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Adsorption and Photodegradation of Dimethyl Methylphosphonate Vapor at TiO_2 Surfaces

Moss, John A. and Szczepankiewicz, Steven H. and Park, Eleanor and Hoffmann, Michael R. (2005) Adsorption and Photodegradation of Dimethyl Methylphosphonate Vapor at TiO_2 Surfaces. Journal of Physical Chemistry B, 109 (42). pp. 19779-19785. ISSN 1520-6106. https://resolver.caltech.edu/CaltechAUTHORS:20150806-062700164

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Abstract

The adsorption and degradation of the nerve agent simulant dimethyl methylphosphonate (DMMP) over UV-irradiated TiO2 powders and thin films has been investigated. Adsorption of vapor-phase DMMP on TiO_2 powder is characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Photochemically assisted oxidation of adsorbed DMMP is carried out in situ by irradiation of samples in the DRIFTS accessory, giving kinetic data and information on specific site binding of DMMP and catalyst poisoning. Gas-phase intermediates from a static vapor phase reaction are identified by gas chromatography−mass spectrometry analysis, and surface-bound intermediates and products are analyzed by high-performance liquid chromatography−mass spectrometry, and ion chromatography of both aqueous and organic extractions from the TiO_2. Adsorbed DMMP is photodegraded in a stepwise fashion to give methylphosphonic acid, PO_4^(3-), H_2O, and CO_2 as products. A proposed reaction pathway is consistent with a rapid degradation of DMMP but with extensive poisoning of the catalyst by surface-bound phosphonate products.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/jp052057jDOIArticle
http://pubs.acs.org/doi/abs/10.1021/jp052057jPublisherArticle
ORCID:
AuthorORCID
Hoffmann, Michael R.0000-0001-6495-1946
Additional Information:© 2005 American Chemical Society. Received: April 20, 2005; In Final Form: July 11, 2005. Publication Date (Web): October 5, 2005. Financial support of this work was provided by a grant from DARPA (through a cooperative research program with the Northrop-Grumman Corporation).
Funders:
Funding AgencyGrant Number
Defense Advanced Research Projects Agency (DARPA)UNSPECIFIED
Northrop-Grumman CorporationUNSPECIFIED
Issue or Number:42
Record Number:CaltechAUTHORS:20150806-062700164
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150806-062700164
Official Citation:Adsorption and Photodegradation of Dimethyl Methylphosphonate Vapor at TiO2 Surfaces John A. Moss, Steven H. Szczepankiewicz, Eleanor Park, and Michael R. Hoffmann The Journal of Physical Chemistry B 2005 109 (42), 19779-19785 DOI: 10.1021/jp052057j
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59258
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:06 Aug 2015 16:34
Last Modified:03 Mar 2020 13:01

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