Browsing by Author "Wu, Tsai-Fang"

Now showing 1 - 3 of 3

Electrochemical Photocatalytic Degradation of Orange G Using TiO2 Films Prepared by Cathodic Deposition
(2014-01-01)
Wu, Tsai-Fang
;
Lin, Wei-Chieh
;
Hsiao, Yu-Cheng
;
Su, Chih-Hao
;
Hu, Chi-Chang
Herein, we report that organic dyes with poor adsorption on photocatalysts (e. g., OG (orange G) on TiO2) can only be significantly degraded via the indirect oxidation process by the electrochemical photocatalytic (EPC) or photo-electro-Fenton (PEF) mechanisms because of their enhanced electron-hole separation for generating H2O2. The TiO2/Ti photo-anodes were prepared by cathodic deposition from a bath containing TiCl3, HCl, H2O2, and NaNO3 under a two-electrode mode for EPC dye degradation. Effects of the deposition cell voltage, deposition time, and annealing temperature on the photocatalytic activity of TiO2 films, evaluated by the photocurrent density, are systematically investigated. The surface morphologies and crystalline structure of various TiO2 films were studied using scanning electron microscopic (SEM) and X-ray diffraction (XRD) analyses. The EPC characteristics of TiO2/Ti photo-anodes combined with a graphite cathode toward the OG degradation have also been evaluated. The maximal photocatalytic activity is obtained for the TiO2/Ti photo-anode deposited at a cell voltage of 2.6 V for 20 min and annealed at 700 degrees C in air for 1 hr, which exhibits a photocurrent density of 22.86 mu Amg(-1). The order of degradation modes with respect to decreasing the degradation efficiency of OG is: PEF > EPC > PC (photocatalytic) > EC (electrocatalytic) oxidation. (C) 2014 The Electrochemical Society. All rights reserved.
Evaluating the sensitizing effect on the photocatalytic decoloration of dyes using anatase-TiO2
(2014-04-27)
Hsiao, Yu-Cheng
;
Wu, Tsai-Fang
;
Wang, Yu-Sheng
;
Hu, Chi-Chang
;
Huang, Chihpin
This work tries to clarify the contribution of the dye-sensitizing effect on the photocatalytic decoloration of dyes dissolved in aqueous media using an anatase TiO2 (A-TiO2) photocatalyst. The photocurrentvoltage (J-V) curves of a typical dye-sensitized solar cell (DSSC) with the A-TiO2 photoanodes adsorbed with various dyes, including methylene blue (MB), orange G (OG), rhodamine B (RhB), metanil yellow (MY), acid black 24 (AB24), and N719, are employed to demonstrate the sensitizing characteristics of dyes on A-TiO2. Unlike RhB, the MB, OG, MY, and AB24 cannot work as the photo-sensitizer on A-TiO2 from the J-V curves of DSSCs, reasonably due to the unmatched band position between dyes and A-TiO2. In the photocatalytic decoloration test of these dyes on A-TiO2 in aqueous media, dye adsorption onto A-TiO2 becomes the key factors affecting the photocatalytic decoloration rate because the generation of oxidants species (e.g., Oi(2)(-center dot), OH center dot or photo-excited holes) occurs on the A-TiO2 surface. The contribution of dye-sensitizing on the photocatalytic decoloration of RhB is negligible since the dye-sensitizing/electron-injection/dye-regeneration cycle cannot be completed in the degradation media while adsorbed RhB molecules are unstable when few photo-generated electrons have been injected into the conduction band of A-TiO2, probably leading to the decomposition of RhB. (C) 2013 Elsevier B.V. All rights reserved.
Flow and Film-Forming Characteristics Analysis of Non-Newtonian Fluid Slot Coating
(2014-01-01)
Shu, Wei-Chu
;
Wu, Tsai-Fang
;
Chen, Ren-Haw
;
Cheng, Kuei-Yuan
;
Hsieh, Chih-Wei
The slot coating process in the production of polymer films has a wide range of applications. However, the process cannot be systemized. This study used the computational fluid dynamics software Polyflow to analyze the slot coating process and investigate the influence that the process parameters have on the characteristics of thin-film coating to reduce the time and cost consumed in the experimental methods. The rheological characteristics of the non-Newtonian fluid used in this study were first identified by conducting experiments, and then configured in the simulation software for fitting with mathematical models. In addition, the models of the slot coating process were constructed, and the Arbitrary Lagrangian-Eulerian (ALE) calculation methods were then used in the Polyflow software. The simulation results were then compared to the experimental results and the findings reported in relevant literature, to determine the influence that the process parameters have on the characteristics of thin-film coating. The simulation results were represented graphically in a coating window plot. The comparison results indicate that the viscosity-shear rate characteristic of the material in the shear rate range of optical film coating is an excellent fit for the Cross Law. When the coating speed is too high or the amount of fluid supply is insufficient, phenomena such as break lines, uneven thickness, and air entrainment can occur.