A commercially available TiO2 (P25) was modified to produce nitrogen (N) doped TiO2 prepared by mixing TiO2 powder with various amounts of urea as N precursor using a microwave irradiation heating technique. X-ray photoelectron spectroscopy analysis showed that N chemically bonded with TiO2 produces Ti-N. The measured band gap energy (Eg) of the modified sample was ca. 2.9 eV as detected by UV/Vis-DRS. The optimum modified N doped TiO2 denoted as U3-800 prepared at 230 °C showed an active visible light photoactivity. This observation shows that microwave irradiation is able to form Ti-N at low temperature where this previously cannot be achieved under conventional heating using a muffle furnace at the same temperature. U3-800 showed visible light active photodegradation for 30, 10 and 5 mg L−1 of reactive red 4, crystal violet and Janus green dyes, respectively, in less than 105 min to complete decolorization under suspension mode while no photocatalytic activity was observed under pristine TiO2 under the same conditions. Immobilization of a U3-800 sample was carried out using DSAT as a thin layer binder and the photoactivity of Immobilize/U3-800/DSAT is comparable with suspension mode. Surprisingly, immobilized/U3-800 has a strong coating with glass support material and can be continuously used for 30 cycles without affecting photoactivity performance.
- microwave irradiation
- titanium dioxide
- visible light
- First received 5 January 2016.
- Accepted in revised form 21 December 2016.
- © IWA Publishing 2017