Experimental Investigation of CO2 Solubility in New Amine-Based Deep Eutectic Solvents

Abstract

The growing concern about global warming and climate has raised the research field dedicated to finding solutions. One area that has received considerable attention is the exponential increase of carbon dioxide emissions from the atmosphere from the petroleum and gas industries. So, to solve this problem, researchers investigated new ways to collect CO2 from the air depending on the fact that CO2 is soluble in water because using aqueous amine absorbents to collect CO2 has a lot of drawbacks, such as the need for tremendous energy to recycle the solvent and high operational costs. In this study, a specific type of deep eutectic solvent (DES), namely Choline chloride + monoethanolamine (ChCl-MEA), was used as a promising solvent in the CO2 capture process. Solubility measurements were conducted at 1:6 molar ratios. The amines chosen are typical of basic amines. Experiment absorption data were investigated at various parameters, including a concentration range of 0–3 mol/L, temperatures ranging from 25 to 45 °C, and absorption durations ranging from 60 to 120 minutes, to get the best conditions for high-loading CO2 uptake. The study found that amine-based DESs had a significantly greater absorption capacity than monoethanolamine-based and conventional DESs. The study examined what happened when water was added to a deep eutectic solvent made of choline chloride and monoethanolamine (ChCl-MEA DES). The most effective way to absorb CO2 was physical absorption, which can hold 276.13 mol CO2 per gram of DES at 1 bar and 29.025 °C when mixed with water. The deep eutectic was mixed with water to increase the absorption efficiency. 10 ml of aqueous solution (DESs + water) was taken. The combination of DES and water significantly increased CO2's low solubility. The modified Design-Expert model satisfactorily represents the experimental solubility of CO2 in the solvent. The average percent differences between experimental and projected values were 10.7% and 6.8% for binary and ternary systems, respectively. The optimal conditions for maximum absorption rate were 29.025°C, 2.233 mol/L, and 101 minutes, with an absorption ratio of 0.0734 mol/kg.min and efficiency of absorption of 85.3% for solution DESs and water.