영가철(Fe⁰)과 UV를 이용한 1,4-dioxane 분해 반응시 철농도의 변화와반응 메커니즘의 연구

손현석(Hyun Seok Son),임종권(Jong Kwon Im),조경덕(Kyung Duk Zoh) 大韓環境工學會 2008 대한환경공학회지 Vol.30 No.3

본 논문은 1,4-dioxane의 분해를 위한 F⁰와 Fe²⁺의 반응에서 UV의 영향을 평가하기 위해 반응 중 [Fe²⁺]와 용액 중 총철이온 농도에 대한 [Fe²⁺]의 비([Fe²⁺]/[Fe(t)])의 변화를 조사하였다. UV, F⁰, 그리고 Fe²⁺의 단독반응에 의한 1,4-dioxane의 분해효율은 10% 이하였으며 그 반응 동안 [Fe²⁺]와 [Fe²⁺]/[Fe(t)]의 변화 또한 거의 일어나지 않았다. 그러나 UV 조사에 의해 F⁰의 산화는 약 25% 정도 증가하였을 뿐만 아니라 1,4-dioxane의 분해 효율 또한 개선되었다. Fenton 반응(Fe²⁺+H₂O₂)의 경우 반응초기 90 분까지는 매우 빠른 분해율을 보인 반면 90분 이후에는 1,4-dioxane의 분해가 거의 정지되었다. Fe²⁺와 UV 반응에서는 [Fe²⁺]/ [Fe(t)]가 반응 시작부터 감소하다가 90분 이후부터 완만한 증가를 보였다. F⁰와 UV 반응의 경우 반응속도 상수는 반응시작 90 분 동안 1.84×10-3 min-1에서 Fe²⁺의 변화가 일어나는 시간인 90분 이후 9.33×10-3 min-1로 큰 상승을 보였고 이 변화는 [Fe²⁺]/ [Fe(t)]이 감소이후에 일어났다. [Fe²⁺]/[Fe(t)]는 Fe²⁺와 UV 반응에서 계속적으로 감소하였다. 그러나 그 반응에 ClO₄-를 첨가한 경우 [Fe²⁺]/[Fe(t)]는 완만한 상승을 보였다. 이 결과들은 1,4-dioxane의 분해는 주로 F⁰이 Fe²⁺로 산화되는 기간이 아닌 Fe²⁺가 Fe³⁺로 산화, 환원되는 반응 동안 일어났음을 보여준다. 즉, 1,4-dioxane의 주요 분해는 철순환에서 생성되는 라디칼에 의한 산화작용이라 할 수 있다. 또한 UV와 ClO₄-는 Fe³⁺의 환원에 큰 작용을 하는 것으로 관찰되었고 이는 radical의 지속적인 생산이라는 측면에서 1,4-dioxane의 분해효율을 증가시키기 위해 매우 중요한 부분이라 할 수 있다. The study presents the results of 1,4-dioxane degradation using zero valent (F⁰) or Fe²⁺ ions with and without UV. During the reaction, the change of [Fe²⁺] and [Fe²⁺]/[Fe(t)], the concentration ratio of ferrous ion to total iron ion in solution was measured. Less than 10% degradation of 1,4-dioxane was observed by UV-only, F⁰-only, and Fe²⁺-only conditions, and also the changes of [Fe²⁺] and [Fe²⁺]/[Fe(t)] were minimal in each reaction. However, the oxidation of F⁰ was enhanced with the irradiation of UV by approximately 25% and the improvement of 1,4-dioxane degradation was observed. Fenton reaction (Fe²⁺+H₂O₂) showed higher degradation efficiency of 1,4-dioxane until 90 min, which of the degradation was stopped after that time. In the reaction of Fe²⁺ and UV, the ratio of [Fe²⁺]/[Fe(t)] decreased then slowly increased after a certain time indicating the reduction of Fe³⁺ to Fe²⁺. In case of F⁰ in the presence of UV, the first-order rate constant was found to be 1.84×10-3 min-1 until 90 min, and then changed to 9.33×10-3 min-1 when the oxidation of Fe²⁺ mainly occurred. In this case [Fe²⁺]/[Fe(t)] kept decreasing for the reaction. However, the addition of perchlortae (ClO₄-) in the reaction of F⁰ and UV induced the continuous increase of [Fe²⁺]/[Fe(t)] ratio. The results mean the primary degradation factor of 1,4-dioxane is the oxidation by the radicals generated from the redox reaction between Fe²⁺ and Fe³⁺. Also, both UV and ClO₄- played the role inducing the reduction of Fe³⁺, which is important to degrade 1,4-dioxane by enhancing the generation of radicals.

