In this study, in order to obtain a relation between the liquid – liquid equilibria (LLE) and vapor – liquid equilibria (VLE) behavior of aqueous saltionic liquid (IL) solutions, isopiestic and binodal measurements were carried out for different tetra alkyl ammonium bromide + sodium salt + water systems. In the VLE section, the water activity and constant water activity lines were obtained for binary and ternary aqueous systems of tetra propyl ammonium bromide (TPAB) and tetra butyl ammonium bromide (TBAB) in the absence and presence of the sodium salts sodium citrate (Na3Cit) and sodium nitrate (NaNO3) at T = 298.15 K. In the LLE section, binodal curveswere obtained for aqueous ternary solutions that have phase separation ability (salting-out effect). The ability of the investigated sodium salts for salting-out of the ILs follows the order: Na3Cit > NaNO3. For all systems the constant water activity lines show negative deviation from Zdanovskii−Stokes−Robinson rule (ZSR) and these negative deviations in monophasic region are larger than biphasic region. Water activity data of binary aqueous solutions show that citrate anion is more hydrophilic than nitrate, and TPAB are more hydrophilic than TBAB.
