Photocatalytic Degradation of Methylene Blue by Using ZnO/Longan Seed Activated Carbon Under Visible-Light Region
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Photocatalytic Degradation of Methylene Blue by Using ZnO/Longan Seed Activated Carbon Under Visible‑Light Region Nguyen Van Hung1 · Bui Thi Minh Nguyet2 · Nguyen Huu Nghi1 · Dinh Quang Khieu3 Received: 8 June 2020 / Accepted: 28 August 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract In the present study, the synthesis of zinc oxide/longan seed activated carbon material (ZnO/LSAC) and its photocatalytic activity under the visible-light region are demonstrated. The pyrolysis of the carbonized material prepared from longan seeds and zinc acetate in the alkaline medium was conducted to manufacture ZnO/LSAC. The obtained material was characterized by using X-ray diffraction, Fourier transformation-infrared spectroscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray elemental mapping observation, nitrogen adsorption/desorption isotherms, ultraviolet-diffusive reflectance spectroscopy (DRS–UV–Vis), and photoluminescence spectra. The ZnO nanoparticles with 20–30 nm in diameter are highly dispersed on the LSAC matrix. The combination of ZnO with LSAC promotes visible-light absorption. The photocatalytic activities of the prepared composite were evaluated for the degradation of methylene blue (MB) under visiblelight irradiation. The kinetics and mechanism for photodegradation were addressed. The kinetic data and equilibrium data fit the modified Langmuir–Hinshelwood model. Introducing C to ZnO lattice creates an intermediate energy level and narrows the absorption energy, which results in the visible-light-driven photocatalytic activity of ZnO/LSAC. Reusability studies show that the catalyst retains its original activity even after the third cycle of reuse. Besides MB, the present catalyst could catalyze the photodegradation of other dyes, such as rhodamine B, congo red, and methyl orange. Keywords Zinc oxide · Longan seed · Biomass carbon · Photodegradation · Methylene blue
1 Introduction Various metal oxides and sulfides, such as TiO2, SnO2, ZnO, Bi2MoO6/Bi2S3, and MoS2/CdS, have been used as photocatalysts for the degradation of toxic organic compounds and photocatalytic hydrogen evolution applications [1, 2]. Among the metal oxides, ZnO is a favorable semiconductor Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10904-020-01734-z) contains supplementary material, which is available to authorized users. * Nguyen Van Hung [email protected] * Dinh Quang Khieu [email protected] 1
Center for Chemistry Analysis, Dong Thap University, Cao Lanh 81000, Vietnam
2
Department of Organic Chemistry, Dong Thap University, Cao Lanh 81000, Vietnam
3
University of Sciences, Hue University, Hue 49000, Vietnam
material in the photodegradation of contaminants [3]. However, ZnO exhibits various disadvantages, such as highly photocorrosive nature and the fast recombination of the photo-induced electron–hole pairs [4–6]. Moreover, its photocatalytic activity is limited in the UV region of the spec
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