• Title/Summary/Keyword: $TiO_2$/UV Process

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Preparation of $TiO_2$ thin films by coating-pyrolysis process of Ti-naphthenate (Ti-naphthenate의 코팅-열분해에 의한$TiO_2$ 박막의 제조)

  • 김진영;김승원;장우석;김현태;최상원
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.12 no.1
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    • pp.7-10
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    • 2002
  • $TiO_2$ thin films were prepared by coating and subsequent pyrolysis processes using Titanium-naphthenate as a raw material. $TiO_2$ thin films were made by spin-coating technique on the glass substrates, and heat treated at 45$0^{\circ}C$, The transmittance, refractive index, crystallinity and surface morphology of the $TiO_2$ thin films were measured by UV/Vis spec trophotometer, x-ray diffractometer and scanning electron microscope. $TiO_2$thin films on the slide glass showed the trans mittance of 70-90% and refractive index of 2.6 at 420 nm. The results of XRD and SEM showed that the $TiO_2$ thin films exhibited the anatase phase and the thread-like surface morphology.

Application of Photocatalytic Degradation for Efficient Treatment of Organic Matter in Landfill Leachate in Jeju Island (제주도 매립장 침출수 중 유기물의 효율적 처리를 위한 광촉매 분해 반응의 응용)

  • Lee, Chang-Han;Lee, Taek-Kwan;Cho, Eun-Il;Kam, Sang-Kyu
    • Journal of Environmental Science International
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    • v.31 no.8
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    • pp.677-689
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    • 2022
  • In order to photocatalytically treat organic matter (CODCr) and chromaticity effectively, chemical coagulation and sedimentation processes were employed as a pretreatment of the leachate produced from landfill in Jeju Island. This was performed using FeCl3·6H2O as a coagulant. For the treated leachate, UV/TiO2 and UV/TiO2/H2O2 systems were investigated, using 4 types of UV lamps, including an ozone lamp (24 W), TiO2 as a photocatalyst, and/or H2O2 as an initiator or inhibitor for photocatalytic degradation. In the chemical coagulation and sedimentation process using FeCl3·6H2O, optimum removal was achieved with an initial pH of 6, and a coagulant dosage of 2.0 g/L, culminating in the removal of 40% CODCr and 81% chromaticity. For the UV/TiO2 system utilizing an ozone lamp and 3 g/L of TiO2, the optimum condition was obtained at pH 5. However, the treated CODCr and chromaticity did not meet the emission standards (CODCr: 400 mg/L, chromaticity: 200 degrees) in a clean area. However, for a UV/TiO2/H2O2 system using 1.54 g/L of H2O2 in addition to the above optimum UV/TiO2 system, the results were 395 mg/L and 160 degrees, respectively, which were within the emission standard limits. The effect of the UV lamp on the removal of CODCr, and chromaticity of the leachate decreased in the order of ozone (24 W) lamp > 254 nm (24 W) lamp > ozone (14 W) lamp > 254 nm (14 W) lamp. Only CODCr and chromaticity treated with the ozone (24 W) lamp met the emission standards.

Fabrication of $TiO_2$-silver transparent thin films low-e coated on glass substrate by ink-jet printing (잉크젯 프린팅을 이용한 low-e $TiO_2$-silver 투명박막형성)

  • Yoon, Cho-Rong;Oh, Hyo-Jin;Lee, Nam-Hee;Guo, Yupeng;Kim, Byung-Whan;Kim, Sun-Jae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.511-511
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    • 2007
  • Low-emissivity (low-e) coatings with visible transparency have attracted increased interest m reducing heat radiation loss through window panes from ecological and sustainable aspects. $TiO_2$-silver transparent thin films for low-e have good properties for UV and IR blocking as well as photocatalyst compared to that with commercial UV blocking films such as fluorine doped oxide (FTO), antimony doped tin oxide (ATO), etc. In this study, transparent $TiO_2$-silver thin films were prepared by successive ink-jet printing of commercial nano silver and $TiO_2$ sol. The $TiO_2$ sol, as ink for ink-jet printing, were synthesized by hydrothermal process in the autoclave externally pressurized with $N_2$ gas of 200 bar at $120^{\circ}C$ for 10 hrs. The synthesized $TiO_2$ sols were all formed with brookite phase and their particle size was several to 30 nm. At first nano sized silver sol was coated on glass substrate, after that $TiO_2$ sol was coated by ink-jet printing. With increasing coating thickness of $TiO_2$-silver multilayer by repeated ink-jet coating, the absorbance of UV region (under 400nm) and IR region (over 700nm) also increase reasonably, compared to that with commercial UV blocking films.

