• Title, Summary, Keyword: photocatalytic degradation

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Effects of Water Vapor, Molecular Oxygen and Temperature on the Photocatalytic Degradation of Gas-Phase VOCs using $TiO_2$Photocatalyst: TCE and Acetone

  • Kim, Sang-Bum;Jo, Young-Min;Cha, Wang-Seong
    • Journal of Korean Society for Atmospheric Environment
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    • v.17 no.E2
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    • pp.35-42
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    • 2001
  • Recent development of photocatalytic degradation method that is mediated by TiO$_2$ is of interest in the treatment of volatile organic compounds(VOCs). In this study, trichloroethylene(TCE) and acetone were closely examined in a batch scale of photo-reactor as a function of water vapor, oxygen, and temperature. Water vapor inhibited the photocatalytic degradation of acetone, while there was an optimum concentration in TCE. A lower efficiency was found in nitrogen atmosphere than air, and the effect of oxygen on photocatalytic degradation of acetone was greater than on that of TCE. The optimum reaction temperature on photocatalytic degradation was about 45$^{\circ}C$ for both compounds. NO organic byproducts were detected for both compounds under the present experimental conditions. It was ascertained that the photocatalytic reaction in a batch scale of photo-reactor was very effective in removing VOCs such as TCE and acetone in the gaseous phase.

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Photocatalytic degradation of TCE using solar energy in POFR (플라스틱 광섬유 광촉매 반응기에서 태양에너지를 이용한 TCE의 광촉매 분해)

  • Jeong, Hee-Rok;Moon, Il;Joo, Hyun-Ku;Jun, Myung-Seok
    • Journal of the Korean Solar Energy Society
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    • v.22 no.3
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    • pp.57-65
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    • 2002
  • The photocatalytic degradation of TCE using solar energy in POFR was studied. The use of solar energy was investigated in plastic optica fiber photocatalytic reactor (POFR). In POFR, the main parameters of photocatalytic degradation of TCE were lihgt intensity, thickness of $TiO_2$-coated film on plastic fiber core, the same of total $TiO_2$-coated surface area with changed length. We studied the apparent photonic efficiency and photocatalytic degradation rate of TCE in POFR. The apparent photonic efficiency of various light intensities was decreased by an incresed intensities. The photocatalytic activities of $TiO_2$-coated optical fiber reactor system depended on the coating thickness, and total clad-stripped surface area of POF. Photocatalytic degradation of trichloroethylene ($C_2HCl_3$, TCE) in the gas-phase was elucidated by using $TiO_2$-coated plastic optical fiber reactor. In TCE degradation, in-situ FTIR measurement resulted in mineralization into $CO_2$.

Sequential microbial-photocatalytic degradation of imidacloprid

  • Sharma, Teena;Kaur, Manpreet;Sobti, Amit;Rajor, Anita;Toor, Amrit Pal
    • Environmental Engineering Research
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    • v.25 no.4
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    • pp.597-604
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    • 2020
  • In the present study, the application of sequential biological and photocatalytic process was evaluated as a feasible process for the degradation of imidacloprid (IMI) in soil. Photocatalysis was carried out as a post and pre-treatment to the biological process as Microbial Photocatalytic (MP) and Photocatalytic Microbial (PM), respectively, to enhance the degradation and mineralization of IMI in soil. By both the processes, there was an enhancement in the percentage degradation of IMI i.e 86.2% for PM and 94.6% for MP process. The obtained results indicate that MP process is apparently more efficient in degradation of IMI which was observed with 15 days of biological treatment followed by 18 h of photocatalytic degradation (15 d + 18 h). The present work also reveals that though the difference in terms of the degradation of IMI after 5 d + 18 h, 10 d + 18 h & 15 d+ 18 h of MP process is not drastic, yet significant variation has been observed in terms of mineralization that truly signifies the removal of IMI from the soil. The LC analysis has shown that the intermediates formed during MP process are more and smaller in comparison to PM process, which further provides evidence that MP process is better than PM process for effective degradation of IMI in soil.

