title: Mobilization of metals during treatment of contaminated soils by modified Fenton's reagent using different chelating agents.
abstract: Changes in pH and redox conditions and the application of chelating agents when applying in situ chemical oxidation (ISCO) for remediation of contaminated sites can cause mobilization of metals to the groundwater above threshold limit values. The mechanisms causing the mobilization are not fully understood and have only been investigated in few studies. The present work investigated the mobilization of 9 metals from two very different contaminated soils in bench and pilot tests during treatment with modified Fenton's reagent (MFR) and found significant mobilization of Cu and Pb to the water in mg/l levels. Also Fe, As, Mn, Ni, Zn, Mg, and Ca mobilization was observed. These findings were confirmed in a pilot test where concentrations of Cu and Pb up to 52.2 and 33.7 mg/l were observed, respectively. Overall, the chelating agents tested (EDTA, citrate and pyrophosphate) did not seem to increase mobilization of metals compared to treatment with only hydrogen peroxide and iron. The results strongly indicate that the mobilization is caused by hydrogen peroxide and reactive species including oxidants and reductants formed with MFR. Based on these results, the use of chelating agents for ISCO will not cause an increase in metal mobilization.
authors: Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Niels Bohrs Vej 8, DK-6700 Esbjerg, Denmark.
authors: Lars R
authors: LR
authors: Bennedsen
authors: Anne
authors: A
authors: Krischker
authors: Torben H
authors: TH
authors: Jørgensen
authors: Erik G
authors: EG
authors: Søgaard
mesh_terms: D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*; D010865:Pilot Projects; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: C045076:Fenton's reagent; D008670:Metals; D012989:Soil Pollutants; D006861:Hydrogen Peroxide; D007501:Iron