What Does Non-ideality Mean for Binary Ionic Liquid Mixtures?

Dr. Jindal Shah, Oklahoma State University

Host: Dr. Pratyush Tiwary

Abstract: Ionic liquids are substances that are composed entirely of ions. Negligible vapor pressures and the availability of a large number of cations and anions to tune physicochemical and biological properties for a given chemical process have been the primary drivers for research in this field over the last two and half decades. A major thrust of these investigations is on elucidating changes in the properties of pure ionic liquids by altering the cation, anion or substituents on the ions. Another approach to expand the range of available ionic liquids is to form ionic liquid-ionic liquid mixtures. From a thermodynamic point of view, the knowledge of the extent of non-ideality in these binary ionic liquid mixtures and the molecular level details enable a priori prediction of thermophysical properties of ionic liquid mixture. In this presentation, we will demonstrate that the difference in the molar volume of the ionic liquids forming the mixture and the difference in the hydrogen bonding ability of the anions can serve as metrics for the prediction of non-ideality in the binary ionic liquid systems. Such non-idealities appear in the form local structural organization of anions around the cation in ionic liquid mixtures bearing a common cation and two different anions. We will further highlight that these non-native structures lead to a different dissolution mechanism for CO₂ in mixtures in comparison to that for pure ionic liquids although the CO₂
solubilities obey apparent ideal mixing rule.

Statistical Physics Seminar