Remediation of Soil and Ground Water Contaminated with PAH using Heat and Fe(II)-EDTA Catalyzed Persulfate Oxidation |
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Authors: | Farhad Nadim Kun-Chang Huang Amine M Dahmani |
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Institution: | (1) The Environmental Research Institute, University of Connecticut, Route 44, Longley Building, 270 Middle Turnpike Unit 5210, Storrs, CT 06269-5210, USA |
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Abstract: | The feasibility of degrading 16 USEPA priority polycyclic aromatic (PAH) hydrocarbons (PAHs) with heat and Fe(II)-EDTA catalyzed
persulfate oxidation was investigated in the laboratory. The experiments were conducted to determine the effects of temperature
(i.e. 20 ∘C, 30 ∘C and 40 ∘ C) and iron-chelate levels (i.e., 250 mg/L-, 375 mg/L- and 500 mg/L-Fe(II)) on the degradation of dissolved PAHs in aqueous
systems, using a series of amber glass jars as the reactors that were placed on a shaker inside an incubator for temperature
control. Each experiment was run in duplicate and had two controls (i.e., no persulfate in systems). Samples were collected
after a reaction period of 144 hrs and measured for PAHs, pH and sodium persulfate levels. The extent of degradation of PAHs
was determined by comparing the data for samples with the controls.
The experimental results showed that persulfate oxidation under each of the tested conditions effectively degraded the 16
target PAHs. All of the targeted PAHs were degraded to below the instrument detection limits (∼4 μ/L) from a range of initial
concentration (i.e., 5 μ/L for benzo(a)pyrene to 57 μ/L for Phenanthrene) within 144 hrs with 5 g/L of sodium persulfate at
20 ∘ C, 30 ∘C and 40 ∘C. The data indicated that the persulfate oxidation was effective in degrading the PAHs and that external heat and iron catalysts
might not be needed for the degradation of PAHs.
The Fe(II)-EDTA catalyzed persulfate also effectively degraded PAHs in the study. In addition, the data on the variation of
persulfate concentrations during the experiments indicated that Fe(II)-EDTA accelerated the consumption of persulfate ions.
The obtained degradation data cannot be used to evaluate the influence of temperature and Fe(II) levels on the PAH degradation
because the PAHs under each of the tested conditions were degraded to below the instrument detection limit within the first
sampling point. However, these experiments have demonstrated the feasibility of degrading PAHs in aqueous systems with persulfate
oxidation. Additional tests are being conducted to evaluate the effectiveness of treating PAHs in soils and obtaining the
rate of degradation of PAHs with persulfate oxidation.
Two sets of laboratory experiments were conducted to evaluate the ability of sodium persulfate in oxidizing real world PAH-contaminated
soils collected from a Superfund site in Connecticut. The first set of soil sample were treated only with persulfate and to
the second batch, mixture of persulfate and Fe(II)-EDTA solutions were added. The results of the second test showed that within
24 hours, 75% to 100% of the initial concentrations of seven PAH compounds detected in the soil samples were degraded by sodium
persulfate mixed with FE(II)-EDTA. |
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