Transport properties of mixtures of acid gases with aqueous monoethanolamine solutions: A molecular dynamics study

Diffusivity of CO2 in H2O: A Review of Experimental Studies and Molecular Simulations in the Bulk and in Confinement

“…This study 78 further revealed that the temperature dependence of the self-diffusivities in 10 wt % aqueous MEA solutions are higher than that in 50 wt % solutions. Similar observations were made by Yiannourakou et al 183 for CO 2 in 30 wt % aqueous N-methyldiethanolamine (MDEA) solutions, demonstrating an increase in self-diffusivities from 2.50 × 10 −9 m 2 s −1 at 300 K to 1.03 × 10 −8 m 2 s −1 at 400 K. Polat et al 77 expanded the exploration to unloaded and loaded aqueous MDEA mixtures, showing that CO 2 diffusion is 3.5 times faster in 10 wt % than in 50 wt % aqueous MDEA solutions within a temperature range of 288−333 K. Polat et al 77 attributed the slower diffusion of CO 2 in concentrated MDEA solutions to stronger interactions between CO 2 and surrounding molecules (both water and MDEA). Additionally, investigations 77 into the self-diffusivities of CO 2 in loaded 50 wt % aqueous MDEA solutions revealed a decrease with increasing CO 2 loading, indicating that the CO 2 capture with aqueous MDEA solutions slows down as CO 2 loading increases.…”

“…The versatility of MD simulations has been proven in literature for computing the self-diffusivity of CO 2 in various solvents, such as aqueous alkanolamine solutions, 77,78,183 ionic liquids, 184,185 and deep eutectic solvents. 186,187 MD simulation is a powerful method for the computation of diffusion coefficients of CO 2 in H 2 O that can compliment experimental measurements and provide useful insight into the physical mechanisms governing diffusion at the nanoscale.…”

“…45,78 Furthermore, MD simulations provide the flexibility to ignore reactions between CO 2 and H 2 O, enabling the focus on the diffusion without considering reaction products. 77,189,190 Nevertheless, MD simulation results should always be validated against experimental data to ensure accuracy and reliability in predicting diffusion coefficients under different conditions. To validate computed diffusivities, comparisons with availalble experimental data are performed.…”

“…In the absence of experimental diffusivities, researchers often resort to assessing agreement between the computed and readily accessible experimentally obtained thermodynamic and transport properties, such as densities and viscosities. 77,78,183 2.2.1. Simulation Methods.…”

“…At infinite dilution, the intradiffusivity of CO 2 is practically equal to transport diffusion coefficients. 46,77,255 A comprehensive study of transport diffusivities in aqueous solutions of CO 2 was performed by Zhao et al 242 These authors 242 computed the MS and Fick diffusivities (along with intradiffusivities) of aqueous solutions containing various gases, including CO 2 , for a temperature range of 673−973 K and a CO 2 mole fraction range of 0.01−0.30. While the authors concluded that temperature and the concentration of CO 2 in the solution significantly influence the MS and intradiffusivities, the interpretation of MS diffusivity trends with changing CO 2 concentration remains challenging due to considerable scatter and uncertainties in the presented data (except for the data set at 673 K where a clear trend of increasing MS diffusivities with increasing CO 2 concentration can be seen).…”