VIS-light-induced photocatalytic degradation of methylene blue (MB) dye using PoPD/TiO_2 composite photocatalysts

摘要

In this study, the photocatalytic degradation of methylene blue (MB) was studied experimentally over poly-o-phenylenediamine/TiO_2 composite (PoPD/TiO_2) 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/TiO_2 composites exhibit significantly higher photocatalytic activity than that of pure TiO_2 on the degradation of MB aqueous solution under visible light irradiation. The enhanced photocatalytic activity of PoPD-sensitized TiO_2 composite catalysts can be attributed to the charge transfer from PoPD to TiO_2 and efficient separation of e~-h~+ pairs on the interface of PoPD and TiO_2. The repeatability of photocatalytic activity was also tested. A plausible mechanism was proposed and discussed on the basis of experimental results.