Reduced graphene oxide supported ZnO quantum dots for visible light-induced simultaneous removal of tetracycline and hexavalent chromium

Kumar, K. V. A. and Ch, S. (2020) Reduced graphene oxide supported ZnO quantum dots for visible light-induced simultaneous removal of tetracycline and hexavalent chromium. RSC Advances, 10 (35). pp. 20494-20503. ISSN 2046-2069

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Abstract

Semiconducting nanomaterials play an important role in the photocatalytic removal of aqueous pollutants like heavy metals, organic compounds, pathogens and antibiotics. In this study, we prepared ZnO quantum dots (QD) by the precipitation method and ZnO/rGO materials with varying percentages (0.5-2 wt%) of ZnO were prepared by the hydrothermal method. The synthesized catalysts were characterized by various physicochemical techniques, such as powder X-ray diffraction (XRD), Raman spectroscopy, ultraviolet-visible-diffuse reflectance spectroscopy (UV-VIS-DRS), Transmission Electron Microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR) and Brunauer-Emmett-Teller (BET) analysis to determine the structural as well as textural and surface properties. The photocatalytic activity of the prepared catalysts was analyzed during the individual and simultaneous removal of tetracycline (TC) and hexavalent chromium [Cr(vi)] in aqueous medium. Among all the catalysts, 1.5 wt% ZnO/rGO showed the highest visible light activity, where 68% tetracycline and 84% Cr(vi) abatement was observed after 120 min irradiation time. Moreover, tetracycline showed 70% mineralization. The photocatalytic activity is explained based on the photo-generated electron transfer from the conduction band (CB) of ZnO to the surface of rGO which prevents the recombination of excitons and produces OH˙ and O2−˙; these radicals play an important role in degrading the TC and Cr(vi). The mechanism suggested that the co-existence of oxidizable and reducible species such as TC and Cr(vi) ensured the effective use of the photo-generated electrons and holes that leads to the efficient oxidation of TC and Cr(vi) reduction.

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IITH Creators:

IITH Creators	ORCiD
Ch, Subrahmanyam	https://orcid.org/0000-0002-2643-3854

Item Type:

Article

Uncontrolled Keywords:

Catalyst activity; Chemicals removal (water treatment); Fourier transform infrared spectroscopy; Free radical reactions; Graphene; Heavy metals; High resolution transmission electron microscopy; II-VI semiconductors; Light; Nanocrystals; Photocatalytic activity; Physicochemical properties; Precipitation (chemical); Reduced Graphene Oxide; Semiconductor quantum dots; Wide band gap semiconductors; Zinc oxide

Subjects:

Chemistry
Chemistry > Organic chemistry
Chemical Engineering
Chemical Engineering > Food and Beverage technology
Chemical Engineering > Oils, fats, waxes, gases

Divisions:

Department of Chemistry

Depositing User:

. LibTrainee 2021

Date Deposited:

19 Jun 2021 05:32

Last Modified:

21 Feb 2022 10:18

URI:

http://raiithold.iith.ac.in/id/eprint/7946