The effect of water on the physicochemical properties of an ethylene glycol and choline chloride mixture containing Cu²⁺ ions: electrochemical results and dynamic molecular simulation approach

Abstract

The effect of water on the physicochemical properties of an ethylene glycol and choline chloride mixture containing Cu2+ ions was investigated by electrochemical techniques and molecular dynamics simulation. The experiments and computational calculations were carried out by increasing the water content from 0 up to 10% (v/v). The cyclic voltammetry and chronopotentiometry techniques showed that the diffusion coefficient of Cu2+ ions increased and that the peak potentials for both the Cu2+/Cu+ and Cu+/Cu redox couples shifted towards more positive potentials with the increase in the water content in the solution. The molecular dynamics simulation indicated that the water molecules replaced the ethylene glycol molecules that were coordinated with Cu2+ ions, while the interactions between Cu2+ and Cl- ions were not influenced by the presence of water.

The role of hydrogen bond donor and water content on the electrochemical reduction of Ni2+ from solvents – an experimental and modelling study

“…However, RTILs are sometimes toxic and un-Moreover, ChCl-based DESs are highly hygroscopic. The strong influence of H 2 O on the viscosity and conductivity of the solvents has been reported in many occasions 15,[21][22][23] . More recently, it has also been shown that water affects the dynamics and the electrochemistry of active species 15,21,24,25 .…”

“…Two sets of the most commonly used and studied DESs 14,16,[20][21][22]24,38,39,44,[49][50][51][52] were prepared by mixing and stirring choline chloride (ChCl) (VWR Life Sciene, high purity) with: 1) urea (U) (Merck KGaA, 99.5%), and 2) ethylene glycol (EG) (Merck KGaA, 99.5%) in a 1:2 molar ratio, respectively, at 80 • C for 1 h. To minimize water content when needed, choline chloride and urea were dried at 80 • C for 12 h in a vacuum oven prior to their use. After obtaining homogeneous and transparent solvents, 0.2 M of NiCl 2 •6H 2 O (Merck KGaA, 98%) was added.…”

Computer Simulations of Deep Eutectic Solvents. Challenges, Solutions, and Perspectives

“…The increase in water fraction up to 75 wt % leads to a three-fold increase in thermal conductivity. Bezerra et al explored the effect of water on the electrochemical behavior of Ag+ ions in reline by combining experiments and MD simulations [280]. Using the cyclic voltammetric technique, it was demonstrated that the addition of water catalyzes the electrochemical reduction of Ag + ions in reline DES.…”

Probing the influence of Zn and water on solvation and dynamics in ethaline and reline deep eutectic solvents by 1H nuclear magnetic resonance

“…16 In order to overcome poor physical properties in DESs, the addition of water has been investigated. 12,[17][18][19][20] Computer simulations have revealed that the addition of water, to ethaline or reline DESs, decreases the number of hydrogen bonds formed and consequently lowers the viscosity of both DES systems. 20 However, as more water is added, it has been observed 12 that ChCl-based DESs start to lose their DES structure, and form aqueous solutions, above a 1 : 1 equivalent of water:chloride.…”

“…12,[17][18][19][20] Computer simulations have revealed that the addition of water, to ethaline or reline DESs, decreases the number of hydrogen bonds formed and consequently lowers the viscosity of both DES systems. 20 However, as more water is added, it has been observed 12 that ChCl-based DESs start to lose their DES structure, and form aqueous solutions, above a 1 : 1 equivalent of water:chloride. This transition is also reported to change the electrochemical properties of ChCl-based DESs, in particular, by narrowing their potential window.…”