Washing Procedure to Mobilize Mixed Contaminants from Soil. II. Heavy Metals

• Published in: Journal of environmental quality Vol. 35; no. 6; pp. 2084 - 2091
• Main Authors: Ehsan, S, Prasher, S.O, Marshall, W.D
• Format: Journal Article
• Language: English
• Published: Madison, WI Crop Science Society of America 01.11.2006; American Society of Agronomy
• Subjects: Adsorption; Agronomy. Soil science and plant productions; Applied sciences; Biological and medical sciences; chelating agents; Chelating Agents - chemistry; chelation; Chemical Precipitation; Contaminants; copper; Earth sciences; Earth, ocean, space; Edetic Acid - chemistry; EDTA (chelating agent); Engineering and environment geology. Geothermics; Environmental Pollution - prevention & control; Exact sciences and technology; extraction; Fundamental and applied biological sciences. Psychology; Heavy metals; hexane; Hexanes - chemistry; Hydrogen-Ion Concentration; lead; magnesium; Metals; Metals, Heavy - chemistry; Metals, Heavy - isolation & purification; mobilization; nonionic surfactants; Nutrient removal; PCB; polluted soils; Pollution; Pollution, environment geology; Polychlorinated biphenyls; Polychlorinated Biphenyls - chemistry; Polychlorinated Biphenyls - isolation & purification; Soil contaminants; Soil contamination; Soil Pollutants - chemistry; Soil Pollutants - isolation & purification; soil pollution; soil washing; Surface-Active Agents - chemistry; Surfactants; ultrasonic treatment; VOCs; Volatile organic compounds; Waste Management - economics; Waste Management - methods; Water Purification - economics; Water Purification - methods; Zerovalent metal; Iron; Washing; Surfactant; Soil pollution; Persistent organic pollutant; Precipitation; Aqueous medium; Chlorine Organic compounds; Lead; Hexane; Chemical properties; Ultrasound; Organic compounds; Laboratory study; Non ionic surfactant; EDTA; Polychlorobiphenyl; Contamination; Zinc; Heavy metal; Hydrolysis; Anionic surfactant; Mobilization; Regeneration; Soils; Corrosion; Equilibration; Nickel; Manganese
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2005.0475

We conducted a laboratory study to assess the efficiency of nonionic and anionic surfactants in combination with a sparing quantity of ethylenediaminetetraacetate (EDTA) to simultaneously extract heavy metals (HMs) and polychlorinated biphenyl (PCB) compounds from a field-contaminated soil. A soil wash that mobilized both HMs and PCBs was combined with back-extraction with hexane to remove PCBs from the aqueous wash. The aqueous washing suspension was then regenerated by precipitation of the HMs induced by corrosion and hydrolysis of zero-valent Mg to provide a cleaned soil and innocuous extract. Finally, the washing suspension was recycled twice to mobilize more contaminants from the soil particulate fraction. After ultrasonic equilibration, EDTA in admixture with a nonionic surfactant did not appreciably change the efficiency of mobilization of most heavy metals (Al, Cd, Cr, Fe Mn, Ni, and Zn), but did increase the recovery of Cu and Pb. The release of EDTA from HM complexes was efficient for most metals (99%) but was influenced by the chemical characteristics of the surfactant. The EDTA recovery (62-65%) after three cycles of soil washing, hexane back-extraction, and Mg0 treatment was similar for all reagent combinations. In toto, these studies demonstrate that after treatment with ultrasound, selected heavy metals can be coextracted efficiently from soil with a single washing suspension containing EDTA and a nonionic surfactant.