COSOLVENCY AND SORPTION OF HYDROPHOBIC ORGANIC-CHEMICALS

Sorption of hydrophobic organic chemicals (HOCs) by two soils was measured from mixed solvents containing water plus completely miscible organic solvents (CMOSs) and partially miscible organic solvents (PMOSs). The utility of the log-linear cosolvency model for predicting HOC sorption from solvent mixtures was evaluated. Cosolvent effects of PMOSs on HOC solubility and sorption were compared. Nonpolar PMOSs (e.g., toluene, p-xylene, and TCE) have low aqueous solubilities and when present either as a cosolvent/cosolute in the aqueous phase or as a separate liquid phase do not significantly influence HOC sorption by soils. In contrast, polar PMOSs (e.g., nitrobenzene and o-cresol) have sufficiently high aqueous solubilities that significant decreases in HOC sorption can be measured. The presence of a CMOS increases the PMOS solubility which, in turn, is reflected in increased solubility and decreased sorption of HOCs. Results presented suggest that water-PMOS and sorbent-PMOS interactions need to be considered in predicting the cosolvency of a polar PMOS. © 1990, American Chemical Society. All rights reserved.