Abstract
Abstract This article reports a simple, cost-effective, and eco-friendly biosynthesis of ZnO/Fe3O4 nanocomposites using Callistemon viminalis leaves’ water extract. For the first time, we used a green synthetic route via C. viminalis leaves’ extract to prepare ZnO/Fe3O4 nanocomposites (NCs) using zinc acetate and ferric chloride as precursor materials. Fourier transform infrared (FTIR) spectroscopic results revealed polyphenolic compounds mainly phenolic acids present in the plant extract acted as both reducing and stabilizing agents to synthesize ZnO/Fe3O4 NCs. Outcomes of XRD and X-ray photoelectron spectroscopy confirmed the formation of ZnO–Fe3O4 heterojunction in ZnO/Fe3O4 NCs, with crystallite sizes of 45, 35, and 60 nm, respectively, according to Debye–Scherrer’s formula. EDX confirmed Zn, Fe, and O in the ZnO/Fe3O4 nanocomposite. Scanning electron microscopy and transmission electron microscopy (TEM) analyses revealed the existence of both ZnO and Fe3O4 in the NCs with some agglomeration. The thermal stability of NCs was evaluated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA) in a nitrogen atmosphere. In addition, as-prepared ZnO/Fe3O4 NCs along with biosynthesized ZnO and Fe3O4 (prepared by C. viminalis extract) nanoparticles were examined for photodegradation of methylene blue under visible light irradiation for 150 min. The result reveals that the photodegradation efficiency of ZnO/Fe3O4 NCs (99.09%) was higher compared to that of monometallic ZnO (84.7%) and Fe3O4 (37.1%) nanoparticles.
Highlights
Industrialization and urbanization have increased water pollution to a great extent because of the direct disposal of organic and industrial waste into water bodies [1]
The Fourier transform infrared (FTIR) spectrum of C. viminalis leaves’ extract (Figure 2a) showed some major absorption bands at 3,419, 2921.76, 1718.16, 1451.86, 1368.87, and 1180.95 cm−1 were assigned to O–H stretching of phenolic acids and phenols, C–H stretching in CH3 and CH2, C]O groups in phenolic acids and flavonoids, C]C stretching of the aromatic ring, and C–H deformation in CH3 and C–OH stretching in phenolic acids, respectively, as reported in various literature [39,40,41]
The photodegradation of Methylene blue (MB) in the presence of as-prepared nanoproducts was examined under visible light, and the extent of degradation was measured in terms of absorbance of MB solution using a UV-Vis spectrophotometer after certain intervals of time for 150 min
Summary
Industrialization and urbanization have increased water pollution to a great extent because of the direct disposal of organic and industrial waste into water bodies [1]. The prolonged exposure to MB results in harmful effects, such as cyanosis, skin irritation, and gastrointestinal irritation, in living beings [6] To solve this challenge, many physical and chemical techniques including flocculation–coagulation, surface adsorption, ion-exchange, chemical precipitation, and photocatalytic degradation have been used to remove the dye from waste water [7,8]. Metals and metal oxide nanoparticles have been used as homogeneous or heterogeneous nanocatalysts in various organic syntheses due to the large surface-to-volume ratio of nanoparticles compared to bulk materials [29,30] This strategy provides a simple, cost-effective, and eco-friendly route for the fabrication of nanomaterials [31]. The novelty of this study is to show the efficacy of biosynthesized ZnO/Fe3O4 NCs as a photocatalyst in contrast to ZnO or Fe3O4 NPs for the degradation of MB solution under visible light irradiation
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