Modified Photo-Fenton Reaction을 이용한 Methyl Tert-butyl Ether (MTBE)의 분해 Kinetic 및 메커니즘 규명에 관한 연구

김민경,공성호,Kim, Min-Kyoung,Kong, Sung-Ho 한국지하수토양환경학회 2006 지하수토양환경 Vol.11 No.6

지하 저장 탱크로부터의 유류 유출로 인하여 전세계적으로 넓은 지역의 토양 및 지하수가 오염되고 있다. Methyl tert-butyl ether(MTBE)는 대기 오염 감소를 위하여 널리 사용되고 있는 유류 첨가제이지만 토양 및 지하수로 유입되어 섭취 되었을 때 발암 가능성이 있는 유독 물질이다. 본 연구는 고도 산화 처리 기법 중 유기 오염물의 분해에 높은 효율을 나타내는 고전적 Fenton reaction의 최대 단점인 강한 산성(pH 2.5-3) 의존성을 극복한 새로운 산화 처리 기법을 개발하여 고농도의 MTBE를 효과적으로 분해 하는 것을 그 목적으로 하여 자연 친화적인 chelating agents를 사용하여 중성 영역에서 Fenton reaction을 가능하게 하는 기법인 Modified Fenton reaction과 Ultra Violet light(UV)를 이용하여 분해효율을 극대화 하는 Photo-assisted Fenton reaction을 응용한 Modified Photo-Fenton reaction system을 개발하여 최적 반응 조건 및 반응 차수, 반응 메커니즘을 밝혀내었다. 낮은 독성과 높은 생분해성을 나타낸 Citrate ion을 chelating agents로 선정하였으며 최적 반응 조건은 [$Fe^{3+}$] : [Citrate] = 1 mM : 4 mM, 3% $H_2O_2$, 17.4 kWh/L UV dose, 초기 pH 6.0이며 이 조건에서 1000 ppm MTBE를 분해한 결과 6시간 후 86.75%, 16시간 후 99.99%의 높은 분해율을 나타냈으며 최종 pH는 6.02로 안정적이었다. 또한 Modified Photo-Fenton reaction을 이용한 MTBE 분해 반응은 유사 1차 반응을 나타내었으며 methoxy group이 ${\cdot}OH$ radical과 주로 반응하여 tert-butyl formate(TBF)가 주요 분해 산물이 되는 분해 경로를 따른 다는 것이 밝혀졌다. 본 연구로 개발된 Modified Photo-Fenton reaction에서 발생되는 산화제인 ${\cdot}OH$ radical의 비선택적 반응성을 고려할 때 본 system은 다른 종류의 유기 오염물 분해에도 효과적일 것으로 판단된다. Improper disposal of petroleum and spills from underground storage tanks have created large areas with highly toxic contamination of the soil and groundwater. Methyl tert-butyl ether (MTBE) is widely used as a fuel additive because of its advantageous properties of increasing the octane value and reducing carbon monoxide and hydrocarbon exhausts. However, MTBE is categorized as a possible human carcinogen. This research investigated the Modified Photo-Fenton system which is based on the Modified Fenton reaction and UV light irradiation. The Modified Fenton reaction is effective for MTBE degradation near a neutral pH, using the ferric ion complex composed of a ferric ion and environmentally friendly organic chelating agents. This research was intended to treat high concentrations of MTBE; thus, 1,000 mg/L MTBE was chosen. The objectives of this research are to find the optimal reaction conditions and to elucidate the kinetic and mechanism of MTBE degradation by the Modified Photo-Fenton reaction. Based on the results of experiments, citrate was chosen among eight chelating agents as the candidate for the Modified Photo-Fenton reaction because it has a relatively higher final pH and MTBE removal efficiency than the others, and it has a relatively low toxicity and is rapidly biodegradable. MTBE degradation was found to follow pseudo-first-order kinetics. Under the optimum conditions, [$Fe^{3+}$] : [Citrate] = 1 mM: 4 mM, 3% $H_2O_2$, 17.4 kWh/L UV dose, and initial pH 6.0, the 1000 ppm MTBE was degraded by 86.75% within 6 hours and 99.99% within 16 hours. The final pH value was 6.02. The degradation mechanism of MTBE by the Modified Photo-Fenton Reaction included two diverse pathways and tert-butyl formate (TBF) was identified to be the major degradation intermediate. Attributed to the high solubility, stability, and reactivity of the ferric-citrate complexes in the near neutral condition, this Modified Photo-Fenton reaction is a promising treatment process for high concentrations of MTBE under or near a neutral pH.

