Thermodynamic Properties of Ionic Liquids - Measurements and Predictions -

Abstract

Research of ionic liquids (ILs) is one of the most rapidly growing fields in the past years, focusing on the ultimate aim of large scale industrial applications. Due to their unique tunable properties, such as negligible vapor pressure at room temperature, stable liquid phase over a wide temperature range and thermal stability at high temperatures, ionic liquids are creating an continuously growing interest to use them in synthesis and catalysis as well as extraction processes for the reduction of the amount of volatile organic solvents (VOSs) used in industry. For the general understanding of these materials it is of importance to develop characterization techniques to determine their thermodynamic and physicochemical properties as well as predict properties of unknown Ionic Liquids to optimize their performance and to increase their potential future application areas. Our laboratory in cooperation with several national and international academic and industrial partners is contributing to these efforts by the establishment of various dedicated characterization techniques (like activity coefficient measurements using GC technology) as well as determination of thermodynamic and physicochemical properties from a continuously growing portfolio of (functionalized) ionic liquids. Based on the received property data we published several papers related to the adjacent prediction of properties (like molar enthalpy of vaporization, parachor, interstice volume, interstice fractions, thermal expansion coefficient, standard entropy etc.). Additionally our laboratory created and launched a new most comprehensive Ionic Liquid property data base--delphIL.(www.delphil.net). This fast growing collections of IL data will support researchers in the field to find and evaluate potential materials for their applications and hence decrease the time for new developments. In this chapter we introduce the following techniques, summarize recent published results completed by our own investigations: 1. Activity coefficient measurements using GC technique, 2. Thermodynamic properties determined by adiabatic calorimetry and thermal analysis (DSC, TG-DTG). 3. Estimation and prediction of physicochemical properties of ILs based on experimental density and surface tension data.