Reaction pathways and mechanisms of the electrochemical degradation of phenol on different electrodes

Xiao Yan Li*, Yu Hong Cui, Yu Jie Feng, Zhao Ming Xie, Ji Dong Gu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

498 Scopus citations

Abstract

Laboratory experiments were carried out on the kinetics and pathways of the electrochemical (EC) degradation of phenol at three different types of anodes, Ti/SnO2-Sb, Ti/RuO2, and Pt. Although phenol was oxidised by all of the anodes at a current density of 20 mA/cm2 or a cell voltage of 4.6 V, there was a considerable difference between the three anode types in the effectiveness and performance of EC organic degradation. Phenol was readily mineralized at the Ti/SnO2-Sb anode, but its degradation was much slower at the Ti/RuO2 and Pt anodes. The analytical results of high-performance liquid chromatography (HPLC) and gas chromatography coupled with mass spectrometry (GC/MS) indicated that the intermediate products of EC phenol degradation, including benzoquinone and organic acids, were subsequently oxidised rapidly by the Ti/SnO2-Sb anode, but accumulated in the cells of Ti/RuO2 and Pt. There was also a formation of dark-coloured polymeric compounds and precipitates in the solutions electrolyzed by the Ti/RuO2 and Pt anodes, which was not observed for the Ti/SnO 2-Sb cells. It is argued that anodic property not only affects the reaction kinetics of various steps of EC organic oxidation, but also alters the pathway of phenol electrolysis. Favourable surface treatment, such as the SnO2-Sb coating, provides the anode with an apparent catalytic function for rapid organic oxidation that is probably brought about by hydroxyl radicals generated from anodic water electrolysis.

Original languageEnglish
Pages (from-to)1972-1981
Number of pages10
JournalWater Research
Volume39
Issue number10
DOIs
StatePublished - May 2005
Externally publishedYes

Keywords

  • Anode
  • Electro-oxidation
  • Electrochemistry
  • Free radicals
  • Phenol
  • Wastewater treatment

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