Dioxin removal from contaminated soils by ethanol washing Print
Written by Sofia Jonsson   
Friday, 21 May 2010 14:01
New article published  in Journal of Hazardous Materials by Sofia Jonsson, Umeå University MCN.
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 ◦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 (≥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