• Title/Summary/Keyword: Carbonate anion

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Assessing the anion type effect on the hydro-mechanical properties of smectite from macro and micro-structure aspects

  • Goodarzi, Amir R.;Akbari, Hamid R.
    • Geomechanics and Engineering
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    • v.7 no.2
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    • pp.183-200
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    • 2014
  • The expansivity of clayey soils is a complicated phenomenon which may affect the stability of geotechnical structures and geo-environmental projects. In all common factors for the monitoring of soil expansion, less attention is given to anion type of pore space solutions. Therefore, this paper is concerned with the impact of various concentrations of different inorganic salts including NaCl, $Na_2SO_4$, and $Na_2CO_3$ on the macro and microstructure behavior of the expandable smectite clay. Comparison of the responses of the smectite/NaCl and smectite/$Na_2SO_4$ mixtures indicates that the effect of anion valance on the soil engineering properties is not very pronounced, regardless of the electrolyte concentration. However, at presence of carbonate as potential determining ions (PDIs) the swelling power increases up to 1.5 times compared to sulfate or chloride ions. The samples with $Na_2CO_3$ are also more deformable and show lower osmotic compressibility than the other mixtures. This demonstrates that the barrier performance of smectite greatly decreases in case of anions with the non-specific adsorption (e.g., $Cl^-$ and $SO{_4}^{2-}$) as the salinity of solution increases. Based on the results of the X-ray diffraction and sedimentation tests, the high soil volumetric changes upon exposure to carbonate is attributed to an increase in the repulsive forces between smectite basic unit layers due to the PDI effect of $CO{_3}^{2-}$ and increasing the pH level which enhance the buffering capacity of smectite. The study concluded that the nature of anion through its influence on the re-arrangement of soil microstructure and osmotic phenomena governs the hydro-mechanical parameters of expansive clays. It seems not coinciding with the double layer theory of the Gouy-Chapman double layer model.

Preparation of Ultra Fine Alumina Powder Via Ammonium Aluminium Carbonate Hydroxide (AACH 를 이용한 고순도 알루미나 분말 제조)

  • Tun, Zhu;Shin, Kun-Chul
    • Journal of Industrial Technology
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    • v.24 no.B
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    • pp.65-71
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    • 2004
  • The ultra fine gamma-alumina powder was prepared via ammonium aluminium carbonate hydroxide (AACH). The XRD, SEM, BET, thermal analysis were used to characterize the samples. The effects of various reaction parameters as concentration, of solution, anion on specific area, PH, aging time and thermal decomposition condition on the produced AACH and alumina were discussed.

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Ion and solvent transport during the redox reaction of Polypyrrole and poly(N-substituted pyrrole) films in aprotic solutions

  • Lee Hochun;Kwak Juhyoun
    • Journal of the Korean Electrochemical Society
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    • v.1 no.1
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    • pp.52-54
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    • 1998
  • Polypyrrole (PPy), Poly(N-methyl Pyrrole) (PMPy) and Poly(N-phenyl Pyrrole) (PPhPy) films in acetonitrile (Af and propylene carbonate (PC) have been compared focusing on their different ion and solvent transport behaviors. During the redox reaction of PPy films, cation, anion, and solvent take part in mass transport. Whereas during the redox reaction of PMPy and PPhPy films, anion and solvent transport are dominant but cation transport is negligible. In addition, solvent transport occurs in the same direction with cation transport for PPy films. On the other hand, solvent transport occurs in the opposite direction to anion transport for PMPy films, and it changes its amount and direction with the kind of the dopant anion and the solvent used at electropolymerization for PPhPy films.

Dephosphorylation of Diphenyl-4-Nitrophenyl Phosphinate(DPNPIN) onto 2-Alkylbenzimidazolide Anion in TTABr Micellar Solution (TTABr 미셀 용액속에서 2-알킬벤즈이미다졸 음이온에 의해 추진되는 디페닐-4-니트로페닐 포스페네이트(DPNPIN)의 탈인산화반응)

  • Kim, Jeung-Bea
    • Journal of Environmental Science International
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    • v.24 no.8
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    • pp.981-992
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    • 2015
  • This study is mainly focused on micellar effect of tetradecyltrimethyl ammonium bromide(TTABr) solution including alkylbenzimidazole(R-BI) on dephosphorylation of diphenyl-4-nitrophenylphosphinate(DPNPIN) in carbonate buffer(pH 10.7). Dephosphorylation of DPNPIN is accelerated by $BI^{\Theta}$ ion in $10^2$ M Carbonate buffer(pH 10.7) of $4{\times}10^{-4}$ M TTABr solution up to 80 times as compared with the reaction in Carbonate buffer by no benzimidazole(BI) solution of TTABr. The value of pseudo first order rate constant($k_{\psi}$) of the reaction in TTABr solution reached a maximum rate constant increasing micelle concentration. The reaction mediated by $R-BI^{\Theta}$ in micellar solutions are obviously slower than those by $BI^{\Theta}$, and the reaction rate were decreased with increase of lengths of alkyl groups. It seems due to steric effect of alkyl groups of $R-BI^{\Theta}$ in Stern layer of micellar solution. The surfactant reagent, TTABr, strongly catalyzes the reaction of DPNPIN with R-BI and its anion($R-BI^{\Theta}$) in Carbonate buffer(pH 10.7). For example, $4{\times}10^{-4}$ M TTABr in $1{\times}10^{-4}$ M BI solution increase the rate constant($k_{\psi}=99.7{\times}10^{-4}1/sec$) of the dephosphorylation by a factor ca. 28, when compared with reaction($k_{\psi}=3.5{\times}10^{-4}1/sec$) in BI solution(without TTABr). And no TTABr solution, in BI solution increase the rate constant($k_{\psi}=3.5{\times}10^{-4}1/sec$) of the dephosphorylation by a factor ca. 39, when compared with reaction ($k_{\psi}=1.0{\times}10^{-5}1/sec$) in water solution(without BI).