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Photodegradation of Gaseous Toluene Using Short-Wavelength UV/TiO2 and Treatment of Decomposition Products by Wet Scrubber (단파장자외선/TiO2 공정에 의한 가스상 톨루엔의 분해 및 습식세정장치에 의한 분해생성물의 제거)

  • Jeong, Ju-Young;Jurng, Jong-Soo
    • Journal of Environmental Science International
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    • v.16 no.4
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    • pp.433-440
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    • 2007
  • The photodegradation and by-products of the gaseous toluene with $TiO_2$ (P25) and short-wavelength UV ($UV_{254+185nm}$) radiation were studied. The toluene was decomposed and mineralized efficiently owed to the synergistic effect of photochemical oxidation in the gas phase and photocatalytic oxidation on the $TiO_2$ surface. The toluene by the $UV_{254+185nm}$ photoirradiated $TiO_2$ were mainly mineralized $CO_2$ and CO, but some water-soluble organic intermediates were also formed under severe reaction conditions. The ozone and secondary organic aerosol were produced as undesirable by-products. It was found that wet scrubber was useful as post-treatment to remove water-soluble organic intermediates. Excess ozone could be easily removed by means of a $MnO_2$ ozone-decomposition catalyst. It was also observed that the $MnO_2$ catalyst could decompose organic compounds by using oxygen reactive species formed in process of ozone decomposition.

Advanced Water Treatment by Hybrid Process of Multi-channel Ceramic MF and Photocatalyst: Effect of Organic Materials (광촉매 및 다채널 세라믹 정밀여과 혼성공정에 의한 고탁도 원수의 고도정수처리: 유기물의 영향)

  • Amarsanaa, Bolor;Park, Jin-Yong
    • Membrane Journal
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    • v.21 no.4
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    • pp.351-359
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    • 2011
  • For advanced drinking water treatment of high turbidity water, we used the hybrid process that was composed of photocatalyst packing in space of between outside of multi-channel ceramic microfiltration membrane and membrane module inside. Photocatalyst was polypropylene (PP) beads coated $TiO_2$ powder by CVD (chemical vapor deposition) process. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, standard NOM solution was prepared with humic acid and kaolin. Water-back-flushing of 10 sec was performed per every period of 10 min to minimize membrane fouling. Resistance of membrane fouling ($R_f$) increased and J decreased as concentration of humic acid changed from 2 mg/L to 10 mg/L, and finally the highest total permeate volume ($V_T$) could be obtained at 2 mg/L. Then, treatment efficiency of turbidity and $UV_{254}$ absorbance were above 96.4% and 78.9%, respectively. As results of treatment portions by membrane filtration, photocatalyst adsorption, and photo-oxidation in (MF), (MF + $TiO_2$), (MF + $TiO_2$ + UV) processes, turbidity was treated little by photocatalyst adsorption, and photo-oxidation. However, treatment portions of $UV_{254}$ absorbance by adsorption (MF + $TiO_2$) and photo-oxidation (MF + $TiO_2$ + UV) at humic acid of 4 mg/L and 6 mg/L were above 9.0, 9.5 and 8.1, 10.9%, respectively.

The Study on Preparation Parameters of $TiO_2$Catalyst for Photodecomposition of Ethanol as a VOC (VOC물질중 에탄올 광분해반응을 위한 $TiO_2$촉매의 제초변수 고찰)

  • 이병용;김성욱;정석진
    • Journal of Korean Society for Atmospheric Environment
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    • v.17 no.4
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    • pp.363-370
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    • 2001
  • In this study, TiO$_2$, the popular photocatalyst, was used to decompose ethanol. TiO$_2$was prepared by the sol -gel method and coated on pyrex stick. A 15W, UV-A lamp was used as the UV light source and il gas chromatography (HP 5890) was used to confirm the concentrations of ethanol, $CO_2$and the intermediates. Variation of preparation parameters and calcination temperature for TiO$_2$photocatalysts in the sol -gel method caused changes of ethanol decomposition activity. The best ethanol photodecomposition activity was obtained on the sample when prepared with 0.14 mol of HCI, a mol of ethanol and 1.3 mol of TTIP ware mixed in sol-gel process and calcinated at 50$0^{\circ}C$ for 3 hours. Acetaldehyde was detected as an intermediate and decomposed to carbon dioxide and water at the end of the reaction.

