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Photolysis of chloroform and other organic molecules in aqueous titanium dioxide suspensions

Kormann, C. and Bahnemann, D. W. and Hoffmann, Michael R. (1991) Photolysis of chloroform and other organic molecules in aqueous titanium dioxide suspensions. Environmental Science and Technology, 25 (3). pp. 494-500. ISSN 0013-936X. https://resolver.caltech.edu/CaltechAUTHORS:20150813-105953063

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Abstract

The photocatalytic degradation of chloroform has been investigated in aqueous suspensions of TiO_2 over the wavelength range of 310-380 nm. A detailed reaction mechanism has been proposed in which the rate-determining step is the reaction of surface-bound *OH with adsorbed CHCl_3. A pH-stat titration technique was developed for the measurement of the rates of degradation of chlorinated hydrocarbons. The quantum efficiency (Ф = 0.56 at ⋋ = 330 nm) of the degradation of CHCl_3, was found to be inversely proportional to the square root of the incident light intensity. This relationship can be explained in terms of a direct competition between a second-order recombination of surface-bound 'OH and the rate-determining reaction of surface-bound 'OH with CHCl_3. The rates of degradation of several electron donors have been correlated with their computed surface speciation. The results of this study show that the adsorption of electron donors and acceptors to the TiO_2 surface plays a more important role in determining the rate of the photocatalytic reactions than the effect of pH-dependent Fermi-level shifts.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/es00015a018DOIArticle
http://pubs.acs.org/doi/abs/10.1021/es00015a018PublisherArticle
ORCID:
AuthorORCID
Hoffmann, Michael R.0000-0002-0432-6564
Additional Information:© 1991 American Chemical Society. Received for review September 7,1990. Accepted October 2,1990. This research was supported by grants from the US. Environmental Protection Agency (R 813326-01-0 and R 825041-01-0). We are grateful to Drs. Dieter Gunz and German Mills for their help on this project. We appreciate the generous donation of the P25 TiO_2 by the Degussa Corp.
Funders:
Funding AgencyGrant Number
Environmental Protection Agency (EPA)R 813326-01-0
Environmental Protection Agency (EPA)R 825041-01-0
Issue or Number:3
Record Number:CaltechAUTHORS:20150813-105953063
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150813-105953063
Official Citation:Photolysis of chloroform and other organic molecules in aqueous titanium dioxide suspensions C. Kormann, D. W. Bahnemann, and Michael R. Hoffmann Environmental Science & Technology 1991 25 (3), 494-500 DOI: 10.1021/es00015a018
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59484
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:14 Aug 2015 15:44
Last Modified:03 Oct 2019 08:47

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