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COLBALT-MEDIATED ACTIVATION OF PEROXYMONOSULFATE AND SULFATE RADICAL ATTACK ON PHENOLIC COMPOUNDS, IMPLICATIONS OF CHLORIDE IONS
Citation:
ANIPSITAKIS, G. P., D. D. DIONYSIOU, AND M. GONZALEZ. COLBALT-MEDIATED ACTIVATION OF PEROXYMONOSULFATE AND SULFATE RADICAL ATTACK ON PHENOLIC COMPOUNDS, IMPLICATIONS OF CHLORIDE IONS. J. Schnoor (ed.), ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 40(3):1000-1007, (2006).
Description:
This study reports on the sulfate radical pathway of room temperature degradation of two phenolic compounds in water. The radicals were produced by the cobalt-mediated decomposition of peroxymonosulfate (Oxone) in an aqueous homogeneous system. The major intermediates formed from the transformation of 2,4-dichlorophenol (2,4-DCP) were 2,4,6-trichlorophenol, 2,3,5,6-tetrachloro-1,4-benzenediol, 1,1,3,3-tetrachloroacetone, pentachloroacetone and carbon tetrachloride. Those resulting from the transformation of phenol with the presence of chloride in solution were 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol, 1,1,3,3-tetrachloroacetone and pentachloroacetone. In the absence of chloride, phenol transformed into 2,4-cyclohexadiene-1,4-dione (quinone), 1,2-benzenedion (catechol) and 1,4-benzenediol (hydroquinone). Several parameters were varied and their impact on the transformation of the organics is also discussed. The parameters varied and their impact on the transformation of the organics is also discussed. The parameters varied were the initial concentration of the organic-substrate, the dose of Oxone used, the cobalt counteranion and in particular the impact of chloride ions and the quenching agent utilized for terminating the reaction. This is one of the very few studies dealing with intermediates formed via sulfate radical attack (SRA) on phenolic compounds. It is also the first study that explores the sulfate radical mechanism of oxidation, when sulfate radicals are generated via the Co/Oxone reagent. Furthermore, it provides strong evidence on the interaction of chloride ions with sulfate radicals leading to halogenation of organics in water.