• 한국염색가공학회지
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• 제6권2호
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• pp.1-9
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• 1994

In order to study the effect of mordanting on silk fabrics treated with tannin, those fabrics were treated with Al, Cu, Cr, Fe, Sn by pre and post mordanting. It was studied about color change, weighting effect, dgree of photodegradation by pre and post mordanting. The results are as fallows ; 1. On the addition of mordants into mimosa and tannic acid solution, &{\lambda}_{max}& of the former was slightly blue-shifted, on the other hand, &{\lambda}_{max}& of the latter was obviously Red-shifted. 2. In case of Cu, Cr, Pre mordanting, weighting effect were appeared. Weighting effect of silk fabrics treated with Tannic acid increased higher than mimosa by mordanting. 3. In color change, Silk fabrics treated with Mimosa and Tannic acid generally changed to red direction and fabrics treated with tannic acid changed to yellow direction by pre and post mordanting. 4. In the photodegradation, the degree of photodegradation on mordanted fabrics increased. Its degree was slack in Cu, Cr, Post mordanting. On the other hand, Al, Fe, Sn were greate. Silk fabrics treated with Mimosa and Tannic acid got inhibiting effect on photodegradation.

• 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.

• Environmental Engineering Research
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• 제21권2호
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• pp.188-195
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• 2016

$17{\alpha}$-Ethynylestradiol (EE2) has gotten growing concerns due to its widely detected in the environment and high estrogenic potency. However, the knowledge on the photochemical behaviors of EE2 in natural waters is still limited. Herein, the photodegradation and estrogenic potency variation of EE2 induced by nitrate were studied using a sunlight simulator consisted by a 300 W medium pressure mercury lamp and 290 nm cut-off filters. It was found that EE2 could be photodegraded at a rate of $0.0193h^{-1}$ in pure aqueous solutions, and the photodegradation of EE2 could be significantly promoted by nitrate. The photodegradation removal rate of EE2 was increased from 9% in Milli-Q water to 85% in 2.0 mM nitrate solutions. Reactive species scavenging experiments demonstrated that the photogenerated $HO{\bullet}$ contributed about 55% to EE2 degradation. Fe(III), Cl- and dissolved humic acid (DHA) could inhibit the photodegradation of EE2 by competing the incident light and photogenerated $HO{\bullet}$, while $HCO_3{^-}$ had no influence on EE2 photodegradation. EE2 was determined to be phototransformed into organic chemicals without estrogenic potency by GC-MS and MCF-7 cell proliferation toxicity tests. These findings could extend our knowledge on the photochemical behaviors of steroid estrogens and provide information for ecological risk assessment.

• Environmental Engineering Research
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• 제25권4호
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• pp.529-535
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• 2020

The present study investigated the photodegradation of synthetic organic dye; violet-3B, without and with the addition of C-N-codoped TiO₂ catalyst using a visible halogen-lamp as a light source. The catalyst was synthesized by using a peroxo sol-gel method with free-organic solvent. The effects of initial dye concentration, catalyst dosage, and pH solution on the photodegradation of violet-3B were examined. The efficiency of the photodegradation process for violet-3B dye was higher at neutral to less acidic pH. The kinetics reaction rate of photodegradation of violet-3B dye with the addition of C-N-codoped TiO₂ followed pseudo-first order kinetics represented by the Langmuir-Hinshelwood model, and increasing the initial concentration of dyes decreased rate constants of photodegradation. Photodegradation of 5 mg L^-1 violet-3B dye achieved 96% color removal within 240 min of irradiation in the presence of C-N-codoped TiO₂ catalyst, and approximately 44% TOC was removed as a result of the mineralization.

• 산업기술연구
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• 제24권B호
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• pp.133-138
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• 2004

The photodegradation of phenol and toluene with the $TiO_2$-coated polyethylene (PE) particles were investigated in the slurry type photocatalytic reactor, changing the $TiO_2$ particle sizes, initial phenol and toluene concentrations, and the oxygen flow rate. The nano-sized $TiO_2$ photocatalyst particles were prepared by the diffusion flame reactor and they were coated onto PE particles by using the hybridization system for the efficient recollection of $TiO_2$-coated particles after photodegradation experiments. The degradation efficiencies of phenol and toluene with the $TiO_2$-coated PE particles were more than 90% after photodegradation of 80 minutes for most cases. The efficiencies of photodegradation with the $TiO_2$-coated PE particles were found to be lower than those by the pure $TiO_2$ particles by 50%, because of the decrease in specific surface area of $TiO_2$ particles in PE particles.

• 산업기술연구
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• 제26권A호
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• pp.181-188
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• 2006

In this study, we analyzed the effects of several process variables on the removal efficiencies of NO and $SO_2$ by the dielectric barrier discharge process combined with photocatalysts. The $TiO_2$ photocatalysts were coated onto the spherical-shaped glass beads as dielectric materials by the dip-coating method to analyze the effects of photodegradation reaction on the NO and $SO_2$ removal. As the voltage applied to the plasma reactor increases, or as the pulse frequency of applied voltage increases, the NO and $SO_2$ removal efficiencies increase. Also as the residence time increases, or as the initial concentration of NO decreases, the NO and $SO_2$ removal efficiencies increase. The higher the amount of $TiO_2$ particles coated onto the glass bead is, the larger the surface area of $TiO_2$ particles for the photodegradation reaction is and the NO and $SO_2$ are removed more quickly by the faster photodegradation reactions.

