• Title/Summary/Keyword: Oxalate ($C_2O{_4}^{2-}$)

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Lanthanide-Oxalate Coordination Polymers Formed by Reductive Coupling of Carbon Dioxide to Oxalate: [Ln2(3,5-pdc)2(C2O4)(H2O)4]·2H2O (Ln = Eu, Sm, Ho, Dy; pdc = Pyridinedicarbox

  • Huh, Hyun-Sue;Lee, Soon W.
    • Bulletin of the Korean Chemical Society
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    • v.27 no.11
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    • pp.1839-1843
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    • 2006
  • Hydrothermal reactions of $Ln(NO_3)_3{\cdot}5H_2O $ (Ln = Eu (1), Sm (2), Ho (3), Dy (4)) with 3,5-pyridinedicarboxylic acid (3,5-pdcH2) in the presence of 4,4'-bipyridine led to the formation of the 3-D Ln(III)-coordination polymers with a formula unit of $[Ln_2(3,5-pdc)_2(C_2O_4)(H_2O)_4]{\cdot}2H_2O$. These polymers contain a bridging oxalate ligand ($C_2O_4\;^2$). On the basis of GCMS study of the mother liquor remaining after the reaction, we proposed that the $C_2O_4\;^2$ formation proceeds in three steps: (1) Ln(III)-mediated decarboxylation of $3,5-pdcH_2$ to give $CO_2$, (2) the reduction of $CO_2$ to $CO_2\;^{\cdot}$ by the Ln(II) species, and (3) the reductive coupling of the two $CO_2\;^{\cdot}$ radicals to the oxalate ($C_2O_4\;^2$) ion. All polymers were structurally characterized by X-ray diffraction.

A Study on the Synthesis of Aluminum Oxalate from Aluminum Hydroxide (수산화(水酸化)알루미늄으로부터 Aluminum Oxalate의 합성(合成) 연구(硏究))

  • Lee, Hwa-Young;Cho, Byung-Won
    • Resources Recycling
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    • v.18 no.4
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    • pp.38-43
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    • 2009
  • The synthesis of aluminum oxalate, one of the aluminum organic compounds, has been performed using aluminum hydroxide as a raw material. For this aim, domestic aluminum hydroxide of 99.7% purity was dissolved by oxalic acid to produce an aqueous aluminum solution. As a result, it was found that aluminum hydroxide could be dissolved almost completely by the reaction with 1.0 mole/l oxalic acid solution at $90^{\circ}C$ for 16 hr. It was strongly required to keep the ratio of ethanol/Al solution more than 2.0 for the synthesis of aluminum oxalate from the aluminum solution. Furthermore, the pH should be controlled to be more than 8.2 in order to obtain the recovery of aluminum oxalate higher than 90%. From the chemical analysis of aluminum oxalate prepared in this work, the content of $NH_4$, Al and C was found to be 14.5, 7.18 and 17.4%, respectively. Accordingly, the aluminum oxalate synthesized from the aluminum solution was confirmed to be $(NH_4)_3Al(C_2O_4)_3$ $3H_2O$.

Polarographic Study of Titanium Oxalato and Oxalatous Complex (Polarography에 依한 Titanium Oxalato 및 Oxalatous Complex에 關한 硏究)

  • Kim, Hwang-Am;Han, Dong-Jin
    • Journal of the Korean Chemical Society
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    • v.9 no.2
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    • pp.71-74
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    • 1965
  • Reduction of Ti(Ⅳ)-oxalate complex on dropping mercury electrode has been studied as a function of oxalate concentration and of pH varied with HCl. Assuming there are equilibrium $TiO(C_2O_4)_2= \;+\;2H^+\;=\;Ti^{+4}\;+\;2C_2O_4\;=\;+\;H_2O,\;K_4$ in addition to $TiO(C_2O_4)_2\;^=\;=\;TiO^{++}\;+\;2C_2O_4=\;K_2\;Ti(C_2O_4)_2\;^-\;=\;Ti^{+3}\;+\;2C_2O_4=\;K_3$ in the system cathodic wave has been well explained for that pH is higher than 0.5. The equilibrium constants $K_2,\;K_3$ and $K_4$ have been to be $2{\times}10^{-12},\;5{\times}10^{-13}$ and $10^{-11}$, respectively. The reduction of Ti(Ⅳ)-oxalate system is $Ti^{+4}\;+\;e\;{\to}\;Ti^{+3}$ in the concentration of hydrochloric acid, higher than 3M.

