• 한국인쇄학회지
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• 제12권1호
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• pp.81.1-91
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• 1994

Irradiation of aromatic diazonium salts resulted in an effcient elimination of nitrogen, yielding substitution products. This paper was not only studies about photolysis of aromatic diazonium with double salts but also coexistence of ion and radical when they was photolysis. Photolysis of aromatic diazonium was depend on excite wave length therefore photolysis products out put different absorption intensity such other. We also confirmed coexistence of ion and radical when they was accomplished photolysis. In case of BD, there are ion decomposition process about 90 percentage, decreased ion decomposition process the other side radical`s it was becomeing increased according to excite of short-wave length.

• 한국식품영양학회지
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• 제11권3호
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• pp.267-271
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• 1998

Seyferth 시약인 phenyl(tribromomethyl) mercury 및 diazomethane의 식품보존제인 dehydroacetic acid 및 coumarin과의 발암성과 그 반응기작을 분자 구조적 관점에서 알아보기 위하여 UV/vis 조건과 laser flash photolysis 시켰을 때의 결과는 다음과 같다. 1. Diazomethane과 Phenyl(tribromomethyl) mercury와 dehydroacetic acid와 diazomethane과의 반응은 광화학적 분해 반응에서 생성된 : CBr2와 : CH2 카르벤 중간체의 이탈기 효과에 따라 발암성이 크게 나타났다. 2. laser flash photolysis 상에서 반응시켰을 때 식품보존제의 발암성이 UV/vis 상에서의 photolysis 때보다 크게 나타났다.

• Bulletin of the Korean Chemical Society
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• 제23권6호
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• pp.865-872
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• 2002

A systematic way of determining the equilibrium orientation of carbon monoxide (CO) in heme proteins using time-resolved polarized mid-IR spectroscopy is presented. The polarization anisotropy at pump-probe delay time of zero in the limit of zero photolysis and the angular distrbution function of CO are required to obtain the equilibrium orientation of CO. An approach is developed for determining the polarization anisotropy in the zero-photolysis limit from the anisotropy measured under finite photolysis conditions in an optically thick sample where the fraction of molecules photolyzed decreased as the pump pulse passes through and is absorbed by the sample. This approach is verified by measuring the polarization anisotropy of CO of carbonmonoxy myoglobin at various levels of photolysis. This method can be readily applied to other photoselection experiments determining precise angle between transition dipoles.

• Environmental Analysis Health and Toxicology
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• 제12권3_4호
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• pp.1-13
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• 1997

First- and second-order kinetic oxidation rates of trichlorobenzenes (TCBs) were obtained and compared by a chemical activation system (CAS) which mimics mixed functional oxidase activity. The system consists of EDTA, ferrous sulfate, ascorbic acid, and $H_2O_2$ in potassium phosphdte buffer (monobasic at pH 7.4). The rate of transformation in CAS was enhanced in the presence and absence of catalase in the sequence 1, 2, 3-TCB < 1, 2, 4-TCB < 1, 3, 5-TCB. In general, the rates of degradation were greater in the test media with catalase. The effect of photolysis on the degradation of the TCBs with the CAS were examined. Sensitized photolysis with nitrite, Fenton's reagent, TiO$_2$ and triethylamine (TEA) studied in concert with the CAS demonstrated significant enhancement of the degradation rate of TCBs. Disappearance rates of TCBs in CAS with prior photolysis or prior photosensitization were at least 10-fold higher than the sum of the rate for each single experiment. This study proves that the combination of the CAS and photolysis can be used as a suitable technique for enhancing degradation of TCBs in aqueous systems.

• 한국재료학회지
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• 제26권8호
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• pp.406-411
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• 2016

In order to reuse the photocatalyst and enhance the photolysis efficiency, we have used atmospheric pressure dielectric barrier discharge (APDBD) to clean and activate $TiO_2$ powder. The photocatalytic activity of the $TiO_2$ powder before and after APDBD treatment was evaluated by the degradation of methylene blue (MB) in aqueous solution. The apparent reaction rate constant of photolysis of the first sample of reused $TiO_2$ cleaned by APDBD improved to a level up to 0.32h-1 higher than the 30 % value of the initial $TiO_2$ powder. As the number of photolysis reactions and APDBD cleanings increased, the apparent rate constants gradually decreased; however, the fourth photolysis reaction still showed a value that was greater than 10% of the initial value. In addition, APDBD treatment enhanced the process by which $TiO_2$ effectively adsorbed MB at every photolysis stage.

