• Title/Summary/Keyword: Precipitation chemistry

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Application of Polyaniline to an Enzyme-Amplified Electrochemical Immunosensor as an Electroactive Report Molecule

  • Kwon, Seong-Jung;Seo, Myung-Eun;Yang, Hae-Sik;Kim, Sang-Youl;Kwak, Ju-Hyoun
    • Bulletin of the Korean Chemical Society
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    • v.31 no.11
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    • pp.3103-3108
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    • 2010
  • Conducting polymers (CPs) are widely used as matrixes for the entrapment of enzymes in analytical chemistry and biosensing devices. However, enzyme-catalyzed polymerization of CPs is rarely used for immunosensing due to the difficulties involved in the quantitative analysis of colloidal CPs in solution phase. In this study, an enzyme-amplified electrocatalytic immunosensor employing a CP as a redox marker has been developed. A polyanionic polymer matrix, $\alpha$-amino-$\omega$-thiol terminated poly(acrylic acid), was employed for precipitation of CP. The acrylic acid group acts as a polyanionic template. The thiol terminus of the polymer was used to produce self-assembled monolayers (SAMs) on Au electrodes and the amine terminus was employed for immobilization of biomolecules. In an enzymeamplified sandwich type immunosensor, the polyaniline (PANI) produced enzymatically is attracted by the electrostatic force of the matrix polymer. The precipitated PANI was characterized by electrochemical methods.

Synthesis of Poly(AA-co-EGDMA) Microgels by Precipitation Polymerization in Polystyrene Gel (폴리스티렌겔내에서 침전중합법에 의한 Poly(AA-co-EGDMA) Microgel의 합성)

  • Kim, Kong Soo;Cho, Byung Ho;Cho, Suk Hyeong
    • Applied Chemistry for Engineering
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    • v.7 no.2
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    • pp.350-355
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    • 1996
  • Poly(AA-co-EGDMA) microgels were prepared by precipitation polymerization in highly swollen polystyrene gel solution. The polymerization was carried out in selective solvent such as cyclohexane/acetone at $60^{\circ}C$. Poly(AA-co-EGDMA) microgels with various site of $0.18{\sim}0.55{\mu}m$ were obtained from different concentration of polystyrene(PS), concentration of crosslinking agent(EGDMA), ratio of Ps/monomer and volume ratio of solvents. The particle size of poly(AA-co-EGDMA) microgels decreased with increasing the concentration of PS and increased with that of EGDMA.

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Effect of Additives on Physical Properties of Dover Sole Skin Gelatin Prepared by Ethanol Fractional Precipitation (에탄올처리 찰가자미류껍질 젤라틴의 물리적 특성에 대한 첨가물의 영향)

  • Cho, Soon-Yeong;Ha, Jin-Hwan;Lee, Eung-Ho;Kim, Jin-Soo
    • Applied Biological Chemistry
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    • v.38 no.4
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    • pp.330-333
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    • 1995
  • Effects of additives on physical properties of dover sole skin gelatin prepared by fractional precipitation with ethanol were investigated to obtain basic data for utilizing as food protein source. Physical properties such as gel strength, melting point, gelling point and viscosity of both ethanol- and non-treated gelatins were improved as ferric ion, sugar and ethanol were added to gelatin sol, but were deteriorated as sodium hydroxide and acids were added. Insignificant difference in effects of physical properties on additives such as ferric ion, sodium chloride, sugar, acids and ethanol between ethanol- and non-treated gelatins were not observed.

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Morphological changes of $BaCO_3$ microcrystal with the synthetic conditions (합성조건에 따른 $BaCO_3$ 마이크로 결정의 형태 변화)

  • Choi, Eun-Jee;Huh, Young-Duk
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.19 no.5
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    • pp.223-227
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    • 2009
  • $BaCO_3$ crystals with various morphology were prepared using precipitation, hydrothermal and ligand-assisted methods. An irregular structure of $BaCO_3$ microparticle was obtained by simple precipitation method from $Ba(NO_3)_2$ and $Na_2CO_3$ in aqueous solution. Hexagonal pyramidals of $BaCO_3$ were synthesized using a hydrothermal method between $Ba(NO_3)_2$ and urea. Hexagonal rods of $BaCO_3$ were also synthesized using the ligand-assisted hydrothermal method. The aspect ratio of $BaCO_3$ hexagonal rods was increased with the concentration of ligand.

