Aqueous Potassium Salt of L-Cysteine as Potential CO2 Removal Solvent: An Investigation on Physicochemical Properties and CO2 Loading Capacity

The operational and economic constraints suffered by amine solvents for CO2 removal have motivated the research on an alternative solvent with better performance and cost-effectiveness. Amino acid salt (AAS) has been identified as an interesting green solvent, an alternative to commercial amine solvents. The present work evaluated the physicochemical and CO2-solubility properties of potassium L-cysteine (K-CYS), a naturally occurring amino-acid-based solvent for CO2 removal from natural gas. Its physicochemical properties, including density, viscosity, and refractive index, were measured at different temperatures ranging between 298.15 and 333.15 K and a concentration range of 5 to 30 wt.%. Based on the experiment, all properties were found to decrease with increasing temperature and increase with increasing concentration. The experiments also demonstrated a significant reduction of CO2 loading from 2.4190 to 1.1802 mol of CO2/mol of K-CYS with increasing solvent concentration from 10 to 30 wt% at 313.15 K and 20 bar (g).