Ionic liquids (ILs) have been touted as the next great class of environmentally-friendly solvents due to their lack of vapor-pressure and molecularly "tunable" properties. New types of ionic liquids and new applications are being developed at a rapid pace for extractions, reactions, and materials processing. Systems that couple ILs with organic solvents and especially with compressed CO2, have a number of advantages for process development. Compressed CO2 ameliorates many of the challenges (e.g. viscosity, solubility, etc.) using ionic liquids. However, there exists little to no interfacial mass transfer data and no emphasis on process intensification for any of these biphasic systems. Without an understanding of the mass transfer coefficients and related phenomena, widespread use cannot occur. Therefore, this research will attempt to establish a foundational methodology for process development using several model ionic liquids, solvents, and solutes. Advance theoretical and modeling techniques will be employed to allow rapid implementation of any specific or future ionic liquid.
Intellectual Merit:
Ionic liquids are finding numerous potential uses for a wide variety of extractions, reactions, and material processing applications. As common separation techniques, such as distillation, are not feasible for some separation, there is increasing interest in biphasic fluid scenarios are most commonly employed. However, interfacial mass transfer must be known for process optimization. Little to no experimental data exists even for the most common ionic liquids and other solvents and solutes. This proposal will represent the first systematic experimental and theoretical study of the mass transfer coefficients, viscosity, diffusivity, and surface tension of solutes in biphasic ionic liquid systems. Coupling CO2 overcomes many of the challenges of ionic liquids: high viscosity/low diffusivity; low solubility of
reactions gases/substrates; difficult separation of mixtures with ILs; and most ionic salts are solid not liquid. However, there are no studies concerned with the interfacial mass transfer in biphasic ionic liquids/CO2 systems. This proposal will uniquely investigate the beneficial properties of ionic liquids related to mass transfer. The mass transfer data will be obtained using advanced imaging and processing of pendant and flowing droplets with a detailed hydrodynamic model.
Broader Impact:
A thorough understanding of the fundamentals of ionic liquid mass transport properties will allow process intensification and industrial application, which could lead to a decrease in the exposure to both society and the environment. In addition, novel processes with ILs that have achieved high levels of efficiency will also be available to the public. Compressed CO2 or, in some cases, a wise choice of conventional solvents, may also lead to the realization of the potential environmental advantage of ionic liquids. This project will introduce students to the necessary experimental and theoretical modeling skills to properly design environmentally benign alternatives and critically compare them to conventional technology. Moreover, the entire process will lead to incorporation of excellent case-studies in current courses at the University of Kansas: Environmentally-Benign Reaction Engineering and Environmental Assessment of Chemical Processing. Exhibits will be demonstrated at local events at KU, such as the "Carnival of Chemistry" and Engineering "EXPO" for undergraduate and high-school students. The PI has currently recruited a female African student for work on this project to promote diversity in education.
