title: Solar photocatalytic activity of TiO2 modified with WO3 on the degradation of an organophosphorus pesticide.
abstract: In this study, the solar photocatalytic activity (SPA) of WO3/TiO2 photocatalysts synthesized by the sol-gel method with two different percentages of WO3 (2 and 5%wt) was evaluated using malathion as a model contaminant. For comparative purpose bare TiO2 was also prepared by sol-gel process. The powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectance UV-vis spectroscopy (DRUV-vis), specific surface area by the BET method (SSABET), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy with a high annular angle dark field detector (STEM-HAADF). The XRD, Raman, HRTEM and STEM-HAADF analyses indicated that WO3 was present as a monoclinic crystalline phase with nanometric cluster sizes (1.1 ± 0.1 nm for 2% WO3/TiO2 and 1.35 ± 0.3 nm for 5% WO3/TiO2) and uniformly dispersed on the surface of TiO2. The particle size of the materials was 19.4 ± 3.3 nm and 25.6 ± 3 nm for 2% and 5% WO3/TiO2, respectively. The SPA was evaluated on the degradation of commercial malathion pesticide using natural solar light. The 2% WO3/TiO2 photocatalyst exhibited the best photocatalytic activity achieving 76% of total organic carbon (TOC) abatement after 300 min compared to the 5% WO3/TiO2 and bare TiO2 photocatalysts, which achieved 28 and 47% mineralization, respectively. Finally, experiments were performed to assess 2% WO3/TiO2 catalyst activity on repeated uses; after several successive cycles its photocatalytic activity was retained showing long-term stability.
authors.affiliation: Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, San Nicolás de los Garza, N.L., Mexico(1).
authors.forename: N A
authors.initials: NA
authors.lastname: Ramos-Delgado
authors.forename: M A
authors.initials: MA
authors.lastname: Gracia-Pinilla
authors.forename: L
authors.initials: L
authors.lastname: Maya-Treviño
authors.forename: L
authors.initials: L
authors.lastname: Hinojosa-Reyes
authors.forename: J L
authors.initials: JL
authors.lastname: Guzman-Mar
authors.forename: A
authors.initials: A
authors.lastname: Hernández-Ramírez
mesh_terms: D002384:Catalysis; D008294:Malathion / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry / Q000528:radiation effects*; D010575:Pesticides / Q000737:chemistry*; D010782:Photolysis; D013472:Sunlight; D014025:Titanium / Q000737:chemistry / Q000528:radiation effects*; D014414:Tungsten / Q000737:chemistry / Q000528:radiation effects*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D010087:Oxides; D010575:Pesticides; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; C511604:tungsten oxide; D014025:Titanium; D008294:Malathion; D014414:Tungsten
keywords: Long-term stability; Photocatalytic activity; WO(3)–TiO(2)