title: A washing procedure to mobilize mixed contaminants from soil: I. Polychlorinated biphenyl compounds.
abstract: We conducted a laboratory study to assess the feasibility of a washing process with nonionic and anionic surfactants in combination with ethylenediaminetetraacetate (EDTA) for the simultaneous mobilization of heavy metals and polychlorinated biphenyls (PCBs) from a field-contaminated soil. Unit processes consisting of complexometric extraction and surfactant-assisted mobilization were combined with reagent regeneration and detoxification steps to generate innocuous products. Ten minutes of ultrasonic mixing of the soil with a combination of 30 mL L(-1) surfactant suspension and a sparing quantity (2 mmol) of EDTA mobilized appreciable quantities of PCBs, virtually all of the available Cd, Cu, Mn, and Pb, and lesser amounts of the Zn, Ni, and Cr but only small quantities of Al and Fe. Relative to individual reagents, combinations of surfactant (Brij 98, Triton X-301, or Triton XQS-20) with EDTA did not influence PCB extraction efficiencies perceptibly. Of the three surfactants, the Brij 98 proved to be the most efficient for three successive extractions with a single charge, mobilizing 83% of the PCBs, whereas companion extractions that used fresh reagent each time mobilized 87% of the soil PCB content. The decreased PCB mobilization with the same quantity of anionic surfactant (71 or 68%) resulted from losses during the EDTA regeneration process with zero-valent Mg. In toto, these studies demonstrate that PCB compounds and selected heavy metals can be coextracted efficiently from soil with three successive washes with the same washing suspension containing EDTA and a nonionic surfactant.
authors.affiliation: Department of Food Science and Agricultural Chemistry, Macdonald Campus of McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, QC, Canada H9X 3V9.
authors.forename: Sadia
authors.initials: S
authors.lastname: Ehsan
authors.forename: Shiv O
authors.initials: SO
authors.lastname: Prasher
authors.forename: William D
authors.initials: WD
authors.lastname: Marshall
mesh_terms: D002614:Chelating Agents / Q000737:chemistry; D004492:Edetic Acid / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry / Q000302:isolation & purification*; D011078:Polychlorinated Biphenyls / Q000737:chemistry / Q000302:isolation & purification*; D012989:Soil Pollutants / Q000737:chemistry / Q000302:isolation & purification*; D013501:Surface-Active Agents / Q000737:chemistry*; D013997:Time Factors; D018508:Water Purification / Q000191:economics / Q000379:methods*
chemical_list: D002614:Chelating Agents; D019216:Metals, Heavy; D012989:Soil Pollutants; D013501:Surface-Active Agents; D004492:Edetic Acid; D011078:Polychlorinated Biphenyls