Electrochemical oxidation of organics in sulfate solutions on boron-doped diamond electrode: Multiple pathways for sulfate radical generation

Yong Uk Shin, Ha Young Yoo, Yong Yoon Ahn, Min Sik Kim, Kang Lee, Seungho Yu, Changha Lee, Kangwoo Cho, Hyoung il Kim, Jaesang Lee

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

This study scrutinized the roles of sulfate radicals (SO 4 [rad] ) and peroxydisulfate (PDS) formed from SO 4 2− in electrochemical organic oxidation on a boron-doped diamond (BDD) electrode. The substrate-specific performance of electrochemical oxidation using SO 4 2− as the electrolyte aligned with the reactivity of SO 4 [rad] produced via radiolysis- or heat-induced PDS activation, but was distinct from the non-selective oxidation efficiency observed in an aqueous ClO 4 solution. A comparison of the treatment efficiencies using different electrolytes (i.e., Cl , SO 4 2− , and ClO 4 ) showed no pronounced enhancing effect of SO 4 [rad] on the anodic oxidation of diverse organics (except perfluorooctanoate), which implied that direct electron transfer and hydroxyl radical-induced oxidation proceeded as complementary reaction routes. Repeated electrolytic oxidation caused substantial electrolyte exchange from Cl to ClO 4 , which retarded organic oxidation accompanied by ClO 4 accumulation. Conversely, high-yield PDS production observed when SO 4 2− was used instead barely reduced treatment efficiency. Together with SO 4 [rad] detection in the electron paramagnetic resonance spectrum, a correlation between 4-chlorophenol oxidation rate and the faradaic efficiency for SO 4 2− formation, monitored in PDS solutions while varying the cathode material, suggested cathodic PDS activation. The electrocatalytic performance was demonstrated to be further improved with anodically formed PDS activation through naturally occurring resistive heating or combination with UV photolysis as a post-treatment step.

Original languageEnglish
Pages (from-to)156-165
Number of pages10
JournalApplied Catalysis B: Environmental
Volume254
DOIs
Publication statusPublished - 2019 Oct 5

Keywords

  • Anodic oxidation
  • Boron-doped diamond electrode
  • Persulfate activation
  • Resistive heating
  • Sulfate radical

ASJC Scopus subject areas

  • Catalysis
  • Environmental Science(all)
  • Process Chemistry and Technology

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