• 한국지반환경공학회 논문집
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• 제13권5호
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• pp.5-12
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• 2012

항생제는 환경에 지속적인 노출과 저항성으로 인해 우려물질로 간주되고 있다. 항생제의 제한적인 생분해능에 따른 하수처리장에서의 불완전한 제거와 광범위한 사용으로 인해 상대적으로 많은 양이 환경에 방류되고 있는 실정이다. 이에 본 연구에서는 다양한 촉매(Titanium dioxide; $TiO_2$, Hydroxyapatite; HAP)를 통해 항생제의 하나인 sulfamethoxazole의 동역학적 흡착과 광촉매반응에 대해 연구하였으며, 부가적으로 통계적 분석방법인 반응표면법(RSM)을 이용하여 UV/$TiO_2$/HAP 시스템에서의 운전인자의 영향을 살펴보았다. 동역학적 연구결과로 $TiO_2$/HAP의 흡착반응은 유사 2차 반응을 따르는 것으로 나타났으며, 입자내 확산 모델의 적용 결과, 반응속도 상수는 각각 $TiO_2$=$0.064min^{-1}$, HAP=$0.2866min^{-1}$와 $TiO_2$/HAP=$0.3708min^{-1}$으로 나타났다. RSM의 결과로는 ANOVA에서의 회귀항의 유의성이 나타났으며(P-value<0.05) 높은 결정계수 값($R^2$=96.2%, $R^2_{Adj}$=89.3%)이 나타나 이차 회귀모델의 예측이 만족스러운 것으로 관찰되었다. 그리고 Y(SMX 제거율, %)에 대해 예측된 최적 조건들은 코드화된 인자 기준으로 각각 $x_1$(SMX의 초기농도)=-0.7828, $x_2$(촉매의 양)=0.9974 그리고 $x_3$(반응시간)=0.5738로 나타났다. 입자내 확산 모델과 광촉매 산화 반응의 결과에 따르면 $TiO_2$/HAP 공정이 일반적인 고도산화공정에 비해 효율적인 것으로 관찰되었다.

• 한국물환경학회지
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• 제25권1호
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• pp.90-95
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• 2009

This study investigates the oxidative degradation of N-nitrosodimethylamine (NDMA), a probable human carcinogen, by advanced oxidation process (i.e., UV process). The experiments were performed with various pH, initial concentration, UV intensity, and addition of $H_2O_2$ or $TiO_2$ on UV process. The results showed that the direct UV photolysis was the most effective treatment method. The lower pH, intial concentration and higher intensity of UV stimulated higher NDMA removal. However, addition of oxidant ($H_2O_2$, $TiO_2$) slows down photochemical treatment of NDMA since the oxidant can filter out the UV light and block it to reach the NDMA molecules. Dimethylamine (DMA) and nitrite were found to be a major byproduct from NDMA oxidation. To evaluate the chronic toxicity effects of UV-treated NDMA on the growth of microalgae, "Skeletonema costatum", was studied as long term experiments. Results demonstrated that after the 13 days exposure the chronic toxicity was decreased about 15% with application of UV process on NDMA degradation.

• 한국재료학회지
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• 제20권4호
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• pp.228-234
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• 2010

In this paper, Fe-$TiO_2$ and Fe-fullerene/$TiO_2$ composite photocatalysts were prepared with titanium (IV) n-butoxide (TNB) by a sol-gel method. $TiO_2$, Fe-$TiO_2$ and Fe-fullerene/$TiO_2$ were characterized by scanning electron microscopy (SEM), Transmission electron microscope (TEM), specific surface area (BET), X-ray diffraction analysis (XRD) and energy dispersive X-ray spectroscopy (EDX). The photocatalytic activities were evaluated by the photocatalytic oxidation of methylene blue (MB) solution. XRD patterns of the composites showed that the photocatalyst composite contained a typical single and clear anatase phase. The surface properties shown by SEM presented a characterization of the texture on Fe-fullerene/$TiO_2$ composites and showed a homogenous composition in the particles for the titanium sources used. The EDX spectra for the elemental identification showed the presence of O, C and Ti elements. Moreover, peaks of the Fe element were observed in the Fe-$TiO_2$ and Fe-fullerene/$TiO_2$ composites. The degradation of MB solution by UV-light irradiation in the presence of photocatalyst compounds was investigated in complete darkness. The degradation of MB concentration in aqueous solution occurred via three kinds of physical phenomena: quantum efficiency of the fullerene; organo-metallic reaction of the Fe compound; and decomposition of $TiO_2$. The degradation rate of the methylene blue solution increased when using Fe-fullerene/$TiO_2$ compounds.