Degradation of Volatile Hydrocarbons Using Continuous-Flow Photocatalytic Systems with Enhanced Catalytic Surface Areas

  • Jo, Wan-Kuen;Yang, Sung-Hoon;Shin, Seung-Ho;Yang, Sung-Bong
    • Environmental Engineering Research
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    • v.16 no.2
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    • pp.91-96
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    • 2011
  • Limited information is available on the degradation of volatile hydrocarbons determined via the use of plate-inserted photocatalytic reactors. This has led to the evaluation of surface areas of cylindrical continuous-flow photocatalytic reactors for the degradation of three selected aromatic hydrocarbons. Three types of reactors were prepared: a double cylinder-type, a single cylindrical-type without plates and a single cylindrical-type with inserted glass tubes. According to diffuse reflectance, FTIR and X-ray diffraction (XRD) spectroscopy, the surface characteristics of a coated photocatalyst were very similar to those of raw $TiO_2$, thereby suggesting that the coated photocatalyst exhibited the same photocatalytic activity as the raw $TiO_2$. The photocatalytic degradation efficiencies were significantly or slightly higher for the single cylinder-type reactor than for the double cylinder-type reactor which had a greater catalytic surface area. However, for all target compounds, the degradation efficiencies increased gradually when the number of plates was increased. Accordingly, it was suggested that the surface area being enhanced for the plate-inserted reactor would elevate the photocatalytic degradation efficiency effectively. In addition, this study confirmed that both initial concentrations of target compounds and flow rates were important parameters for the photocatalytic removal mechanism of these plate-inserted photocatalytic reactors.

Photocatalytic Degradation of Brilliant Blue FCF with TiO2 Suspension (TiO2현탁액에 의한 Brilliant Blue FCF의 광촉매 분해)

  • Jeong, Gap Seop;Choe, Su Il
    • Journal of Environmental Science International
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    • v.13 no.6
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    • pp.599-603
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    • 2004
  • In a batch reactor, the characteristics of photocatalytic degradation of brilliant blue FCF in titanium dioxide suspension was studied under the irradiation of ultra-violet ray. Photocatalytic degradation in anatase type of TiO$_2$ was more effective than in rutile type of $TiO_2$ below the dosage of 5g. The degradation rate was slightly increased with decreasing initial pH of brilliant blue FCF aqueous solution, but rapidly increased with the addition of oxidant. Potassium bromate acted as more effective oxidant than ammonium persulfate. The photocatalytic degradation rate of brilliant blue FCF was pseudo-first order with rate constants of 0.012, 0.006 and $0.003min^{-1}$ at initial pH 3.1, 5.2 and 7.1 of brilliant blue FCF solution, respectively.

A Photocatalytic Degradation of Bromate over Nanosized Titanium Dioxide Prepared by Reverse Micelle (역상마이셀에 의한 나노크기 이산화티탄의 제조 및 브로메이트 광분해 특성)

  • 이만식;홍성수;박홍재;정영언;박원우
    • Journal of Environmental Science International
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    • v.11 no.9
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    • pp.987-992
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    • 2002
  • Nanosized titania sol has been produced by the controlled hydrolysis of titanium tetraisopropoxide(TTIP) in sodium bis(2-ethylhexyl)sulfosuccinate(AOT) reverse micelles. The physical properties, such as crystallite size and crystallinity according to R ratio have been investigated by FT-IR, XRD and UV-DRS. In addition, the photocatalytic degradation of bromate has been studied by using batch reactor in the presence of UV light in order to compare the photocatalytic activity of prepared nanosized titania. It is shown that the anatase structure appears in the 300~$600^{\circ}C$ calcination temperature range and the formation of anatase into rutile starts above $700^{\circ}C$. The crystallite size increases with increasing R ratio. In the photocatalytic degradation of bromate, the photocatalytic decomposition of bromate shows the decomposition rate increases with decreasing initial concentration of bromate and with increasing intensity of light.

