• Journal of Korean Society for Atmospheric Environment
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• v.22 no.E1
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• pp.19-26
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• 2006

The decomposition of gaseous $CH_3CHO$ was investigated by metal loaded $TiO_2$ (pure $TiO_2,\;Pt/TiO_2,\;Pd/TiO_2,\;Mn/TiO_2\;and\;Ag/TiO_2$) with $UV/TiO_2$ process and $UV/TiO_2/O_3$ process at room temperature and atmospheric pressure. Metal loaded $TiO_2$ was prepared by photodeposition. Decomposition of $CH_3CHO$ was carried out in a flow-type photochemical reaction system using three 10W black light lamps ($300{\sim}400nm$) as a light source. The experimental results showed that the degradation rate of $CH_3CHO$ was increased with Pt and Ag on $TiO_2$ compared to pure $TiO_2$, but decreased with depositing Pd and Mn on pure $TiO_2$. The considerable increase in the degradation efficiency of the $CH_3CHO$ was found by a combination of photocatalysis and ozonation as compared to only by ozonation or photocatalysis. Loading of Pt on $TiO_2$ promoted conversion of gaseous ozone. The degradation rate of gaseous $CH_3CHO$ decreased with an increase of water vapor in the feed stream for the both $UV/TiO_2\;and\;UV/TiO_2/O_3$ processes. The pure $TiO_2$ was more affected by the water vapor than Pt loaded $TiO_2$.

• Korean Journal of Materials Research
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• v.10 no.4
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• pp.264-269
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• 2000

TiO$_2$thin films were prepared on the glass by a conventional spin coating method with $TiO_2$ sol(30wt%, anatase). The thickness of the thin films were controlled by the number of coating cycles: one cycle is composed of spin coating, drying, and heating process. The reaction rate of the film was obtained by the photodecomposition of gaseous benzene under 0.44 and 2.0mW/$\textrm{cm}^2$ UV light on the film surface. For an incident UV light intensity of 0.44mW/$\textrm{cm}^2$, the reaction rate was increased with the thickness of the film, caused by extent of surface area, but there was no change over the thickness of about 4$\mu\textrm{m}$. The porous $TiO_2$ thin film has comparatively vast effective surface area, which under relatively high-intensity UV illumination causes the reaction rate to be controlled by the film thickness.

• International Journal of Highway Engineering
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• v.15 no.5
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• pp.65-73
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• 2013

PURPOSES : This study is to suggest future development direction and application of environmental noise barriers as multi-functional soundproof wall. METHODS : Based on the literature review, case study and patent search, research and patent trend were investigated. Patent search was conducted by Patent searching tools, 'Focust'. RESULTS : As environmental noise barriers, Vegetative soundproof wall, photovoltaic soundproof wall, and air-pollution reduction soundproof wall were investigated. First of all, In Korea, Vegetative soundproof wall is being developed mostly as soundproof wall that has vegetation foundation inside, to meet the domestic condition with 23 patent applications. Second, Photovoltaic soundproof wall is being developed mainly with efficiency of photovoltaic system rather than soundproofing. And it is limited to one generation solar cell technology, although Solar cell technology is developing at a rapid pace. On the other hand, for reducing air-pollutant by soundproof wall, a variety of methods are being suggested (filtration, adsorption, and photocatalytic oxidation), and one of them, adsorption are applied for developing air pollution reduction soundproof wall in Korea. CONCLUSIONS: The above soundproof wall is not simple structure, but road facility applied fusion technique. Therefore, as one system, it is difficult to harmonize due to various considerations for design factor. However, if it's possible that a benefits of one system apply to another system, Synergy effect may be created. In the foreseeable future, soundproof wall may be considered as a road system using fusion technique rather than just functional facility. Therefore, substantial studies for applying multi-functional soundproof wall on the road are needed for the future.

• Journal of the Korean institute of surface engineering
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• v.40 no.4
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• pp.190-196
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• 2007

Dye sensitized solar cells(DSSC) are the most promising future energy resource due to their high energy efficiency, low production cost, and simple manufacturing process. But one problem in DSSC is short life time compared to silicon solar cells. This problem occurred from photocatalytic degradation of dye material by nanometer sized $TiO_2$ particles. To prevent dye degradation as well as to increase its life time, the transparent coating film is needed for UV blocking. In this study, we synthesized nanometer sized $TiO_2$ particles in sols by increasing its internal pressure up to 200 bar in autoclave at $120^{\circ}C$ for 10 hrs. The synthesized $TiO_2$ sols were all formed with brookite phase and their particle size was several nm to 30 nm. Synthesized $TiO_2$ sols were coated on the backside of fluorine doped tin oxide(FTO) glass by ink jet printing method. With increasing coating thickness by repeated ink jet coating, the absorbance of UV region (under 400 nm) also increases reasonably. Decomposition test of titania powders dispersed in 0.1 mM amaranth solution covered with $TiO_2$ coating glass shows more stable dye properties under UV irradiation, compared to that with as-received FTO glass.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.4
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• pp.69-77
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• 2019

In this study, we evaluated the mechanical properties and nitrogen oxides removal characteristics according to the type and incorporation rate of the photocatalyst and investigated the method of separated placement for the production of economical and efficient photocatalyst concrete. As a result, when the photocatalyst incorporation rate was 5%, the highest compressive strength and elastic modulus were measured. As a result of evaluating the nitrogen oxides removal performance by the photocatalytic reaction, as the photocatalyst incorporation rate increased, the nitrogen oxide removal rate increased. At this time, the nitrogen oxides removal performance of photocatalyst P-25 was better than the NP-A. In consideration of economic efficiency, we have provided a method of separated placement for casting a constant thickness of concrete surface with photocatalyst concrete and evaluated the integrated performance at this time. As a result, it appears to be equal to or higher than mechanical performance and durability performance as compared with Plain, and it is judged that the integrated behavior is satisfied.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.5
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• pp.413-420
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• 2023

