Modification and characterization of microwave assisted N doped TiO2 – a photodegradation study under suspension and immobilized system

Abstract

A commercially available TiO 2 (P25) was modified to produce nitrogen (N) doped TiO 2 prepared by mixing TiO 2 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 TiO 2 produces Ti-N. The measured band gap energy ( E g ) of the modified sample was ca . 2.9 eV as detected by UV-Vis/DRS. The optimum modified N doped TiO 2 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 whereas this previously could not 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 TiO 2 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 the 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.