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ROLE OF REDUCTANTS IN THE ENHANCED DESORPTION AND TRANSFORMATION OF CHOROALIPHATIC COMPOUNDS BY MODIFIED FENTON'S REACTIONS. (R826163)
Citation:
Watts, R. J., B. C. Bottenberg, T. F. Hess, M. D. Jensen, AND A. L. Teel. ROLE OF REDUCTANTS IN THE ENHANCED DESORPTION AND TRANSFORMATION OF CHOROALIPHATIC COMPOUNDS BY MODIFIED FENTON'S REACTIONS. (R826163). ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 33(19):3432-3437, (1999).
Description:
The mechanism for enhanced desorption of chloroaliphatic compounds from a
silty loam soil by modified Fenton's reagent was investigated using a series of
probe compounds of varying hydrophobicities. Hexachloroethane, which has
negligible reactivity with hydroxyl radicals, was transformed more rapidly in
modified Fenton's reactions (
0.3 M hydrogen
peroxide) than it was lost by gas-purge desorption, suggesting the existence of
a non-hydroxyl radical mechanism. The addition of excess 2-propanol to scavenge
hydroxyl radicals slowed, but did not stop, the desorption and degradation of
hexachloroethane. In the presence of the reductant scavenger chloroform,
hexachloroethane did not desorb and was not degraded, indicating that a
reductive pathway in vigorous Fenton-like reactions is responsible for enhanced
contaminant desorption. Fenton-like degradation of hexachloroethane yielded the
reduced product pentachloroethane, confirming the presence of a reductive
mechanism. In the presence of excess 2-propanol, toluene, which has negligible
reactivity with reductants, was displaced from the soil but not degraded. The
results are consistent with enhanced contaminant desorption by reductants,
followed by oxidation and reduction in the aqueous phase. Vigorous Fenton-like
reactions in which reductants and hydroxyl radicals are generated may provide a
universal treatment matrix in which contaminants are desorbed and then oxidized
and reduced in a single system.