• 한국식품위생안전성학회지
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• 제19권2호
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• pp.97-103
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• 2004

Piperophos에 대한 광분해 실험을 수행하여 속도상수와 분해생성물을 측정하였다. 햇빛을 이용한 광분해 실험은 2003년 10월 3일부터 10월 22일 까지 하였으며 상당기간 동안 농약이 햇빛에 안정함을 확인할 수 있었고, humic acid의 광관여 효과가 없음을 알 수 있었다. 자외선을 이용한 광분해 실험에서 piperophos는 자외선을 단독 조사하였을 때 자외선의 세기가 클수록 상대적으로 빠르게 분해되었으며, 광분해 촉매제인 TiO$_2$를 첨가하였을 경우에는 첨가하지 않고 자외선만 조사한 경우보다 상대적으로 느리게 분해되었다. 또, TiO$_2$의 양을 증가시켜도 별 차이가 없었다. 광분해에 의한 분해산물을 확인하고자 UMS분석을 한 결과 piperophos의 분해생성물은 m/z=166의 O,O-dipropyl phosphorodithioate로 추정된다.

• Journal of Photoscience
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• 제5권3호
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• pp.111-120
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• 1998

Sensitized photolysis of two onium borates (diphenyliodoium and dimethylphenacylsulfonium tetrakis(pentafluorophenyl)borate, 1a and 2a , respectively) and cationic photopolymerization of an epoxy monomer by the photolysis were investigate. The onium borates were sensitized by the excited singlet of the athracenes(non-substituted, 9-methyl-and 9, 10-dimethylanthracene) and generated acid by decomposing teemselves. The quantum yields of photobleaching of the anthracenes($\Phi$-AH) and acid generatiion (øacid) by the onium borates were the same order as those of the corresponding onium salts in aerated solutions (methanol and acetoitrile) and in argon(Ar) saturated acetonitrile. However, in the photolysis of the iodonium borates 1a in Ar saturated MeOH , øacid was much higher than the corresponding ø-AH. The acid generated by the photolysis of the onium borates initiated cationic polymerization of an epoxy monomer. The values of both rate of polymerization (Rp) and degree of conversion on the photopolymerization for the iodonium borated 1a were higher than those of the sulfoium borate 2a. In the photopolymerization for the iodonium borate 1a, both the Rp value and the degree of conversinio increased upon the addition of glycerol as a hydrogen donor. It is suggested that the increase of both values may be caused with the increase of øacid by addition of glycerol.

• 한국환경과학회지
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• 제11권7호
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• pp.743-748
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• 2002

UV photolysis process is little known in parts of air pollution treatment, so there are not many applications in field. Therefore we have to do more experiment and study application possibility for treatment of VOCs(Volatile organic compounds). To solve these problems, we have been studying for simultaneous application of this technology. It has shown that concentration of TCE and B.T.X., diameter of reactor and wavelength of lamp have effected on decomposition efficiency. Analysis of TCE and B.T.X. concentration was carried out by GC-FID. A cylinderical reactor consisting of a quartz tube and a centrally located lamp(${\psi}25mm$) was used. The length and diameter of reactor were 1800mm, 75mm. It has shown that the generated ozone concentration goes up 250ppm when using 64watt ozone lamp. When using Photolysis process only, the rates of fractional conversion of each material are TCE 79%, Benzene 65%, Toluene 68%, Xylene 76%. This phenomenon can be rationalized in terms of the different bond energy that indicates how easily VOCs species can be decomposed.

• 한국환경보건학회지
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• 제26권2호
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• pp.49-58
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• 2000

The present study was performed to investigate photodegradation rate constants and degradation products of phosphamidon and profenofos by the USEPA method. The two pesticides were very stable in 16 days exposure of sunlight from September 3 to 22, 1999 and humic acid had no sensitizing effect on the photolysis of each pesticide in sunlight. In the UV irradiation test, phosphamidon was rapidly degraded as increasing UV intensity. In case of UV irradiation with TiO2 and with TiO2 powder amount, degradation of profenofos showed no significant difference with UV irradiation. Photodegradation rate of profenofos was slower than that of phosphamidon. In order to identify photolysis products, the extracts of degradation products were analyzed by GC/MS. The mass spectra of photolysis products of phosphamidon were at m/z 153 and 149, those of the profenofos were at m/z 208 and 240, respectively. It was suggested that the photolysis products of phosphamidon were 0, 0-dimethyl phosphate(DMP) and N, N-diethylchloroacetamide, those of profenofos were 4-bromo-2-chlorophenol and 0-ethyl-S-propyl phosphate.

• Bulletin of the Korean Chemical Society
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• 제6권4호
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• pp.234-238
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• 1985

The photoisomerization of 5-styryl-1,3-dimethyluracil is studied with nanosecond laser flash photolysis technique at room temperature. The laser flash photolysis of E-isomer produces the transient absorption spectrum regarded as the triplet-triplet absorption, but the transient absorption of Z-isomer does not show the typical decay curve, probably due to the facile photocyclization reaction during the laser flash photolysis. Using the energy transfer method on nanosecond laser spectroscopy, the energy of the lowest triplet state for E isomer is estimated to lie between 41.8 and 47 kcal/mol. The triplet lifetime for E-isomer obtained from the decay curve of the transient absorption is ca. 93ns. The $S_1 → T_1$ intersystem crossing of E-isomer on direct excitation is relatively inefficient at room temperature supporting the singlet mechanism for direct photoisomerization.