재활시스템 구동을 위한 수소저장합금의 제조 특성 분석

신미연,권대규,유창호 제어로봇시스템학회 2019 제어로봇시스템학회 각 지부별 자료집 Vol.2019 No.1

In this paper, Zr0.9Ti0.1Cr0.6Fe1.4 and Zr0.9Ti0.1Cr0.7Fe1.3 were selected as Metal-Hydride(MH) alloys for driving the rehabilitative system. The MH alloys were fabricated by Arc-melting and the compositions of its were analyzed by Field Emission Scaning Electron Microscope(FE-SEM), Energy Dispersive X-ray Spectroscopy(EDS), X-Ray Diffractometry(XRD) and Inductively Coupled Plasma(ICP). As a result of the analysis, the alloys were nonuniform in composition although it was prepared as a single phase of hexagonal structure. In the future, the hydrogen storage capacity of the MH alloys will be evaluated by producing P-C-T diagram of each MH alloys. And MH alloys will be used at driving actuation system for confirming its actual performance.

은(Ag) 나노입자가 코팅된 페롭스카이트 La_0.7Sr_0.3Co_0.3Fe_0.7O_3−δ 의 Mössbauer 분광연구

엄영랑(Young Rang Uhm),이창규(Chang Kyu Rhee),김철성(Chul Sung Kim) 한국자기학회 2012 韓國磁氣學會誌 Vol.22 No.2

The Ag nanoparticles attached La_0.7Sr_0.3Co_0.3Fe_0.7O_3?δ (LSCF) perovskites were prepared by plasma method. The Ag nanoparticles with size of several nanometers deposited from the Ag target were coated on the surface of LSCF powders with size range from 0.2 to 3 μm. The agglomeration of Ag particles annealed at 800℃ under inert gas of Ar were rarely observed. The inter-diffusion between surface Ag and core LSCF is effectively strong to prevent aggregation of Ag nanoparticles. The wave number of FT-IR spectra for LSCF were largely shifted as the concentration of Ag on LSCF up to 2.11 wt.%. The ionic states of irons in LSCF were measured by Mossbauer spectroscopy. The small amount of Fe⁴⁺ ions are converted to Fe³⁺ ions after Ag nanopartcles were coated on LSCF.

비자성상 첨가에 의한 ThMn<SUB>12</SUB> 구조의 철계 자성합금의 자기적 특성 향상

천휘동(Hui-Dong Qian),임정태(Jung Tae Lim),박지훈(Jihoon Park),최철진(Chul-Jin Choi) 한국자기학회 2020 韓國磁氣學會誌 Vol.30 No.3