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Facile Separation of Zinc Oxalate to Oxalate and its Conversion to Glycolic Acid via Electrochemical Reduction (ZnC2O4의 Oxalate로의 효과적 분리 및 이의 전기화학적 환원을 통한 글리콜산으로의 전환)

  • Sunmi Im;Yiseul Park
    • Clean Technology
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    • v.29 no.1
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    • pp.46-52
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    • 2023
  • Oxalic acid has been traditionally obtained via the oxidation of carbohydrates using nitric acid and catalysts. However, this process produces a variety of nitrogen oxides during oxidation and requires a separation process due to its various intermediates. These products and additional steps increase the harmfulness and complexity of the process. Recently, the electrochemical reduction of carbon dioxide into oxalic acid has been suggested as an environmentally friendly and efficient technology for the production of oxalic acid. In this electrochemical conversion system, zinc oxalate (ZnC2O4) is obtained by the reaction of Zn2+ ions produced by Zn oxidation and oxalate ions produced by CO2 reduction. ZnC2O4 can then be converted to form oxalic acid, but this requires the use of a strong acid and heat. In this study, a system was proposed that can easily convert ZnC2O4 to oxalic acid without the use of a strong acid while also allowing for easy separation. In addition, this proposed system can also further convert the products into glycolic acid which is a high-value-added chemical. ZnC2O4 was effectively separated into Zn(OH)2 powder and oxalate solution through a chemical treatment and a vacuum filtration process. Then the Zn(OH)2 and oxalate were electrochemically converted to zinc and glycolic acid, respectively.

Synthesis of $\beta$-Alumina By Oxalate Coprecipitation Method and Its Crystallization Behavior (Oxalate 공침법에 의한 $\beta$-Alumina 합성과 결정화 거동)

  • 박용민;양유철;김형욱;박성수;손영국
    • Journal of the Korean Ceramic Society
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    • v.32 no.4
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    • pp.455-461
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    • 1995
  • To investigate the synthesis of $\beta$-Al2O3 and its crystallization behavior by oxalate coprecipitation method, the optimum pH range for oxalate coprecipitates has been theoretically calculated from the solubility products and the equilibrium constans of each metal ionic species and their solubility diagram wa obtained. The optimum pH range for oxalate coprecipitates at room temperature was estimated as <4. In experiment, we found that the optimum condition for oxalate coprecipitates was pH<1, which was not doped with pH controller. The Na+ ions were easily exchanged for the NH4+ ions of NH4OH which was used as pH controller, and those NH4+ ions were supposed to affect the crystallization behavior of $\beta$-Al2O3. The thermal decomposition of all complexes was almost complete below 40$0^{\circ}C$. The primary product of the decomposition process was m-Al2O3, which transformed to $\beta$"- or $\beta$-Al2O3 at temperature higher than 100$0^{\circ}C$. We found that the powder prepared at 120$0^{\circ}C$ had only $\beta$"- and $\beta$-Al2O3.EX>-Al2O3.

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Wet Chemical Preparation of Li-rich LiMn$_2$O$_4$ Spinel by Oxalate Precipitation (Oxalate 침전을 이용한 Li-과량 LiMn$_2$O$_4$ Spinel의 습식합성가 분말 특성)

  • 이병우;김세호
    • Journal of the Korean Ceramic Society
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    • v.36 no.7
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    • pp.698-704
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    • 1999
  • Li rich Li1+xMn2-xO4(x=0.07) spinel powders were prepared by an oxalate precipitation of wet chemical methods at temperature lower than $600^{\circ}C$. The FTIR results showed that the powders prepared at $600^{\circ}C$ had high degree of crystal quality comparing with the spinel powders prepared by solid state reaction at 75$0^{\circ}C$ which was the lowest synthesis temperature of the solid state reaction method. The particle size of powders prepared by the oxalate precipitation at $600^{\circ}C$ was smaller than 0.2${\mu}{\textrm}{m}$ and the specific surface area was 11.01 m2/g A heat treatment over 90$0^{\circ}C$ formed second phase in the precipitates. It was shown that there were phase transitions at temperatures. T1,T2 and T2. The transitions involved weight loss and gain during heating and cooling. The low temperature synthesis below $600^{\circ}C$ avoided the second phase formation and the prepared powders showed improved compositional and physical properties for secondary lithium battery applications.

