Surfactant enhanced solubilization of residual trichloroethene: an experimental and numerical analysis

The ability of an aqueous polyoxyethylene (20) sorbitan monooleate solution to solubilize a residual trichloroethene (TCE) saturation, present as a tr apped dense non-aqueous phase liquid (DNAPL), was studied in a series of co lumn experiments. Different flow regimes and stopflow scenarios were applie d. No mobilization of the DNAPL was observed, leading to the assumption tha t the only recovery mechanism was a surfactant enhanced micellar solubiliza tion of the TCE molecules. The solubilization of TCE by the surfactant solu tion was observed to be rate-limited under the applied conditions and the e xchange rate depended on pore water velocity and volumetric DNAPL content. A phenomenological power-law model between the mass transfer rate and the p r,re water velocity and volumetric DNAPL content was implemented in a numer ical model to describe DNAPL dissolution, advection and dispersion in the w ater phase. The applied model accounts for non-flow dissolution. The obtain ed mass transfer rate parameters provide a good fit to the experimental dat a also for no-flow conditions. Compared to other mass transfer rate models the obtained relationship predicts lower mass transfer rates and an interce pt in case of zero flow. (C) 2000 Elsevier Science B.V. All rights reserved .