• Journal of Photoscience
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• 제12권1호
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• pp.17-23
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• 2005

Application of a new photocatalyst has been attempted to improve the efficiency and rates of photocatalytic degradation of azo dyes by using a model dye such as Methyl Orange. As a new photocatalyst, $TiO_2$ encapsulated EFAL-removed zeolite Y ($TiO_2$ /EFAL-removed zeolite Y) has been synthesized by ion-exchange in the mixture of EFAL-removed zeolite Y with 0.05 M aqueous [$(NH_4)_2 TiO(C_2O_4)_2.H_2O$] [$TiO(C_2O_4)_2.H_2O$]. This new photocatalyst has been characterized by measuring XRD, IR and reflectance absorption spectra as well as ICP analysis, and it was found that the framework structure of $TiO_2$ /EFAL-removed zeolite Y is not changed by removing the extra-framework aluminum (EFAL) from the normal zeolite Y and the $TiO_2$ inside the photocatalyst exists in the form of $(TiO^{2+})_n$ nanoclusters. Based on the ICP analysis, the Si/Al ratio of the $TiO_2$ /EFAL-removed zeolite Y and the weight of $TiO_2$ were determined to be 23 and 0.061g in 1.0g photocatalyst, respectively. It was also found that adsorption of the azo dye in the $TiO_2$ /EFAL-removed zeolite is very effective (about 80 % of the substrate used). This efficient adsorption contributes to the synergistic photocatalytic activities of the $TiO_2$ /EFAL-removed zeolite by minimizing the required flux diffusion of the substrate. Thus, the photocatalytic reduction of methyl orange (MO) was found to be 8 times more effective in the presence of $TiO_2$ /EFAL-removed zeolite Y than in the presence of $TiO_2$ /normal zeolite Y. Furthermore, the photocatalytic reduction of MO by using 1.0 g of the $TiO_2$ /EFAL-removed zeolite Y containing 0.061g of $TiO_2$ is much faster than that carried out by using 1.0 g of Degussa P-25.

• Environmental Engineering Research
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• 제21권3호
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• pp.291-296
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• 2016

Application of photocatalytic nanoparticles has been recently gaining an increased attention as air purifying material for sustainable urban development. The present work reports the photocatalytic removal of gaseous phase nitrogen oxides ($NO_x$) using $TiO_2$-coated zeolite to be applied as a filter media for the urban green infrastructure such as raingardens. The $TiO_2$-coated zeolite was synthesized by simple wet chemistry method and tested in a continuous-flow photo-reactor for its removal efficiency of $NO_x$ under different conditions of the weight percentage of $TiO_2$ coated on the zeolite, and gas retention time. The removal efficiency of $NO_x$ in general increased as the weight percentage of $TiO_2$ coated on the zeolite increased up to 15-20%. Greater than 90% of $NO_x$ was removed at a retention time of one minute using the $TiO_2$-coated zeolite ($TiO_2$ weight percentage = 20%). Overall, $TiO_2$-coated zeolite showed greater efficiency of $NO_x$ removal compared to $TiO_2$ powder probably by providing additional reaction sites from the porous structure of zeolite. It was presumed that the degradation of $NO_x$ is attributed to both the physical adsorption and photocatalytic oxidation that could simultaneously occur at the catalyst surface.

• Rapid Communication in Photoscience
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• 제4권1호
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• pp.19-21
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• 2015

Zeolite is an ideal host material for encapsulating nano-size metal catalyst species because of its defined microporous structure, prominent adsorption/condensation properties, high surface area, chemical/thermal stability, and transparency to light. In this study, $TiO_2$ photocatalyst was incorporated in highly hydrophobic Y zeolite and its photocatalytic activity was examined in the photocatalytic oxidation of olefins under UV-light irradiation using molecular oxygen as an oxygen source. $TiO_2$ nanoparticles incorporated in hydrophobic Y zeolite exhibited a markedly enhanced photocatalytic activity compared with bare $TiO_2$ owing to its excellent affinity toward organic moieties, which facilitates the mass transfer of organic substrates and allows them to efficiently access to the neighboring active $TiO_2$ surface.

