• Title, Summary, Keyword: Photocatalytic degradation

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Photocatalytic Degradation of Algae and its By-product using Rotating Photocatalytic Oxidation Disk Reactor

  • Son, Hee-Jong;Jung, Chul-Woo;Bae, Sang-Dae
    • Environmental Engineering Research
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    • v.14 no.3
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    • pp.170-173
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    • 2009
  • This study examined the special technique of photocatalytic degradation (RPODisk) for removal of taste and odor causing materials, algae, and algal toxin. The RPODisk was effective for removal of these troublesome contaminants. It outperformed the fixed media and the UV irradiation for geosmin removal. The RPODisk performance was comparable to the combination of the UV irradiation with TiO2. The RPODisk performance was affected by the rotating speed. The faster the speed was, the better the performance. The RPODisk was also effective for removal of algae and algal toxin. The algal activity reduced by 80% after 30 mins of the treatment. More toxic microcystin (MC)-LR was more difficult to remove than MC-RR. The times for 50% removal were 23.7 mins for MC-LR and 14.1 mins for MC-RR. Almost 100 mins of the contact time was required to completely remove MC-LR at the rotating speed of 260 rpm.

The Microwave-assisted Photocatalytic Degradation of Methylene Blue Solution Using TiO2 Balls Prepared by Chemical Vapor Deposition (CVD법으로 제조된 산화티탄 볼과 마이크로웨이브를 이용한 메틸렌블루 수용액의 광촉매분해)

  • Park, Sang-Sook;Park, Jae-Hyeon;Kim, Sun-Jae;Jung, Sang-Chul
    • Korean Chemical Engineering Research
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    • v.46 no.6
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    • pp.1063-1068
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    • 2008
  • The photocatalytic degradation of methylene blue water solution was carried out by irradiating microwave and UV light simultaneously using $TiO_2$ photocatalyst balls prepared by Chemical Vapor Deposition method. A microwave-discharged electrodeless UV lamp was developed to use microwave and UV simultaneously for photocatalytic reactions. The results of photocatalytic degradation of methylene blue showed that the decomposition rate increased with the microwave intensity, the circulating fluid velocity and auxiliary oxidizing agents added. Especially, the rate constant of $H_2O_2$-added photocatalytic reaction increased about three times from $0.0061min^{-1}$ to $0.0197min^{-1}$ when microwave was additionally irradiated. This study demonstrates that the microwave irradiation can play a very important role in photocatalytic degradation using peroxides although it is not easy to quantitatively assess the effect of microwave on photocatalytic reactions from the experimental data of this study.

Microwave-assisted Photocatalytic Degradation of Methylene Blue (마이크로웨이브가 부가된 광촉매에 의한 메틸렌블루의 분해)

  • Kim, Yu-Bong;Jo, A-Ra;Ra, Deog-Gwan;Park, Jae-Hyeon;Kim, Sun-Jae;Jung, Sang-Chul
    • Journal of Korean Society of Environmental Engineers
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    • v.30 no.8
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    • pp.817-822
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    • 2008
  • In this study, the photocatalytic degradation of methylene blue in TiO$_2$ particles-dispersed water solution was carried out by irradiating microwave and UV light simultaneously. A microwave-discharged electrodeless UV lamp was developed to use microwave and UV simultaneously for photocatalytic reactions. The results of photocatalytic degradation of methylene blue showed that the decomposition rate increased with the microwave intensity, the circulating fluid velocity, and the amount of TiO$_2$ particles and auxiliary oxidizing agents added. Especially, the rate constant of H$_2$O$_2$-added photocatalytic reaction increased about three times from 0.0075 min$^{-1}$ to 0.0250 min$^{-1}$ when microwave was additionally irradiated. This study demonstrates that the microwave irradiation can play a very important role in photocatalytic degradation using peroxides although it is not easy to quantitatively assess the effect of microwave on photocatalytic reactions from the experimental data of this study.

