The simultaneous removal of heavy metals and organic contaminants over a Bi2WO6/mesoporous TiO2 nanotube composite photocatalyst

In this study, Bi2WO6/mesoporous TiO2 nanotube composites (BWO/TNTs) were successfully synthesized to remove the heavy metal Cr(VI) and refractory organic compound dibutyl phthalate (DBP) from contaminated water under visible light. Coupling TNTs with BWO can greatly improve the photocatalytic activity of the catalyst for treating Cr(VI)–DBP mixed pollutants because of synergetic effects from Cr(VI) and DBP. Specifically, the visible-light photocatalytic activities of 3% BWO/TNTs for removing DBP and Cr(VI) from mixed pollutant solutions were 10.8 and 3.8 times higher than those of BWO. Firstly, this system can take full advantage of charge carriers and can spatially separate reduction sites and oxidation sites in the photocatalyst. Secondly, TNTs has a unique multiscale channel structure that can enhance mass transfer and light utilization. These characteristics lead to very obvious photocatalytic activity improvements. In addition, the BWO/TNTs composite photocatalysts exhibited excellent stability and durability under visible and UV light irradiation. This work demonstrated a feasible method for fabricating composite photocatalysts and applied them to the simultaneous removal of heavy metal and refractory organic pollutants from contaminated water.