https://doi.org/10.1016/j.ccst.2022.100040
“Solubility is an important parameter in evaluating the capability of absorbents, which was calculated through the following equation.
(17)xb=nb/(na+nb)
Here, subscript b refers to CO2 while a refers to absorbent. So xb represents the mole fraction of CO2 in the solution, nb denotes the moles of CO2 dissolved in the absorbent while na is the initial moles of absorbent in the vessel. The moles of absorbent in the equilibrium vessel na can be calculated using the following equation. Subscript b refers to CO2.
(18)na=ρV/M
Here, ρ, V,M refer to the density, volume and relative molecular mass, respectively.
nb can be expressed through equation 19.
(19)nb=(ng,a−ng,b)−nE
Where, ng,a and ng,b are the initial moles and final moles of CO2 in the gas buffer tank, respectively. In other words, ng,a−ng,b means the sum moles of CO2 inflated into equilibrium vessel. nE refer to the total moles of the gas in equilibrium vessel when the system is in equilibrium. nE can be calculated through equilibrium partial pressure (PE), which can be expressed by Eq. 20.
(20)pE=p−pi−pasxa
Here, p represents the total pressure while pi represents the partial pressure of the inert gas in the equilibrium vessel. In this work, pi can be approximated as zero. pas refers to the saturated vapor pressure of absorbent in equilibrium. ng,a, ng,b and nb can be calculated through SRK EOS as well as the experimental data.
Before the solubility experiment, CO2 was firstly dissolved in both polycarbonate and water using this apparatus to ensure the reliability of the device. Results showed that the differences between experimental data and literature data is less than 3% (Gui et al., 2011), which demonstrated the accuracy of experimental results in this study.
“