Degradation of Chlorinated Hydrocarbons via a Light-Emitting Diode Derived Photocatalyst

  • Jo, Wan-Kuen;Lee, Joon Yeob
    • Environmental Engineering Research
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    • v.18 no.1
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    • pp.21-28
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    • 2013
  • In this study, the applicability of visible light-emitting-diodes (LEDs) to the photocatalytic degradation of indoor-level trichloroethylene (TCE) and perchloroethylene (PCE) over N-doped $TiO_2$ (N-$TiO_2$) was examined under a range of operational conditions. The N-$TiO_2$ photocatalyst was calcined at $650^{\circ}C$ (labeled N-650) showed the lowest degradation efficiencies for TCE and PCE, while the N-$TiO_2$ photocatalysts calcined at $350^{\circ}C$, $450^{\circ}C$, and $550^{\circ}C$ (labeled as N-350, N-450, and N-550, respectively) exhibited similar or slightly different degradation efficiencies to those of TCE and PCE. These results were supported by the X-ray diffraction patterns of N-350, N-450, N-550, and N-650. The respective average degradation efficiencies for TCE and PCE were 96% and 77% for the 8-W lamp/N-$TiO_2$ system, 32% and 20% for the violet LED/N-$TiO_2$ system, and ~0% and 4% for the blue LED/N-$TiO_2$ system. However, the normalized photocatalytic degradation efficiencies for TCE and PCE for the violet LED-irradiated N-$TiO_2$ system were higher than those from the 8-W fluorescent daylight lamp-irradiated N-$TiO_2$ system. Although the difference was not substantial, the degradation efficiencies exhibited a decreasing trend with increasing input concentrations. The degradation efficiencies for TCE and PCE decreased with increasing air flow rates. In general, the degradation efficiencies for both target compounds decreased as relative humidity increased. Consequently, it was indicated that violet LEDs can be utilized as energy-efficient light sources for the photocatalytic degradation of TCE and PCE, if operational conditions of N-$TiO_2$ photocatalytic system are optimized.

광촉매 반응에 의한 환경호르몬 분해특성

  • 박재홍;안상우;장순웅
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • pp.358-361
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    • 2004
  • The photocatalytic degradation of Endocrine Discruptors, dibuthyl phthalate(DBP) has been investigated over TiO$_2$ photocatalysts irradiated with a ultraviolet (UV) light. The effect of operational parameters, i.e., reaction time, light intensity, pH and additive on the degradation rate of aqueous solution of Endocrine Discruptors has been examined. Results show that the employment of efficient photocatalysts and the selection of optimal operational parameters may lead to degradation of Endocrine Discruptors solutions.

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Photocatalytic degradation of MTBE in gas phase (광촉매 반응에 의한 기상 MTBE 분해)

  • Park, Sang-Eun;Joo, Hyun-Ku;Jeong, Hee-Rok;Chun, Myung-Suk;Auh, Chung-Moo;Kang, Joon-Wun
    • Journal of the Korean Solar Energy Society
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    • v.21 no.2
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    • pp.55-67
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    • 2001
  • This study contains the photocatalytic degradation of methyl-tert-butyl ether(MTBE), one of water-contaminating substances, into $CO_2$. Herein was investigated factors, kinetics, and reaction pathways related with MTBE degradation. This works is possible to be applied in the field of environmental remediation such as undergroundwater purification with optimized system configuration in the near future.

