• Title/Summary/Keyword: $UV-TiO_2$

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Degradation of THM precursor using $TiO_2$ photocatalytic oxidation in the water treatment processes (정수처리공정에서 $TiO_2$광촉매를 이용한 THM전구물질 제거에 관한 연구)

  • Cho Deok-Hee;Seo Su-Man
    • 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.

UV Absorption of Nano-thick $TiO_2$ Prepared Using an ALD (ALD 방법으로 제조된 나노급 $TiO_2$에 의한 자외선 차단효과 연구)

  • Han, Jeung-Jo;Song, Oh-Sung;Ryu, Ji-Ho;Yoon, Ki-Jeong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.8 no.4
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    • pp.726-732
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    • 2007
  • We fabricated UV absorption functional $10{\sim}50nm-TiO_{2-x}/quartz$ structures layer using ALD (atomic layer deposition) method. We deposited $10nm-TiO_{2-x}$ layer on quartz substrate using ALD, and film thickness was determined by an ellipsometer. The others specimen thickness was controlled by ALD time lineally. We characterized controlling phase UV and visible optical property using an X-ray difractometer, a UV-VIS-IR spectrometer and a digital camera. $ALD-TiO_{2-x}$ layers were non-stoichiometric $TiO_{2-x}$ form and amorphous phases comparing with bulk $TiO_2$. While the conventional bulk $TiO_2$ had band gap of $3.0{\sim}3.2eV$ resulting in absorption edges at 380 nm and 415 nm, $ALD-TiO_{2-x}$ layers showed absorption edges at 197 nm and 250 nm. Therefore, our nano-thick $ALD-TiO_{2-x}$ was able to absorb shorter UV region and showed excellent transmittance in visible region. Our result implies that our newly proposed nano-thick $TiO_{2-x}$ using ALD process may improve transmittance in visible rays and be able to absorb shorter UV light effectively.

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Effect of particle size of TiO2 and octyl-methoxycinnamate (OMC) content on sun protection factor (SPF)

  • Choi, Jaeyeong;Kim, Suyeon;Kim, Woonjung;Eum, Chul Hun;Lee, Seungho
    • Analytical Science and Technology
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    • v.30 no.4
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    • pp.159-166
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    • 2017
  • Exposure to UV light, i.e., UV-A (320-400 nm) or UV-B (290-320 nm) radiation, can cause skin cancer. Titanium dioxide ($TiO_2$) effectively disperses UV light. Therefore, it is used as a physical UV filter in many UV light blockers. Usually, the $TiO_2$ content in commercialized UV blockers is 25 % at most. To block UV-B, a chemical UV blocker, octyl-methoxy cinnamate (OMC) is used. OMC is commonly used in combination with $TiO_2$. In this study, $TiO_2$ and OMC were mixed in different proportions to produce UV blockers with different compositions. Also the changes in the sun protection factor (SPF) based on the composition and $TiO_2$ particle sizes were investigated. In order to analyze the $TiO_2$ particle size, dynamic light scattering (DLS) and asymmetrical flow field-flow fractionation (AsFlFFF) were used. The results showed that the SPF was influenced by the proportion of $TiO_2$ and OMC, where the proportion of $TiO_2$ induced a more significant influence. In addition, changes in the $TiO_2$ particle size based on the proportion of OMC were observed.

The Deodorization and Antibacterial Activities of PLA Films Embedded with TiO2 Nanoparticles (TiO2 나노입자를 함유한 PLA 필름의 탈취성과 항균성)

  • Koo, Gwang-Hoe;Jang, Jin-Ho
    • Textile Coloration and Finishing
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    • v.20 no.6
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    • pp.1-7
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    • 2008
  • The effects of $TiO_2$ contents and UV irradiation treatment on the surface properties of PLA films embedded with $TiO_2$ nanoparticle were investigated. Whereas UV irradiation decreased reflectance of the treated PLA films proportionally with increasing UV energy, the reflectance of PLA/$TiO_2$ films increased with increasing UV energy. The UV irradiation treatment caused PLA/$TiO_2$ blend films more polar as indicated in the generation of new carbonyl group and decrease in zeta potentials, which was more pronounced with the introduction of $TiO_2$. Upon UV irradiation, $TiO_2$ particles appeared on the film surface as observed in SEM images. The PLA/$TiO_2$ blend films showed photocatalytic properties such as photobleaching of methylene blue, deodorization of ammonia and antimicrobial activity in comparison with pure PLA films.

