Ultrasonic-Assisted Extraction to Release Heavy Metals from Contaminated Soil

The soil used in this research was obtained from a heavy metal-contaminated site near a Pb-smelting plant. For ultrasonic-assisted extraction, citrate and ethylenediaminetetraacetic acid (EDTA) were used as leaching solutions. When using 0.05 and 0.1 M citrates, the highest extraction efficiency was obtained at 30 W. For both citrate and EDTA, the efficiency increased with sonic time and showed the maximum at 12 min. At the same concentration (0.05 M), EDTA was better than citrate at extraction. Despite the short extraction time, the extraction efficiencies of metals with sonication were higher than those of soil washing for both 0.05 M citrate and 0.05 M EDTA. Extraction of metallic elements from contaminated soil could be enhanced with the aid of ultrasonic treatment.