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Photocatalytic oxidation mechanism of arsenite on tungsten trioxide under visible light

Paper ID Volume ID Publish Year Pages File Format Full-Text
26107 43935 2015 6 PDF Available
Title
Photocatalytic oxidation mechanism of arsenite on tungsten trioxide under visible light
Abstract

•The oxidation of As(III) to As(V) on WO3 primarily proceeds through two-hole transfer.•OH radical scavengers had little effect on the oxidation rate of As(III) to As(V).•As(III) enhanced the photocurrent by reacting with hole.•As(III) on WO3 acts as an external charge recombination center.

The oxidation of arsenite (As(III)) to arsenate (As(V)) and the involved oxidants on tungsten trioxide (WO3) under visible light were mechanically investigated. Three oxidant species, valence-band hole (hvb+), hydrogen peroxide (H2O2), and hydroxyl radical (OH), can be generated on WO3 under visible light. However, As(III) was not oxidized to As(V) in the presence of H2O2. In addition, the oxidation rate of As(III) to As(V) was not reduced in the presence of OH scavenger. These results indicate that the oxidation of As(III) to As(V) is primarily initiated by hole, but both OH and H2O2 are little involved in As(III) oxidation to As(V). This hole-mediated oxidation of As(III) to As(V) on WO3 was further confirmed by X-ray photoelectron spectroscopy (XPS) analysis (i.e., the adsorption of As(III) on WO3) and photoelectrochemical measurement (i.e., the enhanced photocurrent by As(III) addition). Although OH is little involved in As(III) oxidation to As(V), the production of OH was reduced in the presence of As(III). This behavior implies that As(III) on WO3 acts as an external charge recombination center, where the oxidation of As(III) to intermediate As(IV) species by hole or OH is immediately followed by the reduction of As(IV) to As(III) by conduction-band electron (ecb–). Therefore, the direct oxidation of As(III) to As(V) by two-hole transfer can be proposed as the primary oxidation pathway of As(III) to As(V) on WO3 under visible light.

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Keywords
Photocatalysis; Tungsten trioxide; Arsenite; Oxidation mechanism; Primary oxidant
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Photocatalytic oxidation mechanism of arsenite on tungsten trioxide under visible light
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 311, 1 October 2015, Pages 35–40
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