• Title, Summary, Keyword: $CaCO_3$ 제조

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Electrocatalytic Performances of La0.6Ca0.4CoO3 and Pb2Ru2O6 prepared by Amorphous Citrate Precursor Method (Amorphous Citrate Precursor 법으로 제조한 La0.6Ca0.4CoO3와 Pb2Ru2O6의 전기화학적 촉매능)

  • Lee, Churl Kyoung;Sohn, Hun-Joon
    • Applied Chemistry for Engineering
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    • v.10 no.3
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    • pp.331-335
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    • 1999
  • The transition metal oxides have been of interest as bifunctional electrocatalysts for bifunctional air electrodes. The amorphous citrate precursor (ACP) process has been optimized to prepare perovskite (La0.6Ca0.4CoO3) and pyrochlore (Pb2Ru2O6) powders with high surface area, and consequent improvement of The electrocatalytic performance in an air electrode with thermal treatment. PTFE -bonded gas diffusion electrodes loaded with perovskitc and pyrochlore catalysts showed good bifunctional performances. The electrodes were fairly stable up to 100 hour in the galvanostatic mode at ${\pm}25mA/cm^2$, from which these electrodes offer promise as practical bifunctional air electrodes.

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Preparation and Properties of Cellulose Diacetate/$CaCO_3$ Composite (Cellulose Diacetate/$CaCO_3$ 복합체의 제조 및 물성)

  • Lim, Hwan-Kyu;Kye, Hyoung-San;Won, Sung-Ho;Nam, Jae-Do;Lee, Young-Kwan
    • Polymer(Korea)
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    • v.32 no.2
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    • pp.178-182
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    • 2008
  • Cellulose diacetate (CDA) and calcium carbonate ($CaCO_3$) biodegradable composites were prepared by melt mixing in a twin screw extruder and their physical properties were examined. In the melt processing, triacetine and epoxidized soybean oil were added to the composites as a plasticizer and lubricant, respectively. The optimal conditions for the preparation of the biodegradable composites were determined. Acetic acids ($CH_3COOH$) were made by pyrolysis acetyl group ($-OC (O)CH_3$) of CDA and TA in melt processing. Increasing the amount of $CaCO_3$ in the composites resulted in further enhancement of the $CH_3COOH$ absorption effects. The tensile strength and elongation were decreased, and Young's modulus and $T_g$ value increased with increasing amount of $CaCO_3$.

A Study on Synthesis of CaCO3 & MgO/Mg(OH)2 from Dolomite Using the Strong Acidic Cation Exchange Resin (강산성 양이온 교환수지를 통한 백운석으로부터 CaCO3 및 MgO/Mg(OH)2 합성에 관한 연구)

  • Hwang, Dae Ju;Yu, Young Hwan
    • Korean Chemical Engineering Research
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    • v.57 no.6
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    • pp.812-825
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    • 2019
  • Two dolomite samples mined from the different mines were calcined using a batch-type microwave kiln ($950/60min^{\circ}C$) to produce $CaO{\cdot}MgO$. The hydration of the $CaO{\cdot}MgO$ samples shows different reactivity. MgO was separated by reacting with a strong acid cation exchange resin using the reactivity of the hydration properties of light dolomite ($CaO{\cdot}MgO$). Calcium ($Ca-(R-SO_3)_2$) was separated from the prepared $CaO{\cdot}MgO$ by the cation exchange resin ($CaO{\cdot}MgO:R-SO_3H=1:12mass%$). High purity MgO (higher than 94 mass %) with unburned $CaCO_3$ (1~2 mass %) was obtained by the separation process. The separated MgO was heated at $950^{\circ}C$ for 60 minutes to afford high purity MgO with MgO content higher than 96%. And High-grade $CaCO_3$ was prepared from the reaction with calcium adsorbed resin ($Ca-(R-SO_3)_2$) and NaOH, $CO_2$ gas.

