• Title/Summary/Keyword: 결정화 시약

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Effects of crystallization reagent and pH on the sulfide crystallization of Cu and Ni in fluidized bed reactor (유동층 반응기를 이용한 구리와 니켈의 황화물 결정화에 결정화 시약 및 pH가 미치는 영향)

  • Jeong, Eunhoo;Shim, Soojin;Yun, Seong Taek;Hong, Seok Won
    • Journal of Korean Society of Water and Wastewater
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    • v.28 no.2
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    • pp.207-215
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    • 2014
  • Wastewater containing heavy metals such as copper (Cu) and nickel (Ni) is harmful to humans and the environment due to its high toxicity. Crystallization in a fluidized bed reactor (FBR) has recently received significant attention for heavy metal removal and recovery. It is necessary to find optimum reaction conditions to enhance crystallization efficacy. In this study, the effects of crystallization reagent and pH were investigated to maximize crystallization efficacy of Cu-S and Ni-S in a FBR. CaS and $Na_2S{\cdot}9H_2O$ were used as crystallization reagent, and pH were varied in the range of 1 to 7. Additionally, each optimum crystallization condition for Cu and Ni were sequentially employed in two FBRs for their selective removal from the mixture of Cu and Ni. As major results, the crystallization of Cu was most effective in the range of pH 1-2 for both CaS and $Na_2S{\cdot}9H_2O$ reagents. At pH 1, Cu was completely removed within five minutes. Ni showed a superior reactivity with S in $Na_2S{\cdot}9H_2O$ compared to that in CaS at pH 7. When applying each optimum crystallization condition sequentially, only Cu was firstly crystallized at pH 1 with CaS, and then, in the second FBR, the residual Ni was completely removed at pH 7 with $Na_2S{\cdot}9H_2O$. Each crystal recovered from two different FBRs was mainly composed of CuxSy and NiS, respectively. Our results revealed that Cu and Ni can be selectively recovered as reusable resources from the mixture by controlling pH and choosing crystallization reagent accordingly.

A study on the pyrolysis of lithium carbonate for conversion of lithium hydroxide from lithium carbonate (탄산리튬으로부터 수산화리튬 전환을 위하여 탄산리튬의 열분해에 대한 연구)

  • Park, Jae Eun;Park, Min Hwa;Seo, Hyeong Jun;Kim, Tae Seong;Kim, Dae Weon;Kim, Bo Ram;Choi, Hee Lack
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.31 no.2
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    • pp.89-95
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    • 2021
  • Research on the production of lithium hydroxide (LiOH) has been actively conducted in response to the increasing demand for high nickel-based positive electrode materials for lithium-ion batteries. Herein we studied the conversion of lithium oxide (Li2O) through thermal decomposition of lithium carbonate for the production of lithium hydroxide from lithium carbonate (Li2CO3). The reaction mechanism of lithium carbonate with alumina, quartz and graphite crucible during heat treatment was confirmed. When graphite crucible was used, complete lithium oxide powder was obtained. Based on the TG analysis results, reagent-grade lithium carbonate was heat-treated at 700℃, 900℃ and 1100℃ for various time and atmosphere conditions. XRD analysis showed the produced lithium oxide showed high crystallinity at 1100℃ for 1 hour in a nitrogen atmosphere. In addition, several reagent-grade lithium oxides were reacted at 100℃ to convert to lithium hydroxide. XRD analysis confirmed that lithium hydroxide (LiOH) and lithium hydroxide monohydrate (LiOH·H2O) were produced.

Manufacture of a Gamma-ray Source using the Neutron Activation and Determination of a HPGe Detector Efficiency (중성자 방사화법을 이용한 감마선원 제조 및 HPGe 검출기 효율 결정)

  • Seo, Bum-Kyoung;Lee, Kil-Yong;Yoon, Yoon-Yeol;Lee, Kune-Woo
    • Journal of Radiation Protection and Research
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    • v.29 no.1
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    • pp.17-23
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    • 2004
  • In order to save time and money needed in the purchase commonly used gamma-ray standard sources, a new radioactive standard source was manufactured by the neutron activation of some regent in the research reactor HANARO. The source was manufactured with an aqueous solution by mixing and dissolving the irradiated reagents. The manufactured source was compared with a commercial standard source. It was confirmed that it could be used as an efficiency calibration source. Also, in order to compare the variation of efficiency due to the volume difference for various containers used in radioactivity assay, the efficiency variation as a function of sample volume was investigated.

