The inhibitive effect of ethanolamine on corrosion behavior of aluminium in NaCl solution saturated with CO2

Abstract

In this study, the inhibitive effect of ethanolamine on corrosion behavior of aluminium was investigated in 3 wt. % NaCl solution, saturated with CO2. All the experiments were carried out at 20°C. Ethanolamine was added at different concentrations between 1 mM and 8 mM. In order to determine the corrosion inhibition efficiency of investigated inhibitor and the optimal concentration of inhibitor that provides the lowest corrosion of aluminium, the open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), linear sweep voltametry (LSV) measurements, weight loss measurements as well as scanning electron microscopy technique (SEM) were performed. The electrochemical study and weight loss measurements indicated that the minimum corrosion rate and maximum inhibition efficiency was detected for concentration of 5 mM of ethanolamine, as well as the ethanolamine did not change the mechanism of aluminium dissolution. The adsorption of ethanolamine was found to obey Frumkin adsorption isotherm at concentrations up to 5 mM, but further increase in concentration was found to deviate from Frumkin adsorption isotherm. The calculated value for interaction parameter a indicates attractive lateral interactions in the adsorbed inhibitor layer. The obtained value of standard free energy of adsorption, ΔGads θ, confirms that the adsorption process is favorable, spontaneous physisorption process.