Degradation of tetrabromobisphenol A by ferrate(VI)-CaSO3 process: Kinetics, products, and impacts on following disinfection by-products formation

Reactive High-Valent Iron Intermediates in Enhancing Treatment of Water by Ferrate

“…In the last two decades, researchers have examined the oxidation properties of Fe VI O 4 2– with pollutants such as cyanides, sulfides, thiols, phenols, anilines, pharmaceuticals, endocrine disrupting compounds, and other toxins. ,,− ,,,,− The Hammett relationships were also derived to gain insight into the factors that govern the kinetics of the reactions between Fe VI O 4 2– and pollutants. ,, Transformation products of organic pollutants suggested preferential attacks of Fe VI O 4 2– toward the reduced sulfur (−II) moiety of the molecule with stepwise oxidation to sulfenyl, sulfinic, sulfonic acids, and eventually sulfate. Reactions of phenolic compounds with Fe VI O 4 2– indicated hydroxylation and coupling reactions. ,− ,,,,− Detailed mechanisms have been previously reviewed . In the reaction with the cyanotoxin microcystin-LR (MC-LR), Fe VI O 4 2– carried out hydroxylation of the aromatic ring, the diene, and the double bond of the methyldehydroalanine (Mdha) amino acid residue, followed by the fragmentation of the cyclic MC-LR structure .…”

“…Studies on ferrates using Mossbauer spectroscopy are largely limited to solid state chemistry. 151,184−189 Incorporation of 57 Fe into solid K 2 FeO 4 samples has been applied to minimize the required iron content for Mossbauer measurements. 184,190,191 Investigations on ferrates in solution require rapid freezing of the liquid to obtain solid samples prior to performing Mossbauer spectroscopy measurements (i.e., frozen solution).…”

“…Investigations Using Model Compounds. The role of Fe IV /Fe V intermediates on the Fe VI O 4 2− -reductant (R)pollutant (X) system was explored by oxidizing phenyl methyl 57 Fe Mossbauer spectrum of Fe(VI) + (EtOH 140 mL + CH 3 COOH 10 mL). (B) 57 Fe Mossbauer spectrum of the solution frozen after 1−2 s of the Fe V transformation in ethanol.…”

“…The role of Fe IV /Fe V intermediates on the Fe VI O 4 2− -reductant (R)pollutant (X) system was explored by oxidizing phenyl methyl 57 Fe Mossbauer spectrum of Fe(VI) + (EtOH 140 mL + CH 3 COOH 10 mL). (B) 57 Fe Mossbauer spectrum of the solution frozen after 1−2 s of the Fe V transformation in ethanol. (C) 57 sulfoxide (PMSO) or dimethyl sulfoxide (DMSO) as a model compound, which could be oxidized to form phenyl methyl sulfone (PMSO 2 ) or dimethyl sulfone (DMSO 2 ) 59,166 through the OAT process.…”

“…Fe VI O 4 2– has been reported to oxidize a wide range of concerning pollutants. ,,− Although successful applications of Fe VI O 4 2– have been demonstrated, progress toward understanding the oxidation mechanisms has been made only in the past few years. ,,,,− Studies have been conducted to distinguish the one-electron and two-electron (or oxygen-atom) transfer steps of the oxidative reactions of Fe VI O 4 2– using the redox potentials of the pollutants. − This initial understanding revealed that the oxidation capacity of Fe VI O 4 2– (i.e., moles of electron equivalent per mole of oxidant) depends on the involvement of intermediate iron species, Fe V and Fe IV , in the reactions. In other words, the involvement of such high-valent species increases the oxidation capacity of Fe VI O 4 2– .…”