Comparative removal of imidacloprid, bisphenol‐S and azithromycin with ferrate and FeCl3 and assessment of the resulting toxicity

Shaoqing Zhang, Jia-Qian Jiang*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

BACKGROUND
Emerging micro‐pollutants (EMPs) in water have received high attention due to their potential hazards onto human health and ecological security. Ferrate has been researched in recent years to remove both particulate and dissolved impurities (including EMPs) from water and its promising performance has been attributed to the high oxidation capacity and coagulation functions. However, limited researches have compared ferrate with coagulation alone in the treatment of EMPs, and this is one of major objectives of this study.

RESULTS
Three EMPs, imidacloprid (IMP), bisphenol‐S (BS) and azithromycin (AZM) were chosen for this study. In all cases ferrate outperformed to ferric chloride for the removal of the EMPs. For a given ferrate dose of 0.05 mM, 99% of BS, 85% of AZM and 78% of IMP were removed for start concentration of 10 μg L−1. However, if start concentration was 1000 μg L−1, removal efficiency was decreased to 82% for BS, 62% for AZM and 22% for IMP. pH 5 was favorable to the EMPs removal by ferrate for the study conditions. Although higher removals of IMP, BS and AZM were achieved by ferrate in comparison to that by ferric chloride, only 20% DOC removal was achieved by the ferrate. The formation of various oxidation products in the degradation process resulted in the disparity of the solution toxicity; that of BS was reduced but that of IMP and AZM increased after ferrate treatment. Nevertheless, toxicity of ferric chloride treated samples was all increased.

CONCLUSION
Ferrate has higher efficiency comparing with FeCl3 to remove IMP, BS and AZM. Degradation of the EMPs by ferrate was more efficient in acidic condition (pH 5) and at the EMPs’ lower initial concentrations for the given conditions. IMP was more resistant to the ferrate treatment comparing with BS and AZM under the same conditions. Overall, 20% DOC reduction was achieved by ferrate for pH 5. Finally, the toxicity of BS can be reduced but that of IMP and AZM was increased after ferrate treatment, whilst the toxicity of ferric chloride treated samples was all increased.
Original languageEnglish
JournalJournal of Chemical Technology and Biotechnology
Early online date21 Jun 2020
DOIs
Publication statusE-pub ahead of print - 21 Jun 2020

Keywords

  • degradation
  • emerging micro-pollutants
  • ferrate
  • ferric chloride
  • oxidation
  • toxicity assessment
  • water treatment

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