Surfactant Solubilization of Organic Compounds in Soil/Aqueous Systems

Abstract

Hydrophobic organic compounds (HOCs) are modeled as being distributed between aqueous, micellar, and sorbent compartments in a soil/aqueous system containing nonionic surfactant micelles. The partitioning of HOC between the hydrophobic interiors of the nonionic surfactant micelles and the surrounding solution can be characterized with a mole fraction partition coefficient. Nonionic surfactant sorption onto soil may be described by a maximum sorption parameter. Sorbed surfactant molecules tend to increase HOC sorption, and free surfactant monomers in solution tend to decrease HOC sorption by increasing the HOC apparent aqueous solubility; these effects can be represented by a modified HOC soil/water partition coefficient. The distribution of HOC between the three compartments can be estimated using a physicochemical model, for which model parameter values conceptually may be obtained from independent experiments.