Three Kinetic Patterns for the Oxidation of Emerging Organic Contaminants by Fe(VI): The Critical Roles of Fe(V) and Fe(IV)

Shuchang Wang, Yang Deng, Binbin Shao, Jiahui Zhu, Zixin Hu, Xiaohong Guan

Research output: Contribution to journalArticlepeer-review

Abstract

For the first time, this study showed that the apparent second-order rate constants (kapp) of six selected emerging organic contaminants (EOCs) oxidation by Fe(VI) increased, remained constant, or declined with time, depending on [EOC]0/[Fe(VI)]0, pH, and EOCs species. Employing excess caffeine as the quenching reagent for Fe(V) and Fe(IV), it was found that Fe(V)/Fe(IV) contributed to 20-30% of phenol and bisphenol F degradation by Fe(VI), and the contributions of Fe(V)/Fe(IV) remained nearly constant with time under all the tested conditions. However, the contributions of Fe(V)/Fe(IV) accounted for over 50% during the oxidation of sulfamethoxazole, bisphenol S, and iohexol by Fe(VI), and the variation trends of kapp of their degradation by Fe(VI) with time displayed three different patterns, which coincided with those of the contributions of Fe(V)/Fe(IV) to their decomposition with time. Results of the quenching experiments were validated by simulating the oxidation kinetic data of methyl phenyl sulfoxide by Fe(VI), which revealed that the variation trends of kapp with time were significantly determined by the change in the molar ratio of Fe(V) to Fe(VI) with time, highlighting the key role of Fe(V) in the oxidative process. This study provides comprehensive and insightful information on the roles of Fe(V)/Fe(IV) during EOC oxidation by Fe(VI).

Original languageEnglish
Pages (from-to)11338-11347
Number of pages10
JournalEnvironmental Science and Technology
Volume55
Issue number16
DOIs
StatePublished - 17 Aug 2021

Keywords

  • auto-accelerating trend
  • auto-decelerating trend
  • ferrates
  • linear trend
  • oxidation kinetics

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