665
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0
200
400
600
800
1000
1200
mole fraction of CO
2
Pressure(kpa)
ATPPB:4DEG
ATPPB:10DEG
ATPPB:4TEG
ATPPB:10TEG
ChCl:4TEG
ChCl:4DEG
Fig. 13 CO 2 solubility in phosphonium-based DESs at 303.15 K
for same HBDs, DESs with phosphonium as HBAs have significantly higher CO 2
uptake. Also, DESs with higher HBD chain length show higher CO 2 solubility.
The solubility in the hydrophobic solvents was also investigated. Zubeir et al. synthesized six different DESs and investigated the CO 2 solubility from 298 to 323 K
[143, 144]. Their results indicate that the CO 2 absorption in the prepared DESs was
similar to renowned fluorinated ILs. These solvents could be helpful where the water
content is more and can affect the CO 2 solubility of hydrophilic solvents. Table  4
presents the comparison of different DESs for the ability to capture CO 2 .
Table 4 Comparison of CO 2 solubility in different DESs
Solvents (HBD/
HBA)
T (K)
P
(bar)
CO 2 loading (mol CO 2 /
mol solvent)
CO 2 loading
(g CO 2 /g solvent)
Reference
4MAE/TBAB
303.15 10.46 0.30
0.106
[145]
3TEA/TBAB
298.15 10.00 0.08
0.021
[137]
4EAE/TBAB
303.15 09.93 0.22
0.071
[145]
6DEA/TBAB
303.15 10.11 0.11
0.036
[146]
6EA/TBAB
298.15 10.00 0.12
0.059
[137]
6EA/MTPPhBr 298.15 10.00 0.14
0.072
[137]
GUA/2EA
298.15 11.29 1.36 (mol/kg)
0.060
[147]
6EA/TPAC
298.15 10.57 0.94 (mol/kg)
0.041
[147]
4MAE/BTEACl 303.15 10.07 0.24
0.100
[145]
6DEA/ChCl
303.15 09.71 0.09
0.036
[146]
Potential Application of Ionic Liquids and Deep Eutectic Solvents in Reduction…