• 제목/요약/키워드: Cu-based composite

검색결과 85건 처리시간 0.02초

Biomimetic Copper Complex Containing Polymer Modified Electrode for Electrocatalytic Reduction of Oxygen

  • Saravanakumar, D.;Nagarale, Rajaram Krishna;Jirimali, Harish Chandra;Lee, Jong Myung;Song, Jieun;Lee, Junghyun;Shin, Woonsup
    • Journal of Electrochemical Science and Technology
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    • 제7권4호
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    • pp.298-305
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    • 2016
  • The development of non-precious metal based electrocatalysts is highly desired for the oxygen reduction reaction (ORR) as alternates to noble metal based ORR electrocatalysts. Herein, we report mononulcear copper(II) complex $[CuLbpy]ClO_4$ (L=4-[(2-hydroxyphenylimino)methyl]benzoic acid) containing poly(allylamine.HCl) polymer (PAlACuLbpy) as an electrocatalyst for oxygen reduction reaction (ORR). PAlACuLbpy was mixed with poly(acrylic acid) and tetraethylortho silicate to prepare a composite and then deposited on the screen printed electrode surface. The modified electrode (PAlACuLbpy/PCE) is highly stable and showed a quasi-reversible redox behavior with $E_{1/2}=-0.2V$ vs. Ag/AgCl(3 M KCl) in 0.1 M phosphate buffer at pH 7 under argon atmosphere. PAlACuLbpy/PCE exhibited a remarkable ORR activity with an onset potential of -0.1 V vs Ag/AgCl in 0.1 M PB (pH 7) in the presence of oxygen. The kinetics for ORR was studied by rotating disk voltammetry in neutral aqueous medium and the results indicated that the number of electrons involving in the ORR is four and the conversion products are water and hydrogen peroxide.

Probabilistic fatigue assessment of rib-to-deck joints using thickened edge U-ribs

  • Heng, Junlin;Zheng, Kaifeng;Kaewunruen, Sakdirat;Zhu, Jin;Baniotopoulos, Charalampos
    • Steel and Composite Structures
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    • 제35권6호
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    • pp.799-813
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    • 2020
  • Fatigue cracks of rib-to-deck (RD) joints have been frequently observed in the orthotropic steel decks (OSD) using conventional U-ribs (CU). Thickened edge U-rib (TEU) is proposed to enhance the fatigue strength of RD joints, and its effectiveness has been proved through fatigue tests. In-depth full-scale tests are further carried out to investigate both the fatigue strength and fractography of RD joints. Based on the test result, the mean fatigue strength of TEU specimens is 21% and 17% higher than that of CU specimens in terms of nominal and hot spot stress, respectively. Meanwhile, the development of fatigue cracks has been measured using the strain gauges installed along the welded joint. It is found that such the crack remains almost in semi-elliptical shape during the initiation and propagation. For the further application of TEUs, the design curve under the specific survival rate is required for the RD joints using TEUs. Since the fatigue strength of welded joints is highly scattered, the design curves derived by using the limited test data only are not reliable enough to be used as the reference. On this ground, an experiment-numerical hybrid approach is employed. Basing on the fatigue test, a probabilistic assessment model has been established to predict the fatigue strength of RD joints. In the model, the randomness in material properties, initial flaws and local geometries has been taken into consideration. The multiple-site initiation and coalescence of fatigue cracks are also considered to improve the accuracy. Validation of the model has been rigorously conducted using the test data. By extending the validated model, large-scale databases of fatigue life could be generated in a short period. Through the regression analysis on the generated database, design curves of the RD joint have been derived under the 95% survival rate. As the result, FAT 85 and FAT 110 curves with the power index m of 2.89 are recommended in the fatigue evaluation on the RD joint using TEUs in terms of nominal stress and hot spot stress respectively. Meanwhile, FAT 70 and FAT 90 curves with m of 2.92 are suggested in the evaluation on the RD joint using CUs in terms of nominal stress and hot spot stress, respectively.

