The influence of a surfactant on the rate of phenanthrene mass transfer into water

Polycyclic aromatic hydrocarbons (PAH) are hydrophobic pollutants found in contaminated soils at many sites in the U.S. One method proposed to improve remediation of PAH contaminated soil is to add surfactants to help mobilize these and other poorly soluble compounds. Previous work on the effects of surfactants on PAH and other pollutants has focused on equilibrium phenomena. The influence of a surfactant on the rate of dissolution of phenanthrene, a model PAH, was determined in this study. Phenanthrene dissolution kinetics depended on the observed mass transfer coefficient and the apparent saturation concentration, both of which depended on surfactant concentration. A simple two-step mass transfer model was developed to describe the relationship between dissolution rate and surfactant concentration. This approach may be useful in estimating effects on mass transfer kinetics for a variety of surfactants using data that are either available in the literature or are readily measured.