Fenton 반응과 OCV Holding에 의한 PEMFC 고분자 전해질 막의 열화비교

오소형,곽아현,이대웅,이무석,이동훈,박권필 한국화학공학회 2019 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.57 No.6

The Fenton reaction, which evaluates the electrochemical durability of polymer membranes of polymer electrolyte fuel cells (PEMFC), and the degradation of polymer membranes by OCV holding method are compared. The Fenton reaction is a method that can evaluate the chemical durability of the polymer membrane at outside the cell in a shorter time than the OCV Holding method. The Fenton reaction was carried out at 30% hydrogen peroxide, 10 ppm iron, and 80 oC for 24 hours. OCV Holding was driven at 90 oC, 30% relative humidity and OCV for 168 hours. The Fenton reaction caused a lot of degradation inside the polymer membrane. On the other hand, in OCV Holding, the membrane thickness was thinned by the entire surface and internal degradation. The fluorine emission rate was more than 10 times higher than that of OCV Holding due to the Fenton reaction. The hydrogen permeation rate increased about 30% at 24 hours of Fenton reaction. At OCV Holding, hydrogen permeability decreased after 24 hours and then increased. As a whole, there was a difference in a membranes deteriorated by Fenton reaction and OCV Holding. 고분자전해질연료전지(PEMFC)의 고분자막의 전기화학적 내구성을 평가하는 펜톤(Fenton)반응과 개회로전위 유지(OCV Holding)방법에 의한 고분자 막의 열화 결과를 비교하였다. 펜톤 반응은 셀 밖에서 OCV Holding 방법보다 더 짧은시간에 고분자막의 화학적인 내구를 평가할 수 있는 방법이다. 펜톤 반응은 과산화수소 30%, 철이온 80 ppm, 80 oC에서24시간 실시하였다. OCV Holding은 90 oC, 상대습도 30%, OCV에서 168시간 시간 구동하였다. 펜톤 반응에 의해서는 고분자막의 내부에서 열화가 많이 발생하는 현상을 보였다. 반면에 OCV Holding에서는 표면과 내부 전체적인 열화에의해 막 두께가 얇아졌다. 펜톤 반응에 의해 불소유출속도는 OCV Holding에 비해 10배 이상 높았다. 수소투과속도는펜톤 반응 24시간에 약 30%증가하였다. OCV Holding에서는 24시간에 수소투과도가 감소하였고 이후 증가하는 경향을보였다. 전체적으로 펜톤 반응과 OCV Holding에 의한 고분자막 열화는 차이가 있었다.

Fenton Reaction을 이용한 Phenanthrene 오염 토양 처리에서 Acetate의 영향

성요셉(Joseph Seong),박주양(Joo Yang Park) 大韓環境工學會 2009 대한환경공학회지 Vol.31 No.5

오염토양에 펜톤 반응을 적용함에 있어서 과산화수소의 빠른 소모로 과량의 과산화수소가 요구되어지는 것이 단점으로 지적되고 있다. 이에 본 연구에서는 대표적인 PAHs물질인 phenanthrene으로 오염된 토양 처리를 위해 철의 리간드로 acetate를 사용하여 과산화수소의 안정성 확보를 통하여 공정의 효율을 높이고자 하였다. Acetate는 철의 몰농도에 대비하여 0.5배에서 3배(2~12 mM)까지 주입하였고, 과산화수소는 분해 효율에 미치는 영향을 배제하기 위해 낮은 농도인 0.7%를 주입하였다. Acetate가 주입되어 과산화수소의 잔류시간은 최대 50배 이상 증가하였으며, 과산화수소의 안정성이 확보됨에 따라 phenanthrene의 제거율도 70%까지 향상되었다. 반응 중에 철은 2가와 3가로 산화환원을 반복하였고 과산화수소가 모두 분해되는 시점부터 HO₂·에 의해 2가철로 환원이 이루어졌다. 과산화수소의 영향으로 반응중의 pH는 산성영역을 나타냈으며, acetate가 8 mM 이상 주입되었을 때 4~5범위 내에 머무르는 것을 확인하였다. Fenton reaction에 의해 철의 리간드로 사용된 acetate 역시 분해가 이루어지는 것을 확인할 수 있었으며, phenanthrene의 비해 분해되는 시점이 느린 것으로 나타나 분해되어지는 경쟁관계에서 phenanthrene이 우세한 것으로 판단된다. 이상의 연구결과를 통해 오염 토양처리에 기존 Fenton reaction의 효율성과 경제성을 향상시킬 수 있는 가능성을 확인할 수 있었으며, 중성영역의 pH로 확장된 연구 등을 통해 좀 더 현실적인 공법으로 발전할 수 있으리라 판단된다. Due to rapid consumption of hydrogen peroxide, large amount of hydrogen peroxide is required when Fenton reaction is applied to the contaminated soil. In this study, acetate was employed as a ligand of Fe²⁺ to enhance the efficiency of removal of phenanthrene by securing the stability of hydrogen peroxide. 0.5~3 times of acetate (2~12mM) was added to compare with molar concentration of Fe²⁺. Low initial concentration of hydrogen peroxide was 0.7% to eliminate side effect of removal efficiency. The results showed that hydrogen peroxide lifetime was lasted up to 72 hours, or more than 50 times of normal lifetime. Phenanthrene removal efficiency was improved up to 70% due to stabilized hydrogen peroxide. Ferrous ion was oxidized to ferric ion and oxidation-reduction was repeated during the reaction. Finally ferric ion was reduced to ferrous by HO₂·. It was confirmed that, due to the influence of hydrogen peroxide, pH was acid region and it remained at the range of 4~5 when 8 mM or more of acetate was added. Acetate which was used as the ligand of Fe was also decomposed by Fenton reaction. The decomposition time of acetate was slower than phenanthrene. Therefore, it was able to come to the conclusion that phenanthrene was superior to acetate at the competition for decomposition. Through the results of this study, it was able to identify the possibilities to improve the efficiency of Fenton reaction in the contaminated soil and its economic feasibility, and to move to more realistic technique through research expanded to neutral pH region.