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Photocatalytic Degradation of 2,4,6-Trinitrotoluene in Wastewater Using a Thin-Film TiO2 Reactor

  • Shin, Gi-Bum;Kim, Yeong-Kwan
    • Environmental Engineering Research
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    • v.13 no.1
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    • pp.28-32
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    • 2008
  • The photocatalytic treatment of water contaminated with 2,4,6-trinitrotoluene (TNT) was explored in bench-scale experiments in batch mode using a Pyrex tube coated with a thin film of $TiO_2$ located inside a photoreactor. The reactor was aerated by purging it with compressed air before initiating the photocatalytic reaction. The rate of TNT degradation approximated first-order kinetics. The reaction rate constant decreased as the TNT concentration increased from 25 to 100 mg/L, while the first-order kinetics could be modeled using a Langmuir adsorption isotherm. The addition of the organic reductants methanol and EDTA significantly enhanced the rate of TNT degradation, with optimum results in the presence of 20% methanol by volume. EDTA increased the rate of TNT removal by enhancing the role of the reductants.

The Photocatalytic Degradation Properties of PET and Nylon 6 Fabrics Treated with Nano $TiO_2$ (나노 $TiO_2$로 가공한 폴리에스터와 나일론 직물의 광분해성에 관한 연구)

  • Hong, Kyung-Hwa;Kang, Tae-Jin
    • Textile Science and Engineering
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    • v.42 no.4
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    • pp.235-240
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    • 2005
  • In this study, we prepared $TiO_2$ nanoparticles $(<\~10nm)$ whose crystalline structure were predominantly anatase. However, during the pad-dry-cure process, many of the $TiO_2$ particles aggregated on the surface of nylon and PET fabrics. The antimicrobial activities and photocatalytic degradation properties of the Ti02 treated nylon and PET fabrics were analyzed and the results suggest that the $TiO_2$ promotes the degradation of the nylon and PET polymers.

Fabrication of Ag/In2O3/TiO2/HNTs hybrid-structured and plasma effect photocatalysts for enhanced charges transfer and photocatalytic activity

  • Wang, Huiqin;Wu, Dongyao;Liu, Chongyang;Guan, Jingru;Li, Jinze;Huo, Pengwei;Liu, Xinlin;Wang, Qian;Yan, Yongsheng
    • Journal of Industrial and Engineering Chemistry
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    • v.67
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    • pp.164-174
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    • 2018
  • The purpose of this work designed hybrid-structured and plasma effect photocatalyst of $Ag/In_2O_3/TiO_2/HNTs$ via sol-gel and photo-reduction methods. The structures, morphologies, optical and photoelectric performances of as-prepared photocatalysts were characterized via XRD, TEM, XPS, BET, UV-vis DRS, PL and photocurrents. The photocatalytic activity was evaluated by degradation of TC. The results showed that the hybrid-structure and plasma effect can effectively cause the multi-transfer of electrons and increase the separation rate of electron and hole pairs which obtained high photocatalytic activity. The photocatalytic degradation processes reveal that $^{\bullet}O_2{^-}$ and $h^+$ are major active species.

Enhanced Photocatalytic Properties of Visible Light Responsive La/TiO2-Graphene Composites for the Removal of Rhodamin B in Water

  • Areerob, Yonrapach;Oh, Won-Chun
    • Journal of the Korean Chemical Society
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    • v.61 no.4
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    • pp.168-178
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    • 2017
  • $La/TiO_2$ - graphene composites were synthesized in this study, and applied to the photocatalytic degradation of Rhodamine B (RhB) under UV-visible light irradiation. X-ray diffraction (XRD), surface analysis, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) analysis demonstrated that $La/TiO_2$ nanoparticles were well distributed on the surface of graphene, and formed the heterostructure of $La/TiO_2$-graphene. Compared to the pure $TiO_2$, $La/TiO_2$-graphene composites displayed much higher photocatalytic activities in RhB degradation under UV-visible light irradiation. The photocatalytic data of $La/TiO_2$-graphene composites exhibit extended light absorption in the visible light region, and possess better charge separation capability than that of pure $TiO_2$. The high photocatalytic activity was attributed to the composite's high adsorptivity, extended light absorption, and increased charge separation efficiency, due to the excellent electrical properties of graphene, and the large surface contact between graphene and $La/TiO_2$ nanoparticles.