Studies on the dissolution of polycyclic aromatic hydrocarbons from contaminated materials using a novel dialysis tubing experimental method

Assessment of risk and remediation strategies at contaminated sites require s that both the amounts of contaminants present and their potential for rel ease from materials and soils be evaluated. The release, or dissolution, of polycyclic aromatic hydrocarbons (PAHs) from contaminated materials to wat er was therefore investigated. To facilitate investigations of PAH dissolut ion from physically disparate materials such as solid coal tars, creosote, oil, and spent oxide, an experimental method for measuring dissolved PAHs w as developed employing dialysis tubing in a batch-type system. This was val idated and compared to aqueous-phase PAH concentrations measured using more traditional techniques and also predicted using Raoult's law. The experime ntal procedure was successfully used to determine 'near equilibrium' aqueou s concentrations of PAHs, but it could only he used to determine relative r ates of approach to equilibrium as the dialysis tubing effected the rate co nstants. It was found that the contaminant materials influenced dissolution , in particular the close to equilibrium concentrations. For materials chem ically similar to PAHs, such as nonaqueous-phase liquids (NAPLs), the conce ntrations could be predicted using Raoult's law. For materials that were ch emically dissimilar to PAHs, such as spent oxide, release was more thermody namically Favorable than for NAPLs.