Aqueous salting-out effect of inorganic cations and anions on non-electrolytes

The salting-out effects of 27 lithium, sodium, potassium, ammonium and magnesium salts and HCl on chloroform, benzene, chlorobenzene and anisole were characterized in aqueous solutions at 303 K by measuring the Henry’s law constants. The concentration of the salt solutions was 0.5 mol dm−3, i.e., similar to the salinity of sea water. The solubility change was described in terms of the Setschenow constant, KS(salt,solute). The highest salting-out effects were observed for the solutions of salts involving doubly charged anions, and the smallest for image. The individual ionic Setschenow constants, KS(cation,solute) and KS(anion,solute), were determined by multilinear regression, using the assumption of additivity for the ions. Cl− was selected as the reference ion for calculation of the KS(ion,solute) values of the other ions. The estimations resulted systematically in significant positive KS(cation,solute) values, ranging from 0.13 ± 0.026 (image) to 0.28 ± 0.032 (Mg2+), which were hardly affected by the accompanying anion in solution, and only slightly affected by the non-electrolytes present. image resulted in a slight salting-in effect: KS(image,solute) = −0.083 ± 0.019; the other anions displayed salting-out effect for all of the non-electrolytes studied, with KS(anion,solute) ranging between 0.090 ± 0.008 (image) and 0.21 ± 0.035 (image).