Quantification of perfluorooctanoic acid decomposition mechanism applying negative voltage to anode during photoelectrochemical process

Yongyue Zhou, Yonghyeon Lee, Yangmin Ren, Mingcan Cui, Jeehyeong Khim

Research output: Contribution to journalArticlepeer-review

Abstract

Perfluorooctanoic acid (PFOA) is a carcinogen with a high binding energy between fluorine and carbon and is symmetrically linked, making it difficult to treat. In this study, a self-doped TiO2 nanotube array (TNTA) was used as the anode and platinum as the cathode to quantify the PFOA removal mechanism using a photoelectrochemical (PEC) system. The external voltage was negative compared to that of the anode. In addition, NO3 and t-BuOH were used as scavengers to quantify the PFOA oxidation/reduction mechanism in the PEC system. As a result of the study, TNTA crystals are TiO2 anatase, and the band gap energy was 3.42. The synergy index of PEC was 1.25, and the best electrolyte was SO42−. The PFOA decomposition activation energy corresponds to 70.84 kJ mol−1. Moreover, ΔH# and ΔS# correspond to 68.34 kJ mol−1 and 0.190 kJ mol−1 K−1, respectively. When the external negative voltage was 1 V, the contributions of the oxidation/reduction reaction during PFOA decomposition were 60% and 40%, and when the external negative voltage was 5 V, the contributions of the redox reaction were 45% and 55%. As the external negative voltage increased, the contribution of the reduction reaction increased as the number of electrons applied to the anode increased. When PFOA was decomposed, the by-products were C7F13O2H, C6F11O2H, C5F9O2H, and C4F7O2H, respectively. This study is expected to be used as basic data for research on the effects of other factors on the oxidation/reduction as well as the selection of anode and cathode materials on the decomposition of pollutants other than PFOA when using a PEC system.

Original languageEnglish
Article number131311
JournalChemosphere
Volume284
DOIs
Publication statusPublished - 2021 Dec

Keywords

  • Applying negative voltage to anode
  • Mechanism
  • Pathway
  • Photoelectrochemical
  • Scavenger
  • TiO nanotube arrays anode

ASJC Scopus subject areas

  • Environmental Engineering
  • Chemistry(all)
  • Environmental Chemistry
  • Pollution
  • Public Health, Environmental and Occupational Health
  • Health, Toxicology and Mutagenesis

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