• Title/Summary/Keyword: Reaction solution

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Effect of Curing Temperature on Geopolymeric Polycondensation of Blast Furnace Slag (고로슬래그의 지오폴리머 축중합반응에 미치는 양생온도의 영향)

  • Jeon, Chang-Seob;Song, Tae-Woong
    • Journal of the Korean Ceramic Society
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    • v.48 no.6
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    • pp.610-616
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    • 2011
  • The effect of curing temperature on basic geopolymeric reactivity and hardening behaviour of blast furnace slag were investigated using the mixture of pulverized slag and several alkaline solutions of relatively high concentration. For the pastes prepared at several different temperatures between 20$^{\circ}C$ and 90$^{\circ}C$, setting time and heat of reaction were examined while mineralogical and morphological examinations were performed for the hardened paste after curing period at same temperature. The geopolymeric reaction of slag was revealed to be accelerated strongly according to the curing temperature regardless of the sort and concentration of the alkaline solution. The increase of concentration of the alkaline solution within 9M and the existence of silicic ion in the solution also promoted the reaction severely. The mineral component and their ratio of the hardened paste were revealed to be influenced by the chemical species and silicic ion contained in alkaline solution rather than by the curing temperature. The higher temperature and longer period of curing stage were effective for the sustained formation of geopolymer and succeed improvement of density and uniformity of morphology of the final hardened body.

Synthesis of Ultra-fine Hydroxyapatite Powders by Hydrothermal Reaction (수열반응에 의한 Hydroxyapatite 초미분말의 제조)

  • 민경소;최재웅;최상흘
    • Journal of the Korean Ceramic Society
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    • v.29 no.12
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    • pp.997-1003
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    • 1992
  • Ultra-fine hydroxyapatite powders were synthesized by the hydrothermal reaction of Ca(OH)2 suspension or Ca(NO3)2$.$4H2O solution with (NH4)2HPO4 solution, and the powders were characterized for each synthetic condition. Crystalline hydroxyapatite powders have average grain size of less than 50 nm. By increasing the reaction pressure, the crystallinity was improved, and the crystals were preferentially growing along c-axis. When Ca(NO3)2$.$4H2O of high solubility was used, hydroxyapatite of single phase was produced. However when Ca(OH)2 of low solubility was used more than 0.334 mol/ι, unreacted Ca(OH)2 remained. Diffraction spot patterns of transmission electron microscope show that powders synthesized by the hydrothermal reaction were composed of single crystals of hexagonal phase.

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Dissolution Kinetics of Sphalerite in Aqueous Ferric Chloride Solution (염화제이철 수용액에서 섬아연광의 용해에 관한 속도론적 연구)

  • Yoo, Seung-Joon;Park, Hyung-Sang;Choi, Cheong-Song;So, Chil-Sup
    • Economic and Environmental Geology
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    • v.26 no.3
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    • pp.421-429
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    • 1993
  • Dissolution reactions of chemical grade zinc sulfide and natural sphalerite were studied in ferric chloride solution as an oxidant. To enhance the leaching reaction, ultrasonic technique was employed in this investigation. For the reaction with pure zinc sulfide, chemical reaction was the rate limiting step in the range of low conversion irrespective of applying ultrasonic wave. And the diffusion through liquid film instead of diffusion through product layer of free sulfur was the rate determining step because ultrasonic vibration removes the product from reaction zone. In the case of sphalerite with the ultrasonic vibrator, it was found that inert mineral layer diffusion was the rate determining step, in which the elemental sulfurs formed were removed by the ultrasonic action. Experimental results showed that the ultrasonic technique proved to be the methods which can significants improve the leaching performance.

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A Study on the Hydrothermal Synthesis of Clay Mineral (II) -Hydrothermal Synthesis of Clay Mineral from Anorthite in San.Chung District of Korea- (수열반응에 의한 인공점토의 합성연구 (II) -경남 산청산 회장석으로부터 인공점토의 수열합성에 관한 연구-)

  • 이응상;이상훈
    • Journal of the Korean Ceramic Society
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    • v.32 no.6
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    • pp.735-747
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    • 1995
  • The synthesis of clay mineral through the hydrothermal reaction of the anorthite, which is distributed in San Chung-District of Korea and called as the ground rock for halloysite-kaolin, has been investigated. It was observed that this anorthite sample was easily converted into clay mineral with 0.5 wt% HCl solution at a temperature below 20$0^{\circ}C$ under a pressure about 15 atm. The conversion reaction was promoted by adding aluminum chloride under the condition concerned. Aluminum chloride was considered to supply the insufficient aluminum ion during the conversion reaction and to reprepare the acid solution-condition by adding the HCl-component as a by-product. According to the electron micrographs, it was confirmed that fine tubular or needle-shaped halloysite-kaolin minerals with the crystal length shorter than about 1.1${\mu}{\textrm}{m}$ could be obtained by the hydrothermal reaction for 5 days under those conditions.

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A Study on Hydrogel-Based CK Agent Detecting Gel Using Konig Reaction (Konig 반응을 이용한 CK 작용제 탐지젤 개발에 관한 연구)

  • Kim, Kyungmin;Kim, Kyung-pil
    • Journal of the Korea Institute of Military Science and Technology
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    • v.18 no.6
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    • pp.829-834
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    • 2015
  • A simple and sensitive hydrogel-based detecting gel has been presented for the qualitative determination of cyanogen chloride(CK) using Konig reaction. To optimize Konig reaction conditions, the effects of pyridine and barbituric acid concentration were investigated. Under the optimized conditions, CK gas concentration was directly related with absorbance change at 567 nm. Based on aqueous solution test results, we finally prepared CK detecting hydrogel by absorbing pyridine and barbituric acid solution. Color change of the prepared CK detecting hydrogel was clearly observed when the detecting gel was exposed to 10 ppm CK gas.

