| Solvents are used in a wide range of industrial processes, such as fluids for liquid extraction, reaction media, and heat transfer applications. In general, these solvents are volatile organic compounds or VOCs. Vapor emissions of VOCs to the atmosphere pose many health, environmental, and economic concerns. Therefore, other types of solvents are necessary to reduce or eliminate the problems with VOCs while still meeting the needs of industry. Room temperature ionic liquids have gained increased interest in recent years as potential "green" replacements for volatile organic solvents in a number of applications due to their unique properties. Ionic liquids (ILs), composed of organic cations with organic or inorganic anions, have similar properties as conventional organic solvents. However, ILs have a negligible vapor pressure, meaning the loss of solvent to the environment due to vaporization is effectively eliminated. The properties of IL can also be tailored for a specific process or application by choice of the cation and anion for the salt.; The objective of this work was to determine the impact of different IL characteristics on two properties of ionic liquids: liquid-liquid phase behavior of ILs with organic solvents and water and thermal decomposition of the IL. Knowledge of the impact of different IL characteristics, such as anion and cation, on these properties is very important to fully utilize ILs for future applications and for gaining a fundamental understanding of the factors that govern these properties. The choice of anion and cation plays a huge role in determining the liquid phase behavior with other liquids, with several types of intermolecular interactions possible for ILs, such as hydrogen bonding, van der Waals forces, and pi-pi interactions. For the decomposition of ILs, the choice of anion has the largest impact. From this work, ILs with the [(CF3SO2)2N] anion show good potential for alcohol-water separations, while the use of ILs for high temperature applications should be limited to temperatures below 240 °C for inert systems and 200 °C for oxidative systems. |
