Abstract
The adsorption isotherms of water at 303 K and N2 at 77 K on various kinds of porous carbons were compared with each other. The saturated amounts of water adsorbed on carbons almost coincided with amounts of N2 adsorption in micropores. Although carbon aerogel samples have mesopores of the great pore volume, the saturated amount of adsorbed water was close to the micropore volume which is much small than the mesopore volume. These adsorption data on carbon aerogels indicated that the water molecules are not adsorbed in mesopores, but in micropores only. The adsorption isotherms of water on activated carbon having micropores of smaller than 0.7 nm in width had no clear adsorption hysteresis, while the water adsorption isotherms on micropores of greater than 0.7 nm had a remarkable adsorption hysteresis above P/P0 = 0.5. The disappearance of the clear hysteresis for smaller micropores suggested that the cluster of water molecules of about 0.7 nm in size gives rise to the water adsorption on the hydrophobic micropores; the formation and the structure of clusters of water molecules were associated with the adsorption mechanism. The cluster-mediated pore filling mechanism was proposed with a special relevance to the evidence on the formation of the ordered water molecular assembly in the carbon micropores by in situ X-ray diffraction.
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References
Adachi, H., Introduction to Quantum Material Chemistry (Japanese), chap. 8, Sankyou Shuppan, Tokyo, 1991.
Adamson, A.W., Physical Chemistry of Surfaces, p. 397, Wiley Interscience, New York, 1990.
Bellissent-Funel, M.-C., R. Sridi-Dorbez, and L. Bosio, “X-Ray and Neutron Scattering Studies of the Structure of Water at a Hydrophobic Surface,” J. