The solubility of toluene in aqueous salt solutions

The solubility of toluene has been measured in distilled water, and in various inorganic salt solutions. Values of the Setschenow constant, KS, which quantify toluene solubility versus salt concentration, have been determined for each salt. Values of KS are compared to the activity of water for the salt solutions. Data from this study, consistent with earlier data, suggests that the effects of salts upon toluene solubility are non-additive. This contrasts the additive behavior of inorganic salts upon the solubility of nonpolar organic compounds, such as benzene and naphthalene, reported in the literature. Specific interaction between slightly polar toluene and ions in solution is suggested as a possible explanation for the non-additive effect of salts on the solubility of toluene.