High-pressure carbon dioxide solubility in a deep eutectic solvent (Choline Chloride/MDEA) + sulfolane—Experimental study and thermodynamic modeling using PC-SAFT equation of state

Abstract

In recent years, releasing post-combustion CO2 into the atmosphere has led to global warming. Air contamination has appeared as a challenge for governments, so several approaches have been used to overcome this issue. So far, physical and chemical solvents have been employed by researchers for CO2 capture. These years deep eutectic solvents (DES) have emerged as an alternative to traditional solvents. In this study, we have investigated a mixture of DES + a physical solvent for the CO2 solubility measurement using a static vapor-liquid equilibrium cell. In this work, the DES was composed of Choline Chloride and MDEA in a molar ratio of 1 to 6 which is blended with sulfolane in weight percentages of 5,10, and 15. We performed the experiments at temperatures of 323.15, 333.15, and 343.15 K and a pressure range of up to 5 MPa. In our previous work, we had already investigated the influence of piperazine on the present DES that led to enhancing CO2 absorption in the mixture, while adding sulfolane to the DES in the present work does not present a positive effect on CO2 solubility in the DES. Enhancing pressure and reducing temperature also led to increasing CO2 solubility. Finally, we modeled the solubility data with the PC-SAFT equation of state. The modeling results were in excellent agreement with the experimental data for DES-CO2, DES-sulfolane-CO2, and DES-piperazine-CO2 systems, so the PC-SAFT EoS successfully estimated the carbon dioxide solubility in the present systems with the absolute average deviation percent of less than unity.