Perfluorooctanoic Acid (PFOA) Removal by Sonication Assisted Photo-Catalytic Oxidation
Date Issued
2008
Date
2008
Author(s)
Tsai, Jia-Hong
Abstract
The objective is to utilize ultrasonic irradiation assisted photo-catalysis which divided into sequential operation and simultaneous operation for perfluorooctanoic acid (PFOA) removal in this study. The process is called “sonophotocatalysis.” The specific surface area of synthesized sol-gel TiO2 was 38.54 (m2/g) by BET analysis and the particle diameter was about 30 to 50 nm by TEM. Its crystal structure was a mixture of anatase and rutile showed by XRD analysis. Also, it had 3.03 eV for energy band gap. The removal efficiency of PFOA was 22% and rate constant of zero-order equation, k, was 0.0292 (hr-1) for only photo-catalysis. It was increased to 49% and 0.0866 (hr-1) of pseudo first-order rate constant, k, due to the synergistic effect in simultaneous operation. Because ultrasonic irradiation can disperse TiO2 more evenly, prevent the agglomerate of TiO2, and keep the reactive surface of TiO2 being refreshed to increase mass transfer between TiO2 and reactant. However, the removal efficiency of PFOA was increased to 64% and 0.1309 (hr-1) of k by using sol-gel TiO2. But sequential operation was useless. In addition, the removal efficiency was better at pH=10 > pH=4 > pH=7 because there are much hydroxide radicals (．OH) to react with PFOA at pH=10. PFOA was also efficient to degrade to intermediates, such as PFHpA, PFHxA and fluoride ion to be harmfulless.
Subjects
Perfluorooctanoic acid (PFOA)
Sonophotocatalysis
Synergistic effect
Type
thesis
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