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Structural modifications in Au/Al2O3–CeO2 mixed oxides as a function of Ce4+ content and its effects in the mineralization of the herbicide diuron

Paper ID Volume ID Publish Year Pages File Format Full-Text
28048 44057 2012 10 PDF Available
Title
Structural modifications in Au/Al2O3–CeO2 mixed oxides as a function of Ce4+ content and its effects in the mineralization of the herbicide diuron
Abstract

Nanocrystalline Au/Al2O3–CeO2 photocatalysts with different CeO2 contents were prepared by the sol–gel method. Gold was deposited by a deposition–precipitation approach. Nitrogen adsorption, X-ray diffraction, Rietveld refinement, radial distribution functions, UV–vis spectroscopy (diffuse reflectance), FT-IR and transmission electron microscopy (TEM) techniques were used for the characterization of the synthesized Au/Al2O3–CeO2 samples. The photodegradation of the herbicide diuron (C9H10Cl2N2O) in aqueous media using an UV light emission source was used to evaluate the photocatalytic behavior of these nanomaterials. High specific surface areas (326–124 m2/g) and a band gap in the UV region 3.25–3.15 eV were obtained in these solids. XRD patterns showed that Au/Al2O3–CeO2 mixed oxides contain crystal structures of ceria and γ-alumina. Although, both ceria and γ-alumina are cubic structures, ceria phase is remarkably predominant with respect to the alumina phase. Mineralization of diuron was determined by measuring the total organic carbon (TOC) remaining in the irradiated solution. All the samples, including bare Au/Al2O3 solid, are quite active for the decomposition of the herbicide; however, the analysis of the TOC after 2.5 h in irradiation showed that only photocatalysts containing CeO2 are capable to reach up to 77% of mineralization of the herbicide.

Graphical abstractIn Au/Al2O3–CeO2 photocatalyts important effect of CeO2 crystallite size in the mineralization of the herbicide diuron was noticed.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Gold supported on alumina–ceria are photoactive catalysts. ► Photoactivity in herbicide diuron is a depending ceria particle size reaction. ► Supported gold enhances diuron photodegradation. ► Alumina modifies cerium oxide band gap to low energy. ► Mineralization up to 77% of diuron was reached in gold–alumina–ceria semiconductors.

Keywords
Alumina–ceria mixed oxides; Photocatalysts; Herbicide diuron; Gold nanoparticles; Rietveld refinement
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Structural modifications in Au/Al2O3–CeO2 mixed oxides as a function of Ce4+ content and its effects in the mineralization of the herbicide diuron
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 243, 1 September 2012, Pages 23–32
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us