• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.105-114
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• 2007

The most advanced oxidation processes (AOPs) are based on reactivity of strong and non-selective oxidants such as hydroxyl radical (${\cdot}OH$). Decomposition of typical DNAPL chlorinated compounds (TCE, PCE) using various advanced oxidation processes ($UV/Fe^{3+}$-chelating agent/$H_2O_2$ process, $UV/H_2O_2$ process) was approached to develop appropriate methods treating chlorinated compound (TCE, PCE) for further field application. $UV/H_2O_2$ oxidation system was most efficient for degrading TCE and PCE at neutral pH and the system could remove 99.92% of TCE after 150 min reaction time at pH 6($[H_2O_2]$ = 147 mM, UVdose = 17.4 kwh/L) and degrade 99.99% of PCE within 120 min ($[H_2O_2]$ = 29.4 mM, UVdose = 52.2 kwh/L). Whereas, $UV/Fe^{3+}$-chelating agent/$H_2O_2$ system removed TCE and PCE ca. > 90% (UVdose = 34.8 kwh/L, $[Fe^{3+}]$ = 0.1 mM, [Oxalate] = 0.6 mM, $[H_2O_2]$ = 147 mM) and 98% after 6hrs (UVdose = 17.4 kwh/L, $[Fe^{3+}]$ = 0.1 mM, [Oxalate] = 0.6 mM, $[H_2O_2]$ = 29.4 mM), respectively. We improved the reproduction system with addition of UV light to modified Fenton reaction by increasing reduction rate of $Fe^{3+}$ to $Fe^{2+}$. We expect that the system save the treatment time and improve the removal efficiencies. Moreover, we expect the activity of low molecular organic compounds such as acetate or oxalate be effective for maintaining pH condition as neutral. This oxidation system could be an economical, environmental friendly, and practical treatment process since the organic compounds and iron minerals exist in nature soil conditions.

• Journal of Korean Society on Water Environment
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• v.35 no.6
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• pp.459-469
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• 2019

The ozonation of sulfamethoxazole (SMX) was performed at 20℃ using a pilot scale countercurrent bubble column reactor. Ozonation systems were combined with UV irradiation and TiO₂ addition. As the oxidation reaction proceeded in each treatment system, the pH of the sample decreased and in the O₃/UV/TiO₂ system, the pH change was the largest from 4.54 to 2.02. Under these experimental conditions, the scavenger impact of carbonate is negligible. The highest COD and TOC removal rate was observed in the O₃/UV/TiO₂ system due to the UV irradiation and the photocatalytic effect of TiO₂. Also, the highest mineralization ratio(ε) value is 0.2 in the O₃/UV/TiO₂ system, which means theoxidation capacity of the systems. The highest SMX degradation rate constants calculated by COD and TOC values (COD and TOC) were 2.15 × 10^-4 sec^-1 and 1.00 × 10^-4 sec^-1 in the O₃/UV/TiO₂ system, respectively. The activation energy (E_a) of ozone treatment follows the Arrhenius law. It was calculated based on _COD and _TOC. Each activation energy decreased in order of single O₃> O₃/TiO₂> O₃/UV > O₃/UV/TiO₂ system. The result showed that ΔH^≠ is more effective than ΔS^≠ in each SMX ozontaionsystem, that is characteristic of the common oxidation reaction.

• 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.

• 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.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.663-670
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• 2007

This study was performed to provide basic information for evaluating the efficiency and applicable extent of photocatalysis and ozonation for the treatment of dye wastewater. The treatability of dye wastewater by $UV/TiO_2$ and $UV/TiO_2/O_3$ advanced oxidation process (AOP) was investigated under various conditions. The experiments were conducted in a batch reactor of 50 liters equipped with twelve UV Lamps of 16W. In $UV/TiO_2$ AOP, the removal efficiency of TCODMn and Color increased to 58% and 67% respectively with increasing UV intensity. Also, The removal efficiency of TCODMn and Color increased to 97% and 99% respectively with increasing $H_2O_2$. Acid area was more efficient than neutral and alkalic areas in wastewater treatment, and pH 5 was the most effective and the treatment efficiency continually increased as the amount of photocatalyst was increased. When the photocatalyst was increased, TCODMn was removed faster than Color.

• Journal of Korean Society on Water Environment
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• v.33 no.6
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• pp.736-743
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• 2017

