Physicochemical Properties and Applications of Deep Eutectic Solvents for CO2 Capture

Rising anthropogenic greenhouse gas concentrations, notably CO2 emissions, have led to environmental issues that affect both humans and ecosystems. CO2 separation makes it easier to reduce energy use and CO2 emissions, both of which are essential for combating the concern of global warming. The use of ionic liquids (ILs) as CO2 capture solvents is recommended. However, the high viscosity, toxicity, cost, and poor biodegradability of ILs limit their large-scale application. In recent years, deep eutectic solvents (DESs) have been created with improved CO2 separation efficiency, lower preparation costs, and less negative environmental impact. The state-of-the-art of the physicochemical properties of DESs in connection to their influence on CO2 capture processes and the studies of CO2 solubility in DESs are discussed. The absorption mechanism of CO2 in DESs and the effect of temperatures, pressures, and hydrogen bond donors (HBDs) on the solubility of CO2 in DESs are overviewed and analyzed, and future research directions on this topic are suggested.