American Society of Civil Engineers


Oxidative and Reductive Pathways in Iron-Ethylenediaminetetraacetic Acid–Activated Persulfate Systems


by Mushtaque Ahmad, (Graduate student, Dept. of Civil and Environmental Engineering, Washington State Univ., Pullman, WA.), Amy L. Teel, (Research Associate Professor, Dept. of Civil and Environmental Engineering, Washington State Univ., Pullman, WA.), Olha S. Furman, (Postdoctoral Associate, Dept. of Civil and Environmental Engineering, Washington State Univ., Pullman, WA.), Joshua I. Reed, (Graduate student, Dept. of Civil and Environmental Engineering, Washington State Univ., Pullman, WA.), and Richard J. Watts, (corresponding author), M.ASCE, (Professor, Dept. of Civil and Environmental Engineering, Washington State Univ., Pullman, WA. E-mail: rjwatts@wsu.edu)

Journal of Environmental Engineering, Vol. 138, No. 4, April 2012, pp. 411-418, (doi:  http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000496)

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Document type: Journal Paper
Abstract: The iron (II)-ethylenediaminetetraacetic acid (EDTA) and iron (III)-EDTA activation of persulfate was compared using reactant-specific probe compounds: the combined sulfate radical and hydroxyl radical probe anisole, the hydroxyl radical probe nitrobenzene, and the reductant/nucleophile probe hexachloroethane. Iron (II)-EDTA and iron (III)-EDTA were equally effective for activating persulfate decomposition and for generating reductants/nucleophiles at pH 5, while iron (III)-EDTA was a more effective activator than iron (II)-EDTA for generating oxidants. Use of the combined sulfate radical and hydroxyl radical scavenger isopropanol and the hydroxyl radical scavenger tert-butanol demonstrated that approximately 86 and 73% of the oxidation activity in iron (II)-EDTA and iron (III)-EDTA-activated persulfate systems, respectively, was attributable to hydroxyl radical activity. The generation of hydroxyl radical in iron-EDTA-activated persulfate systems at pH 5 was confirmed using electron spin resonance spectroscopy. The results of these pathway analyses, in conjunction with confirmation of the results using the common groundwater contaminant trichloroethylene (TCE), show that iron (II)-EDTA and iron (III)-EDTA-activated persulfate may be an effective system for the in situ remediation of contaminated groundwater.


ASCE Subject Headings:
Groundwater pollution
Hazardous wastes
Soil pollution
Soil treatment
Oxidation