The study of $Pt-TiO_{2}$ nanostructure electrode with UV for methanol oxidation (($Pt-TiO_{2}$ 나노구조에서의 UV에 의한 메탄올 산화반응연구)

  • Han, Sang-Beom;Song, You-Jung;Lee, Jong-Min;Park, Kyung-Won
    • 한국신재생에너지학회:학술대회논문집
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    • 2007.06a
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    • pp.220-223
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    • 2007
  • 이 논문은 DMFC와 태양전지의 하이브리드형 연료전지에 적합한 $TiO_{2}$구조에 대한 연구로서, DMFC에 사용되는 귀금속 Pt의 사용량을 줄이기 위해 Pt를 $TiO_{2}$광촉매 지지체에 함침 시켜 UV가 조사될 때 Pt의 활성을 극대화시키기 위한 연구이다. $TiO_{2}$는 Rutile결정 구조를 이루었으며, 반응 시간에 따라 나노막대 모양을 형성하였다. $NaBH_{4}$ 환원법을 통해 Pt를 함침 시켜 전극을 제조하였다. 이 전극들은 UV가 입사되지 않을 때보다 UV가 입사될 때 메탄올 산화성능이 주목할 만큼 향상되었다. 특히 긴 막대모양의 $TiO_{2}$에 백금이 잘 분산된 촉매의 메탄올 산화반응 성능이 크게 향상되었다. 이러한 $Pt/TiO_{2}$의 주목할 만한 성능 향상은 UV가 조사될 때 빛에 의해 생성된 $TiO_{2}$의 hole들에 의해 메탄올 산화반응이 향상된 것으로 사료된다.

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Advanced Oxidation Processes of Secondary Effluent for Reuse (재사용을 위한 하수처리장 방류수의 고급산화처리)

  • 조일형;송경석;성기석;정문호;이홍근;조경덕
    • Journal of Environmental Health Sciences
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    • v.26 no.3
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    • pp.61-68
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    • 2000
  • The use of photo-catalytic processes in pollution abatement and resource has a significant economic importance. Therefore, the applications of photochemical oxidation of secondary effluent driven by UV, TiO2, TiO2/UV, H2O2/UV and TiO2/H2O2/UV, have been investigated in order to treat the secondary effluent from municipal sewage. Various experimental parameters such as BOD, CODcr, Nurbidity, total P, and SPC were examined in each photo-catalytic reaction system. The results showed that the application of single oxidant such as UV, TiO2 only has a minor effect on parameters reduction (CODcr, BOD, etc) to treat the secondary effluent, whereas the combinations of oxidants increase the removal efficiency. The best removal efficiency in every parameters was achieved by the combination of TiO2, H2O2 and UV. It was also found that the optimum amount of TiO2 for the treatment was 1g/ι to achieve water reuse standard. From the results, the photocatalytic reaction system can be an alternative as a post-treatment to treat the secondary effluent from municipal sewage.

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A Study on the Operational Variables of the UV-TiO$_2$ Based Photocatalytic Air Cleaning System (UV-TiO$_2$ 광촉매 기반의 공기 정화 시스템의 운전조건에 대한 연구)

  • Han, Chang-Seok;Chang, Hyuk-Sang
    • Journal of Korean Society of Environmental Engineers
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    • v.30 no.3
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    • pp.293-301
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    • 2008
  • A study on the operational variables of the UV-TiO$_2$ based photocatalytic air cleaning system was tried. In this study, to examine effects as various air cleaning system conditions, a duct-type reactor was made, and TiO$_2$ was immobilized on a stainless mesh. Benzene was chosen as a target compound. Removal experiments for benzene were done under different initial benzene concentration, air velocity, TiO$_2$ loading, area coated TiO$_2$ as the same TiO$_2$ loading, and UV light intensity conditions. During the experiments, relative humidity was 55%, and reactor temperature was 45$^{\circ}C$. As a result, the photocatalytic degradation of benzene decreased as the inlet concentration increased. But the photocatalytic degradation increased as the concentration boundary layer thickness, amount of TiO$_2$, area coated TiO$_2$ as the same amount of TiO$_2$, and UV light intensity increased. Based on results of current study, they can be applied to the design of air cleaning system over low level VOCs in the indoor air.

