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

Abstract:

The ability of an aqueous polyoxyethylene (20) sorbitan monooleate solution to solubilize a residual trichloroethene (TCE) saturation, present as a trapped dense non-aqueous phase liquid (DNAPL), was studied in a series of column experiments. Different flow regimes and stopflow scenarios were applied. No mobilization of the DNAPL was observed, leading to the assumption that the only recovery mechanism was a surfactant enhanced micellar solubilization of the TCE molecules. The solubilization of TCE by the surfactant solution was observed to be rate-limited under the applied conditions and the exchange rate depended on pore water velocity and volumetric DNAPL content. A phenomenological power-law model between the mass transfer rate and the pore water velocity and volumetric DNAPL content was implemented in a numerical model to describe DNAPL dissolution, advection and dispersion in the water phase. The applied model accounts for non-flow dissolution. The obtained mass transfer rate parameters provide a good fit to the experimental data also for no-flow conditions. Compared to other mass transfer rate models the obtained relationship predicts lower mass transfer rates and an intercept in case of zero flow. Copyright (C) 2000 Elsevier Science B.V.