Recent Advances in the Synthesis, Application and Economic Feasibility of Ionic Liquids and Deep Eutectic Solvents for CO2 Capture: A Review

Global warming is one of the major problems in the developing world, and one of the major causes of global warming is the generation of carbon dioxide (CO2) because of the burning of fossil fuels. Burning fossil fuels to meet the energy demand of households and industries is unavoidable. The current commercial and experimental techniques used for capturing and storing CO2 have serious operational and environmental constraints. The amine-based absorption technique for CO2 capture has a low absorption and desorption ratio, and the volatile and corrosive nature of the solvent further complicates the situation. To overcome all of these problems, researchers have used ionic liquids (ILs) and deep eutectic solvents (DESs) as a replacement for commercial amine-based solvents. ILs and deep eutectic solvents are tunable solvents that have a very low vapor pressure, thus making them an ideal medium for CO2 capture. Moreover, most ionic liquids and deep eutectic solvents have low toxicity and can be recycled without a significant loss in their CO2 capture capability. This paper first gives a brief overview of the ILs and DESs used for CO2 capture, followed by the functionalization of ILs to enhance CO2 capture. Moreover, it provides details on the conversion of CO2 into different valuable products using ILs and DESs, along with an economic perspective on using both of these solvents for CO2 capture. Furthermore, it provides insight into the difficulties and drawbacks that are faced by industries when using ILs and DESs.