In this study, 4-nonylphenol (4-NP), an endocrine disrupting chemical, was removed by ozone treatment processes under the various experimental conditions including UV irradiation, $TiO_2$ addition. The ozone flow rate and concentration were maintained at $1.0L{\cdot}min^{-1}$ and $70{\pm}5mg{\cdot}L^{-1}$. The pH, COD and TOC of the samples were obtained every 10 minutes for 60 minutes in laboratory scale batch reactor. We found that the combination of UV irradiation and $TiO_2$ addition for ozonation improves the removal efficiency of COD and TOC in 4-NP aqueous solution. In case of the $O_3/UV/TiO_2$ system, COD and TOC were greatly reduced to 85.3 ~ 94.0% and 89.2 ~ 97.2%, respectively. 4-NP degradation rate constants, $k_{COD}$ and $k_{TOC}$, were calculated based on the COD and TOC values. Significantly, $k_{COD}$ and $k_{TOC}$ were improved in the $O_3/UV/TiO_2$ treatment process compared with single $O_3$ process, because the oxidation and the mineralization of 4-NP were increased by generating of the hydroxyl radical. The $k_{COD}$ and $k_{TOC}$ were obtained to be $5.81{\times}10^{-4}{\sim}10.8{\times}10^{-4}sec^{-1}$ and $11.9{\times}10^{-4}{\sim}19.4{\times}10^{-4}sec^{-1}$ in the $O_3/UV/TiO_2$ process. Activation energy ($E_a$) of ozone oxidation reaction based on $k_{COD}$ and $k_{TOC}$ were increased in order of $O_3/UV/TiO_2$ < $O3/UV$ < $O_3/TiO_2$ < $O_3$ process. It was confirmed that the addition of $TiO_2$ and UV irradiation to the ozone oxidation reaction significantly reduced the $E_a$ value and the degradation of 4-NP.

• 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.

• Journal of Sensor Science and Technology
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• v.18 no.1
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• pp.48-53
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• 2009

$Eu^{2+}$-doped ${SrAl_2}{O_4}$ and $Eu^{2+}$, $Dy^{3+}$ co-doped ${SrAl_2}{O_4}$ phosphors have been synthesized by conventional solid state method. Photocurrent properties of $Eu^{2+}$ doped ${SrAl_2}{O_4}$ and $Eu^{2+}$, $Dy^{3+}$ co-doped ${SrAl_2}{O_4}$ phosphors, in order to elucidate $Dy^{3+}$ co-doping effect, during and after ceasing ultraviolet-ray (UV) irradiation have been investigated. The photocurrent of $Eu^{2+}$, $Dy^{3+}$ co-doped ${SrAl_2}{O_4}$ phosphors during UV irradiation was 4-times lower than that of $Eu^{2+}$-doped ${SrAl_2}{O_4}$ during UV irradiation, and 7-times higher than that of $Eu^{2+}$-doped ${SrAl_2}{O_4}$ after ceasing UV irradiation. The photocurrent results indicated that holes of charge carriers captured in hole trapping center during the UV irradiation and liberated after-glow process, and made clear that $Dy^{3+}$ of co-dopant acted as a hole trap. The photocurrent of ${SrAl_2}{O_4}$ showed a good proportional relationship to UV intensity in the range of $1{\sim}5mW/cm^2$, and $Eu^{2+}$-doped ${SrAl_2}{O_4}$ was confirmed to be a possible UV sensor.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.4
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• pp.64-72
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• 1996

The effect of $O_3$, $O_3/pH$, and $O_3/H_2O_2$, $O_3/UV$, and $H_2O_2/UV$ advanced oxidation process(AOP) were investigated for the treatment of tetrachloroethylen(PCE) at various condition. The removal efficiency of 10, 20, and 30ppm PCE by ozonation were almost same, only about 60%. And pseudo first-order rate constants, ko for overall oxidation was about 0.097($min^{-1}$). In the $O_3/pH$ AOP experiment for the 20ppm PCE, the removal rate of PCE increased with the increase of pH. However, mineralization rate of PCE at pH 7 was higher than at pH 10. In the $O_3/H_2O_2$ AOP, the removal rate of PCE was the highest at peroxide-to-ozone dosage ratio of about 0.9, which PCE was removed over 99.95%. Despite 42% of PCE was directly photolyzed by the UV irradiation, the removal efficiency of PCE by $O_3/UV$ AOP was only about 70%. In $H_2O_2/UV$ AOP, the removal efficiency of PCE increased to about 98% in proportion to the $H_2O_2$ injection concentration at constant UV intensity of 5W/l.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3767-3771
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• 2012

In this study, we investigate the potential use of $TiO_2@SiO_2$ and $ZnO@SiO_2$ core/shell nanoparticles (NPs) as effective UV shielding agent. In the typical synthesis, $SiO_2$ was coated over different types of $TiO_2$ (anatase and rutile) and ZnO by sol-gel method. The synthesized $TiO_2@SiO_2$ and $ZnO@SiO_2$ NPs were characterized by UV-Vis, XRD, SEM and TEM. The UV-vis absorbance and transmittance spectra of core@shell NPs showed an efficient blocking effect in the UV region and more than 90% transmittance in the visible region. XRD and SAED studies confirmed the formation of amorphous $SiO_2$ coated over the $TiO_2$ and ZnO NPs. The FESEM and TEM images shows that coating of $SiO_2$ over the surface of anatase, rutile $TiO_2$ and ZnO NPs resulted in the increase in particle size by ~30 nm. In order to study the UV light shielding capability of the samples, photocatalytic degradation of methylene blue dye on $TiO_2@SiO_2$ and $ZnO@SiO_2$ NPs was performed. Photocatalytic activity for both types of $TiO_2$ NPs was partially suppressed. In comparison, the photocatalytic activity of ZnO almost vanished after the $SiO_2$ coating.