Enhancement effect of phosphate and silicate on water defluoridation by calcined gypsum

  • Al-Rawajfeh, Aiman Eid;Alrawashdeh, Albara I.;Aldawdeyah, Asma;Hassan, Shorouq;Qarqouda, Ruba
    • Advances in environmental research
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    • v.2 no.1
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    • pp.35-49
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    • 2013
  • Research work on removal of fluoride from water, referred to as water defluoridation, has resulted into the development of a number of technologies over the years but they suffer from either cost or efficiency drawbacks. In this work, enhancement effects of phosphate and silicate on defluoridation of water by low-cost Plaster of Paris (calcined gypsum) were studied. To our knowledge, the influence of silicate on defluoridation was not reported. It was claimed, that the presence of some ions in the treated water samples, was decreasing the fluoride removal since these ions compete the fluoride ions on occupying the available adsorption sites, however, phosphate and silicate ions, from its sodium slats, have enhanced the fluoride % removal, hence, precipitation of calcium-fluoro compounds of these ions can be suggested. Percentage removal of $F^-$ by neat Plaster is 48%, the electrical conductance (EC) curve shows the typical curve of Plaster setting which begins at 20 min and finished at 30 min. The addition of phosphate and silicate ions enhances the removal of fluoride to high extent > 90%. Thermodynamics parameters showed spontaneous fluoride removal by neat Plaster and Plaster-silicate system. The percentage removal with time showed second-order reaction kinetics.

Characteristics of $SnO_2$ Prepared by Preparation Method with Ammonium Nitrate (Ammonium Nitrate를 이용한 침전법으로 제조된 $SnO_2$ 특성분석)

  • Son, Hyang-Ho;Lee, Won-Gyu
    • Applied Chemistry for Engineering
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    • v.21 no.4
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    • pp.440-444
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    • 2010
  • $SnO_2$ powders were prepared from the calcination of stannic acids precipitated from the aqueous solution of $SnCl_4$ with ammonium nitrate as a precipitator at $90^{\circ}C$. For the comparison of properties, the stannic acids were prepared from the homogeneous precipitation method using urea as a precipitator at the same temperature. The stannic acid from ammonium nitrate at a thermal gravity analysis showed the weight loss until $700^{\circ}C$ and the percentage of total weight loss was 16.5%. The crystallization of stannic acid into $SnO_2$ finished in the calcination at $600^{\circ}C$ for 2 h. The crystallite size of $SnO_2$ increased with the increase of calcination temperature and initial concentration of $SnCl_4$ solution. In case of the same calcination condition, $SnO_2$ prepared from homogeneous precipitation using urea had a relatively smaller crystallite size rather than $SnO_2$ prepared from ammonium nitrate.

Synthesis of Manganese Hydrogen Phosphate Hydrate by Controlled Double-jet Precipitation (더블제트 침전법에 의한 제이인산망간염 수화물의 새로운 합성 방법)

  • Kim, Won-Seok;Kang, Yong;Kim, Yeong-Cheol
    • Applied Chemistry for Engineering
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    • v.19 no.1
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    • pp.66-72
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    • 2008
  • Manganese hydrogen phosphate hydrate, $MnHPO_4{\cdot}2.25H_2O$, is a major constituent of the pre-conditioning compositions for the manganese phosphate coating treatment over carbon steel substrate. This compound is conventionally produced by the synthesis in the aqueous solution process followed by the filtration and drying processes and a series of size reduction and classification processes in dry state. However, it is evident that the conventional process is neither environment-friendly nor cost-effective. In this work, a new process principle was examined based on the controlled double-jet precipitation technology to produce the manganese chemical product of fairly uniform particle size distribution in an aqueous solution media. The effects of stabilizing agents were comparatively studied by the scanning electron microscope analysis in a uniformity point of view of the resulting particle size. Polyvinylpyrrolidone and Gum Arabic were excellent in controlling the crystal growth step, resulting in fairly uniform size distributions of the particles from the controlled double-jet process.

