• Journal of the Korean Ceramic Society
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• v.50 no.1
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• pp.50-56
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• 2013

Phosphorescent materials coated with titanium dioxide were fabricated and photocatalytic reactions between these materials and VOCs gases were examined. A thin film (approx. 100 nm) of nanosized $TiO_2$ was deposited on the $Sr_4Al_{14}O_{25}$ : $Eu^{2+}$, $Dy^{3+}$, $Ag^+$ phosphor using low-pressure chemical vapor deposition (LPCVD). The characteristics of the photocatalytic reaction were examined in terms of the decomposition of benzene gas using a gas chromatography (GC) system under ultraviolet (${\lambda}$ = 365 nm) and visible light (${\lambda}$ > 420 nm) irradiation. $TiO_2$-coated $Sr_4Al_{14}O_{25}$ : $Eu^{2+}$, $Dy^{3+}$, $Ag^+$ phosphor showed different photocatalytic behavior compared with pure $TiO_2$. $TiO_2$-coated phosphorescent materials showed a much faster photocatalytic decomposition of benzene gas under visible irradiation compared to the pure $TiO_2$ for which the result was practically negligible. This suggests that the extension of the absorption wavelength to visible light occurred through energy band bending by a heterojunction at the interface of the $Sr_4Al_{14}O_{25}-TiO_2$ composite. Also, the $Sr_4Al_{14}O_{25}-TiO_2$ composite showed the photocatalytic decomposition of benzene in darkness due to the photon light emitted from the $Sr_4Al_{14}O_{25}$ phosphors.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.423-423
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• 2011

Zinc oxide is metal oxide semiconductor with the 3.37 eV bandgap energy. Zinc oxide is very attractive materials for many application fields. Zinc Oxide has many advantages such as high conductivity and good transmittance in visible region. Also it is cheaper than other semiconductor materials such as indium tin oxide (ITO). Therefore, ZnO is alternative material for ITO. ZnO is attracting attention for its application to transparent conductive oxide (TCO) films, surface acoustic wave (SAW), films bulk acoustic resonator (FBAR), piezoelectric materials, gas-sensing, solar cells and photocatalyst. In this study, we synthesized ZnO nanoparticles and defined their physical and chemical properties. Also we studied about the application of ZnO nanoparticles as a photocatalyst and try to find a enhancement photocatalytic activity of ZnO nanorticles.. We synthesized ZnO nanoparticles using spray-pyrolysis method and defined the physical and optical properties of ZnO nanoparticles in experiment I. When the ZnO are exposed to UV light, reduction and oxidation (REDOX) reaction will occur on the ZnO surface and generate O2- and OH radicals. These powerful oxidizing agents are proven to be effective in decomposition of the harmful organic materials and convert them into CO2 and H2O. Therefore, we investigated that the photocatalytic activity was increased through the surface modification of synthesized ZnO nanoparticles. In experiment II, we studied on the stability of ZnO nanoparticles in water. It is well known that ZnO is unstable in water in comparison with TiO2. Zn(OH)2 was formed at the ZnO surface and ZnO become inactive as a photocatalyst when ZnO is present in the solution. Therefore, we prepared synthesized ZnO nanoparticles that were immersed in the water and dried in the oven. After that, we measured photocatalytic activities of prepared samples and find the cause of their photocatalytic activity changes.

• Journal of Energy Engineering
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• v.14 no.2 s.42
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• pp.105-111
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• 2005

In this study, the photocatalytic degradtion of D-glucose with the micro channel reactor was performed on the various experimental conditions. To apply the $TiO_2$ coating on the micro channel reactor, $TiO_2$ solution was synthesized by hydrolysis of titanium oxysulfate. The feeding rate was proportional to degradation rate of D-glucose solution over the micro channel reactor. Also, the reaction rate constant and Langmuir adsorption coefficient were calculated under various experimental conditions. And the results of these system photonic efficiencies were calculated. This study aims to understand the photocatalytic degradation characteristics on $TiO_2$ coating in the micro channel reactor experimented by the feed batch reaction system.

• Journal of Environmental Science International
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• v.13 no.10
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• pp.921-928
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• 2004

The photocatalytic decolorization of Rhodamine B (RhB) was studied using immobilized $TiO_2$ and fluidized bed reactor. Immobilized $TiO_2$(length: 1$\~$2 mm, width: 1$\~$3 mm, thickness: 0.5$\~$2 mm) onto silicone sealant was employed as the photocatalyst and a 30 W germicidal lamp was used as the light source and the reactor volume was 4.8 L. The effects of parameters such as the amounts of photocatalyst, initial concentration, initial pH, superficial velocity, $H_2O_2$ and anion additives. ($NO_3^{-},\;SO_4^{2-},\;Cl^{-},\;CO_3^{2-}$) The results showed that the optimum dosage of the immobilized $TiO_2$ were 87.0 g/L. Initial removal rate of RhB of the immobilized $TiO_2$ was 1.5 times higher than that of the powder $TiO_2$ because of the adsorption onto the surface of immobilized $TiO_2$ In the conditions of acidic pH, initial reaction rate was increased slowly and reaction time was shorted. The effect of anion type on the reaction rate was not much.

