Assessment of nitrogen-fluorine-codoped TiO2 under visible light for degradation of BPA: Implication for field remediation

Synthesized nitrogen-fluorine-codoped-TiO2 (N-F-TiO2) nanoparticles, in comparison to commercial Sigma TiO2, were used to investigate the photocatalytic degradation of bisphenol A (BPA) as a model pollutant in aqueous solutions responding to visible light. The photocatalytic activities were first evaluated by studying the degradation of BPA under simulated sunlight (SSL) and visible light (VL). The light absorption of N-F-TiO2, in relation to the undoped TiO2, shifted to the visible light region. The visible-light-driven-degradation of BPA with N-F-TiO2 was much higher (61.2%) after 4h of irradiation than that with Sigma TiO2 (19.2%), (p < 0.01). Moreover, the role of reactive oxygen species (ROS) was also investigated. Superoxide (O-2(center dot-)) was recognized to be the major ROS in degrading BPA under visible light. The correlation between visible-light-driven photocatalytic degradation and the physicochemical properties of N-F-TiO2 is discussed as well. In this study, enhanced catalytic activity under visible light was found to be strongly dependent on surface-area-to-volume-ratio, visible light absorption, and superoxide formation, induced by N- and F-doping. In addition, the potential field application of N-F-TiO2 was investigated with river water. The results highly demonstrated the use of N-F-TiO2 in environmental remediation as a green and sustainable alternative technology. (C) 2015 Elsevier B.V. All rights reserved.