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Characterization of Vacuum Dried Y, Ba, and Cu Oxalate Precipitates (진공건조에 의한 Y, Ba, Cu 질산염의 Oxalate 침전물에 대한 연구)

  • Kim, Bae-Yeon;Lee, Deuk-Yong;Kim, Chul-Min;Lee, Chang-Jae;Jung, Sung-Sik
    • Journal of the Korean Ceramic Society
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    • v.44 no.8
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    • pp.457-463
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    • 2007
  • Y, Ba and Cu nitrates were precipitated by oxalic acid at pH 4. The Y, Ba and Cu oxalate powders were vacuum dried and characterized by XRD, DT/TGA and etc. Yttrium nitrate precipitated as $NH_4Y(C_2O_4){_2}H_2O$ and converted to $Y_2O_3$ above $450^{\circ}C$. Ba precipitated with two phases, $Ba(HC_2O_4){_2}2H_2O\;and\;Ba(C_2O_4)$. The amount of each precipitates was 4 : 1, Cu precipitated non-hydrated form, $Cu(C_2O_4)$. The vacuum drying was successful to characterize precipitated powder, which had been generally known as amorphous gel.

Experimental Determination of Equilibrium Constants of Copper Complexes in Aqueous Environment

  • Cho, Young-Il
    • Journal of Environmental Science International
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    • v.21 no.5
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    • pp.555-562
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    • 2012
  • The experimental determination of equilibrium constants is required to estimate concentrations of reagents and/or products in environmental chemical reactions. For an example, the choice of copper (Cu) complexation reactions was motivated by their fast kinetics and the ease of measurement of Cu by an ion-sensitive electrode. Each individual titrant of sulfate ($SO{_4}^{2-}$) and oxalate ($C_2O{_4}^{2-}$) was expected to have its own unique characteristics, depending on the bonding in Culigands connected to the aqueous species. The complexation reaction of Cu with $SO{_4}^{2-}$ somewhat fast reached equilibrium status compared with $C_2O{_4}^{2-}$. The experimental equilibrium constants ($K_{eq}$) of copper sulfate ($CuSO_4$) and copper oxalate ($CuC_2O_4$) were determined $10^{2.2}$ and $10^{3{\sim}4.3}$, respectively.

A Study on the Dielectric Properties of $SrTiO_3$ Sintered Body Synthesized by Oxalate Method (수산염법으로 합성한 $SrTiO_3$ 소결체의 유전특성에 관한 연구)

  • 김병호;이만규;김석우
    • Journal of the Korean Ceramic Society
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    • v.28 no.3
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    • pp.215-224
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    • 1991
  • The synthesis of SrTiO3 powders having high purity and homogeneous submicron particle size was attempted by the oxalate method. The microstructure and dielectric properties of SrTiO3 based boundary layer capacitor (BLC) were investigated. Strontium titanyl oxalate[SrTiO(C2O4)2.4H2O] was prepared from the mixing solution of (Sr, Ti) using oxalic acid(H2C2O4) as a precipitating agent at 8$0^{\circ}C$. The crystalline SrTiO3 powder was obtained by thermal decomposition of the precipitate above $600^{\circ}C$. The crystalline SrTiO3 powder containing Nb2O5 as a dopant, TiO2 and SiO2 as additives was sintered at 1360~144$0^{\circ}C$ in the reducing atmosphere to get semiconductive SrTiO3. Insulating material containing PbO-Bi2O3-B2O3 frit was printed on the sintered semiconductive SrTiO3 and fired at 120$0^{\circ}C$ for 2h to get the grain boundary diffusion.

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Separation of $Cd^{2+}$ and $Pb^{2+}$ by means of their coprecipitation on $BaTiO(C_2O_4)_2{\cdot}4H_2O$ precipitate ($BaTiO(C_2O_4)_2{\cdot}4H_2O$ 공침법에 의한 $Cd^{2+}$$Pb^{2+}$의 분리)

  • Min, Chonkyu;Noh, Taeyong;Lee, Chul
    • Analytical Science and Technology
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    • v.10 no.1
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    • pp.31-34
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    • 1997
  • Barium titanyl oxalate which is a precursor of barium titanate has been precipitated at pH 4~5 by a rapid addition of aqueous titanyl oxalate solution to artificial environmental water samples containing equivalent weight of $Ba^{2+}$ ions. Quantitative recoveries of $Cd^{2+}$ and $Pb^{2+}$ from the water samples has been confirmed and found to be usable as a possible method of preconcentration for their determination.

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