• 공업화학
• /
• 제28권6호
• /
• pp.619-625
• /
• 2017

본 연구에서는 하이드로퍼옥시 라디칼 생성단계에서 반응 부산물로 생성되는 과산화수소를 정량하여 수산화라디칼의 생성 및 비스페놀 A (BPA)의 분해특성을 조사하였다. 라디칼 연쇄반응이 일어나지 않는 조건에서는 Criegee mechanism과 동일하게 오존에 의한 직접산화반응만이 BPA를 분해시키는 것으로 나타났다. 라디칼 연쇄반응이 일어나는 pH 6.5 및 9.5의 조건에서는 비선택적 산화반응이 일어나 수산화라디칼의 생성을 간접적으로 확인할 수 있었다. 투입된 촉매에 의한 BPA의 분해효율은 $O_3$/PAC ${\geq}$ $O_3/H_2O_2$ > $O_3$/high pH > $O_3$ alone 공정 순으로 나타났다. 오존/촉매공정들의 산화반응 동안에는 0.03~0.08 mM의 과산화수소가 지속적으로 측정되었다. $O_3$/high pH 공정의 경우, BPA가 반응시작 50 min 만에 완전히 분해되었지만, TOC (총유기탄소) 제거율은 29%로 산화반응 중 생성된 중간물질을 충분히 산화시키지 못하는 것으로 나타났다(선택적 산화반응). $O_3/H_2O_2$ 및 $O_3$/PAC 공정에서는 BPA가 반응시작 40 min 만에 완전히 분해되었으며, TOC 제거율은 각각 57% 및 66% 정도로 반응 중간체들을 산화(비선택적 산화반응)시키는 것으로 나타났다.

• Environmental Analysis Health and Toxicology
• /
• 제19권3호
• /
• pp.251-259
• /
• 2004

Xenoestrogens are chemicals with diverse structure that mimic estrogen. Bisphenol A, a monomer of polycarbonate and epoxy resins, has been detected in canned food and human saliva. Bisphenol A stimulate cell proliferation and induce expression of estrogen -response genes in vitro. The purpose of the this study was to evaluate cell proliferation of bisphenol A in the presence of a rat liver 59 mix contaning cytochrome P450 enzymes and Cu (II). The fragmentation of intact DNA, a parameter of apoptotic cell death, was evaluated quantitatively by diphenylamine reaction method. Bisphenol A induced apoptotic cell death in a dose-dependent manner The effect of radical scavenger on the apoptotic cell death induced bisphenol A was investigated. The DNA fragmentation induced by bisphenol A was significantly inhibited by addition of radical scavenger to the culture medium. This indicated that elevated oxidative stress caused by imbalance between the production and removal of free radicals occurred in cells. Taken together, these results suggest that free radical reacts with Cu (II) leading oxidative stress.

• Environmental Analysis Health and Toxicology
• /
• 제18권3호
• /
• pp.175-182
• /
• 2003

Bisphenol A shares similarities in structure, metabolism and action with DES, a known human teratogen and carcinogen. Bisphenol A, a monomer of polycarbonate and epoxy resins, has been detected in canned food and human saliva. The purpose of the this study was to evaluate the cytotoxicity, cell proliferation of bisphenol A In the presence of a rat liver S9 mix, contaning cytochrome P450 enzymes, and Cu (II). In the present study, Bisphenol A in combination with Cu (II) exhibited a enhancement in cytotoxicity which were inhibited by free radical scavengers. The content of malondialdehyde, an end product of lipid peroxidation, was also found to increase with concentration of bisphenol A. Also, we examined the change of CuZn-SOD, Mn-SOD, catalase and GPx activities in the MCF-7 cells exposed to bisphenol A. The activities of CuZn-SOD, CPx, catalase were found to decrease with bisphenol A concentration. Meanwhile, the activity of Mn-SOD was unchanged. This indicated that elevated oxidative stress caused by imbalance between the production and removal of free radicals occurred in cells.

