# Ionic Liquids Hybridization for Carbon Dioxide Capture: A Review
## 2 ILs Utilization for CO\({}_{2}\) Capture
Meanwhile, a study by [PERSON] revealed that viscosity and heat capacity have a direct effect on the capital and operating cost as those properties involve in both the energy requirement and the design of absorption column [15]. For instance, a heat generator used to increase the operating temperature is employed to reduce the viscosity of ILs, thereby enhancing the rate of CO\({}_{2}\) diffusivity [52; 53]. Never  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & \multicolumn{4}{c}{**Conditions**} & \multicolumn{4}{c}{**CO\({}_{2}\) Absorption Capacity**} \\ \cline{3-10}
**Class of ILs** & **ILs** & \(\mathbf{T}\) & \(\mathbf{P}\) & \(\mathbf{t}\) & **Male** & **molCO\({}_{2}\)/mol** & **wt\%** & **Ref. ** \\  & & (\(\mathbf{{}^{\circ}}\)C) & **(bar)** & **(min)** & **Fraction** & **IL** & **wt\%** & **Ref. ** \\ \hline \multirow{11}{* \begin{tabular}{} \end{tabular}  } & [BMIM][PF\({}_{6}\)] & —\({}^{e}\) & 80 & —\({}^{e}\) & 0.600 & —\({}^{e}\) & —\({}^{e}\) & [18] \\  & [BMIM][PF\({}_{6}\)] & 25 & 13 & —\({}^{e}\) & \(-\)0.210 & —\({}^{e}\) & —\({}^{e}\) & [23] \\  & [BMIM][PF\({}_{6}\)] & 40 & 93 & —\({}^{e}\) & 0.720 & —\({}^{e}\) & —\({}^{e}\) & [22] \\  & [BMIM][PF\({}_{6}\)] & 25 & 13 & —\({}^{e}\) & \(-\)0.190 & —\({}^{e}\) & —\({}^{e}\) & [23] \\  & [BMIM][TF\({}_{3}\)] & 25 & 13 & —\({}^{e}\) & \(-\)0.280 & —\({}^{e}\) & —\({}^{e}\) & [23] \\  & [EMMIM][Tf\({}_{2}\)N] & 25 & 13 & —\({}^{e}\) & \(-\)0.260 & —\({}^{e}\) & —\({}^{e}\) & [23] \\  & [HMIM][Tf\({}_{2}\)N] & 40 & 83.7 & —\({}^{e}\) & 0.720 & —\({}^{e}\) & —\({}^{e}\) & [27] \\  & [OMIM][Tf\({}_{2}\)N] & 40 & 83.7 & —\({}^{e}\) & 0.763 & —\({}^{e}\) & —\({}^{e}\) & [27] \\ \hline \multirow{11}{*}{ \begin{tabular}{} \end{tabular}  } & [AEmim][Tf\({}_{2}\)N] & 30 & 1.6 & —\({}^{e}\) & —\({}^{e}\) & 0.490 & —\({}^{e}\) & [28] \\  & [AEmim][BF\({}_{4}\)] & 30 & 1.6 & —\({}^{e}\) & —\({}^{e}\) & 0.425 & —\({}^{e}\) & [28] \\  & [AEmim][DCA] & 30 & 1.6 & —\({}^{e}\) & —\({}^{e}\) & 0.435 & —\({}^{e}\) & [28] \\  & [P\({}_{228}\)][6 Brnda] & 58.9 & 0.83 & —\({}^{e}\) & —\({}^{e}\) & \(-\)1.00 & —\({}^{e}\) & [31] \\  & [DMAMA][Af][Af-PhO] & 30 & 1.5 & —\({}^{e}\) & \(-\)\({}^{e}\) & 0.86 & —\({}^{e}\) & [32] \\  & [E\({}_{1}\)Py][(CN)\({}_{3}\)], & 30 & 20 & —\({}^{e}\) & 0.473 & —\({}^{e}\) & —\({}^{e}\) & [29] \\  & [E\({}_{1}\)Py][N(CN)\({}_{2}\)] & 30 & 20 & —\({}^{e}\) & 0.382 & —\({}^{e}\) & —\({}^{e}\) & [29] \\  & [E\({}_{1}\)Py][SCN] & 30 & 20 & —\({}^{e}\) & 0.184 & —\({}^{e}\) & —\({}^{e}\) & [29] \\  & aq-[APmim][Br] & 30 & —\({}^{e}\) & —\({}^{e}\) & —\({}^{e}\) & 0.65 & —\({}^{e}\) & [43] \\ \hline \multirow{11}{*}{\ \begin{tabular}{} \end{tabular}  } & [MDAP][TF\({}_{2}\)N]-PDC & 0 & 1.0 & —\({}^{e}\) & —\({}^{e}\) & —\({}^{e}\) & 1.390 & [34] \\  & [PBIMT][BF\({}_{4}\)] & 22 & 0.80 & 600 & —\({}^{e}\) & —\({}^{e}\) & 0.241 & [33] \\  & [PVBMI][PF\({}_{6}\)] & 22 & 0.80 & 600 & —\({}^{e}\) & —\({}^{e}\) & 0.322 & [33] \\  & [PVBMI][BF\({}_{4}\)] & 22 & 0.80 & 600 & —\({}^{e}\) & —\({}^{e}\) & 0.305 & [33] \\  & HPIL-C1 (1) & 25 & 1.0 & —\({}^{e}\) & —\({}^{e}\) & —\({}^{e}\) & 5.30 & [35] \\ \hline \multirow{11}{*}{ \begin{tabular}{} \end{tabular}  } & [P\({}_{66614}\)][Pro] & 25 & 1.01 & —\({}^{e}\) & —\({}^{e}\) & 0.91 & —\({}^{e}\) & [40] \\  & [P\({}_{66614}\)][Met] & 25 & 1.01 & —\({}^{e}\) & —\({}^{e}\) & 0.99 & —\({}^{e}\) & [40] \\  & [Pf\({}_{66614}\)][Gly] & 25 & 1.01 & —\({}^{e}\) & —\({}^{e}\) & 0.97 & —\({}^{e}\) & [40] \\  & [B\({}_{4}  
theless, it is worth noting that this approach can have a counterproductive effect as the solubility selectivity of CO2 in ILs typically decreases with increasing temperature [54]. In summary, the viscosity of ILs plays a central role in experimental and process design for CO2 absorption. Therefore, the aim of this paper is to discuss the current development in capturing CO2, particularly in the efforts to overcome the viscosity challenge.