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TREATMENT OF PAHS AND PCBS USING SULFATE RADICAL-BASED OXIDATION PROCESSES
Citation:
RASTOGI, A., S. R. AL-ABED, AND D. D. DIONYSIOU. TREATMENT OF PAHS AND PCBS USING SULFATE RADICAL-BASED OXIDATION PROCESSES. Presented at 232nd American Chemical Society (ACS) National Meeting, San Francisco, CA, September 10 - 14, 2006.
Description:
Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in aquatic systems pose serious threat to public health due to their toxicity and potential carcinogenicity [1]. Sulfate radical-based oxidation processes can be effectively used for degradation of these recalcitrant compounds. Peroxymonosulfate (PMS) and persulfate (PS) are two common oxidants used for sulfate radical-based oxidation processes [2,3].
Persulfate is widely used in many industrial processes such as polymerization and metal surface oxidation [4]. Persulfate has been recently studied as an oxidant alternative for treating organic contaminants in contaminated soil and groundwater. Persulfate anions (S2O82-) can be thermally or chemically activated by transition metal ions to produce sulfate free radicals (SO4-0), which are very powerful oxidants [5]. High aqueous solubility, relatively low cost and benign end products makes the persulfate oxidation a promising choice among the advanced oxidation process (AOPs) for remediation of contaminated ground water.
Thermal activation of persulfate is the most common of such methods used for treatment of contaminants. Studies using heat-assisted persulfate oxidation reported that the employed process effectively degraded methyl tert-butyl (MtBE) [6], trichloroethylene (TCE) and 1,1,1-trichloroethane [5]. Thermal activation of persulfate shows very promising results in contaminant degradation. However, this is a cost intensive process and heating the subsurface may lead to the migration of VOCs from the liquid to the gas phase. A potential alternative to thermal activation is chemical activation of persulfate by transition metals to produce sulfate radicals. The presence of a transition metal can act as a catalyst to accelerate the decomposition of persulfate into sulfate free radicals. The typical catalysts found in the literature include the ions of copper, silver, manganese, and iron [7].
Peroxymonosulfate provides powerful oxidation for a wide variety of industrial and consumer uses [8], Anisptaskis et al., recently studied the cobalt based activation of peroxymonosulfate for degradation of chlorophenols. Co-PMS system was found to be superior than Fenton reagent and showed no pH limitaion for degradation of 2,4-DCP and atrazine [2].
In this study, we investigated the degradation of 2-chlorobiphenyl (PCB) and naphthlene (PAH) using sulfate radical-based oxidation technologies. Generation of sulfate radical was achieved by coupling of the transition metal with peroxymonosulfate and persulfate. Iron (Fe(II), Fe(III)) was selected as the transition metal in this study, because of its environmental friendly nature and cost effectiveness.