Identifying the Nonradical Mechanism in the Peroxymonosulfate Activation Process: Singlet Oxygenation Versus Mediated Electron Transfer

Eun Tae Yun, Jeong Hoon Lee, Jaesung Kim, Hee Deung Park, Jaesang Lee

Research output: Contribution to journalArticlepeer-review

848 Citations (Scopus)

Abstract

Select persulfate activation processes were demonstrated to initiate oxidation not reliant on sulfate radicals, although the underlying mechanism has yet to be identified. This study explored singlet oxygenation and mediated electron transfer as plausible nonradical mechanisms for organic degradation by carbon nanotube (CNT)-activated peroxymonosulfate (PMS). The degradation of furfuryl alcohol (FFA) as a singlet oxygen (1O2) indicator and the kinetic retardation of FFA oxidation in the presence of l-histidine and azide as 1O2 quenchers apparently supported a role of 1O2 in the CNT/PMS system. However, the 1O2 scavenging effect was ascribed to a rapid PMS depletion by l-histidine and azide. A comparison of CNT/PMS and photoexcited Rose Bengal (RB) excluded the possibility of singlet oxygenation during heterogeneous persulfate activation. In contrast to the case of excited RB, solvent exchange (H2O to D2O) did not enhance FFA degradation by CNT/PMS and the pH- and substrate-dependent reactivity of CNT/PMS did not reflect the selective nature of 1O2. Alternatively, concomitant PMS reduction and trichlorophenol oxidation were achieved when PMS and trichlorophenol were physically separated in two chambers using a conductive vertically aligned CNT membrane. This result suggested that CNT-mediated electron transfer from organics to persulfate was primarily responsible for the nonradical degradative route.

Original languageEnglish
Pages (from-to)7032-7042
Number of pages11
JournalEnvironmental Science and Technology
Volume52
Issue number12
DOIs
Publication statusPublished - 2018 Jun 19

Bibliographical note

Funding Information:
This study was supported by a National Research Foundation of Korea grant funded by the Korean Government (No. 2017R1A2B4002235) and a grant from the National Research Foundation of Korea funded by the Ministry of Science, ICT, and Future Planning (No. 2016M3A7B4909318).

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry

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