Equilibrium solubility of carbon dioxide in aqueous 2-((2-aminoethyl)amino)ethanol and N-methyldiethanolamine solution and modeling by electrolyte mPR-CPA EoS

• Solubility of carbon dioxide in aqueous solutions of AEEA and MDEA is measured.
• Temperature and pressures ranges are 308.2 K to 368.2 K and 101 kPa to 4448 kPa.
• AEEA–water VLE data are obtained experimentally at 86.6 kPa.
• Dielectric constant of AEEA is measured in the temperature range of 293.2 K to 348.2 K.
• Solubility of CO2 in aqueous mixture of AEEA and MDEA is obtained by emPR-CPA EoS.

In the present work, the equilibrium solubility of carbon dioxide (CO2) in aqueous amine mixture solutions of 2-((2-aminoethyl)amino)ethanol (AEEA) and N-methyldiethanolamine (MDEA) is measured in the temperature range of 308.2 K to 368.2 K and the pressure range of 101 kPa to 4448 kPa. The (vapor + liquid) equilibrium of binary AEEA and water system is measured at constant pressure of 86.6 kPa. The dielectric constant of AEEA is also obtained experimentally in the temperature range of 293.2 K to 348.2 K. For thermodynamic modeling the electrolyte modified Peng-Robinson cubic plus association equation of state (emPR-CPA EoS) [A.T. Zoghi, F. Feyzi, M.R. Dehghani, Ind. Eng. Chem. Res. 51 (2012) 9875–9885] is applied and the solubility of CO2 in the aqueous mixture of AEEA and MDEA is obtained. In order to model the quaternary system, parameters of the emPR-CPA EoS are first adjusted for pure components. Then, the binary molecular interaction parameters for binary sub systems (CO2–Water, CO2–MDEA, CO2–AEEA, MDEA–Water, AEEA–Water) and the ionic interaction parameters for ternary sub systems (MDEA–CO2–Water) and (AEEA–CO2–Water) are optimized. By the emPR-CPA EoS the CO2 solubility is obtained in the ternary sub-systems (MDEA–CO2–Water) and (AEEA–CO2–Water) with average absolute percent deviations (AAD%) equal to 17.32 and 14.63, respectively. Finally, the equilibrium solubility of CO2 in aqueous mixture of AEEA + MDEA is obtained with AAD% = 24.3 and root mean square relative deviation percent (RMSD%) = 27.67.

Comparison between the calculated and experimental solubility of CO2 in 30 wt.% aqueous AEEA (♦; ▴;
• ; ■: experimental data by Ma’mun et al. [2], ◊; △; ○; □: experimental data by Zoghi et al. [6]).Figure optionsDownload as PowerPoint slide