Photoreduction of Cr(VI) in water using Bi₂O₃- ZrO₂ nanocomposite under visible light irradiation

Chromium(VI) is a common heavy metal pollutant and extensively used in variety of industrial processes. In the present study, bismuth oxide-zirconium oxide nanocomposite (Bi₂O₃-ZrO₂) was synthesized to improve photoreduction of Cr(VI) under visible light irradiation. The synthesized photocatalyst was characterized by UV-visible-diffuse reflectance spectroscopy (UV-vis-DRS), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (B.E.T) surface area analysis and photoluminescence spectroscopy (PL). Bi₂O ₃-ZrO₂ was found to be more photoactive than Bi ₂O₃, ZrO₂, TiO₂ and ZnO for the reduction of Cr (VI). The influences of various reaction parameters like the effect of catalyst concentration, initial Cr(VI) concentration and addition of inorganic salts on the photocatalytic activity have been investigated in detail. Meanwhile, the stability of Bi₂O₃-ZrO₂ was investigated by repeatedly performing Cr(VI) photoreducing experiments.