Keto-enol heterocycles as new compounds of corrosion inhibitors for carbon steel in 1 M HCl: Weight loss, electrochemical and quantum chemical investigation

In this paper, the effect of Keto-enol derivatives namely (Z)-3-hydroxy-1-(pyridin-2-yl)but-2-en-1-one (KE-1) and (Z)-1-(1,5-dimethyl-1H-pyrazol-3-yl)-3-hydroxy-3-(pyridin-2-yl)prop-2-en-1-one (KE-2)on the inhibition of carbon steel (CS) corrosion in 1 M HCl has been studied using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and quantum chemical study. Weight loss measurements indicate that these compounds reduce the corrosion rate of carbon steel in acidic solution and the inhibition effect increases with the inhibitors concentration but decreases with temperature. The electrochemical polarization study revealed that the tested Keto-enol derivatives are mixed type. EIS show that the KE-1 and KE-2 form an adsorptive layer on the metallic surface. The adsorption of the KEs on the carbon steel surface obeys the Langmuir adsorption isotherm. The results of quantum chemical calculations and Monte Carlo simulation studies are in good agreement with experimental results. (C) 2017 Elsevier B.V. All rights reserved.