Ionic Liquids as Green Solvents: A Comprehensive Review

Abstract

Common reaction media, volatile organic solvents (VOS), contribute significantly to air pollution and pose challenges in separation and recycling processes. As environmental awareness grows, researchers are focusing on developing alternative, eco-friendly solvent systems to replace these traditional VOS. Ionic liquids (ILs) have emerged as promising "green" solvents due to their extremely low vapor pressure and high thermal stability, providing advantages in containment, product recovery, and recyclability. ILs exhibit varying stability to moisture and miscibility with molecular liquids, and their properties like density, melting point, and viscosity can be tailored by selecting appropriate cation and/or anion components. Beyond their role in chemical reactions, ILs find applications in separations, extractions, electroanalytical processes, and chemical sensing. The high ionic character of ILs significantly enhances reaction rates in various chemical processes. These versatile features position ILs as potential alternatives to VOS in a wide range of industrial applications. Moreover, their use as industrial solvents can have economic, social, and ecological impacts by influencing human health and environmental factors. In summary, the exploration of ILs as green solvents represents a crucial step towards addressing environmental concerns associated with traditional volatile organic solvents in industrial chemical processes.