Electrochemical impedance study of the effect of water additives on the rate of mild steel corrosion in deep eutectic solvent ethaline

The effect of water on the corrosion rate of mild steel in deep eutectic solvent, Ethaline, was investigated by electrochemical impedance spectroscopy technique. Quantitative characteristics of the process of corrosive destruction of metallic samples have been obtained, the peculiarities of this process have been determined and its mechanism has been established by selecting an equivalent electrical circuit. It was shown that increasing of water content in this ionic liquid leads to an appreciable increase in the corrosion rate. It was stated that the growth of corrosion activity of Ethaline mixture can be associated with the appearance of water in its composition and it is chiefly connected with the changes of physicochemical properties of this mixture. With increasing the water content in the investigated liquid mixture, decreasing of viscosity and density are observed. These changes in physicochemical properties of Ethaline can be resulted from the destruction of hydrogen bonds, existing between the components of the mixture, that leads to an increase in depolarizer transport to the surface of the samples and, as a consequence, to the acceleration of the corrosion.