Degradation of Humic Acid Using N-Doped TiO2 (질소를 도핑한 TiO2를 이용한 부식산 분해)

  • So, Ji-Yang;Rhee, Dong-Seock
    • Journal of Industrial Technology
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    • v.31 no.B
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    • pp.119-125
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    • 2011
  • N-doped Titanium oxides were prepared by using urea as a source of nitrogen. The photoactivities of the doped $TiO_2$ were evaluated on the basis of degradation of humic acid in aqueous solutions with different light sources, ultraviolet lamp, fluorescent lamp and solar light. XRD analysis was conducted to identify the crystal structure of the synthesized photocatalysts. N-doped $TiO_2$ and $pure-TiO_2$ was anatase type. SEM results showed that spherical particles were formed, which are the characteristics of the anatase form. N doped $TiO_2$ showed higher $UV_{254}$ decrease ratio and DOC removal ratio compared to $pure-TiO_2$. The humic acid degradation reaction using the UV-A lamp and UV-C lamp was assigned to pseudo-first order reaction. For solar light, only $pure-TiO_2$ and $N-TiO_2$ exhibited the pseudo-first order reaction.

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Comparative Studies Of the $UV/H_2O_2,\;UV/TiO_2/H_2O_2$ and Photo-Fenton Oxidation for Degradation of Citric Acid ($UV/H_2O_2,\;UV/TiO_2/H_2O_2$, Photo-Fenton 산화방법에 의한 Citric Acid의 분해효율 비교)

  • Seo, Min-Hye;Cho, Soon-Haing;Ha, Dong-Yun
    • Journal of Korean Society of Environmental Engineers
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    • v.28 no.4
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    • pp.429-437
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    • 2006
  • To establish the efficient treatment technology of chemical cleaning wastewater from power plant, several AOPs($UV/H_2O_2,\;UV/TiO_2/H_2O_2$, Photo-Fenton oxidation) were investigated. Treatment efficiencies and the electrical energy requirements based on the EE/O parameter(the electrical energy, required per order of pollutant removal in $1m^3$ wastewater) were evaluated. TOC removal efficiencies of $UV/H_2O_2,\;UV/TiO_2/H_2O_2$, Photo-Fenton oxidation at the optimum conditions were 95.5%, 92.3%, 91.5%, respectively. The electrical energy requirements of $UV/H_2O_2,\;UV/TiO_2/H_2O_2$, Photo-Fenton oxidation were $11.26kWh/m^3,\;3.85kWh/m^3,\;0.799kWh/m^3$, respectively. From these results, it could be concluded that all of the three oxidation processes were effective for the degradation of citric acid. Considering the treatment efficiency and economical aspect, photo-Fenton oxidation was the most efficient treatment process among the three processes tested.

A Study on the Swine Wastewater Treatment Using UV/TiO2/H2O2 (UV/TiO2/H2O2를 이용한 축산폐수처리에 대한 연구)

  • Kim, Chang-Kyun;Chung, Ho-Jin
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.3B
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    • pp.321-327
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    • 2006
  • This study was performed to provide basic information for evaluating the efficiency and applicable extent of photocatalysis for the treatment of swine wastewater. Acid area was more efficient than neutral and alkalic areas in wastewater treatment, and level of pH3 was the most effective and the treatment efficiency continually increased as the amount of photocatalyst was increased. When the photocatalyst was increased, $TCOD_{Mn}$ was removed faster than chromaticity. Pollutants were more effectively eliminated with both UV light illumination and $TiO_2$ than with either UV or $TiO_2$ alone. The removal efficiency was increased with the addition of $H_2O_2$ as an oxidant, but the removal efficiency was decreased with over an dosage of $H_2O_2$. The optimal dosage of $H_2O_2$ was 200 mg/L. Continuous injection of $H_2O_2$ was required for effective oxidation.