ESTIMATING THE EQUILIBRIUM AQUEOUS CONCENTRATIONS OF POLYNUCLEAR AROMATIC-HYDROCARBONS IN COMPLEX-MIXTURES

By use of a two-phase liquid-liquid equilibrium model, the distribution of nonpolar solutes between water (polar phase) and soil organic matter (nonpolar phase) was related to principles of equilibrium chemistry. Batch equilibrium experiments were conducted with field-contaminated soils. Aqueous concentrations were measured directly, predicted through the use of organic cosolvents, and calculated from Raoult's law, thereby providing a three-way comparison of solute behavior in water. Results showed that composition of the nonpolar phase strongly influences the solute concentrations in the polar phase, suggesting that Raoult's law is applicable to complex mixtures. Tar-water partitioning experiments demonstrated that the distribution of solutes in complex mixtures is analogous to partitioning among multiple solvents.