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Journal of Environmental Quality Abstract - Organic Compounds in the Environment

Zerovalent Iron Nanoparticles for Treatment of Ground Water Contaminated by Hexachlorocyclohexanes


This article in JEQ

  1. Vol. 37 No. 6, p. 2192-2201
    Received: Oct 12, 2007

    * Corresponding author(s): wez3@lehigh.edu
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  1. Daniel W. Elliotta,
  2. Hsing-Lung Lienb and
  3. Wei-xian Zhang *c
  1. a Geosyntec Consultants, Lawrenceville, NJ 08648
    b Dep. of Civil & Environmental Engineering, National Univ. of Kaohsiung, 811 Kaohsiung, Taiwan ROC
    c Dep. of Civil & Environmental Engineering, Lehigh Univ., Bethlehem, PA 18015


Ground water and aquifer samples from a site contaminated by hexachlorocyclohexanes (HCHs; C6H6Cl6) were exposed to nanoscale iron particles to evaluate the technology as a potential remediation method. The summed concentration of the HCH isomers in ground water was approximately 5.16 μmol L−1 (1500 μg L−1). Batch experiments with 2.2 to 27.0 g L−1 iron nanoparticles showed that more than 95% of the HCHs were removed from solution within 48 h. Using a pseudo first-order kinetics model, the HCH isomers were removed in accordance with the trend γ ≅ α > β > δ. This seems to be correlated with the orientation (axial vs. equatorial) of the chlorine atoms lost in the dihaloelimination steps. Although the reactivity of the HCH isomers has been investigated in the classical organic chemistry literature, the present study was the first in the environmental remediation arena. The rate of removal is directly correlated to the number of axial chlorines. The observed rate constant varied from 0.04 to 0.65 h−1, and the rate constant normalized to the iron surface area concentration ranged from 5.4 × 10−4 to 8.8 × 10−4 L m−2 h−1 Post-test extractions of the reactor contents detected little HCH remaining in solution or on the iron surfaces, reinforcing the contention that reaction rather than sorption was the operative mechanism for the HCH removal. Together with previously published work on a wide variety of chlorinated organic solvents, this work further demonstrates the potential of zerovalent iron nanoparticles for treatment and remediation of persistent organic pollutants.

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