One-pot Synthesis of Nickel and Tungsten Carbide Nanoparticles Supported Mesoporous Carbon Electrocatalyst for Oxygen Reduction Reaction (산소환원반응을 위한 니켈-텅스텐 카바이드 나노입자 담지 메조포러스 카본 촉매의 단일 합성 및 그 특성 평가)

  • Kim, Hyemin
    • Journal of the Korean institute of surface engineering
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    • v.51 no.3
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    • pp.179-184
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    • 2018
  • In this study, Ni and tungsten carbide (WC) nanoparticles are simultaneously synthesized with the mesoporous carbon nanoparticles (CNP) using a solution plasma processing (SPP) in the benzene. The Ni and WC nanoparticles were formed through the sputtering effect of electrodes during discharge, and mean time CNP were formed through reduction reaction. TEM observation showed that loaded Ni and WC nanoparticles were evenly dispersed on the CNP. The results of electrochemical analysis demonstrated that an introduction of Ni nanoparticles promoted to improve catalytic activity for oxygen reduction reaction (ORR). Moreover, Ni-WC/CNP lead to fast electron transfer process compared to that of WC/CNP. Therefore, the inexpensive Ni-WC/CNP might be a promising as catalytic material for cathodes in fuel cell applications.

Photochemical Reaction of Nalidixic Acid in Methanol

  • Park, Hyoung-Ryun;Park, Ok-Hyun;Lee, Hong-Yune;Seo Jung-Ja;Bark, Ki-Min
    • Bulletin of the Korean Chemical Society
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    • v.24 no.11
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    • pp.1618-1622
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    • 2003
  • The photochemical reactions of methanolic nalidixic acid (NAL) solution in the absence and in the presence of air have been investigated using 300 nm UV light. From the reactions, 1-ethyl-7-methyl-4-oxo-4-hydro-1,8-naphthyridine (EMDN),formic acid, and formaldehyde are produced. In the presence of air, hydrogen peroxide is also detected along with the products listed above. The presence of oxygen during the irradiation of methanolic NAL solution effects on the product yield. The initial quantum yields of the products and of the NAL decomposition are determined. Possible reaction pathways for the photochemical reaction are suggested on the basis of the products analysis.

Kinetic Studies on the Reaction of Iron (Ⅲ) with D-penicillamine in Acidic Solution$^1$

  • Hyun-Jae Park;Yung-Hee Oh Kim;Jung-Ae Shim;Sung-Nak Choi
    • Bulletin of the Korean Chemical Society
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    • v.14 no.4
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    • pp.444-449
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    • 1993
  • Anaerobic oxidation of D-penicillamine by Fe(III) in acidic solution has been studied kinetically by the use of stopped-flow system. The reaction is biphasic with a rapid complexation of 1: 1 complex, $Fepen^+$ (pen= D-penicillamine dianion) which is then internally reduced to Fe(II) and disulfide. Rates of both the complexation and the redox process are pH dependent and also are affected by the presence of chloride ion. Different from the reaction of Cu(II) with D-penicillamine, partially oxidized mixed-valence complex is not formed even transiently in this reaction.

Analytical Solutions of Unsteady Reaction-Diffusion Equation with Time-Dependent Boundary Conditions for Porous Particles

  • Cho, Young-Sang
    • Korean Chemical Engineering Research
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    • v.57 no.5
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    • pp.652-665
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    • 2019
  • Analytical solutions of the reactant concentration inside porous spherical catalytic particles were obtained from unsteady reaction-diffusion equation by applying eigenfunction expansion method. Various surface concentrations as exponentially decaying or oscillating function were considered as boundary conditions to solve the unsteady partial differential equation as a function of radial distance and time. Dirac delta function was also used for the instantaneous injection of the reactant as the surface boundary condition to calculate average reactant concentration inside the particles as a function of time by Laplace transform. Besides spherical morphology, other geometries of particles, such as cylinder or slab, were considered to obtain the solution of the reaction-diffusion equation, and the results were compared with the solution in spherical coordinate. The concentration inside the particles based on calculation was compared with the bulk concentration of the reactant molecules measured by photocatalytic decomposition as a function of time.

Photochemical Reaction of Dichloromethane in Aqueous Solution

  • 박형련;정영태;김명선;우희권;함희숙
    • Bulletin of the Korean Chemical Society
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    • v.18 no.3
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    • pp.287-291
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    • 1997
  • The photochemical reaction of aqueous dichloromethane in the absence (saturated with argon) and the presence of O2 (saturated with air or oxygen) has been investigated using 184.9 nm UV light. The irradiation of the solution causes the formation of 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane and chloride ion. The initial quantum yield of the products in the absence of oxygen was determined to be 8.6 × 10-3, 7.3 × 10-3, 4.4 × 10-3 and 2.3 × 10-2, respectively. In addition to these main products, small amounts of 1,2,3-trichloropropane, 1,1,2,2,3-pentachloropropane, 1,1,2,3,3-pentachloropropane, 1,3-dichloropropane and 1,1,2,2,3,3-hexachloropropane were detected. In the presence of oxygen, hydrogen peroxide was also detected along with the products listed above. With increasing the concentration of oxygen, while formation of the chlorinated organic products diminished, formation of chloride ion increased. Probable reaction mechanisms for the photochemical reaction were presented on the basis of products analysis.