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چکیده
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The action of particular electrolytes in altering the solution properties of ionic liquids is well documented, although the origin of this effect is not clearly defined. In order to clarify this point, the aim of this work is to obtain further evidence about the salting-out effect produced by the addition of different salts to aqueous solutions of water miscible ionic liquids by evaluating the effect of a large series of salts on the vapor-liquid equilibria, liquid-liquid phase diagram, volumetric, compressibility, and conductometric properties of ionic liquids 1-alkyl-3-methylimidazolium halide ([Cnmim][X]). In the first part of this work, the experimental measurements of water activity at 298.15 and 308.15 K for aqueous binary and ternary solutions containing 1-alkyl-3-methylimidazolium bromide ([Rmim][Br], R ) butyl (C4), heptyl (C7), and octyl (C8)), sodium dihydrogen citrate (NaH2Cit), disodium hydrogen citrate (Na2HCit), and trisodium citrate (Na3Cit) are taken using both vapor pressure osmometry (VPO) and improved isopiestic methods. The effect of temperature, charge on the anion of sodium citrate salts, and alkyl chain length of ionic liquids on the vapor-liquid equilibria properties of the investigated systems are studied. The constant water activity lines of all the ternary systems show large negative deviation from the linear isopiestic relation (Zdanovskii-Stokes-Robinson rule) derived using the semi-ideal hydration model, and the vapor pressure depression for a ternary solution is much larger than the sum of those for the corresponding binary solutions with the same molality of the ternary solution. The results have been interpreted in terms of the solute-water and solute-solute interactions. In the second part of this work, the effects of the addition of (NH4)3Cit, K3Cit, Na3Cit, (NH4)2HPO4, and (NH4)3PO4 on the liquid-liquid phase diagram, apparent molar volume, isentropic compressibility, and conductivity of aqueous solutions containing the model ion
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