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Download fileOxidation of Chlorinated Ethenes by Heat-Activated Persulfate: Kinetics and Products
journal contribution
posted on 2007-02-01, 00:00 authored by Rachel H. Waldemer, Paul G. Tratnyek, Richard L. Johnson, James T. NurmiIn situ chemical oxidation (ISCO) and in situ thermal
remediation (ISTR) are applicable to treatment of groundwater
contaminated with chlorinated ethenes. ISCO with
persulfate (S2O82-) requires activation, and this can be
achieved with the heat from ISTR, so there may be advantages
to combining these technologies. To explore this possibility,
we determined the kinetics and products of chlorinated
ethene oxidation with heat-activated persulfate and compared
them to the temperature dependence of other degradation
pathways. The kinetics of chlorinated ethene disappearance
were pseudo-first-order for 1−2 half-lives, and the resulting
rate constantsmeasured from 30 to 70 °Cfit the
Arrhenius equation, yielding apparent activation energies
of 101 ± 4 kJ mol-1 for tetrachloroethene (PCE), 108 ± 3 kJ
mol-1 for trichloroethene (TCE), 144 ± 5 kJ mol-1 for cis-1,2-dichloroethene (cis-DCE), and 141 ± 2 kJ mol-1 for trans-1,2-dichloroethene (trans-DCE). Chlorinated byproducts were
observed, but most of the parent material was completely
dechlorinated. Arrhenius parameters for hydrolysis and
oxidation by persulfate or permanganate were used
to calculate rates of chlorinated ethene degradation by
these processes over the range of temperatures relevant
to ISTR and the range of oxidant concentrations and
pH relevant to ISCO.
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Keywords
temperature dependencechlorinated ethene disappearancekineticISCOpersulfateChlorinated Ethenesmoldegradation pathwaysISTRchlorinated ethene degradationPCEchlorinated ethenesTCEChlorinated byproductsoxidant concentrationschemical oxidationArrhenius parametersS 2OArrhenius equationparent materialactivation energieschlorinated ethene oxidationkJ