Title

Photocatalytic decomposition of organophosphonates fluorophenols in irradiated titanium dioxide suspensions

Document Type

Thesis

Degree

Master of Science (MS)

Department

Chemistry

First Advisor's Name

Kevin E. O'Shea

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Jeffrey Joens

Third Advisor's Name

Ramon Lopez de la Vega

Date of Defense

9-4-1997

Abstract

Dimethyl methyl phosphonate (DMMP), diethyl methyl phosphonate (DEMP), and fluorophenols undergo rapid decomposition upon TiO2 catalyzed photooxidation in air saturated aqueous solution. The degradation rates of DMMP were determined over a range of temperatures, under solar and artificial irradiation with and without simultaneous sonication. Solar illumination is effective for the degradation and the use of low energy of sonication increases the rate of mineralization. The surface area and the type of TiO2 dramatically affect the photoactivity of the catalyst. A number of intermediate products are formed and ultimately oxidized to phosphate and carbon dioxide. Possible reaction mechanisms and pathways for DMMP and DEMP are proposed. The Langmuir- Hinshelwood kinetic parameters for the photocatalysis of fluorophenols suggest modestly different reactivity for each isomer. The adsorption constant is largest for the ortho isomer consistent with the adsorption onto TiO2 through both hydroxyl and fluoride groups to form a chelated type structure.

Identifier

FI13101542

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