## 4 Results and Discussion
### Sensitivity Index  
For each set of performance indices reported in Tables 5-7, the corresponding sensitivity indices were calculated, namely \(\Omega_{1}(\zeta)\), \(\Omega_{2}(\zeta)\), and \(\Omega_{3}(\zeta)\) versus \(\zeta\). The results are shown in Figures 3-5, respectively. Solvents that exhibited mild slopes in the contours were less sensitive in variations and scored low in the sensitivity index. Solvents were more resilient to variations by keeping the performance indices close to the values at the nominal operating point and could be good candidate solvents for CO\({}_{2}\) capture as they exhibited the ability to alleviate the effects of disturbances. In Figures 3-5, we designated the area of positive \(\zeta\) as an unfavorable scenario because disturbances caused deterioration in the performance indicators. For example, \(Q_{\text{\emph{regen}}}\), _NEP_, etc. increase in that direction, which was undesired. On the other hand, when a performance indicator improved due to disturbances (e.g., a reduction of \(Q_{\text{\emph{regen}}}\)), this direction of variability was designated as a favorable scenario. It could be argued that in this case, solvents with a high sensitivity to variability would be desirable as they appeared to exploit the effects of disturbances. However, such a conclusion would require a more detailed analysis of other issues, such as the duration of variability and the dynamic solvent behavior. It is generally desired to avoid solvents and operating conditions that deviate significantly from the intended system operation. In Figure 3, the solvent mixture DEA/MDEA appeared to be the most promising mixture through the sensitivity analysis. In the region close to \(\zeta\) = [0.17, 0.23], DEA and MEA/MDEA exhibited low sensitivity, followed by MPA/MDEA and AMP. MCA, MAPA, DEEA/MAPA, and AMP/PZ seemed to be more sensitive to variability than other amines. In the region of \(\zeta\) = [\(-\)0.05, \(-\)0.15] with the opposite direction, DEA/MDEA continued to be the least sensitive mixture. DEEA/MAPA also exhibited resilience against variations. MPA/MDEA, MEA/MDEA, and MCA exhibited the same behavior. DEA and MEA seemed to be more sensitive in this region. AMP and AMP/PZ seemed to have a sharp profile in this area. Figure 4: Sensitivity index \(\Omega_{2}(\zeta)\) versus the parametric variation magnitude coordinate \(\zeta\). Figure 3: Sensitivity index \(\Omega_{1}(\zeta)\) versus the parametric variation magnitude coordinate \(\zeta\). Figure 4 shows the sensitivity index \(\Omega_{2}(\zeta)\), which was calculated based on step 6 of the described framework. The performance indices in this case were \(NEP\), \(m_{am}\), and \(\Delta\alpha\). The disturbances were the same as in the previous case. The solvent mixture DEA/MDEA continued to exhibit the least sensitivity to variability throughout the investigated range of disturbances. In the region of \(\zeta=\) [0.15, 0.25], DEA seemed to be less sensitive to variations in the selected parameters. AMP, MAPA, MEA/MDEA, and MPA/MDEA seemed to be more susceptible than DEA to disturbances in this case. MEA, MCA, AMP/PZ, and DEEA/MAPA seemed to be very sensitive to variability, and such mixtures should be avoided when there are exogenous changes. In the region of \(\zeta=\) [\(-\)0.1, \(-\)0.2] in the opposite direction, DEA/MDEA appeared to be the least sensitive mixture. DEEA/MAPA and MCA, followed by MPA/MDEA and MEA/MDEA, exhibited a tolerance against variations. DEA, AMP, and MAPA presented the same behavior. However, MEA and especially AMP/PZ seemed to be more sensitive in this region than the other selected solvents. Figure 5 shows the sensitivity index \(\Omega_{3}(\zeta)\) based on the performance indices of \(R_{lost}\), \(C_{sol}\), and \(\Delta\alpha\). Solvents that exhibited sharp contours in the region [0.15, 0.25] seemed to be sensitive in variations and exhibited high sensitivity to variability; such solvents were AMP/PZ, MEA, DEEA/MAPA, and MCA.