Structural study of hydrated ions in confinement
| Project/Area Number |
17550023
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | Fukuoka University |
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Principal Investigator |
YAMAGUCHI Toshio Fukuoka University, Faculty of Science, Professor, 理学部, 教授 (70158111)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | Nanometer pore / hydrated ion / microscopic structure / MCM-41 / Activated carbon / Aqueous electrolyte solutions / Hydrogen bonding / Acetonitrile / XAFS / X線回折 / 中性子散乱 / 相挙動 / ナノ空間 / 水和構造 / X線・中性子散乱 / 界面 / 水の構造 / メソ細孔 / 拡散係数 |
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| Research Abstract |
In this study, the structure and dynamics of water, methanol, acetonitrile, and several aqueous electrolyte solutions confined in well-controlled MCM-41 with hydrophilic surface and activated carbon fibers with hydrophobic surface have been investigated by differential scanning calorimetry, FTIR, X-ray diffraction and quasi-elalstic neutron scattering.
(1) For MCM-41 C10(pore diameter 21 Å), C14(28 Å), and C18(37 Å), monolayered water are strongly bound to the surface silanol groups (SiOH) with an O-O distance of 2.6 Å, resulting in distorted hydrogen bonding network in capillary-condensed water. The translational diffusion coefficients of water molecules decrease with decreasing pore size and were found to be about half to bulk water.
(2) Methanol molecules confined in MCM-41 C10 and C14 form strong hydrogen bonds with the silanol groups. The structure and dynamics of the methanol molecules on the surface show little dependency on pore size and temperature. On the other hand, capillary-condensed methanol molecules form a chain-like structure as in bulk, but its hydrogen-boned network is very distorted.
(3) Acetonitrile molecule confined in MCM-41 C14 interact with the surface silanol groups by dipole-dipole interactions with an N-O distance of about 3 Å. Translational diffusion of acetonitrile molecules in the pores is more retarded than that in bulk, and its activation energy was found to be about 7-12 kJ/mol, much smaller than that of water.
(4) Capillary-condensed heavy water confined in MCM-41 C10 has shown a dynamical cross-over at around 229 K from low-density water to high-density water.
(5) The aqueous electrolyte solutions confined in MCM-41 C10, C14, C18, and ACF showed a decrease in melting point with lowering surface charge density of ions. The structure of the first hydration shell of the ions is similar to that in bulk.
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Report
(3 results)
Research Products
(29 results)
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[Journal Article] Neutron scattering study on dynamics of water molecules confined in MCM-41.2005
Author(s)
Takahara, S., Kittaka, S., Mori, T, Kuroda, Y, Yamaguchi, T., Bellissent-Funel, M.-C.
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Journal Title
Adsorption 11
Pages: 479-483
Related Report
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[Journal Article] Low temperature properties of acetonitrile confined in MCM-412005
Author(s)
Kittaka, S., Iwashita, T., Serizawa, A., Kranishi, M., Takahara, S., Kuroda, Y., Mori, T., Yamaguchi, T.
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Journal Title
J Phys. Chem. B 109(49)
Pages: 23162-23169
Related Report
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[Journal Article] Collective dynamics of supercritical water2005
Author(s)
Yamaguchi, T., Yoshida, K., Yamamoto, N., Hosokawa, S., Inui, M., Baron, A.Q.R., Tsutsui, S.
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Journal Title
J. Phys. Chem. Solids 66
Pages: 2246-2249
Related Report
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