• 청정기술
• /
• 제23권1호
• /
• pp.54-63
• /
• 2017

산업발전과 공업화로 인해 VOCs의 발생이 증가하고 있고, VOCs는 불쾌감을 주며 불만을 불러일으키는 요인 중 하나이다. 이를 제어하기 위해 본 연구는 식물정유와 광촉매로 흡수제를 제조하여 벤젠과 톨루엔을 제거하고자 하였다. 식물정유물질 선정실험을 수행한 결과, 편백나무의 제거효율이 약 70%로 가장 높게 나타났으며, GC분석 결과 Monoterpene류와 Sesquiterpene로 이루어져 있음을 확인하였다. 광촉매 선정실험 결과, 광촉매 종류는 $TiO_2$의 효율이 가장 높게 나타났으며, UV lamp power는 10 W, $TiO_2$의 양은 $0.1gL^{-1}$부터 효율이 우수하게 나타났다. 수산화라디칼 생성특성 실험결과, $TiO_2$의 농도와 UV lamp power가 클수록 많은 양의 라디칼이 생성되었다. 제조된 흡수제의 제거효율 및 반응속도 실험결과, 제거효율은 최대 약 98%까지 나타났으며, 활성화 에너지는 약 $18kJmol^{-1}$로 나타났다.

• Asian Journal of Atmospheric Environment
• /
• 제4권2호
• /
• pp.63-71
• /
• 2010

The removal characteristics for aromatic and aliphatic VOCs by electron beam (EB) were discussed in terms of several removal variables such as initial VOC concentration, absorbed dose, background gas, moisture content, reactor material and inlet temperature. It was reviewed that only reactor material was an independent variable among the potential control factors concerned. It was also suggested that main mechanism by EB should be radical reaction for the VOC removal rather than that by primary electrons. It was discussed that the removal efficiency of benzene was lower than that of hexane due to a closed benzene ring. In the case of aromatic VOCs, it was observed that the decomposition of the VOCs with more functional groups attached on the benzene ring was much easier than those with less ones. As for aliphatic VOCs, it was also implied that the longer carbon chain was, the higher the removal efficiency became. An EB-catalyst hybrid system was discussed as an alternative way to remove VOCs more effectively than EB-only system due to much less by-products. This hybrid included supporting materials such as cordierite, Y-zeolite, and $\gamma$-alumina.

• 한국물환경학회지
• /
• 제27권2호
• /
• pp.194-199
• /
• 2011

This study has been carried out to evaluate the performance of $PbO_2$ electrode for the purpose of degradation of N,N-Dimethyl-4-nitrosoaniline (RNO, indicator of OH radical), generation of ozone and decolorization of Rhodamine B (RhB) in water. The effect of the applied current (0.2~1.2 A), electrolyte type (NaCl, KCl and $Na_2SO_4$), electrolyte concentration (0.0~2.5 g/L) and solution pH (3~11) were evaluated. Experimental results showed that RhB and RNO removal were increased with the increase of current, NaCl dosage and decrease of pH. Ozone generation tendencies appeared with the almost similar to the RhB and RNO degradation, except of solution pH (Ozone generation was increased with increase of pH). Optimum current for RhB degradation and consumption of electric power was 1.0 A. The RhB degradation with Cl type electrolyte were higher than that with the sulfate type. Optimum NaCl dosage for RhB degradation was 1.0 g/L.

• Korean Chemical Engineering Research
• /
• 제45권3호
• /
• pp.298-303
• /
• 2007

오존을 중심으로 한 다양한 조합의 고급산화 공정(advanced oxidation process: AOP)을 이용하여 2,4,6-trinitrotoluene (TNT) 제조 공정에서 발생되는 난분해성 폐수인 red water(RW)의 유기물 및 색도 제거 연구를 수행하였다. 적용된 고급산화 공정은 $O_3$, $UV/O_3$, $UV/O_3/H_2O_2$, $UV/O_3/H_2O_2/Fe^{2+}$ 공정이었으며, 유기물 및 색도 제거 효과는 $O_3 < $UV/O_3/H_2O_2/Fe^{2+}$ 공정의 순서로 나타났다. $UV/O_3/H_2O_2/Fe^{2+}$ 공정에서 최적 분해조건은 오존 유량 0.053 g/min, $H_2O_2$ 주입농도 10 mM, $FeSO_4$ 주입농도 0.1 mM로 나타났으며, 90 min 동안 유기물 및 색도 제거율은 각각 96, 100%로 나타났다. tert-butyl alcohol(t-buOH)을 이용한 수산화 라디칼(hydroxyl radical : ${\cdot}OH$)의 scavenging 실험을 통해 오존에 UV, $H_2O_2$, $FeSO_4$를 산화제로 조합함으로써 수산화 라디칼의 발생량을 더욱 증가시키고 유기물 제거율을 효과적으로 향상시킬 수 있음을 확인하였다.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제17권2호
• /
• pp.7-14
• /
• 2012

