• 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.

• 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.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.637-645
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• 1994

The LDPE films were photolyzed for 100 hours in UV apparatus with 400-W medium pressure mercury lamp radiating wavelengths longer than 254nm. A simple kinetic model was introduced and was applied to interpret the FT-IR absorbance of carbonyl and hydroperoxide bonds as a function of UV exposure time. From these data, the reaction mechanism and the rate determining step of photodegradation were determined.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.5304-5309
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• 2013

The degradation of methylethylkeone(MEK) was investigated by the continuous single module photocatalytic reactor. Operational conditions were initial concentration of MEK, intensity of photon flux, and activity change according to the long time operation. The photocatalytic degradation was decreased with the increase of MEK concentration, and the degree of decrease was larger at higher flow rate. Removal efficiency of photocatalytic reactor was decreased with the increase of reactor diameter and lamp wavelength under the same residence time condition. Continuous single module photocatalytic reactor was successfully operated without any activity drop during 120hrs operation.

• Applied Biological Chemistry
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• v.17 no.3
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• pp.149-176
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• 1974

Eight substituted diphenyl ether herbicides and some of their photoproducts were studied in terms of solution phase photolysis under simulated environmental conditions by using a Rayonet photochemical reactor. The test compounds absorbed sufficient light energy at the wavelength of 300 nm to undergo various photoreactions. All the photoproducts were confirmed by means of tlc, glc, ir, ms, and/or nmr spectrometry. The results obtained are summarized as follows: Solution phase photolysis of C-6989: An exceedingly large amount of p-nitrophenol formed strongly indicates the readiness of the ether linkage cleavage of this compound as the main reaction in all solvents used. Photoreduction of nitro to amino group(s) and photooxidation of trifluoromethyl to carboxyl group were recognized as minor reactions. Aqueous photolysis of p-nitrophenol: Quinone(0.28%), hydroquinone (0.66%), and p-aminophenol (0.42%) were confirmed as photoproducts, in addition to a relatively small amount of an unknown compound. The mechanisms of formation of these products were proposed to be the nitro-nitrite rearrangement via $n{\rightarrow}{\pi}^*$ excitation and the photoreduction through hydrogen abstractions by radicals, respectively. Solution phase photolysis of Nitrofen: Photochemical reduction leading to the p-amino derivative was the main reaction in n-hexane. In aqueous solution, the photoreduction of nitro to amino group and hydroxylation predominated over the ether linkage cleavage. Nucleophilic displacement of the nitro group by hydroxide ion and replacement of chlorine substituents by hydroxyl group or, to a lesser extent, hydrogen were also observed as minor reactoins. Solution phase photolysis of MO-338: Photoreduction of the nitro to amino group was marked in the n-hexane solution photolysis. In the aqueous solution, photoreduction of the nitro substituent and hydroxylation were the main reactions with replacement of chlorine substituents by the hydroxyl group and hydrogen, and cleavage of the ether linkage as minor reactions. Photolyses of MC-4379, MC-3761, MC-5127, MC-6063, and MC-7181 in n-hexane and cyclohexane: Photoreduction of the nitro group leading to the corresponding amino derivative and replacement of one of the halogen substituents by hydrogen from the solvent used were the key reactions in each compound. Aqueous photolysis of MC-4379: Cleavage of the ether linkage, replacement of the carboxymethyl by hydroxyl group, hydroxylation, and replacement of the nitro by hydroxy group were prominent with photoreduction and dechlorination as minor reactions. Aqueous photolysis of MC-3761: Cleavage of the ether linkage, replacement of the carboxymethyl by hydroxyl group, and photoreduction followed by hydroxylation were the main reactions. Aqueous photolysis of MC-5127: Replacement of carboxyethyl by hydrogen was predominant with ether linkage cleavage, photoreduction, and dechlorination as minor reactions. It was obvious that the decarboxyethylation proceeded more readily than decarboxymethylation occurring in the other compounds. Aqueous photolysis of MC-6063: Cleavage of the ether linkage and photodechlorination were the main reactions. Aqueous photolysis of MC-7181: Replacement of the carboxymethyl group by hydrogen and monodechlorination were the remarkable reactions. Cleavage of the ether linkage and hydroxylation were thought to be the minor reactions. Aqueous photolysis of 3-carboxymethyl-4-nitrophenol: The photo-induced Fries rearrangement common to aromatic esters did not appear to occur in the carboxymethyl group of this type of compound. Conversion of nitro to nitroso group was the main reaction.

• 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.26 no.4
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• pp.311-320
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• 2020

In this study, the photocatalytic degradation of rhodamine B (RhB), methyl orange (MO) and methylene blue (MB) was carried out under visible light irradiation using CdS and CdZnS/ZnO photocatalysts prepared by a simple precipitation method. This study focused on examining the effect of physicochemical properties of dye and photocatalyst on the reaction pathway of photocatalytic degradation. The prepared photocatalysts were characterized by XRD, UV-vis DRS and XPS. Both the CdS and CdZnS/ZnO photocatalysts exhibit an excellent absorption in the visible light and the UV light regions. It was observed that the photocatalytic degradation of MO proceeds via the same reaction mechanism on both the CdS and CdZnS/ZnO photocatalysts. However, the photocatalytic degradation of RhB and MB was found to proceed through a different reaction pathway on the CdS and CdZnS/ZnO catalysts. It is interesting to note that MB dimer was formed on the CdS catalyst at the beginning of the photocatalytic reaction, while the MB monomer was degraded during the overall photocatalytic reaction on CdZnS/ZnO. The above results may be mainly ascribed to the difference of band edge potential of the conduction band in the CdS and CdZnS/ZnO semiconductors and the adsorption property of dye on the catalysts.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.397-399
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• 2007

본 연구는 광전자 촉매시스템을 이용해 $TiO_2$ 졸이 코팅된 구형 비드의 광분해 효율에 대해 고찰한 것이다. $TiO_2$ 졸이 코팅된 구형 비드인 실리카비드 화이트겔(1 2 3형) 세 가지 비드를 사용하였고 실험은 1L 크기의 반응기에 유기 물질을 함유한 인공 폐수를 넣어 비드에 코팅된 $TiO_2$의 분해 활성을 고찰할 목적으로 실행되었다. 그 결과, $500^{\circ}C$에서 3hr에서 소성한 실리카 비드가 가장 뛰어난 반응성을 나타내며 인공폐수에서도 분해활성을 나타내는 것을 확인하였다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2000.04a
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• pp.317-320
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• 2000

• 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 $^1O_2$.