Synthesis of Pure Brookite-type TiO2 Nanoparticles from Aqueous TiCl4 Solution with controlled Acidity by Precipitation Method (침전법으로 TiCl4 수용액의 산농도 조절을 통한 나노크기의 순수한 브루카이트상 이산화티타늄 분말 제조)

  • Lee, Jeong Hoon;Yang, Yeong Seok
    • Applied Chemistry for Engineering
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    • v.18 no.6
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    • pp.545-551
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    • 2007
  • HCl concentration, reaction temperature, and $Ti^{4+}$ concentration are the decisive factors in determining the structure of precipitates in the process of synthesis of $TiO_2$ particles from aqueous $TiCl_4$ solution by precipitation and the volumetric proportion of brookite phase in $TiO_2$ particles can be controlled by these factors. Pure brookite-type $TiO_2$ nanoparticles were synthesized by heating the aqueous $TiCl_4$ solution with no more than 1.0 M of $Ti^{4+}$, in which the concentration of HCl was kept in the range of about 2.53~6.41 M during reaction, at the temperature below $70^{\circ}C$ for 20 h. Also, Pure brookite was finally transformed to a rutile phase via an anatase phase through heat-treatment.

Influence of the Molar Ratio of Cl-total:Ti+4 on the Crystalline Structure in Preparation of TiO2 from Aqueous TiOCl2 Solution by Homogeneous Precipitation Method (균일침전법에 의한 이산화티타늄 제조공정에서 TiOCl2 수용액의 Cl-total:Ti+4의 몰 비율이 TiO2 결정구조에 미치는 영향)

  • Lee, Jeong Hoon;Yang, Yeong Seok
    • Applied Chemistry for Engineering
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    • v.16 no.6
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    • pp.785-789
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    • 2005
  • $TiO_2$ powders with rutile and brookite phases were synthesized through homogeneous precipitation of the aqueous $TiOCl_2$ solution, prepared from $TiCl_4$ and HCl solution, and their properties were characterized. Based on the analytical results appropriate molar ratios of ${Cl^-}_{total}:Ti^{+4}$ in precipitating solution for synthesis of pure rutile phase and a mixture of rutile and brookite phases were proposed. The volumetric proportion of brookite increased with increasing HCl concentration under a typical condition obtaining mixed phase of rutile and brookite. The brookite phase in the mixture was transformed to anatase phase by heat treatment at about $800^{\circ}C{\sim}850^{\circ}C$, and finally converted to rutile phase at $1000^{\circ}C$.

Catalytic Combustion of Benzene over CuO-CeO2 Mixed Oxides Prepared by Co-precipitation Method (침전법으로 제조된 CuO-CeO2 혼합산화물에서 벤젠의 촉매연소반응)

  • Hong, Seong Soo
    • Applied Chemistry for Engineering
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    • v.25 no.3
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    • pp.312-317
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    • 2014
  • Catalytic combustion of benzene over CuO-$CeO_2$ mixed oxides prepared by co-precipitation method were investigated. The CuO-$CeO_2$ mixed oxides were also prepared using different precipitant and CuO precursor. They were characterized by XRD, BET, XPS and $H_2-TPR$. In the CuO-$CeO_2$ catalysts, characteristic copper oxide peaks were shown at $2{\Theta}=35.5^{\circ}$ and $38.5^{\circ}$ regardless of the precipitant. The Cu0.35 catalyst prepared using $NH_4OH$ as a precipitant revealed the highest activity on the combustion of benzene. In addition, the pretreatment with hydrogen enhanced the catalytic activity and the catalyst reduced at $400^{\circ}C$ showed the highest activity on the combustion of benzene.