Synthesis of CuO/ZnO Nanocomposites and Their Application in Photodegradation of Toxic Textile Dye

Abstract

CuO/ZnO composites are synthesized using a simple mechanochemical combustion method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FTIR) are used to characterize the prepared oxides. X-ray diffraction reveals that the prepared CuO/ZnO exhibit a wurtzite ZnO crystal structure and the composites are composed of CuO and ZnO. The strong peaks of the Cu, Zn, and O elements are exhibited in the EDX spectrum. The FTIR spectra appear at around 3385 cm −1 and 1637 cm −1 , caused by O-H stretching, and 400 cm −1 to 590 cm −1 , ascribable to Zn-O stretching. The photocatalytic performances of CuO/ZnO nanocomposites are investigated for the degradation of methylene blue (MB) aqueous solution in direct solar irradiation. The degradation value of MB with 5 wt % CuO/ZnO is measured to be 98%, after 2 h of solar irradiation. The reactive • O 2 − and • OH radicals play important roles in the photodegradation of MB. Mineralization of MB is around 91% under sunlight irradiation within 7 h. The photodegradation treatment for the textile wastewater using sunlight is an easy technique-simply handled, and economical. Therefore, the solar photodegradation technique may be a very effective method for the treatment of wastewater instead of photodegradation with the artificial and expensive Hg-Xe lamp.methyl orange. Kuriakose et al. [14] prepared CuO/ZnO nanocomposites using the carbothermal evaporation method and evaluated the photocatalytic degradation of methylene blue and methyl orange dyes under sunlight irradiation. Wang el al. [15] prepared MnO@MnOx microspheres through the solvothermal process and reported the degradation of levofloxacin under simulated sunlight irradiation. Nanocomposite photocatalytic technology can be considered a green technology and provides the advantages of abundance, including postpone electron-hole recombination, higher photocatalytic activity, and the ability to convert solar energy to chemical energy, which eventually realizes the solution of energy and environmental issues [16][17][18][19][20][21].ZnO is an n-type semiconductor, having a conductivity of about 10 −7 -10 −3 S/cm. It has a relatively large binding energy of 60 meV. However, the main disadvantages of ZnO are its fast electron-hole recombination rate and inefficient utilization of sunlight that lead to a reduction in photodegradation efficiency. The photodegradation performance of ZnO can be increased by modifying ZnO with transition metals [22]. Among the various transition metals, Cu-doped ZnO nanomaterials are of special interest due to the photocatalytic efficiency enhancement that creates defects in the lattice and reduces the recombination of photogenerated charge carriers [23]. Cu also provides plenty of advantages, such as low cost, more electronegativity than zinc, and a similar atomic size to that of zinc, and leads to better doping efficiency [24]. CuO is a natural p-type semiconductor with a narrow band gap, having a conductivity of 10 −4 ...

Optimization of green biosynthesized visible light active CuO/ZnO nano-photocatalysts for the degradation of organic methylene blue dye

“…The common problems faced by textile industries are related to the residual dyes in the dyeing bath. Such industries implement innovative, rapid, and sustainable treatment methods to enhance the color removal of wastewater [ 4 , 5 ]. Furthermore, legislation and laws related to the limits of discharge and reduction in the removal of colors are increasingly stringent [ 6 ].…”

“…However, the operation cost and maintenance costs of these methods are considered as the basic and determining factors for large-scale applications [ 7 ]. Thus, inexpensive, efficient, eco-friendly and cost-effective alternative technologies are desired to minimize the problems of treatment liquid dye wastes [ 4 ]. Recently, photocatalytic degradation has proved to be a promising technique for the removal of organic dye pollutants by optical catalyst owing to its environmental friendliness and the absence of secondary pollutants [ 8 , 9 ].…”

“…The photocatalytic performance of CuO/ZnO nanocomposites is highly dependent on their surface area, size, and morphology, which can be varied by the method of preparation [ 8 ]. Various methodologies have been developed using chemical, physical, and biological approaches to produce ZnO-NPs, CuO-NPs and/or their coupling nanocomposites of different morphologies and shapes [ 4 , 29 , 30 , 31 ]. Nanoscale sizes and shapes are the main factors that influence the performance of CuO/ZnO nanocomposites during the photolysis processes [ 32 ].…”

Bio-Fabrication of ZnO-CuO Nanoporous Composite and Its Application as Nanolarvicidal Agent for Malaria Vectors

“…3). Nonetheless, the morphological structure of ZnO-CuO was found to be Nanoflakes, Flowerlike, Networked flakes, Nanorod, Nanowire, and Spherinoid by [5,6,9,11,12,31] respectively. Fig.…”

“…Zinc oxide and Copper oxide as well as their nanocomposites are used in various applications. For example ZnO/CuO for photodegradation of toxic textile dye [6][7][8][9][10] [23][24][25]. However, bimetallic (metal/metal), metal/metal oxide or metal oxide/metal oxide nanoparticles are known to have greater larvicidal effect on mosquito larvae than the individual nanoparticles due to synergistic effects [3].…”