• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6952-6957
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• 2014

In photocatalysis, the addition of metal matter to $TiO_2$ can alter the surface properties. As such, the metal can increase the rate of the photodegradation reaction. In this study, a range of modified $TiO_2$ photocatalysts were prepared and tested to improve the activity of photodegradation at a batch-typed photoreactor. To obtain a good sol solution of the $TiO_2$ photocatalyst, several types of dispersion agents and stabilizers were investigated. The photocatalyst solutions were modified with isoproply alcohol as the dispersion agent and sodium silicate as the stabilizer. The effects of various metallic elements on enhancing the photocatalytic activity of $TiO_2$ on the degradation of toluene were examined. Palladium-added $TiO_2$ was found to be the best, whereas copper or tungsten-added also showed good results. In the case of palladium addition, the increase in removal efficiency was 25%. On the other hand, Fe-added $TiO_2$ showed a notable decrease in photocatalytic degradation. Additional doping of copper or tungsten on the $Pd/TiO_2$ had no positive effect on the photodegradation activity.

• Analytical Science and Technology
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• v.7 no.3
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• pp.321-327
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• 1994

The mild thermal decomposition of 7, 7-dimethyl-1, 2, 3, 4, 5-pentaphenyl-7-silanorbornadiene with excess methyl alcohol proceeds to give 1-methoxydimethylsilyl-1, 2, 3, 4, 6-pentaphenylcyclohexa-2, 5-diene which is colorless needle crystal. The cophotolysis of the solution of 7-silanorbornadiene in the excess ethyl alcohol proceeds with loss of silylenes to give ethoxydimethylsilane which is insertion reaction product of silylene with O-H bond of ethyl alcohol. According to above results, it is presumed that the mechanism of photochemical decomposition and that of mild thermochemical decomposition of 7-silanorbornadiene are different.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.2
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• pp.124-130
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• 2013

Of all the brominated flame retardants (BFRs), TBBPA has the largest production volume (50% of the BFRs in current use). It is interest to investigate how they may degrade, because of it can pose an environmental hazard. By using UV-A (${\lambda}=352nm$ ), we have found that the UV-A irradiation increased the photodecomposition reaction rate of TBBPA in an intensity-dependent manner. We also observed 2,6-dibromo-p-benzosemiquinone radical ($a_{2H}=2.36G$, g = 2.0056) generated from TBBPA by reaction with singlet oxygen ($^1O_2$). On the other hand, when an aqueous preparation of HA was irradiated in the presence of TBBPA, the typical spectrum of semiquinone radical was detected by electron spin resonance (ESR). And then, we have found that the photodecomposition rate of TBBPA is decreased in depend on HA concentration. Radical formation and the reactive rate of TBBPA were inhibited by sodium azide used as a singlet oxygen quencher. Therefore we report that a similar $^1O_2$-induced oxidation can be initiate in aqueous solutions of TBBPA dissolved in humic acid (HA) by the UV-A irradiation (${\lambda}=352nm$). From these results, we suggest that the reaction rate of HA with $^1O_2$ is faster than that of TBBPA with $^1O_2$.

• Environmental Analysis Health and Toxicology
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• v.15 no.3
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• pp.93-98
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• 2000

The photosatalytic oxidation of the model compound, 1, 3, 5-trichlorobenzene (1, 3, 5-TCB) has been investigated employing photolysis. The effects of parameters such as illumination time, initial concentration, pH and HA were investigated. Pt(IV)/AMM-Ti particles used as a photocatalyst showed a time-dependent enhancement of the photooxidation/reduction activity in the presence of HA.

• Journal of the Korean Chemical Society
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• v.52 no.1
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• pp.66-72
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• 2008

The photocatalytic degradation of a textile diazo dye in aqueous solution has been investigated under Solar and UV-A light. The effect of various parameters such as concentration of dye, amount of catalyst and pH on the degradation of dye has been studied. Addition of hydrogen peroxide, ammonium persulphate and isopropanol strongly influences the degradation rate. Kinetic analysis of photodegradation reveals that the degradation follows approximately pseudo first order kinetics according to the Langmuir-Hinshelwood model. Carbon dioxide, nitrate and sulphate ions have been identified as mineralisation products. The photocatalyst ZnO was found to be more efficient in UV-A light than in Solar light.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.04a
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• pp.311-312
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• 2002