• Journal of Photoscience
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• 제8권1호
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• pp.27-32
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• 2001

Photoreduction of Methyl Orange Catalyzed by Nile Red-Adsorbed TiO$_2$/Y zeolites. Nile Red was successfully adsorbed on TiO$_2$/Y zeolites and the absorption profile is very broad with maxima, ca. 630 nm. The peak is largely red-shifted compared to that observed in hydrocarbon solvents. Furthermore, a broad and largely Stokes shifted emission band as observed around 660 nm. The largely Stokes shifted emission band should be originated from the excited state structural changes. In order to understand the photocatalytic activities of Nile Red-adsorbed TiO$_2$/Y zeolite, the photoreduction of Methyl Orange(5.0$\times$10$^{-5}$ M) was studied using visible light beyond 320 nm. Methyl Orange was effectively reduced by Nile Red-adsorbed TiO$_2$/Y zeolite, indicating the photocatalytic activity of Nile Red-adsorbed TiO$_2$ zeolites was enhanced by about eight times higher than that of TiO$_2$/Y zeolite.

• 한국재료학회지
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• 제16권11호
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• pp.692-697
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• 2006

Deodorization of natural zeolites have been improved not only for polar but also for non-polar pollutants by sucessive ion exchanges of H and Ag ions starting from Korean natural zeolite with high adsorption capacity. The modified zeolites with $TiO_2$ coating on the surface revealed high deodorization and photocatalytic decomposition effects. Further modification was made with $10{\sim}20nm$ silica nano particles coating on the surface, the resulting composite particles of $SiO_2/TiO_2/modified$ natural zeolite revealed not only comparable deodorization but also better durability and resisatnce to color change compared to the $TiO_2$/modified natural zeolite without much compensation of photocatalytic decomposition effect, when the composite particles were exposed to the polypropylene non-woven fiber coated with organic binder. It is expected for the composite particle prepared here to be used as indoor building materials for indoor air quality control.

• 한국재료학회지
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• 제26권3호
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• pp.149-153
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• 2016

Nanosized zeolites were prepared in an autoclave using tetraethoxysilane (TEOS), tetrapropylammonium hydroxide (TPAOH), and $H_2O$, at various hydrothermal synthesis temperatures. Using transmission electron microscopy and particle size analysis, the nanopowder particulate sizes were revealed to be 10-300 nm. X-ray diffraction analysis confirmed that the synthesized nanopowder was silicalite-1 zeolite. Using atomic layer deposition, the fabricated zeolite nanopowder particles were coated with nanoscale $TiO_2$ films. The $TiO_2$ films were prepared at $300^{\circ}C$ by using $Ti[N(CH_3)_2]_4$ and $H_2O$ as precursor and reactant gas, respectively. In the TEM analysis, the growth rate was ${\sim}0.7{\AA}/cycle$. Zeta potential and sedimentation test results indicated that, owing to the electrostatic repulsion between $TiO_2$-coated layers on the surface of the zeolite nanoparticles, the dispersibility of the coated nanoparticles was higher than that of the uncoated nanoparticles. In addition, the effect of the coated nanoparticles on the photodecomposition was studied for the irradiation time of 240 min; the concentration of methylene blue was found to decrease to 48%.

• 공업화학
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• 제23권6호
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• pp.614-617
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• 2012

티타늄을 함유하는 제올라이트 촉매를 이용한 디시클로펜타디엔(DCPD)의 선택적 에폭시화 반응에 관한 연구를 수행하였다. 티타늄을 함유하는 제올라이트 계 촉매 중에 Ti-제올라이트 Y촉매가 에폭시화 반응에서 가장 좋은 활성을 보였다. 선정된 Ti-제올라이트 Y촉매를 이용하여 DCPD 에폭시화 반응에 미치는 과산화수소/DCPD의 비, 반응온도, 반응시간, 산처리 영향, 촉매의 양에 관한 여러 변수들의 영향이 연구되어 반응조건들이 DCPD 에폭시 반응에 미치는 영향에 관해 연구하였다. 또한 촉매 제조 방법에 따른 촉매에 존재하는 Ti 구조에 대해 IR과 UV-vis 기기를 이용하여 분석하였다.