휘발성 유기화합물(VOCs) 제거를 위한 저온금속촉매 실용화에 관한 연구 (Practical Usage of Low-Temperature Metal Catalyst for the Destruction of Volatile Organic Compounds (VOCs))

  • 정성철;이승환
    • 대한환경공학회지
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    • 제34권6호
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    • pp.397-405
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    • 2012
  • 본 연구는 휴대폰을 비롯한 전자제품 세척공정과 악취유발물질 등에서 배출되는 휘발성 유기화합물(VOCs)을 경제적이고 안전하게 제거하는 기술에 대한 성능평가를 위해 수행되었다. 대부분의 산업공정에서는 VOCs 제거를 위해 활성탄 흡착탑을 가장 많이 사용하고 있으나 제거효율이 낮아 악취배출시설의 허용기준을 만족할 수 없고, 고농도 유기용제 유입 시 화재위험이 있다. 지금까지 연구되어진 금속산화물 촉매는 VOCs 제거효율이 최소 $220^{\circ}C$ 근방에서 50% 이하였다. 본 연구에서는 이 보다 훨씬 낮은 온도인 $100^{\circ}C$ 이하에서 촉매산화가 시작되었고, 약 $160^{\circ}C$ 근방에서 VOCs가 95% 제거됨을 확인할 수 있었다. 적정처리가 가능한 범위는 공간속도가 $6,000hr^{-1}$ 이하일 때 최적의 제거효율을 나타내며, VOCs 유입농도가 200 ppm에서 4,000 ppm 사이, 촉매제어 온도가 $150{\sim}200^{\circ}C$에서 90~99%로 높은 제거효율을 보였고, VOCs 유입농도가 1,000 ppm 이상일 경우에는 자체반응열로 인해 외부열원이 필요 없었다. 본 저온촉매를 적용할 경우 LNG 와 LPG를 연료원으로 사용하는 RTO/RCO방식 대비 설치비는 50%, 연료비는 75% 감소되어 경제성이 높고 온실가스 발생량도 줄일 수 있었다. 그리고 황화합물과 산성가스에 대해서는 피독이 있는 것으로 확인되었다.

폐광 부지의 재해 및 오염대 조사관련 물리탐사자료의 고찰 (Case Studies of Geophysical Mapping of Hazard and Contaminated Zones in Abandoned Mine Lands)

  • 심민섭;주현태;김관수;김지수
    • 지질공학
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    • 제24권4호
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    • pp.525-534
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    • 2014
  • 폐광 부지에서 발생하는 대표적인 환경 문제는 산성으로 오염된 지표수와 지하수, 적재된 폐광석 및 광미, 채굴 활동으로 야기된 지반침하 현상을 들 수 있다. 이 논문은 광해 유형에 따라 재해 및 오염영역을 효율적으로 탐지했던 지구물리탐사방법들을 고찰하는데 있다. 시험 자료로서 토양오염, 산성광산배수, 지반침하, 인공차수막 파손 및 광미/폐광석 적치장을 각각 대표하는 네 개의 폐광 부지를 선택하였다. 자료 검증을 위해 물리탐사자료는 자료의 유형에 따라 시추자료(코어 샘플, 물리검층, 토모그래피 등)와 물 자료(수소이온농도, 전기전도도, 중금속원소 등)와 비교하였다. 토양오염 탐지에 있어서 낮은 전기비저항 이상대는 특히 구리, 납, 아연의 중금속 농도가 높은 지역과 부합된다. 산성광산배수의 유동 경로는 자연전위 곡선에서 음의 전위 이상대, 전기비저항자료에서의 저비저항 이상대, 지하레이더 자료에서의 얕은 투과깊이 영역으로 탐지되었다. 채굴적은 전기비저항 단면에서의 저비저항 이상대, 탄성파토모그래피에서 낮은 속도 영역, 물리검층곡선의 복합해석으로 특징되며, 정확한 위치는 코어자료와 시추공영상자료에서 잘 확인되었다. 침출수 유동을 차단하기 위해 설치된 인공차수막의 파손 구간은 전기비저항 자료에서의 국부적인 이상대로 정확히 탐지되며 매립된 폐석더미는 고비저항 이상대와 저속도 이상대로 특징된다.

