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Kinetics of the Oxidation of Phenols and Phenolic Endocrine Disruptors during Water Treatment with Ferrate (Fe(VI))

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journal contribution
posted on 15.11.2005 by Yunho Lee, Jeyong Yoon, Urs von Gunten
The ability of ferrate (Fe(VI)) to oxidize phenolic endocrine-disrupting chemicals (EDCs) and phenols during water treatment was examined by determining the apparent second-order rate constants (kapp) for the reaction of Fe(VI) with selected environmentally relevant phenolic EDCs (17α-ethinylestradiol, β-estradiol, and bisphenol A) and 10 substituted phenols at pH values ranging from 6 to 11. The three selected groups of EDCs showed appreciable reactivity with Fe(VI) (kapp at pH 7 ranged from 6.4 × 102 to 7.7 × 102 M-1 s-1). The kapp for the substituted phenols studied at pH 7 ranged from 6.6 to 3.6 × 103 M-1 s-1, indicating that many other potential phenolic EDCs can be oxidized by Fe(VI) during water treatment. The Hammett-type correlations were determined for the reaction between HFeO4- and the undissociated (log(k) = 2.24−2.27σ+) and dissociated phenol (log(k) = 4.33−3.60σ+). A comparison of the Hammett correlation obtained for the reaction between HFeO4- and dissociated phenol with those obtained from other drinking water oxidants revealed that HFeO4- is a relatively mild oxidant of phenolic compounds. The effectiveness of Fe(VI) for the oxidative removal of phenolic EDCs was also confirmed in both natural water and wastewater.