Photocatalytic degradation of rhodamine b and methylene orange using tio₂-zro₂ as nanocomposite

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.