Vapor-liquid equilibrium in amino acid salt system: Experiments and modeling

Vapor-liquid equilibrium (VLE) measurements were carried out for both unloaded and CO(2) loaded aqueous amino acid salt (AAS) solutions of the potassium salt of sarcosine (KSAR). Vapor-liquid equilibrium for unloaded solutions; 1.0-5.0 M KSAR was measured using a Swietoslawski ebulliometer for temperatures 40, 60, 80 and 100 degrees C and for total pressures 4.08-97.8 kPa while vapor-liquid equilibrium for CO(2) loaded solutions of 3.5 M KSAR was measured using both low and high temperature VLE apparatuses for 40, 60, 80, 100 and 120 degrees C and for CO(2) partial pressures ranging from 0.03 to 971 kPa. A thermodynamic model representing the AAS solvent system was developed using the extended UNIQUAC framework. The developed model accurately predicts the equilibrium speciation in loaded solutions from (13)C NMR data and gives a very good representation of the solubility of CO(2) in the amino acid salt solution as well as the total pressure of the unloaded system at all measured temperatures, loadings and pressures. (C) 2011 Elsevier Ltd. All rights reserved.