Electrochemical and theoretical investigation on the behavior of the Co2+ ion in three eutectic solvents.

Deep eutectic solvents (DESs) have many advantages, making them a promising alternative in replacing ionic liquids and organic solvents. Besides, DESs have received much prominence due to their diverse applications: Electrodeposition of metals, organic synthesis, gas adsorption, and biodiesel production. Therefore, this work analyzed the effect of the temperature increase (298 K-353 K) on the behavior of the Co2+ ions in three eutectic solvents through electrochemical techniques and computational simulations. From the electrochemical analysis realized, the increase in temperature caused a reduction in specific mass and an increase in the diffusion coefficient. Besides, the activation energy values were of 15.3, 29.9, and 55.2 kJ mol-1 for 1ChCl:2 EG, 1ChCl:2U, and 1ChCl:2G, respectively. The computational simulations indicate that the increased temperature effect caused the replacement of HBD molecules by anions chloride around Co2+ ions for the SDW1 and SDW3 systems between the temperatures of 298 K-353 K, except for the SDW2 system that the replaced occurred in the interval of 313 K-353 K. Besides, the increase of temperature occasioned the increase of strength for Co-Cl interaction and weakened the interactions between the Co2+ ions with the oxygen of HBD molecules.