Roles of Oxidation and Coagulation in Fenton Process for the Removal of Organics in Landfill Leachate

Yoon, Jeyong,Kim, Yoonki,Huh, Jin,Lee, Yunho,Lee, Dongsoo 한국공업화학회 2002 Journal of Industrial and Engineering Chemistry Vol.8 No.5

High potential of coagulation to remove organics has not been fully recognized in Fenton process and coagulation has been used as an auxiliary process removing iron in effluent. This study evaluates the relative role of oxidation and coagulation step of Fenton process in the removing of biologically treated leachate organics of Metropolitan Landfill in Korea. This study showed that to the maximum, 30% of DOC and 40% of COD removal efficiencies were achieved by the Fenton oxidation step alone, whereas, 60% of DOC and 75% of COD removal efficiencies were achieved by the combined Fenton oxidation and subsequent Fenton coagulation step, as the same Fenton's reagent condition ([Fe^2+]_0 = 1250 or 2500 mg/L, and [H_20_2]_0 = 0~3000 mg/L) was applied in laboratory experiments. In addition, it was observed that the rapid decomposition of H_20_2 with time did not lead to the corresponding removal of leachate organics. This means that OH radical generated from the H_2O_2 decompostion is not effectively invoved in degrading the leachate organics, pointing out the possibility of uneconomical use of H_20_2 and unwarranted retention time of Fenton oxidatiom chamber in Fenton leachate treatment plant. Furthermore, the investigation of field Fenton process confirmed the observation of laboratory scale study, revealing that the DOC and COD removal effciencies in the Fenton oxidation step were less than 10~20% prior to the Fenton coagulation step, and major removals of DOC and COD (60~70%) were achieved after the finial Fenton coagulation step. These findings demonstrate the significance of the coagulation in Fenton process and raise a need for individual assessments of both oxidation and coagulation for the optimal design and evaluation of a whole Fenton processes. The individual assessments, however, should be conducted in an integrative manner because the preceding process (oxidation) may affect the performance the next process (coagulation).

PEMFC 고분자막 내구 평가를 위한 Fenton 반응에서 과산화수소 농도 변화에 관한 연구

오소형 ( Sohyung Oh ),김정재 ( Jeongjae Kim ),이대웅 ( Daewoong Lee ),박권필 ( Kwonpil Park ) 한국화학공학회 2018 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.56 No.3