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Characterization of Methylene Blue Decomposition on Fe-ACF/TiO2 Photocatalysts Under UV Irradiation with or Without H2O2

  • Zhang, Kan;Oh, Won-Chun
    • Korean Journal of Materials Research
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    • v.19 no.9
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    • pp.481-487
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    • 2009
  • The photocatalysts of Fe-ACF/$TiO_2$ compositeswere prepared by the sol-gel method and characterized by BET, XRD, SEM, and EDX. It showed that the BET surface area was related to adsorption capacity for each composite. The SEM results showed that ferric compound and titanium dioxide were distributed on the surfaces of ACF. The XRD results showed that Fe-ACF/$TiO_2$ composite only contained an anatase structure with a Fe mediated compound. EDX results showed the presence of C, O, and Ti with Fe peaks in Fe-ACF/$TiO_2$ composites. From the photocataytic degradation effect, $TiO_2$ on activated carbon fiber surface modified with Fe (Fe-ACF/$TiO_2$) could work in the photo-Fenton process. It was revealed that the photo-Fenton reaction gives considerable photocatalytic ability for the decomposition of methylene blue (MB) compared to non-treated ACF/$TiO_2$, and the photo-Fenton reaction was improved by the addition of $H_2O_2$. It was proved that the decomposition of MB under UV (365 nm) irradiation in the presence of $H_2O_2$ predominantly accelerated the oxidation of $Fe^{2+}$ to $Fe^{3+}$ and produced a high concentration of OH radicals.

Photocatalytic Efficiency of Anatase TiO$_2$Thin Film by Reactive Sputtering (Anatase TiO$_2$박막의 미세조직이 광촉매 효과에 미치는 영향)

  • Choe, Yong-Rak;Kim, Seon-Hwa
    • Korean Journal of Materials Research
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    • v.11 no.7
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    • pp.537-544
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    • 2001
  • Anatase $TiO_2$thin films as a photocatalyst were prepared by the reactive magnetron sputtering process. The $TiO_2$thin films were deposited on Si substrates under the various conditions : oxygen partial pressure, working pressure, sputtering time, and D.C. power. The photocatalystic degradation of $TiO_2$thin film have been studied to examine the contribution of surface morphology and crystallinity. The thin films with a good crystallinity or a rough surface showed a high photocatalytic degradation rate on phenol and E.coli 078 experiment. Compared with that of only UV radiation, the photocatalytic efficiency of $TiO_2$thin film under the UV radiation and the $O_2$ flow increased. We found that the crystallity and the morphology were the important factors on the photocatalytic efficiency of TiO$_2$thin film.

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Fabrication of La2O3-TiO2-SiO2 System Glass Derived from a Sol-Gel Process

  • Iwasaki, Mitsunobu;Masaki, Hitoshi;Ito, Seishiro;Park, Won-Kyu
    • Journal of the Korean Ceramic Society
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    • v.44 no.3 s.298
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    • pp.137-141
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    • 2007
  • $La_{2}O_{3}-TiO_{2}-SiO_{2}$ glass, a type that could not obtained so far by the conventional melting method, was prepared successfully using a sol gel process. Glass derived with the sol-gel process has compositions of $5La_{2}O_{3}-5TiO_{2}-90SiO_{2},\;5La_{2}O_{3}-10TiO_{2}-85SiO_{2}$, and $5La_{2}O_{3}-20TiO_{2}75SiO_{2}$. The UV-visible absorption edge of all glass compositions was below 400 nm. The measured density is in the range of 2.55-2.89, and was nearly identical to the calculated density and the refractive index of the glasses derived from the sol-gel ranges from 1.545 to 1.645. The molar additive coefficient of $TiO_{2}$ measured in this ternary system is lower than the calculated value, while the value of $La_{2}O_{3}$ is higher.

Optical properties of metal doped TiO2 thin films prepared by spin coating-pyrolysis process (스핀코팅으로 금속물질을 도핑한 TiO2박막의 광학적 특성)

  • Hwang, Kyu-Seong;Kim, Jai-Min;Jung, Ju-Hyun
    • Journal of Korean Ophthalmic Optics Society
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    • v.12 no.1
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    • pp.17-22
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    • 2007
  • Metal-doped $TiO_2$ thin films were prepared on soda-lime-silica glass substrates by using a spin coating-pyrolysis process. As-deposited films were prefired at $500^{\circ}C$ or 10 min in air. Five-coated films were finally annealed at $600^{\circ}C$ for 30 min in air. High resolution X-ray diffraction, field emission scanning electron microscope and UV spectrophotometer were used to analyze film's property. The largest red shift in optical energy gap is obtained in the Fe-doped $TiO_2$ film.

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