کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5746099 | 1618785 | 2017 | 4 صفحه PDF | دانلود رایگان |
- PPCPs, dyes and phenol were almost decomposed in 30Â s in sulfite/FeVI process.
- Oxygen increases sulfite/FeVI performance slightly.
- Sulfite/FeVI is a chain reaction involving SO3â, SO5â, SO4â and ·OH.
- Sulfite/FeVI process is efficient under neutral and alkaline conditions.
With the addition of sulfite, almost complete removal of seven out of eight tested contaminants, i.e. benzotriazole, phenol, ciprofloxacin, methyl blue, rhodamine B, methyl orange and sulfamethoxazole, was observed in 30 s except for sulfamethoxazole at pH 9.0, while Fe(VI) alone only resulted in less than 6% removal. In this study, the mechanism of sulfite/Fe(VI) process was explored for the first time. Firstly, sulfite attacks Fe(VI) via a 1-eâ transfer forming the primary sulfite radical (SO3â), then SO3â reacts rapidly with oxygen in a diffusion controlled rate to form a much more reactive peroxyl radical SO5â, which further reacts with HSO3â and produces SO4â. All the signals of sulfite, sulfate and hydroxyl radicals were observed in the electron spin resonance (ESR) analysis. The DMPO and alcohol quenching experiments confirmed that sulfite/Fe(VI) process involves radicals as the plausible reactive species for decomposition of organic pollutants, and SO4·-/·OH instead of SO3â/SO5â are the major reactive oxygen species. Since oxygen participates in the formation of the secondary radicals, i.e. SO5â, SO4â and ·OH, the sulfite/Fe(VI) process open to air displayed better performance than that purged with nitrogen. Compared with previous sulfite/Cr(VI) and sulfite/Mn(VII) processes, which are only effective under acidic conditions, sulfite/Fe(VI) process provides an alternative under neutral and alkaline conditions. The extraordinarily fast oxidation of pollutants in sulfite/Fe(VI) process suggests that activation of sulfite by Fe(VI) might lead to a new class of advanced oxidation processes (AOPs) in water treatment.
Journal: Chemosphere - Volume 186, November 2017, Pages 576-579