Recently, Fe-rich alloys with ThMn12 structure have attracted much attention as next generation permanent magnet materials. Among them, Sm(Fe<SUB>0.8</SUB>Co<SUB>0.2</SUB>)<SUB>11</SUB>Ti alloy shows good magnetic properties, however the low coercivity problem is still to be solved. In order to improve the coercivity, Sm(Fe<SUB>0.8</SUB>Co<SUB>0.2</SUB>)<SUB>11</SUB>Ti bulk samples were prepared by adding non-magnetic Sm<SUB>7</SUB>Cu₃ powders (0, 5, and 10 wt%). The crystallographic and magnetic properties of Sm(Fe<SUB>0.8</SUB>Co<SUB>0.2</SUB>)<SUB>11</SUB>Ti added Sm7Cu₃ have been investigated by using X-ray diffractometer (XRD), scaning electron microscope (SEM), and vibrating sample magnetometer (VSM). The phase identity and volume fraction of Sm(Fe<SUB>0.8</SUB>Co<SUB>0.2</SUB>)<SUB>11</SUB>Ti powders were determined by using Rietveld refinement. The phase distribution of grains and grain boundaries was analyzed by using SEM. With increasing Sm<SUB>7</SUB>Cu₃ content, the value of saturation magnetization of Sm(Fe<SUB>0.8</SUB>Co<SUB>0.2</SUB>)<SUB>11</SUB>Ti bulk samples decreased, while their coercivity increased by about 67% with an addition of a non-magnetic phase.

NO의 암모니아 선택적 촉매환원반응을 위한 철 제올라이트 촉매의 내황성에 미치는 조촉매 효과

하호정(Ho-Jung Ha),최준환(Joon-Hwan Choi),한종대(Jong-Dae Han) 한국청정기술학회 2015 청정기술 Vol.21 No.3

UV와 Fe²⁺, 그리고 H₂O₂를 조합한 고급산화 공정에서의 Pentachlorophenol의 분해 속도 연구

손현석(Hyun Seok Son),김문경(Moon Kyung Kim),조경덕(Kyung Duk Zoh) 大韓環境工學會 2007 대한환경공학회지 Vol.29 No.7

본 연구는 PCP를 UV, UV/H₂O₂, Fe²⁺, Fe²⁺/H₂O₂, 그리고 UV/Fe²⁺/H₂O₂의 공정을 이용하여 처리할 때 각각 공정의 처리효율을 비교하여 각 반응의 결합에 의한 개선 효과와 분해 기전을 규명한 연구이다. 실험의 결과 UV 반응에 H₂O₂의 첨가에 따라 약 13배 정도의 유사 일차 반응 속도의 증가를 보였으며, Fe²⁺ 단독 반응에 비해 180 mM과 16 mM의 H₂O₂의 첨가는 각각 4배와 7.25배의 반응속도 증가를 보였다. 또한 Fe²⁺/H₂O₂의 반응에 비해 UV를 조사한 반응의 경우 약 3.1배의 반응 속도의 개선을 보였다. 이러한 반응속도의 증가는 각 반응에서 생성되는 OH 라디칼의 생성과 밀접한 관계가 있었다. Fe²⁺/H₂O₂ 반응에서 일어나는 슬러지 침전 반응은 UV를 조사함으로서 상당부분 제거가 가능하였다. This study was performed to compare and to examine the degradation efficiencies and degradation mechanism of pentachlorophenol(PCP) by UV, UV/H₂O₂, Fe²⁺, Fe²⁺/H₂O₂, and UV/Fe²⁺/H₂O₂ processes. The pseudo-first order rate constant was compared in each process. The addition of H₂O₂ increased the rate constant by 13 times compared to the reaction with UV alone. The reaction rate in Fe²⁺ reaction with PCP increased 4 times and 7.25 times by adding 180 mM H₂O₂ and 16 mM H₂O₂, respectively. Compared to that with Fe²⁺/H₂O₂, the rate constant of the reaction with UV alone reaction increased 3.1 times. These results indicates the enhancement of reaction rate is closely related to the generation of OH radical. The degree of the iron sludge production observed in Fe²⁺/H₂O₂ reaction was significantly reduced by irradiating UV in this process.

