Remediation of Soil and Ground Water Contaminated with PAH using Heat and Fe(II)-EDTA Catalyzed Persulfate Oxidation

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 μg/L) from a range of initial concentration (i.e., 5 μg/L for benzo(a)pyrene to 57 μg/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. 228 F. NADIM ET AL.

Oxidant selection to treat an aged PAH contaminated soil by in situ chemical oxidation

“…Activation can be performed by several methods: thermal photochemical or chemical using dissolved iron or solid iron (e.g. magnetite), in alkaline conditions or with hydrogen peroxide [15,30,[33][34][35].…”

Oxidation and Removal of 1,2,4-Trichlorobenzene using Sodium Persulfate in a Sorption-Desorption Experiment

“…Nadim et al (2004Nadim et al ( , 2005 conducted bench-scale experiments to oxidize polycyclic aromatic hydrocarbon (PAH) compounds in contaminated soil and ground water samples. They were able to successfully remove 75% to 100% of the PAH compounds by persulfate oxidation in two separate laboratory experiments (Nadim et al 2004;Nadim et al 2005). Studies show that persulfate has the potential to be an effective oxidizer of both TCB and sediment organic matter.…”

Selection of oxidant doses for in situ chemical oxidation of soils contaminated by polycyclic aromatic hydrocarbons (PAHs): A review

“…The measurement method may be not specified [30,150,194,206,213,216,221,222,232,233]. Soil organic matter may also be quantified by other methods [36, 39, 41, 42, 49, 53, 55-57, 150, 195, 196, 207, 214, 222, 225, 226, 230, 231, 237-239] or not monitored at all in some studies [32,37,51,208,215,217,223,224,[227][228][229] (Figure 3). Figure 3 3…”