• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.131.1-131.1
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• 2007

• Journal of Environmental Health Sciences
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• v.31 no.5 s.86
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• pp.415-422
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• 2005

The photocatalytic decolorization of Reactive Red 2B(RR2B) was studied using immobilized photocatalyst/UV System. Two pairs of 20 W UV-B and UV-C lamps were employed as the light source. Immobilization of $TiO_2$ was carried out using sponge (as the photocatalyst body) and silicone sealant(as the binder). The effects of parameters such as the thickness, pore size of sponge photocatalyst and attached material on the reactor bottom were investigated. The results showed that the optimum thickness of sponge photocatalyst was 1 cm. Decolorization of reactor which had the bottom coated $TiO_2$ was higher than that of reactor attached aluminum plate. Decolorization of photocatalyst with large pore size(mean pore size, 3.8 mm) was higher than that of the small(mean pore size, 1.75 mm). Initial decolorization of RR2B could be descrived using the Langmuir-Hinshelwood(L-H) model and gave constant values of $0.55mg/l{\cdot}min(k)\;and\;2.65{\times}10^{-2}l/mg(K)$, respectively.

• Korean Journal of Materials Research
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• v.34 no.5
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• pp.254-260
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• 2024

This study is to manufacture a titanium dioxide (TiO₂) photocatalyst by recycling sludge generated using titanium tetrachloride (TiCl₄) as a coagulant. Compared to general sewage, a TiCl₄ coagulant was applied to dyeing wastewater containing a large amount of non-degradable organic compounds to evaluate its performance. Then the generated sludge was dried and fired to prepare a photocatalyst (TFS). Scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), and nitrogen oxide reduction experiments were conducted to analyze the surface properties and evaluate the photoactive ability of the prepared TFS. After using titanium tetrachloride (TiCl₄) as a coagulant in the dyeing wastewater, the water quality characteristics were measured at 84 mg/L of chemical oxygen demand (COD), 10 mg/L of T-N, and 0.9 mg/L of T-P to satisfy the discharge water quality standards. The surface properties of the TFS were investigated and the anatase crystal structure was observed. It was confirmed that the ratio of Ti and O, the main components of TiO₂, accounted for more than 90 %. As a result of the nitric oxide (NO) reduction experiment, 1.56 uMol of NO was reduced to confirm a removal rate of 20.60 %. This is judged to be a photocatalytic performance similar to that of the existing P-25. Therefore, by applying TiCl₄ to the dyeing wastewater, it is possible to solve the problems of the existing coagulant and to reduce the amount of carbon dioxide generated, using an eco-friendly sludge treatment method. In addition, it is believed that environmental and economic advantages can be obtained by manufacturing TiO₂ at an eco-friendly and lower cost than before.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.314-319
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• 2013

In this study, nitrogen doped $TiO_2$ ($N-TiO_2$) coated on an activated carbon pellet (ACP) was prepared using sol-gel and the solid state heat treatment of urea to improve the removal property of volatile organic compounds (VOCs). To explore the visible light photocatalytic activity of the ACP under the light emitting diods (LED), the removal property of benzene gas was characterized by gas chromatography. The SEM and BET results show that the increment of titanium tetra isopropoxide contents leads to the increased $TiO_2$ coating amount of ACP surface and decreased specific surface area. From the results of benzene gas removal, the breakthrough time of ACP10 increased about 2 times compared to that of the ACP. The improved performance was attributed to the $N-TiO_2$ coating on ACP surface, which could be more effective to remove benzene gas under the condition of LED lamp.

• Advances in environmental research
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• v.1 no.4
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• pp.289-304
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• 2012

Tris (2-methyl-1-aziridinyl) phosphine oxide (MAPO) is extremely poisonous and persistent in aqueous media. An efficient UV/nano$TiO_2$ process was employed for its mineralization in a high duty falling film photo-reactor based on an experimental design scheme that considers interactions between the main variables. The influencing variables and their range were determined with preliminary studies. The results show substrate mineralization to some extent under mild conditions of: T = $30^{\circ}C$, pH = 8.5, $[MAPO]_0=60\;mg\;L^{-1}$ and $[TiO_2]=110\;mg\;L^{-1}$. The relative importance of the influencing parameters were initial pH > temperature > $[MAPO]_0$ > [$TiO_2$]; while the interdependence of all the parameters was significant. Accordingly, a reduced quadratic expression was developed. Meanwhile, mineralization kinetic studies, based on chemical oxygen demand, revealed a power law model with order of 2.6 during process time until 150 min.

