Fotoatividade de óxidos mistos Nb2O5/TiO2 aplicados na degradação do herbicida ácido 2,4-diclorofenoxiacético

Abstract

In the present work, syntheses of niobium, titanium and mixed oxides (Nb2O5/TiO2) were carried out by two chemical mixture methodologies: modified sol­gel and modified Pechini. The photocatalysts were characterized by techniques such as: thermogravimetric analysis (TGA), X­ray diffraction (XRD), scanning electron microscopy (SEM), energy diffusive spectroscopy (EDS) and zero charge point (PCZ). The semiconductors were applied for the degradation of the herbicide 2,4­dichlorophenoxyacetic acid, by photocatalytic process, guided by the experimental design of central compound varying the parameters: pH, calcination temperature and catalyst concentration. Results such as those presented by photolysis with 88% degradation of the pollutant, Nb2O5 and TiO2 as values above 98% removal, as well as mixed oxides in molar ratios (Nb2O5: TiO2 = 25:75, 50:50 and 75:25), under reaction conditions of pH 3.0 and catalyst concentration 0.5 g L­1, proved to be significant for the removal of 2,4­D.