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Characterization of the hydroperoxyl/superoxide anion radical (HO2/O2−) formed from the photolysis of immobilized TiO2 in a continuous flow

Paper ID Volume ID Publish Year Pages File Format Full-Text
27947 44051 2008 7 PDF Available
Title
Characterization of the hydroperoxyl/superoxide anion radical (HO2/O2−) formed from the photolysis of immobilized TiO2 in a continuous flow
Abstract

In this study, the steady-state concentrations of HO2/O2− formed from the photocatalysis of immobilized TiO2 were investigated quantitatively by using the kinetic method with a continuous flow injection. In air-equilibrated water, the concentration of HO2/O2− was typically 1.01 (±0.08) × 10−9 M at pH 5.80 in the absence of buffers. The reduction of O2 by photo-induced electrons (ecb−) was increased by the concentration of O2 (from 0 to 0.38 mM). However, in the presence of buffer anions the concentration of HO2/O2− was gradually decreased by increasing pH. This indicates that the suppression of HO2/O2− in the presence of buffer ions is attributed to the blocking of active sites of the immobilized TiO2 photocatalyst and to certain processes, that is, the reaction between HO2/O2− and OH (and/or hvb+). Furthermore, the concentration of HO2/O2− increased with the increasing concentrations of H2O2 and oxalate, and then on the further addition of H2O2 (>10 mM) and oxalate (>2 mM), the concentration of HO2/O2− reached steady values. These results strongly suggest that HO2/O2− formed on TiO2 photocatalysis migrates into the water bulk, and this study can contribute significantly to the body of knowledge regarding HO2/O2− at very low levels.

Keywords
Immobilized TiO2; Hydroperoxyl/superoxide anion radical; Kinetic method; Continuous flow injection
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Characterization of the hydroperoxyl/superoxide anion radical (HO2/O2−) formed from the photolysis of immobilized TiO2 in a continuous flow
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 199, Issue 1, 5 September 2008, Pages 112–118
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