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Photocatalytic oxidation of sulfur dioxide in aqueous suspensions of α-Fe_2O_3)

Faust, Bruce C. and Hoffmann, Michael R. and Bahnemann, Detlef W. (1989) Photocatalytic oxidation of sulfur dioxide in aqueous suspensions of α-Fe_2O_3). Journal of Physical Chemistry, 93 (17). pp. 6371-6381. ISSN 0022-3654. https://resolver.caltech.edu/CaltechAUTHORS:20150814-081853069

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Abstract

The kinetics and mechanism of the photoassisted autoxidation of S(IV) in aqueous colloidal suspensions of α-Fe_2O_3 have been studied over the pH range of 2-10.5. Similar kinetic behavior toward S(IV) was observed for colloidal suspensions of TiO_2. Quantum yields, Ф, 4, ranged from 0.08 to 0.3 with a maximum yield found at pH 5.7. Upon band-gap illumination conduction-band electrons and valence-band holes are separated; the trapped electrons are transferred either to surface bound dioxygen or to Fe(III) sites on or near the surface while the trapped holes accept electrons from adsorbed S(IV) to produce S(V). The formation of S(V) radicals indicates that the reaction proceeds via successive one-electron transfers. The relatively high quantum yields are attributed in part to the desorption of SO_3^- from the α-Fe_2O_3 surface and subsequent initiation of a homogeneous free radical chain autoxidation of S(IV) to S(VI). Kinetic and thermodynamic models for the photoassisted surface chemistry of S(IV) on α-Fe_2O_3 are presented.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/j100354a021DOIArticle
http://pubs.acs.org/doi/abs/10.1021/j100354a021PublisherArticle
ORCID:
AuthorORCID
Hoffmann, Michael R.0000-0001-6495-1946
Alternate Title:Photocatalytic oxidation of sulfur dioxide in aqueous suspensions of .alpha.-iron oxide (Fe2O3)
Additional Information:© 1989 American Chemical Society. (Received: October 31, 1988; In Final Form: February 3, 1989) We gratefully acknowledge the financial support of the US. Environmental Protection Agency (R8116112-01-0 and R8113326-01-0). We are also grateful for the assistance provided by Drs. Liyuan Liang and Claudius Kormann.
Funders:
Funding AgencyGrant Number
Environmental Protection Agency (EPA)R8116112-01-0
Environmental Protection Agency (EPA)R8113326-01-0
Issue or Number:17
Record Number:CaltechAUTHORS:20150814-081853069
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150814-081853069
Official Citation:Photocatalytic oxidation of sulfur dioxide in aqueous suspensions of .alpha.-iron oxide (Fe2O3) Bruce C. Faust, Michael R. Hoffmann, and Detlef W. Bahnemann The Journal of Physical Chemistry 1989 93 (17), 6371-6381 DOI: 10.1021/j100354a021
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59524
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:14 Aug 2015 15:43
Last Modified:03 Mar 2020 13:01

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