IJUP08 - Universidade do Porto

Deep Eutectic solvents: A new kind of Ionic Liquids
R. Costa, F. Silva and C.M. Pereira
Department of Chemistry, Faculty of Science, University of Porto, Portugal.
R. Campo Alegre, 687, 4169 – 007 Porto, Portugal
Ionic liquids (ILs) are salts with melting point below 100°C and have recently attracted
considerable attention as potential alternatives to conventional organic solvents in a variety
of synthetic, catalytic, and electrochemical applications [1]. Deep eutectic solvents (DES)
are a new type of these ionic liquids and are obtained by mixing a large range of
quaternary ammonium salts with metal salts, amides, carboxylic acids or alcohols.
Attractive features of these liquids such the potential to reduce pollution in industrial
processes have led to investigations as alternative reaction media for a variety of
application that usually use organic solvents. Eutectic solvents can be use in catalysis,
electropolishing, metal extraction and metal deposition (e.g. Cr) [2,3].
Chromium plating is a massive industry and all of them use chromic acid technology.
Conventional chromic acid plating processes are extremely hazardous because they use
hexavalent chromium, which is highly toxic and carcinogenic. Choline chloride:chromium
chloride (III).6H2O (cromeline) based ionic liquids allow the use of trivalent chromium
less toxic [4].
I/A
1.0x10 -4
5.0x10 -5
0.0
-5.0x10 -5
-1.0x10 -4
-1.5x10 -4
-2.0x10 -4
scan rate:
5 mV/s
20 mV/s
50 mV/s
100 mV/s
-1.0 -0.8 -0.6 -0.4 -0.2 0.0
E vs SCE/V
Figure 1 – Cyclic voltammogram measured at Hg/cromeline interface.
A cyclic voltammetry experiment, as in other controlled potential experiments, a potential
is applied to the system, and the faradaic current response is measured (a faradaic current is
the current due to a redox reaction) [5]. This technique was applied to study the
Hg/cromeline interface. The work was completed with the study of nucleation that occurs
on mercury surface by chronoamperometry. Data will be presented and discussed later.
References:
[1] A. P. Abbott, G. Capper, S. Gray; Chem. Phys. Chem., 2006, 7, 803 – 806.
[2] A. P.Abbott, G. Capper, K. Mckenzie, K. Ryder; Electrochimica Acta, 2006, 4420 – 4425.
[3] A .P. Abbott, K. J. Mckenzie; Phys. Chem. Chem. Phys., 2006, 8, 4265 – 4279.
[4] A. P. Abbott, G. Capper, D. Davies, R. Rasheed; Chem. Eur. J, 2004, 10, 3769 – 3774.
[5] A. J. Bard, L. R. Faulkner; Electrochemical methods – Fundaments and applications, 2 nd
edition, Wiley&Sons, Inc., N.Y., 2001.
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