Heterogeneous photocatalytic removal and reaction kinetics of Rhodamine-B dye with Au loaded TiO 2 nanohybrid catalysts

Abstract

Heterogeneous photocatalytic removal of Rhodamine-B (RhB) dye by metallic Au nanopatrticles deposited TiO 2 photocatalyst was studied. For this study, a chemical reduction method by hydrazine hydrate for gold deposition was employed in order to synthesize Au/TiO 2 nanocomposite system. For the characterization of the synthesized nanomaterials, X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), the Fourier transformation infrared spectroscopy (FTIR) and photoluminescence spectroscopy (PLS) techniques were performed. The obtained results show that the deposition of gold onto TiO 2 surface could effectively inhibit the recombination of the photoinduced electron and holes, improving the absorption capability for the visible light source and leading to the increased surface OH group density. The degradation experiment reveals that the efficiency of color removal from RhB aqueous solution containing Au/TiO 2 powders for the photocatalytic bleaching of RhB dye is more efficient than that of bare TiO 2 sample upon UV-vis light activation. In addition, degradation kinetics of RhB dye in aqueous suspensions can be well simulated by the Langmuir-Hinshelwood model and obeys the pseudo-first order law, with a decolorization rate of 0.0252 min -1 to the photocatalytic removal of RhB dye.