고분자전해질연료전지(PEMFC)의 고분자막 전기화학적 내구성을 셀 밖에서 평가하는 방법으로 펜톤(Fenton)반응이 많이 이용된다. 본 연구에서는 펜톤 반응에 영향을 주는 인자를 파악하고자 하였다. 반응진행도를 파악하기 위해 펜톤 반응에서는 생성물로서 라디칼을 분석해야 하는데, 라디칼을 분석하기 어려워 반응물인 과산화수소 농도를 분석해 반응진행도를 측정하였다. 온도에 따른 과산화수소 변화속도를 측정해 활성화 에너지를 계산한 결과 180분에서 24.9 kJ/mol이었다. 펜톤반응 속도는 철이온 농도에 많은 영향을 받았다. 80 ℃, 200 rpm, Fe²⁺ 80 ppm 조건에서는 1시간동안에도 과산화수소 농도가 20%이상 처음과 차이가 나므로 용액교체를 자주 하는 것이 막열화 속도를 증가시킴을 보였다. Fenton reaction is widely used as a out of cell method for evaluating the membrane electrochemical durability of Proton Exchange Fuel Cell (PEMFC). In this study, we investigated the factors affecting the Fenton reaction. In order to estimate the degree of the reaction, it is necessary to analyze the radicals as a product in the Fenton reaction. However, since the radicals are difficult to analyze, the degree of the reaction was measured by analyzing the concentration of hydrogen peroxide. The activation energy was calculated from the rate of hydrogen peroxide change with temperature. The activation energy was 24.9 kJ/mol at 180 min. The Fenton reaction rate was affected by the iron ion concentration. At 80 ℃, 200 rpm, and Fe²⁺ 80 ppm, the concentration of hydrogen peroxide was decreased more than 20% even for 1 hour, which shows that frequent solution replacement increases the membrane degradation rate.

Degradation of pyrene in cetylpyridinium chloride-aided soil washing wastewater by pyrite Fenton reaction

Choi, Kyunghoon,Bae, Sungjun,Lee, Woojin Elsevier 2014 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.249 No.-

<P><B>Abstract</B></P> <P>Degradation of pyrene by pyrite Fenton reaction in synthetic cetylpyridinium chloride (CPC)-aided soil washing wastewater (SWW) was investigated in a closed batch reactor. Pyrene in the presence of CPC was gradually degraded in the pyrite Fenton system by 96% in 180min at initial pH 7 showing pseudo-first-order reaction kinetics (0.0194min<SUP>−1</SUP>), while the concentration of pyrene in the absence of CPC decreased abruptly by 91% in 5min and then did not significantly decrease by the end of sampling time (180min). In a classic Fenton system, pyrene in the presence of CPC was degraded by 35% in 180min at initial pH 3. The sustainable reactivity of pyrite Fenton was attributed to slow but continuous dissolution of Fe(II) from the pyrite surface leading to continuous production of reactive radicals during the reaction. Pyrene in the presence of CPC was mainly degraded by OH radicals. Its product study showed that the pyrite Fenton system can successfully degrade pyrene in the CPC-aided SWW without accumulating toxic oxy-pyrenes such as 1,6-pyrenequinone and 1,8-pyrenequinone. CPC was also successfully degraded (95%) in the pyrite Fenton system, forming carbon dioxide and ammonium as main degradation products.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Both pyrene and CPC were effectively degraded in 180min by pyrite Fenton reaction. </LI> <LI> Iron was dissolved continuously and reacted with H<SUB>2</SUB>O<SUB>2</SUB> to produce OH<SUP> </SUP>. </LI> <LI> CPC was degraded to CO<SUB>2</SUB> and ammonium as main degradation products. </LI> <LI> No oxy-pyrenes were accumulated during pyrene degradation in pyrite Fenton system. </LI> </UL> </P>

Mimicking the Fenton reaction-induced wood decay by fungi for pretreatment of lignocellulose

Jung, Young Hoon,Kim, Hyun Kyung,Park, Hyun Min,Park, Yong-Cheol,Park, Kyungmoon,Seo, Jin-Ho,Kim, Kyoung Heon Elsevier 2015 Bioresource technology Vol.179 No.-

<P><B>Abstract</B></P> <P>In this study, the Fenton reaction, which is naturally used by fungi for wood decay, was employed to pretreat rice straw and increase the enzymatic digestibility for the saccharification of lignocellulosic biomass. Using an optimized Fenton’s reagent (FeCl<SUB>3</SUB> and H<SUB>2</SUB>O<SUB>2</SUB>) for pretreatment, an enzymatic digestibility that was 93.2% of the theoretical glucose yield was obtained. This is the first report of the application of the Fenton reaction to lignocellulose pretreatment at a moderate temperature (i.e., 25°C) and with a relatively high loading of biomass (i.e., 10% (w/v)). Substantial improvement in the process economics of cellulosic fuel and chemical production can be achieved by replacing the conventional pretreatment with this Fenton-mimicking process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The Fenton reaction is naturally used by fungi for wood decay. </LI> <LI> The Fenton reaction using FeCl<SUB>3</SUB> and H<SUB>2</SUB>O<SUB>2</SUB> was employed to pretreat rice straw. </LI> <LI> After the Fenton pretreatment, the enzymatic digestibility increased to 93.2%. </LI> </UL> </P>

