhibitor on the steel surface conforms to the model of Langmuir isotherm. Additionally, the thermodynamic parameters for the inhibitor adsorption were estimated and interpreted. FE-SEM/EDX and FTIR investigations confirmed the formation of a defensive film on the electrode surface. The findings obtained from the above methods are in good agreement and are fully supported by Monte Carlo (MC) simulations and density functional theory (DFT) calculations.