Synthesis by sol–gel of WO3/TiO2 for solar photocatalytic degradation of malathion pesticide

In this study, TiO2 modified with WO3 (2 wt.%) was prepared by the sol–gel method, and its photocatalytic activity (PCA) under solar irradiation was evaluated using malathion as the model contaminant. The catalyst was synthesized using tetra butyl orthotitanate (TBT) and ammonium p-tungstate (ApT) as precursors. For comparison, bare TiO2 was also prepared by the sol–gel process. The resulting photocatalysts were characterized by XRD, BET, DRUV–vis, FE-SEM, TEM and STEM. The synthesized TiO2 materials exhibited a crystalline anatase phase with an average particle size of 20 nm. Results of malathion degradation using solar light, indicated that 2%WO3/TiO2 showed better catalytic performance than sol–gel TiO2, achieving a complete degradation after 2 h, while TOC abatement was 63% after 5 h. These results suggest that 2%WO3/TiO2 catalyst is a promising material for solar photocatalytic treatment of water contaminated by pesticides.

Graphical abstractSTEM-HAADF image of 2%WO3/TiO2 catalyst, the small lightest zones represents WO3 clusters.Figure optionsDownload full-size imageDownload high-quality image (78 K)Download as PowerPoint slideHighlights► To evaluate the WO3/TiO2 photocatalytic activity, this is one of the first studies that were carried out using solar energy for degradation of an organophosphorous pesticide. ► The sol–gel technique for the 2%WO3/TiO2 synthesis, allowed the incorporation of WO3 clusters on anatase TiO2 surface, with a good homogeneity in spatial and size distribution. ► The morphological and electronic properties obtained in the coupled WO3/TiO2 catalyst give as a result better performance of the composite than bare TiO2 for malathion degradation under solar light radiation.