Effect of $Ca^{2+}$ and $Co^{3+}$ cations substitution on the properties of $LaCrO_3$ for SOFC interconnect (SOFC 연결재용 $LaCrO_3$ Perovskite 구조에서 $Ca^{2+}$$Co^{3+}$치환첨가효과)

  • An, Yongtae;Choi, Byunghyun;Ji, Mijung;Kwon, Yongjin;Seo, Han;Hwang, Haejin
    • 한국신재생에너지학회:학술대회논문집
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    • pp.136.1-136.1
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    • 2010
  • 고체산화물 연료전지(SOFC)에서 사용되는 연결재의 주 기능은 각 단위 셀의 연료극과 다음 셀의 공기극을 전기적으로 연결하여, 공기와 사용연료의 분리역할을 하기위해 사용된다. SOFC용 연결재는 다른 구성요소 소재보다 높은 전기전도성, 낮은 이온전도성이 요구되며 SOFC는 고온에서 작동되기 때문에 다른 구성 소재들과 유사한 열팽창계수와 물리, 화학적인 안정성이 요구된다. 현재 연결재 제조기술은 plasma coating, sputtering, screen printing, 전사법등 다양한 연구가 진행되고 있다. 본 연구에서는 저렴한 비용으로 대량생산이 용이한 고상반응법을 적용하여 세라믹연결재를 제조하고, 그 특성을 연구하였다. 세라믹 연결재로서 선정한 합성조성은 $(La_{0.7}Ca_{0.3})(Cr_{0.9}Co_{0.1})O_3$로 SOFC 작동온도에서 높은 전기전도도를 나타낸다. LCCO 연결재를 1300, 1400 및 $1500^{\circ}C$에서 합성을 진행하였을 때 출발원료로 $CaCO_3$$CaF_2$로 대체하였을 때의 소결특성을 평가하였고, SEM과 XRD분석을 통하여 균질하고 결정성이 우수한 분말이 합성된 것을 확인하였고 DC impedance analyzer를 사용하여 전기전도도를 측정하였다. TMA를 사용하여 열팽창계수를 측정한 결과 YSZ(${\sim}10.8{\times}10^{-6}/^{\circ}C$)와 동일한 값을 나타내었다.

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Enhancement of Cultivation Efficiency of Bifidobacterium longum Using Calcium Carbonate Buffer System (Calcium Carbonate Buffer System을 이용한 Bifidobacterium longum의 배양 효율 증대에 관한 연구)

  • Lee, Ki-Yong;Hwang, In-Bum;Heo, Tae-Ryeon
    • Korean Journal of Food Science and Technology
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    • v.29 no.1
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    • pp.126-132
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    • 1997
  • Calcium carbonate ($CaCO_3$) immobilized with alginate was studied as buffer system to enhance the cultivation efficiency of Bifidobacterium longum (ATCC 15707) which is inhibited at low pH. To test the bufferring effect of the immobilized $CaCO_3$ beads, pH value in each modified trypticase-proteose peptone-yeast (TPY) broth which is adjusted to pH 4.0 with acetic acid, lactic acid and complex solution of acetic and lactic acid, 3:2 (M:M) was tested by concentration of $CaCO_3$ bead and reaction time. The bufferring effect of $CaCO_3$ bead became higher with increasing the amount of $CaCO_3$ bead in the acidic solution. The growth rate of bifidobacteria and bufferring effect were examined in relation to the amount of $CaCO_3$ bead and concentration of glucose in the modified TPY media. The growth rate of bifidobacteria and bufferring effect were increased with increasing the amount of $CaCO_3$ bead and concentration of glucose. Also, the exponential time of bifidobacteria became longer with increasing the amount of $CaCO_3$ bead and concentration of glucose in the modified TPY media. When we observed the growth rate of bifidobacteria by the method of pH-controlled culture and $CaCO_3$ buffer system, the $CaCO_3$ buffer system was more effective than that of pH-controlled culture. Therefore, this $CaCO_3$ buffer system may be useful as a method to enhance of the cultivation efficiency of bifidobacteria.

