# Ionic Liquids Hybridization for Carbon Dioxide Capture: A Review
## 4 Application of ILs Hybrid Material in Carbon Dioxide
### ILs/Anines
The addition of amines reduced the viscosity of absorbent and significantly enhanced the CO\({}_{2}\) absorption capacity. For example, [BMIM][BF\({}_{4}\)]/MDEA resulted in a higher CO\({}_{2}\) absorption capacity of 0.0526 g CO\({}_{2}\)/g absorbent, whereas the pure ILs achieved only 0.0168 g CO\({}_{2}\)/g absorbent. Additionally, [BEIM][BF\({}_{4}\)]/MDEA and [BEIM][BF\({}_{4}\)] demonstrated CO\({}_{2}\) absorption capacities of 0.0517 and 0.0174g CO\({}_{2}\)/g absorbent, respectively. The absence of peak attributed to carbonyl of carbamate on \({}^{13}\)C NMR spectrum of ILs/MDEA spectra analysis showed the CO\({}_{2}\) capture by using blending mixtures occurred via physical absorption. The study on sorbent regeneration showed [BEIM][BF\({}_{4}\)]/MDEA utilized less energy compared to aqueous amine absorbent. Theoretically, the interaction between the absorbent and CO\({}_{2}\) in physical absorption is primarily based on weak intermolecular forces, which can be readily weakened or disrupted under moderate process conditions. This resulted in low energy input for CO\({}_{2}\) desorption and regeneration compared to chemically driven absorption processes. [PERSON] et al. investigated CO\({}_{2}\) absorption at high pressure by using PILs blended with EDA or DETA [86]. In their work, the mixture of amine/PILs was prepared by extensively mixing various mass ratio of PILs: amine (1:1, 0.5:1, 1:0.5) at room temperature for 24 h. It has been observed that the viscosity of all blended mixtures is lower than the viscosity of pure ILs. The CO\({}_{2}\) absorption was initially performed at 30 \({}^{\circ}\)C and 1 bar, and the result indicates [DMAPAH][Oac]-EDA exhibited 0.260 g CO\({}_{2}\)/g absorbent, which is higher compared to the CO\({}_{2}\) absorption capacity demonstrated by [DMAPAH][Oac] alone. The experimental results also show that the CO\({}_{2}\) absorption increased with the ratio of EDA in [DMAPAH][Oac]. This indicates that EDA is an excellent CO\({}_{2}\) absorbent; however, its performance is limited due to its low thermal stability. The thermal stability of the absorbent has been improved particularly when ILs have been introduced in the mixture ratio of [DMAPAH][Oac]:EDA (0.5:1). The study was further explored by performing CO\({}_{2}\) absorption at temperature range 20-60 \({}^{\circ}\)C using [DMAPAH][Oac]-EDA under atmospheric pressure. The experimental data indicated an increase in CO\({}_{2}\) absorption capacity with the value of 0.295 g CO\({}_{2}\)/g IL at 50 \({}^{\circ}\)C. Addition of 20 wt% water into the mixture of [DMAPAH][Oac]-EDA had resulted in the absorption of 0.2229 g CO\({}_{2}\)/g absorbent. According to the authors, the CO\({}_{2}\) absorption by [DMAPAH][Oac]-EDA involves the transfer of zwitterion into carbamate, which, in the presence of water, was further hydrolyzed to form bicarbonate. The presence of water not only accelerates the transfer rate, but also increases the primary amine availability through hydrolysis of bicarbonate. This, in turn, enhances the CO\({}_{2}\) absorption rate and capacity. Other than that, the recyclability study showed the CO\({}_{2}\) absorption capacity by [DMAPAH][Oac]-EDA exceeded the value of 0.2 g CO\({}_{2}\)/g IL even after it had been recycled three times. However, a decrease in performance was observed, which could be attributed to insufficient desorption and oxidative degradation of EDA. Furthermore, [PERSON] et al. performed a study using a simplex centroid design to investigate the experimental behavior of ternary mixture containing ILs, amine and water towards CO\({}_{2}\) absorption capacity [87]. Two ILs, namely, [BMIM][Oac] and [EMIM][CoSO\({}_{4}\)], were chosen to be combined with amines that possess different basicity properties. The statistical analysis indicated that the concentration of ILs in the ternary mixture had a minimal influence on CO\({}_{2}\) solubility, in which each ILs exhibited a different effect.