Photocatalytic behaviour of WO3/TiO2-N for diclofenac degradation using simulated solar radiation as an activation source
2017
Cordero-García, A. | Turnes Palomino, G. | Hinojosa-Reyes, L. | Guzmán-Mar, J. L. | Maya-Teviño, L. | Hernández-Ramírez, A.
In this study, the photocatalytic removal of an emerging contaminant, diclofenac (DCF) sodium, was performed using the nitrogen-doped WO₃/TiO₂-coupled oxide catalyst (WO₃/TiO₂-N). The catalyst synthesis was accomplished by a sol–gel method using tetrabutyl orthotitanate (C₁₆H₃₆O₄Ti), ammonium p-tungstate [(NH₄)₁₀H₂W₁₂O₄₂·4H₂O] and ammonium nitrate (NH₄NO₃) as the nitrogen source. For comparison, TiO₂ and WO₃/TiO₂ were also prepared under similar conditions. Analysis by X-ray diffraction (XRD), N₂ adsorption–desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV–Vis spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS) were conducted to characterize the synthesized materials. The photocatalytic efficiency of the semiconductors was determined in a batch reactor irradiated with simulated solar light. Residual and mineralized DCF were quantified by high-performance liquid chromatography, total organic carbon analysis and ion exchange chromatography. The results indicated that the tungsten atoms were dispersed on the surface of TiO₂ as WO₃. The partial substitution of oxygen by nitrogen atoms into the lattice of TiO₂ was an important factor to improve the photocatalytic efficiency of WO₃/TiO₂. Therefore, the best photocatalytic activity was obtained with the WO₃/TiO₂-N₀.₁₈ catalyst, reaching 100% DCF transformation at 250 kJ m⁻² and complete mineralization at 400 kJ m⁻² of solar-accumulated energy.
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