Carbon dioxide solubility in aqueous potassium salt solutions of l-proline and dl-α-aminobutyric acid at high pressures

• CO2 solubility in aqueous potassium salt solutions of l-proline and dl-α-aminobutyric acid were studied.
• The CO2 partial pressures studied was up to 1000 kPa.
• The temperatures studied were (313.2, 333.2, 353.2) K.
• The measured data were represented satisfactorily by using the applied correlations.
• The CO2 absorption capacity of the studied systems was high and comparable with monoethanolamine.

In the present work, the solubility of CO2 in aqueous solutions of potassium prolinate (KPr) and potassium α-aminobutyrate (KAABA) was measured at temperatures (313.2, 333.2, and 353.2) K and CO2 partial pressures up to 1000 kPa for amino acid salt concentrations: KPr, w = (7.5, 14.5, and 27.4 wt%) and KAABA, w = (6.9, 13.4, and 25.6 wt%). It was found that the CO2 absorption capacities of the studied amino acid salt systems were considerably high and comparable with that of industrially important alkanolamines including monoethanolamine. The CO2 loadings in aqueous potassium α-aminobutyrate at high pressures were also found to be generally higher than the loadings in aqueous potassium prolinate. A modified Kent–Eisenberg model was applied to correlate the CO2 solubility in the amino acid salt solution as function of CO2 partial pressure, temperature, and concentration. The model gave good representation of the (vapour + liquid) equilibrium data obtained for the amino acid salt systems studied, and provided accurate predictions of the solubility.