title: Dioxin removal from contaminated soils by ethanol washing.
abstract: The aim of this study was to investigate the potential utility of ethanol washing for remediating soils contaminated with polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), as a cost-efficient alternative to conventional remediation methods of PCDD/F-contaminated soils. Initially, screening experiments were performed with a two-level full factorial design to examine the effects of temperature, extraction time and ethanol concentration on the removal efficiency. The screening experiments showed that the ethanol concentration was the most important parameter. In addition, repeated washing cycles considerably improved the results. Ethanol washing conditions were then selected (10 wash cycles with 75% ethanol at 60 degrees C), and applied to four soils with different soil characteristics and contamination levels to test the robustness of the selected method. Treatment efficiencies of 81% and 85% were obtained for a lightly contaminated sandy-silty soil and a highly contaminated clay soil rich in graphite particles, respectively. Even higher treatment efficiencies (> or = 97%) were obtained for two other highly contaminated soils, one of which contained high amounts of organic matter. PCDD/Fs were found to both dissolve in the solvent and migrate into it as species adsorbed to particles. The relative contributions of these mechanisms and the overall efficiency of the removal seem to depend on contaminant concentration, the types of carbon in the soil matrix and the particle size distribution. The study shows that ethanol washing has effective remediation potential for a variety of PCDD/F-contaminated soils.
authors.affiliation: Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden. sofia.jonsson@chem.umu.se
authors.forename: Sofia
authors.initials: S
authors.lastname: Jonsson
authors.forename: Henrik
authors.initials: H
authors.lastname: Lind
authors.forename: Staffan
authors.initials: S
authors.lastname: Lundstedt
authors.forename: Peter
authors.initials: P
authors.lastname: Haglund
authors.forename: Mats
authors.initials: M
authors.lastname: Tysklind
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004147:Dioxins / Q000302:isolation & purification*; D000431:Ethanol / Q000737:chemistry*; D006108:Graphite; D013058:Mass Spectrometry; D052638:Particulate Matter / Q000032:analysis; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives / Q000302:isolation & purification; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000302:isolation & purification*; D012997:Solvents
chemical_list: D004147:Dioxins; D052638:Particulate Matter; D000072317:Polychlorinated Dibenzodioxins; D012987:Soil; D012989:Soil Pollutants; D012997:Solvents; D000431:Ethanol; D006108:Graphite