The dissolution of benzene, toluene, m-xylene and naphthalene from a residually trapped non-aqueous phase liquid under mass transfer limited conditions

The results of dissolution experiments for benzene, toluene, m-xylene and n aphthalene (BTXN) from a relatively insoluble oil phase (tridecane), residu ally trapped in a non-sorbing porous medium, are described. This mixture wa s chosen to simulate dissolution of soluble aromatic compounds from a petro leum hydrocarbon mixture, e.g., crude oil, for which a large fraction of th e mixture is relatively insoluble. The experiments were carried out at a sm all source length to interstitial velocity ratio, L/Lv, so that dissolution would be mass transfer limited (MTL). When fitted to data for toluene, a m ultiregion mass transfer model was found to predict the experimental data s atisfactorily for the other components without adjustment of the mass trans fer rate parameters. These results indicate that the dissolution process ca n be generalized for various hydrophobic organic compounds present in a mul ticomponent non-aqueous phase liquid (NAPL) when mass transfer limitations are present. This also suggests that dissolution data obtained for one comp ound can be useful for predicting the dissolution histories for other compo unds from petroleum hydrocarbon mixtures. (C) 1999 Elsevier Science B.V. Al l rights reserved.