• Title/Summary/Keyword: Molar Conductivity

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Electric Conductivities of LaCl3-KCl Binary Melts (용융 LaCl3-KCl 2성분계 혼합염의 전기전도도)

  • Kim, Kiho
    • Journal of the Korean institute of surface engineering
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    • v.47 no.1
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    • pp.48-52
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    • 2014
  • Electric conductivities of $LaCl_3$-KCl binary melts have been measured by the Kohlausch bridge method over the range from their liquidus temperatures to about 1280 K. The electric conductivity increased with the content of KCl for all over the composition range of binary melts. The composition dependence of the electric conductivity and molar conductivity for the binary melt showed a non-linear relation from the additivity line, and the deviation showed a maximum value at about 60 mol.% KCl. The deviation implies the existence of complex ion of $LaCl^{4-}$ in the melt. Activation energy for electric conductivity of the binary melts decreased monotonously with increasing content of KCl.

Electric Conductivities of LaC $l_3$-LiCl Binary Melts (용융 LaC $l_3$-LiCl 2성분계 혼합염의 전도도)

  • Kim Ki-Ho
    • Journal of the Korean institute of surface engineering
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    • v.37 no.5
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    • pp.301-306
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    • 2004
  • Electric Conductivities of $LaCl_3$-LiCl binary melts have been measured by the Kohlausch bridge method over the range of their liquidus temperatures to about 1200 K. The electric conductivity increases with the content of LiCl for all over the composition range of binary melts. Composition dependence of the electric conductivity and molar conductivity for the binary melt shows a non-linear relation from the additivity line, and the deviations displays a maximum value at about 60 mol % LiCl. This suggest the existence of the complex ion of$ LaCl_{4}^{-}$ in the melt. Activation energy for electric conductivity of the binary melts decrease monotonously with increasing content of LiCl.l.

The research of one-step emulsion polymerization of aniline and its conducting blends with polystyrene (에멀젼중합법으로 제조된 폴리아닐린과 폴리스타이렌과의 전도성블렌드에 대한 연구)

  • 이보현;김태영;김종은;서광석
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.07a
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    • pp.259-262
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    • 2001
  • Stable polyaniline-dodecylbenzenesulfonic acid (PANI-DBSA) fully dissolved in toluene was obtained by a direct one-step emulsion polymerization technique. The polymerization of aniline was carried out in an emulsion comprising water, toluene and DBSA acting both as a surfactant and a dopant for PANI. After the proper washing process was performed, the conductivities of obtained PANI-DBSA complexes increased with increase APS/Aniline molar ratio and DBSA/Aniline molar ratio. The UV-Vis absorption spectra and TGA thermograms of PANI-DBSA complexes also supported these results. PANI-DBSA/PS blends were prepared by mixing PANI-DBSA complexes with PS in toluene. These blends exhibited electrical conductivity of 0.371S/cm at a low PANI-DBSA content (7 wt.%)

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Proton Conducting Behavior of a Novel Composite Based on Phosphosilicate/Poly(Vinyl Alcohol)

  • Huang, Sheng-Jian;Lee, Hoi-Kwan;Kang, Won-Ho
    • Journal of the Korean Ceramic Society
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    • v.42 no.2 s.273
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    • pp.77-80
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    • 2005
  • A series of proton conductive composite membranes based on poly(vinyl alcohol) and phosphosilicate gels powders were successfully prepared. The proton conductivity of these composite was attributed to the phosphosilicate gel, which derived from tetraethoxysilane and phosphoric acid by sol-gel process at a molar ratio of P/Si = 1.5. The proton conductivity increased with increasing both the content of phosphosilicate gel and relative humidity. Temperature dependence of conductivity showed a Vogel-Tamman-Fulcher type behavior, indicating that proton was transferred through a liquidlike phase formed in micropores of phosphosilicate gel. The high conductivity of 0.065 S/cm with a membrane containing 60 wt$\%$ of the gel was obtained at $60^{\circ}C$ at $90\%$ relative humidity.