Growth of Synthetic Emerald Single Crystal by Flux Method (Flux법에 의한 합성 에메랄드 단결정 육성)

  • Park, Sun-Min;Lee, Chul-Tae;Kim, Ho-Kun
    • Applied Chemistry for Engineering
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    • v.7 no.1
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    • pp.34-42
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    • 1996
  • Growth of synthetic emerald [($(BeO)_3(Al_{2-x}Cr_xO_3)(SiO_2)_6$] single crystals was carried out by flux method. In this study, the starting materials were prepared by stoichiometric mixing of BeO, $Al_2O_3$ and $SiO_2$ as reaching components. The conditions for the growth of synthetic emerald single crystals are as follows : temperature range ; $1150{\sim}900^{\circ}C$, cooling rate ; 2, 4, $10^{\circ}C/hr$, flux ; $Li_2CO_3$, $V_2O_5$, dopant ; $Cr_2O_3$. The sizes of $Cr_2O_3$emerald single crystals depending on 2, 4, $10^{\circ}C/hr$ cooling rates. The obtained emerald single crystal was characterized and the following results were obtained : lattice parameter : a=0.921nm, c=0.917nm, crystal system ; hexagonal, crystal size ; max. $0.80{\times}0.95mm^2(c{\times}m)$, orientation ; (1000), $m(10{\bar{1}}0)$.

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Properties of the Ceramic Composites and Glass-Ceramics Prepared by Using the Natural Hydroxyapatite Derived from Tuna bone (참치 뼈에서 추출한 천연 Hydroxyapatite를 이용한 세라믹 복합체 및 Glass-Ceramics의 특성)

  • Choi, Jin-Sam;Lee, Chang-Kook;Jeon, You-Jin;Byun, Hee-Guk;Kim, Se-Kwon
    • Applied Chemistry for Engineering
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    • v.10 no.3
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    • pp.394-399
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    • 1999
  • As the prosthetic application of natural mineral substituted for chemical reagent, composites and a glass-ceramics containing hydro-xyapatite isolated from tuna bone were prepared by solid state reaction. On x-ray examinations, the major phases of composites were identified as pseudowollastonite(${\alpha}-CaSiO_3$) and ${\beta}$-tricalcium phosphate($\beta$-TCP) and the phase of a glass-ceramics was observed as $\beta$-TCP and fluoroapatite caused by $CaF_2$ respectively. SEM images depict that the microstructures of grain at the composites were a function of temperature. The measured strength of a glass-ceramics prepared at $900^{\circ}C$ for 4 hr in air was 90 MPa as a 4-point bending method and this value was similar to the cortical bone, as 50~150 MPa but it was lower than its maximum strength.

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브란운관의 후면유리 폐기물을 이용한 제올라이트 합성

  • Jang, Yeong-Nam;Bae, In-Guk;Chae, Su-Cheon;Ryu, Gyeong-Won
    • Journal of the Korean Professional Engineers Association
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    • v.34 no.2
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    • pp.167-173
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    • 2001
  • Through alkaline hydrothermal activation processes, Na-A type zeolite was synthesized as a single phase withfunnel-glass waste from a television tube factory. The autoclaving was performed in a closed teflon vessel in therange of 80~95"C. The silica-rich solution as a starting material was hydrothermally synthesized with quartz in INNaOH by heating 350"C under the pressure of 1,500 atm. NaA102 was made from NaOH and Al(OH)3 by heating95"c for 2~3 hours and the molar ratios of it were Na20/A1203=1.4 and H20Ha20=8. The equi-dimensional Atype zeolite (1 ~2 U) was formed by the simple mixing of'the silica-rich solution, glass waste and NaA102 for I~3hours-heating at 80"C. The characterization of the reaction product shows Na-A as a single phase. The synthesizedzeolite has cube-dodecahedral form and Ca2+ ion exchange capacity of the Na-A was in the range of 215~220mequivalent/100 g.20mequivalent/100 g.

Synthesis of Na-A Type of Zeolite from Funnel-Glass Waste (브라운관의 후면유리 폐기물을 이용한 제올라이트 합성)

  • 장영남;배인국;채수천;류경원
    • Economic and Environmental Geology
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    • v.34 no.2
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    • pp.167-173
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    • 2001
  • Through alkaline hydrothermal activation processes, Na-A type zeolite was synthesized as a single phase with funnel-glass waste from a television tube factory. The autoclaving was performed in a closed teflon vessel in the range of 80~95$^{\circ}$C. The silica-rich solution as a starting material was hydrothermally synthesized with quartz in IN NaOH by heating 350uC under the pressure of 1,500 atm. $NaAlO_2$ was made from NaOH and Al(OHh by heating 95$^{\circ}$C for 2-3 hours and the molar ratios of it were $Na_2O/Al_2O_3$ = 1.4 and $H_2O/Na_2O$=8. The equi-dimensional A type zeolite (1-2 11) was formed by the simple mixing of the silica-rich solution, glass waste and $NaAlO_23$ for 1-3 hours-heating at $80^{\circ}C$. The characterization of the reaction product shows Na-A as a single phase. The synthesized zeolite has cuba-dodecahedral form and $Ca^{2+}$ ion exchange capacity of the Na-A was in the range of 215-220 mequiva1entilOO g.

