(253d) Volumetric Properties of Mixtures of Ionic Liquids With CO2 Or CO2 + Ethanol

We are exploring new approaches for potential use of ionic liquids in processing of natural polymers and specifically those that are important in processing of lignocellulosic materials. Our approach is to try to combine the desirable attributes of ionic liquids in terms of their solvent power with supercritical fluids to explore the extent to which dissolution levels can be tuned with pressure or fluid compositions. As an initial phase of this activity we have been evaluating the miscibility and volumetric properties (in particular the density and compressibility) of selected ionic liquids with CO₂ and CO₂ + ethanol. In this talk, we will present new data on the volumetric properties of two ionic liquids, namely [EMIM]Ac and [EMIM]Cl and their mixtures with carbon dioxide or carbon dioxide + ethanol, and comment also on the reactive interaction between [EMIM]Ac with CO₂. We will also report on the volumetric properties of mixtures containing Avicel as a model cellulose polymer at high pressures. The data are being generated in a special a high pressure variable-volume view-cell in which position of a movable piston is continually recorded in real-time while its position is altered at controlled rates with the aid of a motorized pressure generator. This position information is then converted to real time changes in the internal volume and hence the density as a function of pressure and/or temperature [1, 2]. The densities at a given temperature are then correlated with a polynomial function of the form ρ = A + BP^-1 + CP + DP^-2 + EP^m were A, B, C, D, E and m are adjustable parameters. These functions were then used to determine the isothermal compressibilities for each mixture.

Acknowledgment:  This research is supported by the National Science Foundation, CBET - Energy for Sustainability Program (CBET  Award # 1250663).

[1] H. Grandelli and E. Kiran, Volumetric properties of mixtures of ionic liquid [EMIM]Ac with CO₂ as potential processing fluids for lignocellulosic materials at high pressures, Proceedings of the 3^rd Iberoamerican Conference on Supercritical Fluids, Prosciba 2013, Cartagena, Colombia, April 1-5, 2013.

[2] J. M. Milanesio, J. C. Hassler, and E. Kiran, Volumetric properties of propane, n-octane an their binary mixtures at high pressures, Industrial and Engineering Chemistry Research, dx.doi.org/10.1021/ie4007084