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

Abstract

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 Cd2+ reduction in real samples and prospective photoelectric materials.

Ex Situ Method for Photoreduction of the Cadmium Ion from Terbium-Loaded Bismuth Vanadium Oxide

“…The solution was quickly taken out for filtration at a predetermined time to determine the mass concentration of Cd (II) in the solution. As mentioned by Hossein et al, on increasing pH from 4 to 7, the percent of photoreduction decreased . It is suggested that the photoreduction of the metallic cation is significantly dependent on their tendency toward the hydrolysis reaction. ,, …”

“…Heavy metals such as lead, mercury, cadmium, nickel, and chromium are found in the wastewater of various industries such as mining, petrochemicals, pharmaceuticals, plastic products, paper, and fabric dyeing. − Because of the adverse effects of heavy metals, many of their derivatives are classified as pollutants . Penetration of heavy metals inside the body leads to various adverse effects and also many diseases .…”

“…Hole scavengers primarily inhibit charge carrier recombination. ,− They also generate secondary reducing hydroxyl radicals, which help with photoreduction. , The choice of an effective photocatalyst is critical in this photoreduction process. Bismuth vanadium oxide (Bi 4 V 2 O 11 ) and doped Bi 4 V 2 O 11 possess some unique properties such as low band gap, low cost, high stability, availability, and environmental friendly nature, which make it an ultimate choice as a catalyst. , The photoreduction efficiency strongly depends on the catalyst physical features such as band gaps. , Therefore, for improving the recombination rate of photogenerated electrons and holes in Bi 4 V 2 O 11 , modification of its activity in the UV–visible region, is necessary. ,,,, Tb 3+ as a low-band-gap material and UV–vis-driven agent has attracted interest because of its low toxicity. Therefore, in this research, it has been attempted to reduce cadmium ions using a Tb 3+ -doped Bi 4 V 2 O 11 (Tb/Bi 4 V 2 O 11 ) photocatalytic system to boost the adsorption and reduction performance.…”

Activated porous carbon supported Pd and ZnO nanocatalysts for trace sensing of carbaryl pesticide in water and food products

“…Upon loading ZnO on the porous carbon framework (middle), new vibration bands appeared at 1041, 901, 719, and 468 cm −1 . 54 They corresponded to asymmetrical and symmetrical Zn–O stretching vibrations. As compared to APC, the OH peak was broadened, indicating that the number of OH increased following the impregnation process, and the intensity peak of the CO band was enhanced due to the overlap with the chloride anions derived from the unreacted precursor.…”

Synthesis of Porous N-doped TiO2 by Using Peroxo Sol-Gel Method for Photocatalytic Reduction of Cd(II)

“…This process can activate and undertake both oxidation and reduction reactions under irradiation of light energy [23]. By conducting this method for the metal ion treatment, especially in the removal of Cd(II), this heavy metals would be directly reduced from its toxic ionic phase (Cd(II)) into non-toxic metallic phase (Cd(0)) [24][25][26]. It is believed that the photocatalytic method for the removal of heavy metals pollutants is more green, clean and economical than the conventional methods [27,28].…”