(643b) Thermodynamics of the Mixtures of Ammonia and Ionic Liquids

Ionic liquids (ILs) are liquid salts composed entirely of ions, and defined to have a melting point below 373 K. Ammonia (NH₃) is one of the most important and largest volume industrial chemicals produced today. The fundamental thermodynamic knowledge for ILs with NH₃ is essential for exploring the feasibility of ILs in various applications such as gas separation and absorption-refrigeration. This study is divided into three parts. In the first part, the vapor-liquid-equilibria of NH₃ in ILs will be reported. The solubility of NH₃ in ILs was measured using the gravimetric method (XEMIS Microbalance, Hiden Iscohema, UK) at pressures up to 0.7 MPa and at temperatures of 283.15, 298.15, 323.15 and 348.15 K. Experimental vapor-liquid-equilibria data was modeled using Peng-Robinson Equation of State and Non-Random Two Liquid (NRTL) activity coefficient models. In the second part, the direct experimental determination of enthalpies of solution of NH₃ in ILs using high pressure Calvet calorimeter (SETERAM BT 2.15, France) will be reported. Heat of solution is a fundamental thermodynamic property that is related to the nature of interaction between the gas and the IL. The enthalpy of NH₃ absorption in IL can reflect the heat effect due to physical dissolution of NH₃ in the IL and heat effect due to chemical interaction between the two if present. In the third and final part, proton Nuclear Magnetic Resonance (1H NMR) technique will be reported to elucidate the interactions between NH₃ and ILs.