VIS-light-induced photocatalytic degradation of methylene blue (MB) dye using PoPD/TiO₂ composite photocatalysts

Abstract

In this study, the photocatalytic degradation of methylene blue (MB) was studied experimentally over poly-o-phenylenediamine/TiO₂ composite (PoPD/TiO₂) photocatalysts irradiated with a light source simulating solar light. The effect of operational parameters, i.e. pH of the solution, photocatalyst content, irradiation time, initial MB concentration, and temperature, on the photocatalytic degradation efficiency was explored and the results obtained were fitted with Langmuir-Hinshelwood model to investigate the degradation kinetics and discussed in detail. Results show that the PoPD/TiO₂ composites exhibit significantly higher photocatalytic activity than that of pure TiO₂ on the degradation of MB aqueous solution under visible light irradiation. The enhanced photocatalytic activity of PoPD-sensitized TiO₂ composite catalysts can be attributed to the charge transfer from PoPD to TiO₂ and efficient separation of e⁻–h⁺ pairs on the interface of PoPD and TiO₂. The repeatability of photocatalytic activity was also tested. A plausible mechanism was proposed and discussed on the basis of experimental results.

Keywords:

• Photocatalysis
• Poly-o-phenylenediamine
• Titanium dioxide
• Methylene blue
• Wastewater treatment

Acknowledgements

We gratefully acknowledge the financial support provided by the National Natural Science Foundation of China (Grant No. 20977013). Partial support by the Fundamental Research Funds for the Central Universities (DUT10LK26) is also acknowledged.