High anatase purity of nitrogen-doped TiO2 nanorice particles for the photocatalytic treatment activity of pharmaceutical wastewater

Abstract

The titanium dioxide photocatalysts modified with nitrogen (N–TiO2) were synthesized via hydrothermal method by using urea (NH2CONH2) as a nitrogen source with various concentrations of dopant. The characterizations of cooperated N–TiO2 were examined by many techniques. The performance of the synthesized N–TiO2 catalysts was evaluated by using the decomposition of ciprofloxacin under UV light irradiation. Additionally, the OH radical production was also estimated. The results revealed that the influence of different concentrations of nitrogen dopant was significant on the physicochemical and structural properties. The surface morphology exhibited the nanorice grain particles in all samples. The trend of particles size and pore diameter decreased, whereas BET surface area slightly increased with increasing of nitrogen contents. The WAXS profiles demonstrated that the photocatalysts displayed the high purity of the anatase crystalline phase and delayed the phase transformation from anatase to rutile. The bandgap energies showed lower than pure anatase crystalline phase. The types of Ti–N–O (substitutional N) and/or Ti–O–N (interstitial N) bonding were formed into TiO2 lattice investigated by XPS technique. The photodegradation of ciprofloxacin increased with increasing of nitrogen contents. The N–TiO2 catalysts can generate OH radical and in-situ OH radical thought the direct photocatalytic degradation of coumarin and ciprofloxacin, respectively. Since, increasing of nitrogen content can increasingly produce OH radical to more react with organic pollutants. The de-mineralization by using the highest nitrogen content sample showed approximately 66% removal at 4 h of reaction time.