• Bulletin of the Korean Chemical Society
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• v.5 no.5
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• pp.194-198
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• 1984

The UV action spectra and quantum yields for photodestruction of tryptophan (Trp) in peptide such as N-acetylphenylalanyl-L-tryptophan (NAPT) and 3-methyl indole (scatole) were determined in aerated aqueous and organic solvents. The photodestruction of aqueous NAPT was shown to be initiated by photoionization without requirement of threshold energy, as demonstrated by the similarity of fluence effect curves obtained for the action at various wavelengths and the wavelength dependence of quantum yield comparable to that reported for the photoionization of L-Trp. N-formylkynurenine (NFK)-type photoproduct, which is a photodynamic sensitizer, was not found to be involved in the photodestruction of Trp in NAPT in aqueous solution. In contrast, the action spectra of NAPT and scatole in organic solvents have revealed evidences for the significant role of internal photosensitization by NFK-type photoproduct in photolysis of Trp in peptide.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.3
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• pp.269-276
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• 2005

Zn, Bi 와 V 금속이온 전구체를 사용하여 모노클리닉 결정구조를 갖는 신규 ZnBiVO4 광촉매를 손쉽게 합성 할 수 있는 방법을 개발하였다. 합성된 $ZnBiVO_4$ 광촉매는 XRD 과 FESEM등을 이용하여 미세구조를 분석하였으며, 분석결과 본 삼성분계 금속산화물 반도체 광촉매는 모노클리닉 결정구조를 갖는 것을 알 수 있었다. 저온 수용액방법에 의해 손쉽게 나노 구조를 갖는 $ZnBiVO_4$가 제조되었으며, 그 광촉매의 최소 입자크기는 20-30 nm 이다. $ZnBiVO_4$ 광촉매는 UV-visible DRS (diffuse reflectance spectroscopy)로 그 띠간격(band gap)을 측정하였으며, FT-IR을 사용하여 구조 및 물질 상의 순도를 확인하였다. 그리고 $H_2S$를 광분해하여 수소를 발생하는($122ml/hr{\cdot}g$) 우수한 광촉매 활성을 보여 주었다.

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.127-134
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• 2016

A series of Ce-doped ZnO (Ce/ZnO) nanostructures were fabricated using the co-precipitation method, then a simply nontoxic hydrothermal approach was proposed for preparation of reduced graphene oxide (rGO)-Ce/ZnO composites. The synthesized composites were investigated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence spectroscopy (PL), electrochemical impedance spectroscopy (EIS), UV-vis diffuse reflectance spectroscopy (DRS) techniques and Raman pattern. The as-synthesized rGO-Ce/ZnO composites showed high photodecomposition efficiency in comparison with the rGO-ZnO, Ce/ZnO, pure ZnO under UV, visible-light and sunlight irradiation. The degradation of methylene blue (MB) (10 mg/L, 100ml) by 95.8% within 60 min by using rGO-2 (10 mg) under sunlight irradiation was observed. The repeated use of the rGO-2 was investigated, and the results showed almost no decay in the catalytic activity.

• Journal of the Korean Ceramic Society
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• v.49 no.5
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• pp.461-468
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• 2012

This study focuses on the difference of photocatalytic activity depending on crystal structure type of nanoparticles ($TiO_2$) and nanotubes (TNT). The photodecomposition of 2-chlorophenol on the synthesized $TiO_2$, Sn-impregnated $TiO_2$, TNT, and Snimpregnated TNT were evaluated. The characteristics of the synthesized photocatalyts, TNT, Sn/TNT, $TiO_2$, and Sn/$TiO_2$ were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-Visible spectroscopy (UV-Vis), and cyclic voltammeter (CV). The water-suspended 2-chlorophenol photodegradation over $TiO_2$ (anatase structure) catalyst was better than that over pure TNT. Particularly, the water-suspended 2-chlorophenol of 10 ppm was perfectly decomposed within 4 h over Sn/$TiO_2$ photocatalyst.

• Transactions of the Korean hydrogen and new energy society
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• v.2 no.1
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• pp.47-56
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• 1990

Pure titanium rods were oxidized by anodic oxidation, furnace oxidation and flame oxidation and used as a electrode in the photodecomposition of water. The maximum photoelectrochemical conversion efficiency(${\eta}$) was found for flame oxidized electrode ($1200^{\circ}C$ for 2 min in air), 0.8 %. Anodically oxidized electrodes have minimum photoelectrochemical conversion efficiencies, 0.3 %. Furnace oxidized electrode ($800^{\circ}C$ for 10min in air) has 0.5% phtoelectrochemical efficiency and shows a band-gap energy of about 2.9eV. The efficiency shows a parallelism with the presence of the metallic interstitial compound $TiO_{O+X}$(X < 0.33) at the metal-semiconductor interface, the thickness of the sub oxide layer and that of the external rutile scale.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.12
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• pp.1151-1160
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• 2009

