Photodegradation of 4-chlorophenoxyacetic acid under visible LED activated N-doped TiO2and the mechanism of stepwise rate increment of the reused catalyst

Amal Abdelhaleem, Wei Chu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

52 Citations (Scopus)


Photodegradation of 4-chlorophenoxyacetic acid (4-CPA) was systematically investigated using N-doped TiO2(N-TiO2) under commercially available visible light emitting diode (Vis LED) as a novel Vis LED illumination in photocatalysis applications. The synergetic effect of Vis LED/N-TiO2process was studied in detail by varying reaction conditions including the initial concentration of 4-CPA, catalyst dosage, light intensity, and initial pH. Additionally, the influence of inorganic anions and radical scavengers on the performance of the Vis LED/N-TiO2process was also evaluated. The Vis LED/N-TiO2was found to be a promising process in terms of mineralization of 4-CPA. It is interesting to note that the performance of this process was not reduced after successive usage of the recycled catalyst; instead, the reaction rate of 4-CPA decay actually increased by using the spent catalyst. The mechanism behind rate enhancement after/during reuse was explored by XPS and FT-IR analyses and it was proven that hydroxyl groups can be incorporated into the catalyst surface by the repeated wetting of N-TiO2after each reuse. This facilitates the formation of hydrogen bonds between the 4-CPA molecules and N-TiO2, thereby allowing more collisions between the trapped 4-CPA and radicals at the interface of bulk solution and catalyst, respectively.
Original languageEnglish
Pages (from-to)491-501
Number of pages11
JournalJournal of Hazardous Materials
Publication statusPublished - 1 Jan 2017


  • Commercial visible LED
  • Herbicides
  • Hydrogen bonding
  • N-doped TiO 2
  • Photodegradation

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

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