• 한국의류학회지
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• 제16권2호
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• pp.181-187
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• 1992

일반적으로 면섬유는 햇빛에 의해서 변색되거나 약해지며 또 그 외에도 여러가지 물리적, 화학적인 변화를 일으키게 된다. 구체적인 화학반응의 메카니즘은 사용되는 광선의 스펙트럼, 대기조건(실내인 경우는 실내 환경조건) , 산소의 유무 그리고 염료 등 첨가물의 종류와 같은 여러 요소에 의해 크게 영향을 받게 된다. 환경조건 중에서 산소의 존재는 매우 중요하지만 open system에서 산소의 농도가 일정하다고 가정할 때 면섬유가 접하고 있는 환경조건 중에서 온도와 습도는 photodegradation의 속도를 결정짓는 중요한 요인으로 작용하게 된다. 박물관,:기념관, 도서관 등의 소장품이 자연광선이나 인공조명으로부터 손상되는 것을 막기 위해서는 먼저 이들의 photodegradation 현상에 대한 연구를 필요로 한다. 본 연구에서는 면시칩포를 자연광선과 가장 흡사한 스펙트럼을 가진 xenon arc lamp를 사용한 내후도 시험기내에서 온도와 습도를 조절하여 이에 따른 반응속도의 차이를 인열강도의 감소와 중합도 저하로 측정하였다. 1차 반응식은 실험결과를 설명하는데 유용하였으며 온 · 습도의 증가는 반응속도를 증가시키는 것으로 나타나 기존의 상반된 연구결과의 차이를 입증하였다. 또 온도와 습도는 상호관련이 있는 것으로 나타났으며 고온인 경우습도의 영향을 더 크게 받는 것으로 분석되었다. 반응의 활성에너지는 $30\~75\%$ RH에서는 12 kcal/mole 정도이며 수분의 함량이 낮을수록 활성화에너지는 커지는 것으로 나타나 수분은 섬유소 분자구조내에서 가소제 (plasticizer)의 역할을 하는 것으로 판명되었다.

• 한국세라믹학회지
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• 제45권6호
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• pp.324-330
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• 2008

Activated carbon/$TiO_2$ (AC/$TiO_2$) composites modified with different concentrations of Fe were prepared. The $N_2$ adsorption data showed that the composites had decreased surface area compared with the pristine activated carbon. This indicated the blocking of the micropores on the surface of AC, which was further supported by observation via SEM. XRD results showed patterns for the composites and an anatase typed titanium dioxide structure with a small part of rutile in a higher Fe concentration (> 1.0 mol/L). EDX results showed the presence of C and, O, with Ti peaks on the composites of Fe-AC/$TiO_2$ with relatively lower Ti concentration, which may be due to the higher Fe concentration incorporated into the composites. Subsequently, the photocatalytic effects on methylene blue (MB) were investigated. The improved decomposition of MB showed the combined effects of adsorptions and photodegradation. Especially, the composites modified by Fe revealed enhanced photodegradation behaviors of MB.

• 한국환경과학회지
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• 제14권7호
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• pp.699-709
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• 2005

This study aimed at improving the $TiO_2$ photocatalytic degradation of HA. In this study, the Degradation of Humic Acid using Jeju Scoria Coated with $WO_3/TiO_2$ in the presence of UV irradiation was investigated as a function of different experimental condition : photocatalyst dosage, $Ca^{2+}\;and\;HCO_{3}_{-}$ addition and pH of the solution. Photodegradation efficiency increased with increasing photocatalyst dosage, the optimum catalyst dosage is 2.5 g/L and Photodegradation efficiency is maximized to $WO_3/TiO_2=3/7$. This indicates that $WO_3$ retains a much higher Lewis surface acidity than $TiO_2,\;and\;WO_3$ has a higher affinity for chemical species having unpaired electrons. The addtion of cation($Ca^{2+}$) in water increased the photodegradaion efficiency. But the addtion of $HCO_{3}^{-}$ ion in water decreased a photodegradation efficiency. Photodegradation efficiency increased with decreasing pH < pzc, the electrostatic repulsion between the HA and the surface of $TiO_2$ decreased.

• 동력기계공학회지
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• 제18권6호
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• pp.133-139
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• 2014

In this research, the photocatalytic degradation of benzothiophene in $TiO_2$ aqueous suspension has been studied. $TiO_2$ photocatalysts are prepared by a sol-gel method. The dominant anatase-structure on $TiO_2$ particles is observed after calcining the $TiO_2$ gel at $500^{\circ}C$ for 1hr. Photocatalysts with various transition metals (Nd, Pd and Pt) loading are tested to evaluate the effect of transition metal impurities on photodegradation. The photocatalytic degradation in most cases follows first-order kinetics. The maximum photodegradation efficiency is obtained with $TiO_2$ dosage of 0.4g/L. The photodegradation efficiency with Pt-$TiO_2$ is higher than pure $TiO_2$ powder. The optimal content value of Pt is 0.5wt.%. Also we investigate the applicability of $H_2O_2$ to increase the efficiency of the $TiO_2$ photocatalytic degradation of benzothiophene. The optimal concentration of $H_2O_2$ is 0.05. The effect of pH is investigated; we obtain the maximum photodegradation efficiency at pH 9. Hydroxy-benzothiophenes and dihydroxy-benzothiophenes are identified as reaction intermediates. It is proposed that benzothiophene is oxidized by OH radical to sequentially form hydroxyl-benzothiophenes, dihydroxybenzothiophenes, and benzothiophenedione.