Photocatalytic Degradation of Rhodamine B and Methylene Orange Using TiO2-ZrO2 as Nanocomposite

Abstract

The present research reports the synthesis of ZrO2-doped TiO2 photocatalysts at different ZrO2 contents (1, 3 and 5% wt.) synthesized by the sol–gel method. The samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction, attenuated total reflectance-Fourier transform infrared, ultraviolet–visible, X-ray photoelectron spectroscopy and N2 adsorption–desorption analysis. The photocatalytic activity of the ZrO2-doped TiO2 was investigated against the dyes methyl orange and rhodamine B through mineralization studies. The ZrO2-doped TiO2 samples presented a semiglobular-ovoid agglomerate shape around 500–800 nm. The samples presented high crystallinity of the TiO2 anatase phase, XPS suggested the formation of Zr–O–Ti bonds and the samples were classified as mesoporous materials with slight changes in the optical features in comparison with pure TiO2. Our study shows that the ZrO2-doped TiO2 composites exhibited a higher photocatalytic activity than just utilizing the synthetized TiO2 and a commercial P25. The different degradation behaviors are attributed to differences in the textural properties, and to the different optical absorptions of the samples due to structural defects created by the level of doping of Zr4+ ions into the TiO2 lattice. Reaction kinetics parameters were calculated by the Langmuir–Hinshelwood model, and a third run cycle of the ZrO2-doped TiO2 at 1% wt. achieved a photocatalytic degradation of 78.1 and 75.5% for RhB and MO, respectively.