Kinetic control of contaminant release from NAPLs--information potential of concentration time profiles

Release of contaminants from non-aqueous phase liquids (NAPLs) is often limited by the dynamic exchange with aqueous solutions governed by a priori unknown kinetic laws. Release experiments require a thorough evaluation of the potential and limitations of kinetic models to reveal release processes. In this study, we investigated the characteristic concentration-time profiles of various models for the release of contaminants from an organic phase into an aqueous solution under no flow conditions. Criteria have been tested that allow for distinction of a first order one domain, a first order two domain, a spherical diffusion model, a spherical diffusion model with a time variable diffusion coefficient, a model for diffusion in a sphere with organic film, and a model for diffusion in a sphere with an aqueous film. The results can serve to evaluate the processes potentially governing release of organic contaminants from non-aqueous liquid phases.