Salt effects on non-electrolyte activity coefficients in mixed aqueous electrolyte solutions—II. Artificial and natural sea waters

Abstract

The previously demonstrated additivity of ionic contributions to the salting-out of non-polar non-electrolytes by mixed aqueous electrolytes has been applied to predict the salt effects on naphthalene solubility ( S, mole 1. −1) at 25° in sea water of chlorosity Cl/1 20 as log S = −3.590 ± 0.003 − (0·00680 ± 0·00009) Cl/1 20. Naphthalene solubility was measured as a function of chlorosity in a ten-salt artificial sea water and precise agreement with the above expression was observed. Four samples of natural sea water and one estuarine water were similarly examined with results indistinguishable from those for artificial sea water or those predicted from the pure salt data. This precise accounting of the non-electrolyte solubility in sea water on the basis of the major electrolyte constituents alone indicates the absence of solubilization phenomena. Applications of such experiments to interstitial and other natural waters in which solubilization processes may indeed regularly occur are considered. The results are also employed as a starting point for the study of salt effects on the solubilization of naphthalene by added surfactants under controlled conditions in sea water. The results of these and similar experiments are employed to re-examine the proposed role of salinity changes in the transport of solubilized hydrocarbons in sediments. Finally, the McDevit-Long theory of non-electrolyte salting is applied to prediction of the effects of depth on non-electrolyte salting coefficients in the oceans.