Holmium-doped TiO₂ nanotubes (Ho-TNTs) were manufactured through anodization treatment and electrochemical deposition, and optimization experiments were conducted using various Holmium doping concentrations and time as variables. Surface as well as electrochemical characteristics were analyzed to study the prepared photocatalysts. Ho-TNTs were found to exist only in anatase phase through X-ray diffraction analysis. Ho-TNTs with 0.01 wt% 100 seconds shows a photocurrent density of 3.788 mA/cm² and an effective photo-conversion efficiency (PCE) of 4.30%, which is more efficient than pure TiO₂ nanotubes (pure-TNTs) (at bias potential 1.5 V vs. Hg/HgO). The photocatalytic activity of the aforementioned Ho-TNTs for hydrogen production was evaluated with the result of -29.20 µmol/h·cm².

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.163-169
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• 2005

Photocatalytic oxidation of Cu(II)-EDTA has been studied using solar/$TiO_2$ photocatalysis as an energy source. Photocatalysis efficiency on the treatment of Cu(II)-EDTA was investigated using different types of solar collectors as well as by variation of the angles of solar collector solar light intensities, flow rates, and areas of solar collector. effect of $H_2O_2$ and types of $TiO_2$ catalyst on the treatment of Cu(II)-EDTA was also investigated. Removal of Cu(II) and DOC was favorable with a hemispherical collector than with a flat collector Removal of Cu(II) and DOC increased with increasing angles of solar collector up to $38^{\circ}$. Slurry type $TiO_2$ showed four-times higher removal efficiency than immobilized type $TiO_2$. Removal of both Cu(II) and DOC at a clear sky of solar light intensity ranging from 0.372 to $2.265\;mW/cm^2$ was greater than removal at a cloudy day of solar light intensity ranging from 0.038 to $1.129\;mW/cm^2$. From the result of this research that the removal efficiency of Cu(II) and DOC increased as the solar light intensity increased, it can be inferred that quantum yield in the destruction of Cu(II)-EDTA may directly related with the solar light intensity. Removal of Cu(II) increased as increasing the area of solar collector and was similar at lower flow rates white removal of Cu(II) was interfered at higher flow rates. When immobilized $TiO_2$ was used, removal efficiency of Cu(II) increased in the presence of $H_2O_2$ while negligible effect was found in the use of $TiO_2$ slurry.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.59-66
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• 2005

[ $TiO_2$ ] was deposited by DC magnetron sputtering on glass surface under various sputtering parameters such as discharge power($0.6{\sim}5.2\;kW$, substrate temperature($R.T{\sim}350^{\circ}C$), Ar and $O_2$ flow ratio with $0{\sim}50\;sccm$($Ar+O_2$ 90 sccm) and about 1 mtorr of pressure. TiO-N thin film was prepared under same sputtering conditions for $TiO_2$ thin film except flow ratio($Ar+O_2+N_2$ 90 sccm). The sheet resistance of thin films deposited under these parameters was measured to analyze electronic characteristic and thin film's thickness(${\alpha}$-step), surface roughness(AFM) and formation construction(FE-SEM, XRD) were also measured to draw optimal sputtering parameters. In order to evaluate photo-activity of thin film($TiO_2$, TiO-N) made in optimal parameters for removal of pollutants, toluene among VOCs and Suncion Yellow among reactive dyes were chosen to probe organic compounds for photo-degradation. It was shown that the photo-catalytic thin films had a significant photo-activation for the chosen contaminants and especially TiO-N thin film showed maximum efficiency of 33% for toluene(5 ppm) removal in visible-light range.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.1-8
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• 2005

In this study, $TiO_2$ powders were prepared by hydro-thermal synthesis with titanium tetra isopropoxide. The prepared $TiO_2$ and the commercial $TiO_2$(P-25, Degussa) were by impregnating $H_2PtCl_6$ solution or the leached solution from the waste catalytic converter of automobile. Modified photocatalysts were analyzed by ICP-AES, UV-DRS, XRD, SEM. And band-gap energy of modified photo-catalyst was found to decreased to 1.76eV and basic structure was changed upon modification by leached solution. Modified photocatalysts were coated on the wallpaper after using mixed solution with adhesive materials(PVC). And then to know the modified photo catalysts tested the reactivity and quantum efficiency in the mixed gas with NO as reactants in the photo catalytic reactor. In the gas phase, photo-catalytic activity of NO was the highest for modified P-25 catalysts(P-25(w)) that P-25(w) was impregnated by leached solution of wasted catalytic converter.

• Clean Technology
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• v.12 no.4
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• pp.244-249
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• 2006

The photocatalytic degradation of trichloroethlylene (TCE), has been investigated over $TiO_2$ photocatalysts irradiated with solar light. The effect of operational parameters, i.e., initial TCE concentration, $TiO_2$ concentration, pH and additives ($H_2O_2$, persulphate($S_2O{_8}^-$)) on the degradation rate of aqueous solution of TCE has been examined. The results presented in this work demonstrated that degradation of the TCE with $TiO_2/solar$ light was enhanced by augumentation in $TiO_2$ loading, pH, and adding additives but was inhibited by increase in initial TCE concentration. Also individual use of $H_2O_2$ was far more effective than using persulphate in TCE removal efficiency. Furthermore, the relative toxicity with a $solar/TiO_2/H_2O_2$ system was about 15% lower than with a $solar/TiO_2/persulphate$ system and about 35% lower than with a $solar/TiO_2$ system within a reaction time of 150 min, respectively.