Step-wise Anion-Exchange in Layered Double Hydroxide Using Solvothermal Treatment

  • Lee, Jong-Hyeon;Rhee, Seog-Woo;Jung, Duk-Young
    • Bulletin of the Korean Chemical Society
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    • v.26 no.2
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    • pp.248-252
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    • 2005
  • Synthetic layered double hydroxides (LDHs), [$Mg_4Al_2(OH)_{12}]CO_3{\cdot}nH_2O$, were prepared in the submicron size of plate-like polycrystals. Anion-exchange reactions with various linear dicarboxylic acids were performed to produce LDH/organic hybrid materials by solvothermal treatment in toluene. X-ray powder diffraction spectra for the products indicated that the interlayer spacings of LDHs remarkably changed, up to 20 $\AA$ when 1,10-decanedicarboxylic acid anions were intercalated as an organic guest. Dicarboxylates-LDHs samples could be also re-exchanged consecutively with other dicarboxylic acids or carbonate without serious destruction of layer structure under the scanning electron microscopic observation.

Synthesis of Terephthalate Intercalated Zn-Al Layered Double Hydroxides Using AZO Thin Film (AZO박막을 이용한 Terephthalate가 삽입된 Zn-Al 층상 이중 수산화물의 합성)

  • Park, Ki-Tae;Yoon, Soon-Gil
    • Korean Journal of Materials Research
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    • v.27 no.3
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    • pp.161-165
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    • 2017
  • In this paper, synthesis of terephthalate intercalated Zn-Al: Layered double hydroxides (LDHs) was studied. We designed freestanding Zn-Al: carbonate LDH nanosheets for a facile exchange technique. The as-prepared Zn-Al carbonate LDHs were converted to terephthalate intercalated Zn-Al:LDHs by ion exchange method. Initially, Al-doped ZnO (AZO) thin films were deposited on p-Si (001) by facing target sputtering. For synthesis of free standing carbonate Zn-Al:LDH, we dipped the AZO thin film in naturally carbonated water for 3 hours. Further, Zn-Al: carbonate LDH nanosheets were immersed in terepthalic acid (TA) solution. The ion exchange phenomena in the terephthalate assisted Zn-Al:LDH were confirmed using FT-IR analysis. The crystal structure of terephthalate intercalated Zn-Al:LDH was investigated by XRD pattern analysis with different mole concentrations of TA solution and reaction times. The optimal conditions for intercalation of terephthalate from carbonated Zn-Al LDH were established using 0.3 M aqueous solution of TA for 24 hours.

Effect of Counter Anions on Solid Electrolyte Interphase Formation on Graphite Electrodes in Propylene Carbonate-based Electrolyte Solutions

  • Song, Hee-Youb;Kim, Seong In;Nogales, Paul Maldonado;Jeong, Soon-Ki
    • Journal of Electrochemical Science and Technology
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    • v.10 no.1
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    • pp.55-60
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    • 2019
  • Herein, the effect of counter anions on the formation of a solid electrolyte interphase (SEI) in a propylene carbonate (PC)-based electrolyte solution was investigated. Although the reversible capacities were different, reversible intercalation and de-intercalation of lithium ions occurred in the graphite negative electrode in the PC-based electrolyte solutions containing 1 M $LiClO_4$, $LiPF_6$, $LiBF_4$, and $LiCF_3SO_3$ at low temperature ($-15^{\circ}C$). This indicated that the surface films acted as an effective SEI to suppress further co-intercalation and decomposition reactions at low temperature. However, the SEIs formed at the low temperature were unstable in 1 M $LiPF_6$ and $LiBF_4/PC$ at room temperature ($25^{\circ}C$). On the other hand, increasing reversible capacity was confirmed in the case of $LiCF_3SO_3/PC$ at room temperature, because the SEI formed at the low temperature was still maintained. These results suggest that counter anions are an important factor to consider for the formation of effective SEIs in PC-based electrolyte solutions.

Synthesis of Hydroxy-terminated Poly(propylene carbonate) (Hydroxy-terminated Poly(propylene carbonate)의 합성)

  • Jung, S.M.;Moon, J.Y.;Park, D.W.;Park, S.W.;Lee, J.K.
    • Applied Chemistry for Engineering
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    • v.9 no.2
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    • pp.273-277
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    • 1998
  • The synthesis of hydroxy-terminated poly(propylene carbonate)(HTPPC) was performed by the reaction of propylene carbonate(PC) with alcohol initiator using metal alkoxides, crown ethers and quaternary onium salts as catalysts. The effects of catalyst structure, types and concentration of alcohol, and solvent were investigated. Among the alkoxide catalysts tested, the ones with higher Lewis acidity and with more nucleophilic alkoxide anion showed higher catalytic activity. Mixed catalysts of metal alkoxied and crown ether showed higher conversion of PC than metal alkoxide alone. Quaternary onium salts of bulky cation exhibited higher catalytic activity. High polar solvent showed higher yield of HTPPC and the yield increased with the decrease of [PC]/[Initiator] ratio.

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