title: TCE recovery mechanisms using micellar and alcohol solutions: phase diagrams and sand column experiments.
abstract: Forty-one phase diagrams and fifteen sand column experiments were conducted to evaluate the efficiency of three types of washing solutions to recover trichloroethylene (TCE) at residual saturation and to identify the recovery mechanisms involved. This study demonstrates that: (1) an alcohol and a surfactant combination is more efficient than an alcohol used alone in water; (2) the prediction of the dominant recovery mechanism from the tie line slopes in phase diagram is accurate and can be reproduced in sand column experiments; and (3) TCE recovery efficiency in sand column experiments is generally well represented by the position of the miscibility curve in phase diagrams in the low concentration range. However, the miscibility curve alone is not sufficient to exactly predict the TCE recovery mechanisms involved. Tie line slopes and the critical tie line have to be taken into consideration to select the active matter as well as its concentration and to predict the dominant recovery mechanism in sand column experiments. The sand column experiments quantified the recovery efficiency of each solution and identified the proportion of the recovery mechanisms (mobilisation vs. solubilisation). Washing solutions with an active matter concentration above the critical tie line caused dominating mobilisation. Mobilisation was also dominant when the active matter of the washing solution partitioned into the organic phase and the active matter concentration was below the critical tie line. Solubilisation and emulsification were dominant for washing solutions containing active matter, which principally partitioned into the aqueous phase and an active matter concentration below the critical tie line.
authors.affiliation: Institut National de la Recherche Scientifique, INRS-Eau, Terre et Environnement, 880 Ch. Ste-Foy, C.P. 7500, Ste-Foy, Quebec, Canada G1V 4C7.
authors.forename: Chantal
authors.initials: C
authors.lastname: St-Pierre
authors.forename: Richard
authors.initials: R
authors.lastname: Martel
authors.forename: Uta
authors.initials: U
authors.lastname: Gabriel
authors.forename: René
authors.initials: R
authors.lastname: Lefebvre
authors.forename: Thomas
authors.initials: T
authors.lastname: Robert
authors.forename: Jalal
authors.initials: J
authors.lastname: Hawari
mesh_terms: D008823:Micelles; D008962:Models, Theoretical; D012822:Silicon Dioxide; D012989:Soil Pollutants / Q000302:isolation & purification*; D012995:Solubility; D012997:Solvents / Q000737:chemistry / Q000302:isolation & purification*; D014241:Trichloroethylene / Q000737:chemistry / Q000302:isolation & purification*; D014873:Water Pollutants / Q000302:isolation & purification*
chemical_list: D008823:Micelles; D012989:Soil Pollutants; D012997:Solvents; D014873:Water Pollutants; D014241:Trichloroethylene; D012822:Silicon Dioxide