Evaluation of ethanol washing on dioxins-polluted soil and sediment based on adsorption relationships

Multi-stage ethanol washing on dioxins-polluted soil and sediment were performed. The results indicated the existence of limit washing concentration (LWC), where no more dioxins were removed from the soil or the sediment by further washing. In each stage, dioxins concentration in the soil, sediment and ethanol could be described satisfactory by the Freundlich equation. The Freundlich capacity factor, K(ef) correlated with the LWC which was estimated to be ca. 1000 pmol g(-1) in the case of soil, and about 150 pmol g(-1) in the case of sediment. Organic contents in the soil and sediment affected the Freundlich intensity parameter, n(-1) but not K(f). A model, which enables the calculation of removal efficiency of PCDD/DFs at each stage using K(f), n, and initial PCDD/DFs concentration, is presented.