| Summary: | 博士 === 國立臺灣科技大學 === 化學工程系 === 91 === Batch and continuous-flow differential optical fiber photoreactors were developed for the photocatalytic oxidation of gaseous benzene in air stream. The surface properties (coverage, roughness and thickness) of the coated TiO2 layer on optical fiber were characterized by SEM micrographs. For TiO2 layer prepared from solutions containing less than 20wt% of TiO2, the thickness of layer was increased linearly with the TiO2 slurry content in solutions. The UV light intensity transmitted along a TiO2 coated optical fiber decreased more rapidly than that transmitted along a non-coated fiber. Based on the experimental results, the light intensity distribution around the coated optical fiber was modeled to determine the optimum configuration for the design of optical fiber reactors under various operational conditions. The experimental results indicate that applied UV light intensity, initial concentration benzene and humidity are the main factors effecting the decomposition of benzene during UV/TiO2 process. The deactivation of TiO2 photocatalyst observed during the reaction was possibly caused by the competing adsorption of organic intermediates, which were identified by FTIR/ATR and GC/MS. The mechanism and pathway of benzene decomposition were proposed as the consecutive rupture of aromatic ring and breakage of the C-C, C=C, CºC or other kinds of bonding related to intermediates. A reactor design equation combined the UV light intensity profile of TiO2 coated fiber and the empirical kinetic expression for the photocatalysis of gaseous benzene was solved numerically and then used to predict the decomposition of benzene within the optical fiber photoreactor at various operating conditions. Experimentally observed conversion of gaseous benzene in the continues-flow differential-type optical fiber photoreactor agreed well with the theoretical solutions modeled by the photoreactor design equation developed via the modified Langmuir-Hinshelwood kinetic expression coupling with continuity equation. The geometry and configuration of optical fiber photoreactors was proposed in this study that a disk-shaped reactor with multi-fiber structure was recommend for further application.
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