Surface hydroxyl groups of synthetic α-FeOOH in promoting {radical dot}OH generation from aqueous ozone: Property and activity relationship

Tao Zhang, Chunjuan Li, Jun Ma*, Hai Tian, Zhimin Qiang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

247 Scopus citations

Abstract

This work investigated the relationship between the property of the surface hydroxyl groups of hydroxylated synthetic α-FeOOH and their catalytic activity in promoting hydroxyl radical ({radical dot}OH) generation from aqueous ozone. Nitrobenzene was used as an ozone-resistant probe to quantify {radical dot}OH generation. ATR-FTIR analysis reveals that sulfate and phosphate suppressed the catalytic activity of α-FeOOH through substituting its surface hydroxyl groups, which implies that the catalyst surface hydroxyl groups were active sites for promoting {radical dot}OH generation. Compared with other synthetic oxo-hydroxides such as β-FeOOH, γ-FeOOH and γ-AlOOH, α-FeOOH achieved a highest Rc value (i.e., 1.11 × 10-7, molar concentration ratio of {radical dot}OH to O3) in catalytic ozonation. No correlation could be established between the surface hydroxyl density and the {radical dot}OH-promoting activity of the oxo-hydroxides. In contrast, their catalytic activity was found to be reversely related to the IR stretching frequencies of surface hydroxyl groups. The results indicate that not all surface hydroxyl groups of the oxo-hydroxides possessed the same high catalytic activity, but the weak surface MeO-H bonds were favorable sites for promoting {radical dot}OH generation from aqueous ozone. The surface hydroxyl-ozone interaction was thus proposed for the catalyzed {radical dot}OH generation, which can explain why neutral surface hydroxyl species of α-FeOOH was more active than protonated or deprotonated species.

Original languageEnglish (US)
Pages (from-to)131-137
Number of pages7
JournalApplied Catalysis B: Environmental
Volume82
Issue number1-2
DOIs
StatePublished - Jul 16 2008

Keywords

  • ATR-FTIR
  • Catalytic ozonation
  • Hydroxyl radical generation
  • Oxo-hydroxide
  • Surface hydroxyl group
  • Synthetic α-FeOOH

ASJC Scopus subject areas

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

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