Henry's law constant of selected environmentally significant compounds in water

Accurate values of Henry's law constant in water are required when modeling the fate of organic pollutants in environmental systems. Unfortunately, for many organics this property is not available in the literature and direct measurement is difficult. An alternative approach is calculation of Henry's law constant from other fundamental properties. By definition Henry's law constant is the product of the compound's pure component vapor pressure and infinite dilution activity coefficient in water. In this work a gas saturation apparatus was used to measure vapor pressures of four poly aromatic hydrocarbons: naphthalene, anthracene, benzo[a]pyrene, and chrysene. Differential ebulliometry was used to measure the aqueous infinite dilution activity coefficients of phenol, pyridine, aniline, quinoline, o-toluidine and p-toluidine at several different temperatures. For compounds where both properties were available, Henry's law constant was calculated. The infinite dilution activity coefficient data were modeled using relationships derived from conformal solution theory and van der Waals one fluid mixing rules. An empirical equation was also applied to modeling the temperature dependency of the Henry's law constants.