Perfluorinated compounds (PFCs) have been recognized as emerging environmental pollutants and are widely distributed all over the world. These compounds are hardly degradable and cause bioaccumulation and biomagnification during present for a long time in the environment: thereby after adversely biota and human bodies. It is difficult to remove PFCs using conventional water/wastewater treatment because of resistant property to photodecomposition, biodegradation and chemical decomposition. Moreover, domestic literature data on the pollution of PFCs in rivers and lakes are limited. In this paper, species, sources and risk of PFCs as well as behavior properties in drinking water/wastewater and treatment processes are demonstrated to encourage the domestic concern about PFCs.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.18
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• pp.8605-8611
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• 2016

The reliability of using diagnostic binary ratios of particulate carcinogenic polycyclic aromatic hydrocarbons (PAHs) as chemical tracers for source characterisation was assessed by collecting PM10 samples from various air quality observatory sites in Thailand. The major objectives of this research were to evaluate the effects of day and night on the alterations of six different PAH diagnostic binary ratios: An/(An + Phe), Fluo/(Fluo + Pyr), B[a]A/(B[a]A + Chry), B[a]P/(B[a]P + B[e]P), Ind/(Ind + B[g,h,i]P), and B[k]F/Ind, and to investigate the impacts of site-specific conditions on the alterations of PAH diagnostic binary ratios by applying the concept of the coefficient of divergence (COD). No significant differences between day and night were found for any of the diagnostic binary ratios of PAHs, which indicates that the photodecomposition process is of minor importance in terms of PAH reduction. Interestingly, comparatively high values of COD for An/(An + Phe) in PM10 collected from sites with heavy traffic and in residential zones underline the influence of heterogeneous reactions triggered by oxidising gaseous species from vehicular exhausts. Therefore, special attention must be paid when interpreting the data of these diagnostic binary ratios, particularly for cases of low-molecular-weight PAHs.

• Journal of the Korean Ceramic Society
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• v.47 no.2
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• pp.169-176
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• 2010

The Fe-treated CNT/$TiO_2$ photocatalysts mixed with anatase and rutile phase have been developed for the decomposition of non-biodegradable different organic dyes like methylene blue (MB), rhodamine B (Rh.B), and methyl orange (MO) in two conditions as ultraviolet and visible light respectively. The results indicate that all the Fe-CNT/$TiO_2$ composites proved to be more efficient photocatalysts since degradation of MB at higher reaction rates, tthe decomposition rate of different dyes increases with an increase of $Fe^{3+}$ concentration in composites the highest rate of decomposition of different dyes was noted under UV irradiation. These results can indicate that the large CNT network is facilitate the electron transfer and strongly adsorb dye molecules on the texted photocatalysts, iron is reactive in the photo-Fenton process resulting in high production of OH radicals and also high activity of the photocatalyst. And Fe particles can generate more photoinduced electrons to conduction band of $TiO_2$ under visible light irradiation. The composites of Fe-CNT/$TiO_2$ photocatalysts synthesized by a sol-gel method were characterized by BET, TEM, SEM, XRD and EDX.

• Transactions of the Korean hydrogen and new energy society
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• v.5 no.1
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• pp.41-49
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• 1994

Ti-Bi alloy was prepared by arc melting of appropriate amounts of titanium and bismuth powder. The photocurrent($I_{ph}$) of Ti-Bi oxide electrode was increased with the increase of Bi content, up to 10wt%. The maximum $I_{ph}$ showed $7.6mA/cm^2$ at V=0.5V vs. SCE. The band gap energy of Ti-Bi oxide electrode was observed to 3.0~2.87eV. Surface barrier($V_s$) of Ti-10Bi oxide electrode showed maximum value(1.08V) but didn't exceed 1.23V, then it was impossible to run $H_2$ generation without any other energy sources other than the light. Ti-Bi oxide electrode was found to be quite stable under alkaline solution and showed no signs of photodecomposition.

• Clean Technology
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• v.4 no.1
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• pp.35-44
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• 1998

Photodecomposition behaviors of volatile organic compounds (VOCs ; benzene, toluene, ethylbenzene and xylenes) over UV irradiation and UV irradiation with $TiO_2$ powder catalyst were studied and the extent of degradation were also investigated under various reaction conditions. The reactions were conducted in a quartz annular reactor equipped with a medium pressure mercury lamp. As a result, the extents of degradation were 92% for toluene and ethylbenzene, 83% for benzene, and 82% for xylenes under UV irradiation. And they were 92% for toluene, 82% for xylene and ethylbenzene, and 53% for benzene under UV irradiation with $TiO_2$ powder. Analyses of reacted samples by FID-gas chromatograph with Purge & Trap concentrator and GC-MS indicated that the aromatics formed many intermediates.