CO2 absorption using aqueous potassium lysinate solutions: Vapor – liquid equilibrium data and modelling

The solubility of CO 2 in aqueous potassium lysinate (LysK) solutions was measured in a stirred reactor at temperatures from 298 to 353   K, for 9.0, 17.4, 25.3, 33.1 and 41.2   mass% LysK and CO 2 partial pressures up to 110   kPa. The vapor-liquid equilibrium (VLE) data were interpreted using the modified Kent-Eisenberg model. The apparent equilibrium constants of carbamate hydrolysis and amino acid deprotonation were correlated as a function of temperature, CO 2 loading (expressed as mole CO 2 per mole LysK) and LysK concentration to fit the experimental solubility data. The proposed model satisfactorily predicted the VLE data for the H 2 O-LysK-CO 2 system, especially at moderate to high CO 2 loading, with an average absolute deviation within 3.2%. Liquid species in the CO 2 -loaded LysK solutions were also qualitatively characterized by 13 C NMR experiments.