Batch tests were carried out to evaluate the thermal treatment of low volatile organic compounds in low-permeability soil. The chemical oxidation by sodium persulfate catalyzed by heat and Fe (II) was evaluated. Enhanced persulfate oxidation of n-decane (C-10), n-dodecane (C-12), n-tetradecane (C-14), n-hexadecane (C-16), and phenanthrene was observed with thermal catalyst, indicating increased sulfate radical production. Slight enhancement of the pollutants oxidation was observed when initial sodium persulfate concentration increased from 5 to 50 g/L. However, the removal efficiency greatly decreased as soil/water ratio increased. It indicates that mass transfer of the pollutants as well as the contact between the pollutants and sulfate radical were inhibited in the presence of solids. In addition, more pollutants can be adsorbed on soil particles and soil oxidant demand increased when soil/water ratio becomes higher. The oxidation of the pollutants was significantly improved when catalyzed by Fe(II). The sodium persulfate consumption increased at the same time because the residual Fe(II) acts as the sulfate radical scavenger.

• 한국환경과학회:학술대회논문집
• /
• 한국환경과학회 1998년도 가을 학술발표회 프로그램
• /
• pp.1-1
• /
• 1998

Advanced (Chemical) oxidation processes (AOP) differ from most conventional ones in that hydroxyl radical(OH.) is considered to be the primary oxidant. Hydroxyl radicalcan react non-selectively with a great number of organic and inorganic chemicals. The typical rate constants of true hydroxyl radical reactions are in the range of between 109 to 1012 sec-1. Many processes are possible to generate hydroxyl radical. These include physical and chemical methods and their combinations. Physical means involves the use of high energy radiation such as gamma ray, electron beam, and acoustic wave. Under an applied high energy radiation, water molecules can be decomposed to yield hydroxyl radicals or aqueous electrons. Chemical means include the use of conventional oxidants such as hydrogen peroxide and ozone, two of the most efficient oxidants in the presence of promoter or catalyst. Hydrogen peroxide in the presence of a catalyst such as divalent iron ions can readily produce hydroxyl radicals. Ozone in the presence of specific chemical species such as OH- or hydrogen peroxide, can also generate hydroxyl radicals. Finally the combination of chemical and physical means can also yield hydroxyl radicals. Hydrogen peroxide in the presence of acoustic wave or ultra violet beam can generate hydroxyl radicals. The principles for hydroxyl radical generation will be discussed. Recent case studied of AOP for water treatment and other environmental of applications will be presented. These include the treatment of contaminated soils using electro-Fenton, lechate treatment with conventional Ponton, treatment of coal for sulfur removal using sonochemical and the treatment of groundwater with enhanced sonochemical processes.

• Advances in Traditional Medicine
• /
• 제10권2호
• /
• pp.51-58
• /
• 2010

Vitex rotundifolia (V. rotundifolia) has been used for treating headache, dizziness, toothache and removal of fever as a traditional medicine in Korea. In the present study, we examined the antioxidant and anti-inflammatory activities of 85% methanol extract of V. rotundifolia. In various radical scavenging assays, V. rotundifolia exhibited strong scavenging effect on 1, 1-diphenyl-2-picrylhydrazyl free radical, superoxide radical, nitric oxide. To elucidate the anti-inflammatory properties of V. rotundifolia, we investigated the inhibition effects of nitric oxide production in IFN-gamma and LPS-stimulated mouse peritoneal macrophages. V. rotundifolia suppressed nitric oxide production, iNOS and COX-2 expression dose-dependently through suppression of NF-$\hat{e}B$ activation without notable cytotoxicity. These findings mean that V. rotundifolia may be beneficial in oxidative stress-mediated inflammatory disorders.