• 공업화학
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• 제7권4호
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• pp.750-756
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• 1996

$TiO_2$ 고정화 물질은 Titanium tetraisopropoxide-isopropanol 용액에 제오라이트와 glass filter를 담지한 후, 이것을 공기중에 건조시켜 $500^{\circ}C$에서 소결하여 얻었다. Chlorothalnoil의 분석은 ECD가 부착된 가스크로마토그래피로 분석하였다. Chlorothalnoil에 대한 분해효율은 $TiO_2$로 지지된 광촉매가 효과적이었고, 3시간 후 완전히 분해되었다. 반응 생성물들은 $TiO_2$로 지지된 제오라이트에서는 $Cl^-$가 5.0ppm, $TiO_2$로 지지된 glass filter에서는 $Cl^-$가 7.5ppm,그리고 $TiO_2$ 분말에서는 $Cl^-$가 2.0ppm 각각 생성되었다. 그러나, $CN^-$는 지지체의 종류에 관계없이 검출한계이하였다.

• 산업기술연구
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• 제21권B호
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• pp.21-26
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• 2001

In this study, the effects of crystalinity, composition and particle size of $TiO_2$ catalysts on the degradations of humic acid in aqueous solution was assessed using the commercially avaliable $TiO_2$ particles. Photocatalytic oxidations of humic acid (HA, Aldrich Co.) solution were carried out in case of adding different types of $TiO_2$ catalysts and their decomposition efficiencies were analyzed with respect to pH, DOC and UV absorbances values for the HA solutions and compared one another. The experimental results showed that $TiO_2$ particles(Degussa P-25) mixed with anataze and rutile gave the highest degradation efficiencies, respectively and much lower degradation efficiency in $TiO_2$ paticles of rutile only type. In comparing among ST series of anataze types, it was observed that the degradation efficiencies generally were increased with increasing $TiO_2$ contents and surface area of the particles. Higher degradation efficiency of HA was also found in zeolite type(D-TZ) of $TiO_2$ paticles compared with hydroxyapatite type (D-TH) of $TiO_2$ particles.

• 한국광물학회지
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• 제20권4호
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• pp.267-275
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• 2007

생활폐기물 소각재를 용융시켜 제조한 슬래그에는 제올라이트 합성에 영향을 주는 많은 불순물이 포함되어 있다. 이러한 불순물들은 원하는 제올라이트 합성을 방해하며, 수율과 순도를 저하시킨다. 용융 슬래그에는 특히 $Fe_2O_3$, FeO 그리고 CaO가 많이 포함되어 있다. 이런 불순물들을 제거하기 위해 염산으로 슬러리의 초기 pH를 1, 3, 5 그리고 7로 하여 각각 처리하였다. 실험결과, 슬러리의 초기 pH가 낮아질수록 $SiO_2,\;Fe_2O_3,\;TiO_2$ 등의 함량은 증가되었으나, $Al_2O_3,\;FeO,\;CaO,\;Na_2O,\;K_2O,\;MgO$ 등의 함량은 감소되었다. 염산처리한 슬래그를 NaOH 용액과 함께 $80^{\circ}C$에서 반응시킨 결과, 슬래그, pH 7과 pH 5에서 처리한 시료로부터는 토버모라이트(tobermorite)가, pH 3과 pH 1에서 처리한 시료로부터는 Na-P1형과 Na-X형 제올라이트가 생성되었다. 또한 CaO가 제올라이트 합성을 방해한다는 것을 확인하였다.