Chemical oxidation of hexachlorocyclohexanes (HCHs) in contaminated soils.
Chemical oxidation of hexachlorocyclohexanes (HCHs) was evaluated in (i) artificially spiked sand with HCH isomers (α, β, γ and δ) and (ii) contaminated soil sampled from a former gravel pit backfilled with wastes of lindane (γ-HCH). Following oxidation treatments were employed: hydrogen peroxide alone (HP), hydrogen peroxide with soluble Fe(II) (Fenton-F), sodium persulfate alone (PS), Fe(II) activated persulfate (AP) and permanganate (PM). GC-MS results revealed a significant degradation of all isomers in spiked soil in the order: F>PS>AP>HP>PM. Soluble Fe(II) enhanced the efficiency of H2O2 but decreased the reactivity of persulfate. Similar trend was observed in contaminated soil, but with less degradation probably caused by scavenging effect of organic matter and soil minerals and/or pollutant unavailability. No significant increase in oxidation efficiency was observed after using availability-enhancement agents in contaminated soil. Other limitation factors (oxidant dose, pH, catalyst type etc.) were also addressed. Among all the isomers tested, β-HCH was the most recalcitrant one which could be explained by higher metabolic and chemical stability. No by-products were observed by GC-MS regardless of the oxidant used. For being the premier study reporting chemical oxidation of HCH isomers in contaminated soils, it will serve as a base for in-situ treatments of sites contaminated by HCH isomers and other persistent organic pollutants.
Université de Lorraine, LIEC, UMR7360, Vandœuvre-lès-Nancy F-54505, France; CNRS, LIEC, UMR7360, Vandœuvre-lès-Nancy F-54505, France; Université de Lorraine, LCPME, UMR7564, Vandœuvre-lès-Nancy F-54505, France; CNRS, LCPME, UMR7564, Villers Les Nancy F-54600, France; Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad 38040, Pakistan. Electronic address: muhammad.usman@uaf.edu.pk.
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Usman
Université de Lorraine, LIEC, UMR7360, Vandœuvre-lès-Nancy F-54505, France; CNRS, LIEC, UMR7360, Vandœuvre-lès-Nancy F-54505, France; Université de Lorraine, LCPME, UMR7564, Vandœuvre-lès-Nancy F-54505, France; CNRS, LCPME, UMR7564, Villers Les Nancy F-54600, France.
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Tascone
Université de Lorraine, LIEC, UMR7360, Vandœuvre-lès-Nancy F-54505, France; CNRS, LIEC, UMR7360, Vandœuvre-lès-Nancy F-54505, France.
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Faure
Ecole Nationale Supérieure de Chimie de Rennes, UMR CNRS 6226, 11 Allée de Beaulieu, 35708 Rennes Cedex 7, France; Université Européenne de Bretagne, France.
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Hanna
D002384:Catalysis; D005296:Ferrous Compounds / Q000737:chemistry; D001556:Hexachlorocyclohexane / Q000032:analysis / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D008903:Minerals / Q000737:chemistry; D008956:Models, Chemical; D010084:Oxidation-Reduction; D017670:Sodium Compounds / Q000737:chemistry; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry
D005296:Ferrous Compounds; D008903:Minerals; D017670:Sodium Compounds; D012987:Soil; D012989:Soil Pollutants; D013431:Sulfates; D001556:Hexachlorocyclohexane; D006861:Hydrogen Peroxide; C024625:sodium persulfate; C023888:beta-hexachlorocyclohexane
Fenton; Hexachlorocyclohexanes; Lindane; Oxidation; Persulfate; Soil