• Journal of Environmental Science International
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• v.14 no.8
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• pp.785-792
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• 2005

In order to reduce roadside and indoor air pollution for volatile organic compounds VOC), it may be necessary to apply photocatalyst-coated construction materials. This study evaluated the technical feasibility of the application of $TiO_2$ photocatalysis for the removal of VOC present in roadside or indoor air. The photocatalytic removal of five target VOC was investigated: benzene, toluene, ethyl benzene and o,m,p-xylenes. Variables tested for the current study included ultraviolet(UV) light intensity coating materials, relative humidity (RH), and input concentrations. Prior to performing the parameter tests, adsorption of VOC onto the current experiment was surveyed, and no adsorption was observed. Stronger UV intensity provided higher photocatalytic destruction(PCD) efficiency of the target compounds. For higher humidity, higher PCD efficiency was observed. The PCD efficiency depended on coating material. Contrary to certain previous findings, lower PCD efficiencies were observed for the experimental condition of higher input concentrations. The current findings suggested that the four parameters tested in the present study should be considered for the application of photocatalyst-coated construction materials in cleaning VOC of roadside or indoor air.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.574-583
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• 2021

Waste air containing ethanol (100 ppmv) and hydrogen sulfide (10 ppmv) was continuously treated by waste air-treating system composed of two annular photocatalytic reactors (effective volume: 1.5 L) packed with porous SiO₂ media carrying TiO₂-anatase photocatalyst, one of which was alternately operated for 32 d/run while the other was regenerated by 100 ℃ hot air with 15 W UV(-A)-light on. As its elimination-behavior of ethanol, the removal efficiencies of ethanol at 1^st, 2^nd and 3^rd operation of the photocatalytic reactor system(A), turned out to be ca. 60, 55 and 54%, respectively, at their steady state condition. Unlike the elimination-behavior of ethanol, its hydrogen sulfide-elimination behavior showed repeated decrease of hydrogen sulfide removal efficiency by its resultant arrival at a lower level of steady state condition. Nevertheless, the removal efficiencies of hydrogen sulfide at 1^st, 2^nd and 3^rd operation of the photocatalytic reactor system, turned out to be ca. 80, 75 and 73%, respectively, at their final steady state condition, higher by ca. 20, 20 and 19% than those of ethanol, respectively. Therefore, assuming that adsorption on porous SiO₂-photocatalyst carrier was regarded to belong to a reversible deactivation and that decreased % of removal efficiency due to the reversible deactivation of photocatalyst including the adsorption was independent of the number of its use upon regeneration, the increments of the decreased % of removal efficiency of ethanol and hydrogen sulfide, due to an irreversible deactivation of photocatalyst, for the 3^rd use of regenerated photocatalyst, compared with the 2^nd use of regenerated photocatalyst, were ca. 1 and 2%, respectively, which was insignificant or the less than those of ca. 5 and 5%, respectively, for the 2^nd use of regenerated photocatalyst compared with the 1^st use of virgin photocatalyst. This trend of the photocatalytic reactor system was observed to be similar to that of the other alternately-operating photocatalytic reactor system.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.108-114
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• 2018

Degradations of durability and aesthetic performance in concrete happen during service life due to surface deterioration and dirt stains. Recently, many researches have been performed on self-cleaning and surface enhancement through surface impregnant using photocatalytic reaction with VOCs(Volatile Organic Compounds) removal. This paper is for preliminary study on surface impregnation with silicate and photocatalysis - $TiO_2$. For the work, two types of silicate based impregnants(CS - Coloidal Silica and SC - Sodium Alumina Silicate) are considered. Several tests for viscosity and surface tension are performed, and pull-off test on impregnated concrete is performed. For the surface impregnated concrete, $TiO_2$ is absorbed through submerging and spraying conditions. Through compressive strength test and SEM analysis, it is evaluated that spraying $TiO_2$ on surface impregnated concrete after 30min. of drying period is very effective both for strength enhancement and surface densification.

• Journal of Hydrogen and New Energy
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• v.11 no.4
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• pp.161-169
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• 2000

In the case of photocatalytic hydrogen production from water, the performance-property relationships of CdS-TiO2 film type composite catalysts were investigated. To control the physical properties of the primary particles, the mixture of CdS and TiO2 nano-sols prepared by the sol-gel method at room temperature was hydrothermally treated at 240oC for 12hr. The film electrodes were prepared by the casting method. The photocurrents measured by a photoelectrochemical method and the hydrogen production rates measured by a photochemical method were closely dependent on the physical properties such as crystalline form, primary particle size and CdS/TiO2 mole ratio, and these varied in the range of 1.2~2.6 mA/cm2 and $1.0{\sim}1.6{\times}10-3mol/hr$, respectively.

• Journal of environmental and Sanitary engineering
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• v.20 no.4 s.58
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• pp.51-58
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• 2005

Photocatalytic degradation using $TiO_2$ Particles suspended in a reactor was experimentally performed to degrade the formaldehyde of indoor pollutants. Exponential increase of degradation appears to prove light availability due to the scattering of W light by particles themselves. Comparative removal studies of formaldehyde were done in both cases of dipping and spraying immobilized techniques of $TiO_2$ Particles suspended in solution. Experiments were performed under several different experimental conditions such as initial concentration of formaldehyde, UV intensity and concentration of photocatalysts. Optimal conditions to degrade formaldehyde were obtained under the conditions of $30\;mg/cm^2$ concentration of catalyst and UV intensity of 30 Watt at the distance of 30 cm using immobilized technique by dipping coating.