High-pressure experimental and theoretical study of CO₂ solubility in aqueous blends of lysine salts with piperazine as new absorbents

Vapour-liquid equilibrium of carbon dioxide loaded potassium and sodium L-lysine salts have been investigated in the region of high-pressure and high loadings. The equilibrium solubility of carbon dioxide was measured in separate aqueous L-lysine alkaline salts for a range of temperature (303.15–363.15 K), solution concentrations (1.0–3.0 M) and pressure (95–4204 kPa). In addition to that, solubility of carbon dioxide in blends of both aforementioned amino acid salts with piperazine were investigated. All the studied solutions exhibited an increase in the carbon dioxide loading values with increase in the pressure and had a negative relationship with increase in the temperature and solvent concentration. Furthermore, the experimental data was correlated by the Kent-Eisenberg model. The correlated values shows a good agreement (AAD% of 5.15%) with experimental values. The regressed parameters of the model allows satisfactory estimation of the loadings of carbon dioxide in all studied solutions, for parametric studies. The study shows that L-lysine salts are potential green solvents for the carbon dioxide capture at high pressure.