• 한국결정성장학회지
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• 제20권4호
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• pp.173-177
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• 2010

Sol-gel method로 합성한 anatase상의 $TiO_2$와 Yb와 Er을 codoping한 $TiO_2:Yb^{3+},\;Er^{3+}$ 파우더의 열적안정성과 이에 따른 광촉매 특성의 변화를 비교하였다. XRD 분석을 통하여 $TiO_2$ 결정성 및 상변화에 $Yb^{3+},\;Er^{3+}$ ions이 미치는 영향을 온도에 따라 비교하였으며 anatase $TiO_2$와 rutile $TiO_2$의 광학적 성질을 UV-Vis을 통하여 비교하였다. UV-Vis 분석결과 anatase $TiO_2:Yb^{3+},\;Er^{3+}$ ions도핑에 의하여 $TiO_2$의 밴드갭이 미세하게 감소함을 확인하였고 이를 통해 광촉매 작용을 향상시킬 수 있음을 확인하였다. $Yb^{3+}$ 이온과 $Er^{3+}$ 이온이 도핑된 $TiO_2:Yb^{3+},\;Er^{3+}$ 파우더를 980 nm에서 PL 분석하여 녹색 및 적색 형광을 하는 up-converting 형광특성을 분석하였다.

• 상하수도학회지
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• 제11권4호
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• pp.133-141
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• 1997

In order to treat the landfill leachate, $UV/TiO_2/H_2O_2$ system connected with biological treatment was investigated, and proper pretreatment methods were examined to reduce the load on the system considering economical and technical efficiency. It was more profitable to put $H_2O_2$ into the system in the early stage for the sample which was treated with $H_2SO_4$ to decrease alkalinity and with $FeCl_3-6H_2O$ flocculation. Because the required reaction time run up by increasing $H_2O_2$ input amount, though the COD was reduced slightly, the optimal $H_2O_2$ input amount should be determined for the desired COD and the economical efficiency. The appropriate way to get the lowest COD in the shortest time was the method to treat the sample which was controlled to pH 3.5 after adjusting to pH 12 and put 500 ppm $H_2O_2$ into the system. In that case, to increase $H_2O_2$ input amount was not profitable for the system efficiency. The sufficient photocatalytic excited time was required to reduce the photocatalytic decomposition time for the sample which was gone through the alkali state.

• 한국재료학회지
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• 제18권10호
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• pp.515-520
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• 2008

We fabricated 10 nm-$TiO_2$ thin films for DSSC (dye sensitized solar cell) electrode application using ALD (atomic layer deposition) method at the low temperatures of $150^{\circ}\;and\;250^{\circ}$. We characterized the crosssectional microstructure, phase, chemical binding energy, and absorption of the $TiO_2$ using TEM, HRXRD, XPS, and UV-VIS-NIR, respectively. TEM analysis showed a 10 nm-thick flat and uniform $TiO_2$ thin film regardless of the deposition temperatures. Through XPS analysis, it was found that the stoichiometric $TiO_2$ phase was formed and confirmed by measuring main characteristic peaks of Ti $2p^1$, Ti $2p^3$, and O 1s indicating the binding energy status. Through UV-VIS-NIR analysis, ALD-$TiO_2$ thin films were found to have a band gap of 3.4 eV resulting in the absorption edges at 360 nm, while the conventional $TiO_2$ films had a band gap of 3.0 eV (rutile)${\sim}$3.2 eV (anatase) with the absorption edges at 380 nm and 410 nm. Our results implied that the newly proposed nano-thick $TiO_2$ film using an ALD process at $150^{\circ}$ had almost the same properties as thsose of film at $250^{\circ}$. Therefore, we confirmed that the ALD-processed $TiO_2$ thin film with nano-thickness formed at low temperatures might be suitable for the electrode process of flexible devices.

• 한국결정학회지
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• 제12권3호
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• pp.177-181
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• 2001

TiO₂박막의 초친수성 특성을 열처리에 따른 박막의 결정구조 변화와 연관지어 연구하였다. 박막은 Sol-Gel법을 이용하여 실리콘 (100)웨이퍼 위에 제조하였다. 1차 소결후, 500℃에서 후열처리한 시편은 anatase 상을, 1000℃에서 열처리한 시편은 rutile 상을 가지며 그 중판 온도인 750℃에서 열처리한 경우는 anatase와 rutile상이 혼재 되어 있다. 이 후열 처리한 시편들은 UV를조사하지 않아도 친수성을 보였고, 특히 750℃에서 열처리한 시편은 5°이하의 초친수성을나타내었다. 친수성을 가지는 시편들은 암실처리 중 서서히 퇴화되어 소수성을 띄게되지만, UV를 조사하면 1시간 이내에 급격히 초진수성을 회복하는 우수한 특성을 보였다.

• 한국표면공학회지
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• 제40권4호
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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.

• Bulletin of the Korean Chemical Society
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• 제23권5호
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• pp.745-748
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• 2002

A novel titania sol for the preparation of hydrophilic TiO2 films was synthesized from TiCl4. TiO2 films were prepared by spraying the sol on glass substrates and the hydrophilic properties of the films were invest igated with illumination of UV light. The contact angle of a water drop on the films decreased to less than 7˚, which indicates the excellent hydrophilicity of the TiO2 films.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2008년도 춘계학술대회 논문집
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• pp.627-629
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• 2008