• Journal of the Korean Ceramic Society
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• v.42 no.1
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• pp.56-61
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• 2005

Highly durable photocatalytic paper containing anatase $TiO_{2}$, active carbon and ceramic fiber, which can adsorb VOCs and decompose them by photo oxidation simultaneously, was manufactured and characterized. Optimum concentration of PDADMAC to let $TiO_{2}$ adhere on the surfaces of active carbon and ceramic fiber selectively was $10\~15$ ppm in a slurry mixture for making photocatalytic paper. The thickness and basis weight of the produced catalytic paper by paper-making method were 0.4 mm and 380 $g/m^{2}$, respectively. Adsorption reaction by active carbon and photocatalytic decomposition reaction by $TiO_{2}$ were proceeded simultaneously, by which the abatement rate was found to be greatly enhanced compared to the similar environment with single adsorption reaction or single photocatalytic reaction only. The selective attachment of $TiO_{2}$ on ceramic fiber and active carbon was found to be very effective in preventing decomposition of substrate by the $TiO_{2}$ attack during exposure to UV light.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.1
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• pp.57-66
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• 2001

Gas phase photocatalytic oxidation of tetrachloroethylene (PCE) under 370 nm ultra-violet irradiation was investigated with TiO$_2$ catalyst. During the photocatalytic oxidation of PCE vapor several kinds of intermediate were produced, and the reaction pathways were proposed on the basis of the production sequency of the intermediates. The intermediates in the pathways of PCE oxidation were hexachloroethane, pentachlotoethane, 1, 1, 2-trichloroethane, carbon tetrachl-oride, dichloroacetylchloride, chloroform, 1,1-dichloroethane, phosgene, CO, $CO_2$, HCl, Cl$_2$.

• Journal of Photoscience
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• v.10 no.3
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• pp.231-236
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• 2003

TiO$_2$ has been used as photocatalyst since two and half decades ago. The efficiency in its photocatalytic reactions has been improved by increasing the surface area of the photocatalyst by supporting fine TiO$_2$ particles on some porous materials. In this work, heteropolytungstic acid (HPA) - encapsulated into the titanium exchanged SBA-15 mesoporous materials (TiSBA-15) were prepared and characterized. Also their photocatalytic effects on decomposition of phenol were investigated and the photodecomposition rates of the phenol were observed to be increased by 2.5 8 fold, as compared to those observed in the presence of HPA-encapsulated SBA-15 or TiSBA-15 without HPA.

• Journal of environmental and Sanitary engineering
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• v.19 no.2
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• pp.1-6
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• 2004

In Bok-Jeong water treatment plant, chlorination is the only technique used for disinfection of drinking water. This disinfecting treatment leads to the formation of trihalomethanes (THMs). This study was carried out to investigate the possibility of improving removal efficiency of THM precursor in the conventional water treatment processes by $TiO_2$ photocatalytic oxidation. Removal efficiencies of DOC, $UV_{254}$, THMFP were low in the conventional water treatment processes. With application of $TiO_2$ photocatalyst, DOC, $UV_{254}$, THMFP were reduced more effectively. As the $TiO_2$ photocatalytic reaction time increased, the removal efficiencies of DOC, $UV_{254}$, THMFP were increased. The $TiO_2$ photocatalytic removal efficiencies of DOC, $UV_{254}$, THMFP were increased with increasing $TiO_2$ dosage. However, over 0.6g/l of $TiO_2$ dosage, the efficiency reached a plateau.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.577-582
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• 2004

The photocatalytic degradation of atrazine and PCP, a endocrine disruptors, has been investigated over $TiO_2$ photocatalysts under ultraviolet (UV) light irradiation. The effect of operational parameters, i.e., pH, light intensity and persulphate concentration on the degradation rate of aqueous solution of atrazine and PCP has been examined. The results presented in this work demonstrate that, as pH and the light intensity increased, the photocatalytic reaction rates were enhanced. Individual use of $TiO_2$-persulphate was far more effective than using only $TiO_2$ in atrazine and PCP removal. Based on the overall experimental results, the photocatalytic oxidation of atrazine and PCP with the coated $TiO_2$ photocatalyst is found to be very effective under the operational conditions delineated in this study.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.295-295
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• 2012

The $TiO_2$ films were prepared in the $H_2SO_4$ solution containing $NH_4F$ at different anodic voltages, to compare the photocatalytic performances of titania for purification of waste water. The microstructure was characterized by a Field-emission scanning electron microscopy (FE-SEM) and X-ray diffractometry (XRD). Chemical bonding states and co-doped elements of F and N were analyzed using surface X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the co-doped $TiO_2$ films was analyzed by the degradation of aniline blue solution. From the result of diffuse reflectance absorption spectroscopy(DRS), it is indicated that the absorption edge of the F-N-codoped $TiO_2$ films shifted toward visible light area, and the photocatalytic reaction of $TiO_2$ was improved by doping an appropriate contents of F and N.