Parameterization of Multi Band Model of Critical Magnetic Fields for the Iron based Superconductor Ba(Fe<SUB>1-x</SUB>Ni<SUB>x</SUB>)₂As₂

Teklie Lissanu Tegegne,Gebregziabher Kahsay 한국자기학회 2021 Journal of Magnetics Vol.26 No.3

In this study, the mathematical expression of temperature dependence upper critical magnetic field (Hc2), angle dependence of upper critical magnetic field (Hc2), and temperature dependence of Ginzburg-Landau (GL) characteristics were investigated. The parameters were computed by using two band Ginzburg-Landau (GL) phenomenological model for Ba(Fe1-xNix)₂As₂ iron based superconductor. Application of very small external magnetic field at low temperature to nickel doped BaFe₂As₂ changes to Ba(Fe1-xNix)₂As₂ iron based superconductor at a critical temperature of 19.5 K. The phase diagrams of the two upper-critical field and GL characteristics length were plotted as a function of angle and temperature for Ba(Fe1-xNix)₂As₂ iron based superconductor using the experimental values. The phase diagram shows the linear dependence of upper critical magnetic field parallel H<SUP>∥c</SUP>c2 and perpendicular (H<SUP>⊥c</SUP>c2) with temperature (T). Correspondingly, the phase diagrams of the upper critical field (Hc2(θ)) versus the angle (θ) were plotted. The parallel and perpendicular to the symmetry axis of coherence length (ξGL(T)) and penetration depth (λGL(T)) versus temperature were plotted. In these plots both parameters are increased with increasing temperature and diverges at the critical temperature for the superconductor Ba(Fe1-xNix)₂As₂. This theoretical investigation was found to be in agreement with the obtained experimental results.

Fe₄N 나노분말과 Fe₁₇Sm₂N<SUB>x</SUB> 자성분말의 자기적 특성

오영우(Young Woo Oh),이정구(Jung Goo Lee),박상준(Sang Jun Park) 한국자기학회 2012 韓國磁氣學會誌 Vol.22 No.3

Nano-magnetic materials such as iron-nitrides have been actively studied as an alternative to the application of high density, high performance needs for next generation information storage and also alternative to the rare earth and neodymium magnet. Fe₄N is the basic materials for magnetic storage media and is one of the important magnetic materials in focus because of its higher magnetic recording density and chemical stability. Single phase γ’-Fe₄N nanoparticles have been prepared by a PAD (Plasma Arc Discharge) method and nitriding in a NH₃-H₂ mixed gases at temperature, 400 ℃ for 4 hrs. Also Fe₁?Sm₂N<SUB>x</SUB> powders were synthesized by nitriding after reduction/diffusion of Fe₁?Sm₂ to compare the magnetic properties with nano-sized Fe₄N particles. The saturation magnetization of Fe₄N and Fe₁?Sm₂N<SUB>x</SUB> were 149 and 117 emu/g, respectively, but the coercive force was considerably smaller than that of bulk or acicular Fe₄N.

F⁰, Fe²⁺, Fe³⁺/H₂O₂ 시스템을 이용한 침출수의 Fenton 산화반응

박성호(Sung Ho Park),한인섭(Ihn Sup Han) 大韓環境工學會 2005 대한환경공학회지 Vol.27 No.4

마이너스 자화 스피넬 산화물의 연 X선 방사광 분광 연구

양민영(Min Young Yang),성승호(Seungho Seong),이은숙(Eunsook Lee),강정수(J.-S. Kang) 한국자기학회 2020 韓國磁氣學會誌 Vol.30 No.2

By employing soft X-ray absorption spectroscopy (XAS) and soft X-ray magnetic circular dichroism (XMCD), the electronic structures of Li<SUB>0.5</SUB>FeCr<SUB>1.5</SUB>O₄ spinel ferrite have been investigated, which exhibits the negative magnetization phenomenon. It is found that that both Fe and Cr ions are trivalent, that most of Fe3+ ions occupy the A (T<SUB>d</SUB>) sites while Cr<SUP>3+</SUP> ions occupy the B (O<SUB>h</SUB>) sites, and that the magnetic moments of Fe ions and those of Cr ions are coupled antiferromagnetically to each other. Hence Li<SUB>0.5</SUB>FeCr<SUB>1.5</SUB>O₄ can be represented as (Fe)<SUB>A</SUB>[Li<SUB>0.5</SUB>Cr<SUB>1.5</SUB>]<SUB>B</SUB>O₄.