From solubility mechanisms to scalable solutions: The evolving landscape of ionic liquids for CO2 capture

The increasing concentration of atmospheric CO₂ calls for the development of efficient and sustainable capture technologies. Ionic liquids (ILs) have become attractive solvent options for next-generation CO₂ capture because of their thermal stability, low vapor pressure, and structurally tunable properties. This review presents a comprehensive analysis of CO₂ solubility in ILs, and the underlying mechanisms of physical absorption driven by van der Waals and quadrupole interactions, as well as the chemical absorption via task-specific ILs (TSILs). The influence of IL composition, viscosity, free volume, and cation–anion combinations on CO₂ uptake is critically investigated. Also, experimental techniques (e.g. gravimetric microbalance, FTIR, TGA) are reviewed as essential for IL screening and performance prediction. Furthermore, key advancements in hybrid systems, such as IL-polymer composites, IL@MOFs, and supported IL membranes (SILMs), are also investigated. The environmental impacts, such as toxicity and biodegradability, are addressed, along with a techno-economic comparison with conventional solvents. The review highlights that challenges persist, especially factors such as viscosity, system-level energetics, cost, and environmental impact. The review validates that IL has a strong potential for modular and high selectivity as a CO₂ capture system.