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Chelant extraction and {open_quotes}redox{close_quotes} manipulation for remediation of heavy metal contaminated soils

Conference ·
OSTI ID:210507
; ;  [1]
  1. Argonne National Lab., IL (United States); and others
This paper summarizes several treatability studies for decontamination of soils at the Aberdeen Proving Ground in Maryland. The surface soil contains elevated levels of heavy metals, especially lead, mercury, and cadmium. Other contaminants include PCBs, 1,1,2,2-tetrachloroethane, and trichloroethene. Batch extraction studies identified ethylenediamine-tetraacetic acid (EDTA) and citric acid as potential chelating agents for soil washing to remove heavy metals. Column flooding experiments using these agents resulted in significantly lower removal efficiencies. The reason for this behavior is thought to be the result of channeling the chelant solution through the soil column and less contact between the extracting solution and the soil. As a result, soil flooding is not recommended. Sonication was ineffective in enhancing the heavy metal extraction efficiencies of chelating agents. Screening tests identified sodium borohydride, sodium metabisulfite, and sodium percarbonate as potential redox agents. Lead and copper removal by EDTA and citric acid extraction was minimially affected by pretreatment with redox agents. Enhanced removal of copper, lead, and zinc was observed in column flooding experiments using sodium borohydride and EDTA. The reagents used for redox manipulation significantly improved the performance of citric acid for removing zinc. The soil was washed using a multiple-stage batch extraction. The overall removal of copper, lead, and zine were 98.9%, 98.9%, and 97.2%, respectively.
OSTI ID:
210507
Report Number(s):
CONF-9509139--
Country of Publication:
United States
Language:
English