펜톤 산화법을 이용한 역삼투 농축폐수 내 유기물 제거

김유경 ( Yu-kyung Kim ),김지연 ( Jiyeon Kim ),서인석 ( Inseok Seo ) 한국수처리학회 2016 한국수처리학회지 Vol.24 No.5

The interest on reuse of wastewater has increased by lack of fresh water supply. Reverse osmosis (RO) process is one of the technology to reuse wastewater. It can be obtained high purity water from wastewater using the revese osmosis membrane. However, it also produces revese osmosis concentrate wastewater, including high levels of organic matter as the result of treatment. This study presents the Fenton`s oxidation treatment as a way to handle the revese osmosis concentrate wastewater. The main objective of this research is to investigate effects of various factors such as pH, hydrogen peroxide (H₂0₂) dose, iron sulfate dose (as ferrous iron, Fe<sup>2+</sup>) and reaction time for removal of organics in revese osmosis concentrate wastewater by using Fenton`s oxidation process. All tests were proceeding under the three steps: Fenton`s reaction, Neutralization and Sedimentation. The results show that the Fenton`s oxidation treatment was very effective in removing organics in revese osmosis concentrate wastewater. The optimum factors in Fenton`s oxidation process of RO concentrate wastewater were determined; pH 3, 500 mg/L as H₂0₂, 1000 mg/L as Fe<sup>2+</sup> and 30 minutes as reaction time. Under the optimum conditions, the removal efficiency of chemical oxygen demand (COD) was about 50 percent. Compared with the other processes, Fenton oxidation has a high removal efficiency of chemical oxygen demand. However, it generates a Fenton sludge and requires additional processing to remove them. Therefore, in order to apply the Fenton`s oxidation in the actual process, it is determined that require additional research on the Fenton sludge treatment.

Mechanism of DNA Cleavage Induced by Fe^(2+) Autoxidation

Jong Moon Kim,김석규 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.3

This work investigated the difference between Fe^(2+) autoxidation-induced and Fenton-type cleavage of pBR322plasmid DNA. ^(•)OH generation reactions in the absence and presence of H_2O_2 under various conditions were also investigated. Although both the Fe^(2+) autoxidation and Fenton-type reactions showed DNA cleavage and ^(•)OH generation, there were significant differences in their efficiencies and reaction rates. The rate and efficiency of the cleavage reaction were higher in the absence of 1.0 mM of H_2O_2 than in its presence in 20 mM phosphate buffer. In contrast, the ^(•)OH generation reaction was more prominent in the presence of H_2O_2 and showed a pH-independent, fast initial reaction rate, but the rate was decreased in the absence of H_2O_2 at across the entire tested pH range. Studies using radical scavengers on DNA cleavage and ^(•)OH generation reactions in both the absence and presence of H_2O_2 confirmed that both reactions spontaneously involved the active oxygen species ^(•)OH, O_2^(•−), ^(1)O_2 and H_2O_2, indicating that a similar process may participate in both reactions. Based on the above observations, a new mechanism for the Fe^(2+) autoxidation-induced DNA cleavage reaction is proposed.

Mechanism of DNA Cleavage Induced by Fe²⁺ Autoxidation

Kim, Jong-Moon,Kim, Seog-K. Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.3

This work investigated the difference between $Fe^{2+}$ autoxidation-induced and Fenton-type cleavage of pBR322 plasmid DNA. $^{\cdot}OH$ generation reactions in the absence and presence of $H_2O_2$ under various conditions were also investigated. Although both the $Fe^{2+}$ autoxidation and Fenton-type reactions showed DNA cleavage and $^{\cdot}OH$ generation, there were significant differences in their efficiencies and reaction rates. The rate and efficiency of the cleavage reaction were higher in the absence of 1.0 mM of $H_2O_2$ than in its presence in 20 mM phosphate buffer. In contrast, the $^{\cdot}OH$ generation reaction was more prominent in the presence of $H_2O_2$ and showed a pH-independent, fast initial reaction rate, but the rate was decreased in the absence of $H_2O_2$ at across the entire tested pH range. Studies using radical scavengers on DNA cleavage and $^{\cdot}OH$ generation reactions in both the absence and presence of $H_2O_2$ confirmed that both reactions spontaneously involved the active oxygen species $^{\cdot}OH$, ${O_2}^{\cdot-}$, $^1O_2$ and $H_2O_2$, indicating that a similar process may participate in both reactions. Based on the above observations, a new mechanism for the $Fe^{2+}$ autoxidation-induced DNA cleavage reaction is proposed.