Details

Autor(en) / Beteiligte

• Bennedsen, Lars R.
• Krischker, Anne
• Jørgensen, Torben H.
• Søgaard, Erik G.

Titel

Mobilization of metals during treatment of contaminated soils by modified Fenton's reagent using different chelating agents

Ist Teil von

• Journal of hazardous materials, 2012-01, Vol.199, p.128-134

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2012

Quelle

MEDLINE

Beschreibungen/Notizen

• ► High concentrations of mobilized metals are found in systems where modified Fenton's reagent (MFR) is used for remediation purposes of organic pollutants. ► Chelating agents for MFR oxidations such as EDTA, citrate and pyrophosphate does not seem to increase mobilization of metals compared to treatments where only hydrogen peroxide and iron are used. ► These results strongly indicate that mobilization of metals found in cases where modified Fenton reagents are involved is caused by hydrogen peroxide and reactive species including oxidants and reductants such as superoxide and hydroperoxid anion formed with MFR or degradation products from the oxidation. 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.