Eight different poly(ethylene glycol) (PEG)/salt aqueous two-phase systems (ATPS's) were characterized at 23 °C. PEGs with different molecular weights (1500 and 8000) were combined with different salts (sodium or potassium citrates and formates) to study the effect of each ATPS constituent in the phase diagram. The binodal curve and several tie-lines were determined for each system using common analytical techniques described in the literature for ATPS's (cloud point method, conductivity, and gravimetric analysis after lyophilization). According to the results, it was found that each ATPS constituent produced a particular effect in the phase diagram. For the salts, changes in the anion produced larger variations in the heterogeneous region size than changes of the cation. Thus, the effect of salt type seems to be largely dependent on the anion, which makes the dominant contribution. The ability to form ATPS's is connected with the Gibbs energy of hydration, ΔG hyd , of the anions: more negative ΔG hyd values facilitate ATPS formation. Changes in the PEG molecular weight affected also the phase diagram: the size of the heterogeneous region increases with the increase in the polymer molecular weight.

No abstract

In this work, viscosities, densities, and speeds of sound of three binary mixtures containing the ionic liquids 1-ethyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide, [emim][NTf 2 ], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [bmim]-[NTf 2 ], and 1-hexyl-3-methylimidazo-lium bis(trifluoromethylsulfonyl)imide, [hmim][NTf 2 ], mixed with ethanol were measured at atmospheric pressure in the range of (278.15 to 338.15) K, covering the entire range of compositions. From these experimental data, the excess isentropic compressibility and molar isentropic compressibility of pure components and mixtures have been calculated. Additionally, excess properties, such as viscosity deviation, excess molar volume, excess isentropic compressibility, and excess molar isentropic compressibility, have been calculated and fitted with the Redlich−Kister polynomial equation.

No abstract

In this work, the experimental liquid-liquid equilibria (LLE) data of water + ethanol + 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([bmim][Tf2N]) system at different temperatures is presented. The LLE of the systems has been measured between 283 and 323 K.The NRTL and UNIQUAC models were applied to the ternary systems. The interaction parameters obtained from both models successfully correlated the equilibrium compositions, however UNIQUAC gave a more accurate correlation. Finally, the solvent capability of ionic liquid was checked in order to separate the mixture formed by ethanol and water. KEYWORDSThis is a previous version of the article published in Journal of Chemical & Engineering Data. 2015, 60(8): 2426-2433

No abstract

No abstract

No abstract