Photoreduction and Removal of Cadmium Ions over Bentonite Clay-Supported Zinc Oxide Microcubes in an Aqueous Solution

摘要

Cadmium ion is toxic to organisms and shows persistence because of its nondegradability. Photoreduction of the cadmium ion (Cd(II)) was studied using a bentonite-supported Zn oxide (ZnO/BT) photocatalyst in an aqueous medium under ultraviolet light. The prepared ZnO/BT photocatalyst was characterized by diffuse reflectance spectroscopy, field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, photoluminescence spectroscopy, transmission electron microscopy, energy-dispersive spectroscopy, and Brunauer–Emmett–Teller/Barrett–Joyner–Halenda analysis. The effects of main parameters including pH, contact time, initial concentration of cadmium(II) ion, light intensity, temperature, and the photocatalyst dosage were investigated for obtaining appreciate reduction/removal efficiency. The maximum reduction/removal efficiency of 74.8% was obtained at optimized values which were found to be at pH 5, 6 h contact time, 6 ppm Cd(II) ion, 200 W UV light, 45 °C temperature, and 4 g/L of ZnO/BT. Reduction/removal of Cd(II) was significantly affected by light intensity so that the increment in UV intensity from 0 to 200 increased the reduction/removal efficiency from 61.2 to 76.8%. This study reports an inexpensive and environmentally friendly photocatalyst for Cd~(2+) reduction in real samples and prospective photoelectric materials.