Abstract
The photocatalytic degradation of organic pollutants is an effective method of controlling environmental pollution. ZnO nanoparticles (ZnO NPs) were prepared by the solvothermal method and characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–visible diffuse reflectance spectroscopy (UV–Vis DRS). The results showed that the ZnO NPs had a uniform size of 25–40 nm, hexagonal wurtzite structure, and a band gap of 2.99 eV. The photocatalytic degradation of methyl orange (MO) and p-nitrophenol (PNP) was used as a model reaction to evaluate the photocatalytic activity of ZnO NPs. The photocatalytic degradation rates (pseudo-first-order kinetics) of MO and PNP were 92% (0.0128 min−1) and 56.2% (0.0042 min−1), respectively, with a 25 W ultraviolet lamp, MO/PNP concentration = 20 mg/L, ZnO NPs dose = 1.5 g/L, and time = 180 min. The photocatalytic mechanism of ZnO NPs and degradation pathways of MO and PNP were also proposed. The results provide valuable information and guidance for the treatment of wastewater via photocatalytic methods.
Highlights
Energy and environmental issues are the two major limitations that restrict the sustainable development of humankind and have become a focus for all countries in the world.Photocatalytic technology has become an important technical means of solving energy and environmental problems worldwide because of its ability to directly use sunlight to drive the photolysis of water to produce hydrogen, perform organic synthesis, and degrade pollutants [1]
X-ray diffraction (XRD) patterns were recorded on a Bruker D8 Advance X-ray diffracX-ray diffraction (XRD) patterns were recorded on a Bruker D8 Advance X-ray diftometer with Cu Kα radiation (λ = 1.5418 Å) and used to determine the crystal structure fractometer with Cu Kα radiation (λ = 1.5418 Å ) and used to determine the crystal and phase composition of the prepared ZnO nanoparticles (ZnO NPs)
The photocatalytic activity of ZnO experiments, NPs was monitored by theamount degradation of in aqueous solution
Summary
Energy and environmental issues are the two major limitations that restrict the sustainable development of humankind and have become a focus for all countries in the world. ZnO, a new generation of direct band gap, wide-bandgap semiconductors, has a band gap of 3.37 eV, an exciton binding energy of 60 meV, and the advantages of simple preparation, high stability, and low cost [3]. Umar prepared ZnO balls that had a photocatalytic activity of 100% for the degradation of methylene blue (MB) under UV light over 70 min [13]. Pengfei Cheng synthesized sea urchin-like layered ZnO-TiO2 photocatalysts by a hydrothermal method. When the conditions were changed, 100 nm nanoparticles and 250 nm microrod structures were synthesized These particles showed high performance in the photocatalytic degradation of MO and decolorized by almost 100% in only 20 min [16,17]. The specific objectives were (1) to prepare ZnO NPs via a solvothermal method, (2) to evaluate the photocatalytic activity of ZnO NPs by degradation of MO and p-nitrophenol (PNP), and (3) to propose the photocatalytic mechanism of ZnO NPs and degradation pathways of MO and PNP
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