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

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 mu g 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.

Automated summary

The study found that both ozone and ferrate can achieve over 99% reduction in BS concentration and up to 22.5% reduction in DOC when dosed at 0.036 mM. Vibrio fisheri toxicity decreased after ozonation or ferrate oxidation, and mass spectra analysis revealed proposed degradation pathways and identified oxidation products (OPs). The research showed that ferrate treatment is comparable to ozonation in removing BS, and further studies are needed to explore BS removal in different water compositions and to establish more comprehensive operational databases for ferrate oxidation and/or ozonation.