Effect of Ionic Molar Conductivity on Separation Characteristics of Heavy Metals by Nanofiltration Membranes in Waste Water (이온 몰 전도도가 나노여과막에 의한 폐수 중의 중금속 분리특성에 미치는 영향)

  • Oh, Jeong-Ik
    • Land and Housing Review
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    • v.4 no.1
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    • pp.119-124
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    • 2013
  • Generally, the characteristic of nanofiltration membranes were catagorized into charged membrane, sieve effect, interaction between membarnes and target solutes. This study aims to investigate the effect item of heavy metal separation with view of charge nanofiltration membranes. The experiments of nanofiltration were conducted by nanofiltration set-up with operational pressure of 0.24 MPa at $25^{\circ}C$ by using synthetic wastewater containing 0.1mg/L of Cr, Fe, Cu, Zn, As, Sn, Pb. Nanofiltration membranes rejected heavy metals much better than chloride, sulfate and TOC, of which concentration in synthetic wastewater was higher than that of heavy metals. To consider rejection characteristics of various metals by nanofiltration membranes, separation coefficient, which is the molar conductivity ratio of the metal permeation rate to the chloride ion or TOC permeation rate, was introduced. In spite of different materials and different nominal salt rejection of nanofiltration membrane used, the separation coefficients of metals were nearly the same. These phenomena were observed in the relationship between the molar conductivity and the separation coefficient for heavy metals.

Improvement of Mechanical and Electrical Properties of Poly(ethylene glycol) and Cyanoresin Based Polymer Electrolytes

  • Oh Kyung-Wha;Choi Ji-Hyoung;Kim Seong-Hun
    • Fibers and Polymers
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    • v.7 no.2
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    • pp.89-94
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    • 2006
  • Ionic conductivity and mechanical properties of a mixed polymer matrix consisting of poly(ethylene glycol) (PEG) and cyanoresin type M (CRM) with various lithium salts and plasticizer were examined. The CRM used was a copolymer of cyanoethyl pullulan and cyanoethyl poly(vinyl alcohol) with a molar ratio of 1:1, mixed plasticizer was ethylene carbonate (EC) and propylene carbonate (PC) at a volume ratio of 1:1. The conductive behavior of polymer electrolytes in the temperature range of $298{\sim}338\;K$ was investigated. The $PEG/LiClO_4$ complexes exhibited the highest ionic conductivity of ${\sim}10^{-5}S/cm$ at $25^{\circ}C$ with the salt concentration of 1.5 M. In addition, the plasticized $PEG/LiClO_4$ complexes exhibited improvement of ionic conductivity. However, their complexes showed decreased mechanical properties. The improvement of ionic conductivity and mechanical properties could be obtained from the polymer electrolytes by using CRM. The highest ionic conductivity of PEG/CRM/$LiClO_4$/(EC-PC) was $5.33{\time}10^{-4}S/cm$ at $25^{\circ}C$.

Silicon-Based Anode with High Capacity and Performance Produced by Magnesiothermic Coreduction of Silicon Dioxide and Hexachlorobenzene

  • Ma, Kai
    • Journal of Electrochemical Science and Technology
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    • v.12 no.3
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    • pp.317-322
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    • 2021
  • Silicon (Si) has been considered as a promising anode material because of its abundant reserves in nature, low lithium ion (Li+) intercalation/de-intercalation potential (below 0.5 V vs. Li/Li+) and high theoretical capacity of 4200 mA h/g. In this paper, we prepared a silicon-based (Si-based) anode material containing a small amount of silicon carbide by using magnesiothermic coreduction of silica and hexachlorobenzene. Because of good conductivity of silicon carbide, the cycle performance of the silicon-based anode materials containing few silicon carbide is greatly improved compared with pure silicon. The raw materials were formulated according to a silicon-carbon molar ratio of 10:0, 10:1, 10:2 and 10:3, and the obtained products were purified and tested for their electrochemical properties. After 1000 cycles, the specific capacities of the materials with silicon-carbon molar ratios of 10:0, 10:1, 10:2 and 10:3 were still up to 412.3 mA h/g, 970.3 mA h/g, 875.0 mA h/g and 788.6 mA h/g, respectively. Although most of the added carbon reacted with silicon to form silicon carbide, because of the good conductivity of silicon carbide, the cycle performance of silicon-based anode materials was significantly better than that of pure silicon.

