Preliminarily comparative performance of removing bisphenol-S by ferrate oxidation and ozonation

Abstract

Bisphenol-S (BS) has recently raised public concerns for its adverse effect on the health safety and ecological security. BS concentrations were detected in many water resources, ranging from 10 ng L−1 to 300 μg L−1, so that various purification techniques have been sought to remove BS. This study investigated the performance of ozonation and ferrate oxidation in the degradation of BS since they are both promising oxidants with high redox potential among water treatment chemicals. It was observed that both ozone and ferrate can achieve over 99% of BS concentration reduction and up to 22.5% of DOC reduction for dosing 0.036 mM of either ferrate or ozone. The vibrio fisheri toxicity exhibited a decline in the treated samples after ozonation or ferrate oxidation. According to the mass spectra analyzed, the degradation pathways were proposed and oxidation products (OPs) were identified. BS degradation by ozonation and ferrate oxidation followed a similar route and four common OPs (OP-249; OP-497-a; OP-497-b, and OP-201) were detected. While ferrate treatment produced one more intermediate (OP-217), ozonation did not, which is attributed to the intensified decomposition of BS by ozonation. The major impact of this study is that ferrate treatment is comparable to the ozonation in removing BS, and further research continuing from this study is necessary to explore the BS removal in various waters with more complex matrixes (e.g., high natural organic matter contents), to investigate BS degradation mechanisms in depth, and to conduct pilot-scale and full-scale trials to establish operational database in running ferrate oxidation and/or ozonation for the treatment of BS in practical world.

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 .…”

“…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– .…”

Synergistic Effect of Ferrate with Various Water Processing Techniques—A Review

“…Instead of AOPs, ferrate is an innovative technology because of its similarly high redox potential compared to those popular AOPs. Ferrate is regarded as a promising degradation technique in water processing because of the dual functions of its properties, i.e., the oxidation and coagulation of various contaminants [5][6][7][8]. The study of ferrate as a water-cleaning reagent has received great interest, and a series of trials on ferrate treatment have been conducted.…”