New Experimental Data on Thermodynamic Properties of the Aqueous Solution of N,N-Diethyl-N-methylammonium Bromide and N,N-Diethyl-N-methylammonium Methanesulfonate

In this work, new experimental data on thermodynamic properties of ionic liquid (IL) aqueous solutions are presented. The (vapor + liquid) phase equilibria, liquid density, and dynamic viscosity of binary mixtures composed of N,N-diethyl-N-methylammonium bromide ([N-H,N-1,N-2,N-2][Br]), or N,N-diethyl-N-methylammonium methanesulfonate ([N-H,N-1,N-2,N-2](-)[CH3SO3]) and water are presented as functions of temperature and composition. Both ILs were synthesized and specific basic characterization including the NMR spectra and the water content determination was done. The basic thermal properties of the pure IL, including the glass-transition temperature, heat capacity at glass transition, and temperature and enthalpy of (solid + solid) phase transition as well as the temperature and enthalpy of melting were determined using the differential scanning calorimetry (DSC) technique. The isothermal (vapor + liquid) equilibrium (VLE) was measured by the ebulliometric method within a temperature range from T = 338.15 to 368.15 K and pressures up to 85 kPa. Experimental VLE data were successfully correlated using the NRTL equation. The experimental VLE data were tested for thermodynamic consistency using the Van Ness test. The liquid density and the dynamic viscosity were determined as a function of IL's mole fraction over a wide temperature range. For the correlation of physicochemical properties, empirical equations were applied. From the experimental density data, the excess molar volumes were determined and correlated using the Redlich-Kister-type equation.