Thermodynamic Modeling for CO₂ Absorption in Aqueous MDEA Solution with Electrolyte NRTL Model

Accurate modeling of thermodynamic properties for CO 2 absorption in aqueous alkanolamine solutions is essential for the simulation and design of such CO 2 capture processes. In this study, we use the Electrolyte Nonrandom Two-Liquid activity coefficient model to develop a rigorous and thermodynamically consistent representation for the MDEA−H 2 O−CO 2 system. The vapor−liquid equilibrium (VLE), heat capacity, and excess enthalpy data for the binary aqueous amine system are used to determine the NRTL interaction parameters for the MDEA−H 2 O binary. The VLE, heat of absorption, heat capacity, and NMR spectroscopic data for the MDEA−H 2 O−CO 2 ternary system are used to identify the NRTL interaction parameters for the molecule−electrolyte binaries and the previously unavailable standard-state properties of the amine ion, MDEA protonate. The calculated VLE, heat of absorption, heat capacity, and the species concentrations for the MDEA−H 2 O−CO 2 system are compared favorably to experimental data.