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Screening and Possibility of Semi-quantitative Analysis of Explosive Compounds in Soil Using EXPRAY$^{(R)}$ Explosives Field Detection Kit (화약물질 현장검출시약 EXPRAY$^{(R)}$를 이용한 토양내 화약물질 스크리닝 및 준정량화 가능성)

  • Bae, Bum-Han;Cho, Jung-Hyun
    • Journal of Soil and Groundwater Environment
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    • v.14 no.2
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    • pp.45-53
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    • 2009
  • A quick and simple detection method of explosive compounds in environmental matrix (soil and water) can provide a screening step which reduces the number of unnecessary samples and the cost of expensive laboratory analysis at a site investigation. A commercially available EXPRAY$^{(R)}$Explosives Field Detection Kit (EXPRAY) was used to determine the minimum detection concentration and to test the possibility of semi-quantitative analysis of 14 explosive compounds using standard solutions. The results showed that EXPRAY could detect 5 explosive compounds, TNT, RDX, HMX, Tetryl, and TNB, out of 14 US EPA designated explosives. The minimum detection limit of the nitramine explosives was 14 ng/$^2$ for HMX and RDX. EXPRAY was more sensitive to nitroaromatics than the nitramines and the minimum detection limits per unit area (mm$^2$) for Tetryl, TNB, and TNT, were 3 ng, 3 ng, and 0.3 ng, respectively. The semi-quantification of 5 explosive compounds in an order ofmagnitude could be achieved by the intensity of developed color only when EXPRAY was applied on the standard solutions under controlled laboratory conditions. With contaminated soil samples, however, only the presence and type of explosive compounds was identified. Therefore, EXPRAY is an economic and sensitive method that can be used in a screening step for the identification of explosives in the field samples.

1,3-Dioxolane-Based CO2 Selective Polymer Membranes for Gas Separation (1,3-Dioxolane 기반 CO2 선택성 고분자막의 개발)

  • Iqubal Hossain;Asmaul Husna;Ho Bum Park
    • Membrane Journal
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    • v.33 no.3
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    • pp.94-109
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    • 2023
  • 1,3-Dioxolane is an exciting material that has attracted widespread interest in the chemical, paint, and pharmaceutical industries as a solvent, electrolyte, and reagent because 1,3-dioxolane is not toxic, carcinogenic, explosive, auto-flammable, and multifunctional, and due to their excellent miscibility in most organic and aqueous solvent conditions. Recently, this material has received increasing attention as a CO2-selective polymer precursor to separating CO2 from flue gas and natural gas mixtures. Poly(1,3-dioxolane) (PDXL) possesses higher ether oxygen content than polyethylene oxide (PEO), which demonstrates superior membrane CO2/N2 separation properties owing to their polar ether oxygen groups exhibiting strong affinity toward CO2. Thus, PDXL-based membranes displayed an outstanding CO2 solubility selectivity over non-polar (N2, H2, and CH4) gases. However, the polar groups of PDXL, like PEO, promote chain packing efficiency and cause polymer crystallization, thereby reducing its gas permeability, which should be improved. In this short review, we discuss the recent advancement and limitations of PDXL membranes in gas separation applications. To conclude, we provide future perspectives for inhibiting the limits of 1,3-dioxolane-based polymers in the CO2 separation process.

A Study for Kinetics and Oxidation Reaction of Substituted Benzyl Alcohols using Cr(VI)-Heterocyclic Complex(Cr(VI)-Isoquinoline) (Cr(VI)-헤테로고리 착물(Cr(VI)-Isoquinoline)를 이용한 치환 벤질 알코올류의 산화반응과 속도론에 관한 연구)

  • Park, Young-Cho;Kim, Young-Sik
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.11
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    • pp.6000-6007
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    • 2013
  • Cr(VI)-heterocyclic complex[Cr(VI)-isoquinoline] was synthesized by the reaction between of heterocyclic compound(isoquinoline) and chromium trioxide, and characterized by IR and ICP analysis. The oxidation of benzyl alcohol using Cr(VI)-isoquinoline in various solvents showed that the reactivity increased with the increase of the dielectric constant(${\varepsilon}$), in the order : cyclohexene$CH_3$, m-Br, m-$NO_2$). Electron- donating substituents accelerated the reaction, whereas electron acceptor groups retarded the reaction. The Hammett reaction constant(${\rho}$) was -0.69(308K). The observed experimental data have been ratiolized. The hydride ion transfer causes the prior formation of a chromate ester in the rate-determining step.