Thermodynamic modeling of CO₂ absorption in aqueous potassium carbonate solution with electrolyte NRTL model

Aqueous potassium carbonate (K₂CO₃) solution is a favorable choice for CO₂ removal due to low costs and lessened environmental impacts compared to amine solutions. To support process development of CO₂ removal with aqueous solutions, we present a comprehensive thermodynamic model for the H₂O + K₂CO₃ + CO₂ ternary system using electrolyte Nonrandom Two-liquid (eNRTL) activity coefficient model. Experimental data of vapor-liquid equilibrium, heat capacity, excess enthalpy, mean ionic activity coefficient and osmotic coefficient are simultaneously used to determine the temperature dependent eNRTL binary interaction parameters for the ternary system and its binary subsystems. Covering a wide temperature range of 273.15–473.15 K, the K₂CO₃ concentration up to saturation, and the CO₂ loading range of 0–3.6, the model satisfactorily represents all the thermodynamic properties for the system. The model should be a very useful tool in the research, development and design of CO₂ capture processes involving concentrated K₂CO₃ solutions at elevated temperatures and pressures.