Adsorption and Photodegradation of Dimethyl Methylphosphonate Vapor at TiO_2 Surfaces
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.
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).Additional details
- Eprint ID
- 59258
- Resolver ID
- CaltechAUTHORS:20150806-062700164
- Defense Advanced Research Projects Agency (DARPA)
- Northrop-Grumman Corporation
- Created
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2015-08-06Created from EPrint's datestamp field
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2021-11-10Created from EPrint's last_modified field