Calculation of pressure and temperature data as a function of time

The quantity of CO₂ removed refers to the gaseous phase moles transferred to the liquid phase, with respect to the initial amount of gas loaded into the high-pressure vessel. This quantity was calculated using Equation (5):

where ngas is the CO₂ mole number in the gas phase, P is the vessel pressure, V is the gas phase volume, z is the compressibility factor calculated by the Peng–Robinson equation of state [36], and T is the vessel temperature. Moreover, to and t are the initial time and an instantaneous time of the experiment, respectively.

The CO₂ loading refers to the amount of CO₂ removed from the gas phase for each liquid (amine + water) mole initially introduced into the high-pressure vessel. The CO₂ loading was calculated using Equation (6):

where nliquid is the initial number of moles in the liquid phase. Appendix A shows the number of moles in each solution for the different amine concentrations used in this study. For this calculation, the experimental density data of aqueous EDA solutions at 303 K reported by Egorov et al. [37] were used.

t25, t50, and t90 refer to the time required to reach 25%, 50%, and 90%, respectively, of the total amount of CO₂ removed from the gas phase at the end of each experiment.

dn/dt refers to the CO₂ capture rate. This was calculated directly on the curve of the removed amount of CO₂ from the gas as a function of time, and corresponds to the maximum value of gas consumption in the experiments’ first instants. This value was obtained numerically using the initial slope method [38].