A Study on Degradation of Nonylphenol Polyethoxylate Metabolites Using Uv / Photocatalytic Silicagel Treatment

  • Asano, Masahiro;Kishimoto, Naoyuki;Jiku, Fumihiko;Somiya, Isao
    • Journal of Wetlands Research
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    • v.9 no.1
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    • pp.99-105
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    • 2007
  • Nonylphenol polyetoxylates (NPnEOs) metabolites; nonylphenol (NP), nonylphenol monoethoxylate (NP1EO), nonylphenoxyacetic acid (NPEC) (collectively referred to "NPE-c") were examined for their degradations by using of lab-scale UV/photocatalytic silicagel (ultraviolet photocatalytic degradation in the presence of silicagel coated with titanium dioxide as a catalyst) reactor. NPE-c degradations by UV/photocatalytic silicagel treatment reached approximately 85-93 % after 40 min irradiation independently of its initial concentration (between ca. 0.5 and 2.0mg/l). Any intermediates under the NPE-c degradation were not identified by GC/MS sample analysis. Degradations of NPE-c were followed pseudo first-order kinetics. Then, the effectiveness of UV/photocatalytic silicagel treatment for degradation of NPE-c was in the order of NPEC > NP > NP1EO.

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A Kinetic Study on the Photocatalytic Degradation of Gas-Phase VOCs Using TiO$_2$ photocatalyst

  • Kim, Sang-Bum;Jo, Young-Min;Hong, Sung-Chang
    • Journal of Korean Society for Atmospheric Environment
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    • v.17 no.E3
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    • pp.117-124
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    • 2001
  • The present paper examined the kinetics of photocatalytic degradation of volatile organic compounds (VOCs) including gaseous trichloroethylene (TCE) and acetone. In this study, we examined the effects of the initial concentration of VOCs and the light intensity of ultra-violet (UV). A batch photo-reactor was specifically designed for this work. The photocatalytic degradation rate increased with the initial concentration of VOCs but remained almost constant beyond a certain concentration. It matched well with the Langmuir-Hinshelwood (L-H) kinetic model. When the effect of light intensity was concerned, it was found that photocatalytic degradation occurs in two regimes with respect to light intensity.

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Factors influencing a Photocatalytic System in Circulating Batch Mode: Photocatalyst Dosage, DO, Retention Time and Metal Impurities (순환회분식 광촉매시스템의 영향인자 연구: 광촉매 주입량, 용존산소, 체류시간,전자포획 첨가금속)

  • Kim, Il-Kyu
    • Journal of Korean Society of Water and Wastewater
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    • v.27 no.1
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    • pp.49-58
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    • 2013
  • A selected halogenated organic contaminant, monochlorophenol was successfully degraded by photocatalytic reaction in a circulating batch system. The photocatalytic degradation in most cases follows first-order kinetics. The photocatalytic reaction rate increased in the $TiO_2$ dosage range of 0.1 g/L to 0.4 g/L, then decreased with further increase of the dosage. Also the degradation rate increased over the range of the retention time from 0.49 min. to 0.94 min., then decreased with further increase of the retention time in the circulating batch reactor. The photocatalytic activity was enhanced by addition of metal impurities, platinum(Pt) and palladium(Pd) onto the photocatalysts. The photocatalytic degradation rate increased with the increase of Pt and Pd in the content range of 0 to 2wt %, then decreased with further increase of the metal contents. Therefore the metal loading to $TiO_2$ influence the degradation rate of a halogenated organic compound by acting as electron traps, consequently reducing the electron/positive hole pair recombination rate.

Photocatalytic degradation of methylene blue in aqueous solution using ceramsite coated with micro-Cu2O under visible-light irradiation

  • Li, Tianpeng;Sun, Tingting;Aftab, Tallal Bin;Li, Dengxin
    • The Korean Journal of Chemical Engineering
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    • v.34 no.4
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    • pp.1199-1207
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    • 2017
  • A novel ceramsite coated with micro-cuprous oxide ($Cu_2O$) catalyst was prepared and its photocatalytic activity was investigated by determining the degradation of methylene blue (MB) in aqueous solutions under Xe light. The results showed that the catalyst had many outstanding characteristics, such as higher BET specific surface area, larger pore size and stronger visible-light adsorption capacity, suggesting that it is a promising photocatalytic material. Under experimental conditions the initial concentration was 15 mg/L, pH was 3 and photocatalyst dosage was 0.5 g, and the degradation rate of MB reached 93.31% after Xe light was irradiated for 75 min. The photocatalytic degradation of MB followed the pseudo-first-order kinetics model, with high correlation coefficient values ($R^2$ >0.95). Some major degradation intermediates and desired products were identified by GC-MS and IC, respectively. Finally, the degradation pathways of MB by the catalyst under Xe light were proposed.