セピオライト結晶格子のMg(II)のCu(II)による水溶液中での置換反応

書誌事項

タイトル別名
  • Substitution of Mg(II) in Sepiolite with Cu(II) in Aqueous Solution.
  • セピオライト ケッショウ コウシ ノ Mg 2 ノ Cu 2 ニヨル スイ

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抄録

A clay mineral sepiolite is a fibrous magnesia silicate with intramolecular tunnels along the fiber axis and the Mg2+ along the tunnel wall which can be substituted with transition metalions. The substitution reactions of the Mg2+ in a sepiolite with Cu were carried out in various concentrations of CuSO4 aqueous solution at 25°C using a natural sepiolite sample from China.The reaction rate increased with an increase of the concentration of CuSO4 solution. The Mg2+ along the tunnel wall of sepiolite was substituted by Cu2+ about 40% for a period of 30 days. Reaction kinetics was studied and the rate of substitution (v) was represented by the equation of v=k [sep] 0 [Cu2+]/[Cu2+] +K; where K, [sep] 0, [Cu2+] and K were the rate constant, the initial concentration of sepiolite, the concentration of Cu2+ and a constant respectively. The well oriented fibers of the sepiolite substituted with Cu2+ showed an angular dependency to the applied field in the electron paramagnetic resonance (ESR) spectra. The ESR spectra for the well oriented sample which was set perpendicular or parallel to the applied magnetic field, showed different line shapes. The gx, gy and gz calculated from the spectra were 2.37, 2.11 and 2.05 respectively. The hyperfine anisotropy was also observed in the ESR spectra and the hyperfine coupling constants, Ax, Ay and Az, were found to be 8.5, 3.0, and 6.0 mT respectively. These results suggest that the coordination of Cu2+ is a distorted octahedral coordination and the Mg2+ ions along the tunnel wall are substituted by Cu2+ ions.

収録刊行物

  • 粘土科学

    粘土科学 35 (4), 188-191, 1996

    一般社団法人 日本粘土学会

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