Kinetics of the Oxidation of Phenols and Phenolic Endocrine Disruptors during Water Treatment with Ferrate (Fe(VI))
2005-11-15T00:00:00Z (GMT) by
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 (<i>k</i><sub>app</sub>) 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) (<i>k</i><sub>app</sub> at pH 7 ranged from 6.4 × 10<sup>2</sup> to 7.7 × 10<sup>2</sup> M<sup>-1</sup> s<sup>-1</sup>). The <i>k</i><sub>app</sub> for the substituted phenols studied at pH 7 ranged from 6.6 to 3.6 × 10<sup>3</sup> M<sup>-1</sup> s<sup>-1</sup>, 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 HFeO<sub>4</sub><sup>-</sup> and the undissociated (log(<i>k</i>) = 2.24−2.27σ<sup>+</sup>) and dissociated phenol (log(<i>k</i>) = 4.33−3.60σ<sup>+</sup>). A comparison of the Hammett correlation obtained for the reaction between HFeO<sub>4</sub><sup>-</sup> and dissociated phenol with those obtained from other drinking water oxidants revealed that HFeO<sub>4</sub><sup>-</sup> 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.