Enhanced photocatalytic degradation of phenazopyridine using rutile TiO2/clay composite: catalyst recovery and environmental implications

M. Kharouf, A. H. Zyoud, S. H. Zyoud, S. H. Zyoud, N. Qamhieh, A. Hajamohideen, H. S. Hilal

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


This study aims to improve the photocatalytic activity of TiO2 in removing organic contaminants from water. The practical use of TiO2 nanopowder is restricted due to issues related to catalyst recovery and reuse. The study investigates supporting TiO2 on natural clay (Kaolin) for phenazopyridine's photodegradation to address this issue. A series of experiments were carried out, looking at TiO2 supported on clay and unsupported TiO2 (both anatase and rutile phases), while also taking into account N-doping, annealing temperature, and pH values. The outcomes demonstrated that rutile TiO2/Clay (R-TiO2/Clay) exhibited the highest catalytic efficiency, capable of removing up to 90% of phenazopyridine within just 60 min under particular circumstances. It is interesting that the ideal pH for this process was discovered to be 8.7, or roughly equal to the natural surface water pH value which is ranged 6.5–8.5. The optimal photocatalyst annealing temperature was 500 °C, and the optimal photodegradation temperature was 35 °C. Furthermore, catalyst recovery and reuse tests indicated sustained efficiency over four cycles, highlighting its durability. High-performance liquid chromatography, total organic carbon, and elemental analysis validated phenazopyridine's complete breakdown and mineralization. This study emphasizes the significance of supporting TiO2 on clay to improve its photocatalytic activity and circumvent the drawbacks of its nanopowder form, in addition to the clay's synergistic effect due to the acceptable amount of ZnO present in the clay composition, which participates in the photodegradation of phenazopyridine. Due to its wide availability and thermal stability, this composite holds significant potential for water purification and environmental remediation.

Original languageEnglish
Pages (from-to)7491-7508
Number of pages18
JournalInternational Journal of Environmental Science and Technology
Issue number11
Publication statusPublished - Jul 2024


  • Kaolin
  • Natural clay
  • pH
  • Phenazopyridine
  • Photodegradation
  • TiO

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • General Agricultural and Biological Sciences


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