충남탄전, 대동누층군의 셰일과 탄질암에 관한 암석화학 및 환경지구화학적 특성 (Petrochemistry and Environmental Geochemistry of Shale and Coal from the Daedong Supergroup, Chungnam Coal Field, Korea)

  • 이찬희;이현구;김경웅
    • 자원환경지질
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    • 제30권5호
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    • pp.417-431
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    • 1997
  • Characteristics of sedimentary rocks and enrichment of toxic elements in shale and coal from the Chungnam coal field were investigated based upon geochemistry of major, trace and rare earth elements. Shale and coal of the area are interbedded along the Traissic to the Jurassic Daedong Supergroup, which can be subdivided into grey shale, black shale and coal. The coal had been mined, however all the mines are abandonded due to the economic problems. The shale and coal are characterized by relatively low contents of $SiO_2$, and $Al_2O_3$ and high levels of loss-on-ignition (LOI), CaO and $Na_2O$ in comparison with the North American Shale Composite (NASC). Light rare earth elements (La, Ce, Yb and Lu) are highly enriched with the coal. Ratios of $Al_2O_3/Na_2O$ and $K_2O/Na_2O$ in shale and coal range from 30.0 to 351.8 and from 4.2 to 106.8, which have partly negative correlations against $SiO_2/Al_2O_3$ (1.24 to 6.06), respectively. Those are suggested that controls of mineral compositions in shale and coal can be due to substitution and migration of those elements by diagenesis and metamorphism. Shale and coal of the area may be deposited in terrestrial basin deduced from high C/S (39 to 895) and variable composition of organic carbon (0.39 to 18.40 wt.%) and low contents of reduced sulfur (0.01 to 0.05 wt.%). These shale and coal were originated from the high grade metamorphic and/or igneous rocks, and the rare earth elements of those rocks are slightly influenced with diagenesis and metamorphism on the basis of $Al_2O_3$ versus La, La against Ce, Zr versus Yb, the ratios of La/Ce (0.38 to 0.85) and Th/U (3.6 to 14.6). Characteristics of trace and rare earth elements as Co/Th (0.07 to 0.86), La/Sc (0.31 to 11.05), Se/Th (0.28 to 1.06), V/Ni (1.14 to 3.97), Cr/V (1.4 to 28.3), Ni/Co (2.12 to 8.00) and Zr/Hf (22.6~45.1) in the shale and coal argue for inefficient mixing of the simple source lithologies during sedimentation. These rocks also show much variation in $La_N/Yb_N$ (1.36 to 21.68), Th/Yb (3.5 to 20.0) and La/Th (0.31 to 7.89), and their origin is explained by derivation from a mixture of mainly acidic igneous and metamorphic rocks. Average concentrations in the shale and coal are As=7.2 and 7.5, Ba=913 and 974, Cr=500 and 145, Cu=20 and 26, Ni=38 and 35, Pb=30 and 36, and Zn=77 and 92 ppm, respectively, which are similar to those in the NASC. Average enrichment indices for major elements in the shale (0.79) and coal (0.77) are lower than those in the NASC. In addition, average enrichment index for rare earth elements in coal (2.39) is enriched rather than the shale (1.55). On the basis of the NASC, concentrations of minor and/or environmental toxic elements in the shale and coal were depleted of all the elements examined, excepting Cr, Pb, Rb and Th. Average enrichment indices of trace and/or potentially toxic elements (As, Cr, Cu, Ni, Pb, U and Zn) are 1.23 to 1.24 for shale and 1.06 to 1.22 for coal, respectively.

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