환경분야에서 광촉매는 주로 오염물질의 광분해처리에 이용되고 있는데, 기존에 사용되고 있는 광분해 방법은 광촉매 미립자를 수용액에 슬러리 형태로 분산시키거나 fixed bed, fluidized bed에 부착시킨 형태의 반응기들이다. 실험적 수준의 연구로부터 얻어진 여러 연구 결과에 의하면 슬러리 형태의 반응기가 고정화 촉매 반응기보다 효율이 더 높은 것으로 보고되고 있다. 그러나 엔지니어링 관점에서 슬러리형 반응기는 촉매의 재활용과 정화 처리 후 촉매입자를 유체로부터 분리해야하는 결점이 있다. (중략)

• Clean Technology
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• v.16 no.1
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• pp.46-50
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• 2010

This study focuses on the removal of water-suspended toluene of a representative sick house compounds in a liquid photo-system using nanometer-sized Sn-incorporated $TiO_2$ which was synthesized by a solvothermal method. The characteristics of the synthesized Sn-$TiO_2$ were analyzed by X-ray Diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), and UV-visible spectroscopy (UV-Vis). To estimate the photocatalytic activity of Sn-$TiO_2$, the photodegradation of water-suspended toluene was performed, and the remaining concentration was determined using UV-visible spectroscopy. The water-suspended toluene photodegradation over Sn-incorporated $TiO_2$ catalyst was better than that over pure $TiO_2$ (anatase). The water-suspended toluene of 500 ppm was perfectly decomposed within 300 minutes over 0.01 mol% Sn-$TiO_2$.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2002.05b
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• pp.163-167
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• 2002

$TiO_2$ 고정화 지지체를 이용한 유기인계농약의 광분해에 대한 연구 결과 다음과 같은 결론을 얻을 수 있었다. Chlorpyrifos의 광분해 제거효율을 초기 pH 9에서는 반응시간 200분만에 완전 분해되었으며, 초기 pH 7, 5에서는 각각 반응시간 240분, 260분만에 완전히 분해되었다. 또한 Diazinon인 경우 초기 pH 9에서는 반응시간 200분만에 완전 분해되었으며, 초기 pH 7, 5에서는 각각 반응시간 220분, 240분만에 완전히 분해되었다. Chlorphyrifos와 Diazinon은 pH가 증가할수록 즉 산성에서 염기성쪽로 갈수록 반응속도가 증가하는 것을 볼 수 있었다.

• Journal of the Korean GEO-environmental Society
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• v.12 no.10
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• pp.57-62
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• 2011

This study investigated the effects of various inorganic anions($Cl^-$, $NO_3{^-}$, $HCO_3{^-}$) on the Methyl tert Butyl Ether(MTBE) degradation by photocatalysis using statistical method. Generally, this process in general demands the generation of hydroxyl radicals(OH radical) in solution in the presence of UV light. The generation of radicals were affected by inorganic anions in solution that inhibited the photodegradation by their trapping hydroxyl radicals. The effects of inorganic anions were mathematically described as the independent variables such as $Cl^-$, $NO_3{^-}$, and $HCO_3{^-}$, and these were designed by mixture analysis that was one of the response surface methodology(RSM). Regression analysis on ANOVA showed significant p-value(p<0.0001) and high coefficients for determination value($R^2$=99.28%, ${R^2}_{adj}$=98.91%). Contour and response surface plots showed that the effects of inorganic anions for MTBE photodegradation based on $UV/H_2O_2$ process. In the result, $Cl^-$ and $HCO_3{^-}$ inhibited the photodegradation of the MTBE by their trapping hydroxyl radicals, and the interaction by these two factors was observed.

• Proceedings of the Membrane Society of Korea Conference
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• 1993.10a
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• pp.39-39
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• 1993

반도성 세라믹 광촉매 막 반응기 (membrane reactor)에 의한 난분해성 유독 유기물질의 분해공정을 개발하기 위한 기초연구로서 $TiO_2$ 막 반응기의 formic acid 및 trichloromethane에 대한 광분해 효율이 연구되었다. 막 반응기는 용액의 정밀여과 (microfiltration)는 물론 유기물의 광분해를 동시에 수행할 수 있도록 다공성 $TiO_2$ 튜브 (평균기공 : $0.2 \mu m$)를 이용한 새로운 타입으로 ㅐㄱ발되었으며 광원으로는 365 nm 파장을 갖는 UV를 사용하였다. 또한 반응기의 광분해 효율을 증진시키기 위하여 슬립케스팅법으로 제조한 $TiO_2$ 튜브표면을 $TiO_2$ 졸로 코팅하였다.