Preparation and Characterization of Composite Membrane for Low Temperature Direct Methanol Fuel Cells

  • Huang Sheng-Jian;Lee Hoi-Kwan;Kang Won-Ho;Wu Qing
    • Journal of the Microelectronics and Packaging Society
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    • v.11 no.4 s.33
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    • pp.69-73
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    • 2004
  • A series of $H_3PO_4$-doped composite membranes based on poly(vinyl alcohol)(PVA) and silica have been prepared by sol-gel process. The proton conductivity, as well as properties of swelling, methanol permeation, was measured in this study. The proton conductivity increased with the molar ratio of $H_3PO_4$ to silica. With the silica content increasing, swelling degree decreased and methanol permeability showed a slight increase. It suggested that the former was mainly determined by hydrophilicity of the membrane, while the latter was dominated by the interconnectivity of matrix. According to the value of on, the optimal conformations of these composite membranes were 60, 70, 80 wt.$\%$ of PS-x in membranes, where x were 1.5, 1.0, and 0.5, respectively. These composite membranes were thermal stability up to $200^{\circ}C$.

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Polyaniline Prepared by One-step Emulsion Polymerization and Its Conducting Blends (원-스텝 에멀젼 중합법으로 제조된 폴리아닐린과 이를 이용한 전도성 블렌드)

  • 이보현;김태영;김종은;서광석
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.2
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    • pp.153-161
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    • 2002
  • Stable polyaniline-dodecylbenzenesulfonic acid(PANI-DBSA) fully dissolved in toluene was obtained by a direct one-step emulsion polymerization technique. By using the proper molar ratio of APS/aniline monomer and DBSA/aniline monomer, the highest conductivity(7 S/cm) of PANI was obtained. The UV-Vis absorption spectrum of PANI confirmed PANI is emeraldine salt form. PANI/styrene polymers (polystyrene and styrene-butadiene copolymer) blends were prepared by mixing PANI solution with polymers in toluene. These blends exhibited the conductivity of 10$\^$-4/-10$\^$-3/ S/cm at 1 wt. % of PANI content. The mechanical property of conducting blend was decreased and TGA thermograms of conducting blends were similar to that of PANI. It had been checked that the flatness of coating layers of conducting blends decreased with increasing conducting components. It was also found that the morphology of blends was setting closer to that of PANI at higher conducting component contents.

Rejection Characteristics of Various Heavy Metals by Low-pressure Nanofiltration (저압나노여과에 의한 각종 중금속의 제거 특성)

  • Oh, Jeong-Ik;Kim, Han-Seung;Kim, Chung-Hwan
    • Journal of Korean Society of Water and Wastewater
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    • v.18 no.4
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    • pp.493-499
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    • 2004
  • Rejection characteristics of heavy metals by nanofiltration membranes were investigated. Nanofiltration membranes rejected heavy metals much better than chloride, sulfate and TOC, of which concentration in synthetic wastewater was higher than that of heavy metals. To consider rejection characteristics of various metals by nanofiltration membranes, separation coefficient, which is the ratio of the metal permeation rate to the chloride ion or TOC permeation rate, was introduced. In spite of different materials and different nominal salt rejection of nanofiltration membrane used, the separation coefficients of metals were nearly the same. In particular, the separation coefficient of arsenic against chloride ion and TOC was larger than any other separation coefficient of heavy metals. These phenomena were observed in the relationship between the molar conductivity and the separation coefficient for heavy metals.