Photocatalytic oxidation kinetics and mechanisms of meta-substituted phenols by TiO₂/UV : a molecular structure-reactivity study
Master of Science (MS)
First Advisor's Name
Walter Z. Tang
First Advisor's Committee Title
Second Advisor's Name
William J. Cooper
Third Advisor's Name
Kevin E. O'Shea
Fourth Advisor's Name
Hector R. Fuentes
Date of Defense
The oxidation kinetics of m-substituted phenols by TiO2/UV were investigated. An attempt was made to correlate Swain-Lupton parameters (R) for aromatic substituents with the oxidation kinetic constants, based upon molecular structure and reactivity theory. Irradiation experiments were carried out with suspended aqueous TiO 2 powder and substrate mixture in a Rayonet Photochemical Reactor. Langmuir-Hinshelwood model was applied to obtain apparent kinetic rate constants. A linear correlation is observed between Langmuir-Hinshelwood kinetic parameters and Hammett constants for m-chloro, m-bromo and m-fluoro phenols. The changes in p values of Hammett plots at pH 3 suggest that the main degradation pathway may involve a positively charged intermediate, such as a radical cation formed by direct electron transfer to the positive holes at low pH. At high pH levels, however, substrate speciation, surface charge of the semiconductor, and bandgap shift appear to lead to a change in the degradation mechanism.
Foti, Fabius D., "Photocatalytic oxidation kinetics and mechanisms of meta-substituted phenols by TiO₂/UV : a molecular structure-reactivity study" (1993). FIU Electronic Theses and Dissertations. 3406.
In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).