22
Table 1.2 Investigations of the effect of water on deep eutectic solvents’ systems (in chronological order)
Studied system(s)
Water content
Technique(s)
Comments
References
ChCl:U ChCl:thiourea 1:2
14–57–90 and 95 wt%
NMR
The characteristic chloride-HBD
complex was maintained at 14 wt%
water. Yet, a disruption was noticed at or
above 57 wt% water content.
Gutiérrez
et al. (2009)
ChCl:U 1:2
0–90 wt%
MD simulations
The water addition caused a decrease in
the number of urea-urea and urea-Cl
hydrogen bonds owing to the
preferential binding of chloride anions to
water and an increase in the ions’
diffusion. The effect of water became
notable beyond 25–30 wt% water.
Shah and
Mjalli
(2014)
ChCl:U ChCl:EG ChCl:G 1:2
2.5–20 wt%
Pulsed field gradient NMR
Unlike the case of ChCl:G, a difference
between the diffusion coefficients of the
aliphatic and hydroxyl groups of choline
or the HBD was observed when adding
water to both ChCl:U and ChCl:EG,
suggesting an interaction with water.
D’Agostino
et al. (2015)
1,2-Propanediol:ChCl:water 1:1:1
0–100% (v/v)
NMR
At a water content below 50% (v/v), the
NADES structure is maintained.
However, further dilution leads to an
aqueous solution of the free components
of the NADES.
Dai et al.
(2015))
ChCl:G 1:3
25 and 50 wt%
NMR
The interactions between DES
components are weakened up to 25 wt%
water and new interactions with water
are observed. However, in the presence
of 50 wt% water, the interactions
between ChCl and glycerol are
completely disrupted.
Hadj-Kali
et al. (2015)
T. El Achkar et al.