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Optimization of $Nd^{3+}$ ion co-doping in $CaAl_2O_4:\;Eu^{2+}$ blue phosphor ($CaAl_2O_4:Eu^{2+}$ 청색(靑色) 형광체(螢光體)의 $Nd^{3+}$ 도핑 최적화(最適化)에 관한 연구(硏究))

  • Bartwal, Kunwar Singh;Ryu, Ho-Jin
    • Resources Recycling
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    • v.16 no.5
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    • pp.46-50
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    • 2007
  • Blue phosphor calcium aluminate, $CaAl_2O_4:Eu^{2+}$ co-doped with $Nd^{3+}$ was prepared by solid state synthesis method. Phosphor materials with 1 mol% $Eu^{2+}$ and varying compositions of $Nd^{3+}$ show high brightness and long persistent luminescence. The synthesized phosphor materials were investigated by powder x-ray diffraction (XRD), SEM, TEM, photoluminescence excitation and emission studies. Broad band UV excited luminescence of the $CaAl_2O_4:Eu^{2+}:Nd^{3+}$ was observed in the blue region (${\lambda}_{max}=440\;nm$) due to transitions from the $4f^65d^1$ to the $4f^7$ configuration of the $Eu^{2+}$ ion. $Nd^{3+}$ ion doping in the phosphor results in long afterglow phosphorescence when the excitation light is cut off.

A Study of Synthesis and Property of $CaCO_3$/Organic Core-Shell Particle (탄산칼슘 /유기계 Core-Shell 입자의 제조와 물성에 관한 연구)

  • Seul, Soo-Duk
    • Polymer(Korea)
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    • v.34 no.1
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    • pp.38-44
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    • 2010
  • Core-shell particles of inorganic/organic pair were synthesized from $CaCO_3$ absorbed sodium dodecyl benzene sulfonate(SDBS) surfactant. Shell components were synthesized by sequential emulsion polymerization. Various monomers were used as shell components such as methyl methacrylate(MMA), ethyl acrylate(EA), butyl acrylate(BA), and styrene(St). Ammonium persulfate(APS) was used as an initiator and 2-ethylhexyl acylate(2-EHA) was used as a functional monomer, In the $CaCO_3$/organic core-shell particle polymerization, $CaCO_3$ absorbed surfactant SDBS of 0.5 wt% was prepared first and then core $CaCO_3$ was encapsulated by emulsion polymerization. 0.1 wt% of APS was added sequentially to minimize the formation of new monomer particle during shell polymerization. The structure of inorganic/organic core-shell particles were characterized by measuring the decomposition degree of $CaCO_3$ using HCl solution, thermogravimetric analyzer, scanning electron microscope, and transmission electron microscope.

Synthesis of nano-crystalline slaked lime using design of experiment (실험계획법을 이용한 나노 결정 소석회 합성)

  • Kim, Jin-Seong;Kim, Jung-Woo;Lee, Hee-Soo;Kim, Yong-Nam;Shin, Hyun-Gyoo;Kim, Hwan
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.18 no.4
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    • pp.174-178
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    • 2008
  • Nano-crystalline slaked lime was synthesized using design of experiment. In order to synthesize slaked lime, calcium chloride $(CaCl_2)$ and urea were used as starting materials. Calcium chloride solution and urea solution were mixed and heated in vessel that calcium carbonate was precipitated during heating. Precipitates were filtered, washed several times using D.I.water and ethanol and finally dried in oven. Slaked lime $(Ca(OH)_2)$ has been fabricated by the hydration of calcined $CaCO_3$. Design of experiment (Taguchi method) was used to optimize parameter, to minimize noise factors of experiment and to statistically analyze the results. Slaked lime having about 50 nm in optimized crystallite size could be obtained by calcination of $CaCO_3$ at $1000^{\circ}C$ for 0.5 h and hydration with D.I water containing ethanol and oxalic acid.

Properties of Polypropylene/CaCO3 Composites from the Shape of Calcium Carbonate (Polypropylene/CaCO3 복합재료에 있어서 입자 형태에 따른 물성)

  • Lyu, S.G.;Bae, K.S.;Sur, G.S.
    • Applied Chemistry for Engineering
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    • v.8 no.5
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    • pp.771-776
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    • 1997
  • The various shape of calcium carbonate were prepared. For the preparation of the PP/$CaCO_3$ composite, these synthetic calcium carbonate(cubic, spheric and neddle type) and PP were mixed on a two roll mill and the mixture were pressed into plate. The effect of particle shape in the prepared composite on the crystallization temperature, heat of fusion, size of spherulite and mechanical properities were investigated. It was found that the former four were strongly influenced by that. When, especially, vaterite was mixed with PP, the size of spherulite was smaller and the degree of crystallinity was higher than others. Therefore, the tensile strength and Young's modulus were higher.

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