Physicochemical properties and corrosion activity of deep eutectic solvents ethaline and reline towards mild steel

Systematic data on the physicochemical properties of a new class of ionic liquids, deep eutectic solvents (DES), which are based on mixtures of choline chloride with ethylene glycol or urea (ethaline and reline, respectively), have been obtained. The temperature dependences of density, electrical conductivity and viscosity of these ionic liquids were established and characterized. It was shown that an increase in the temperature leads to a decrease in the density and viscosity of solutions that can be explained by increased mobility of ions and molecules of the mixtures due to partial destruction of hydrogen bonds between them. It should be noted that the conductivity of the ethaline solution is significantly higher than that of the reline solution in the investigated temperature range; this is due to diverse interaction between various components of ionic liquids and differences in the vacancies sizes. The basic features of the corrosion destruction of constructional steel were established in the deep eutectic solvents under consideration. It was shown that the deep eutectic solvent ethaline is more corrosive towards mild steel as compared with reline.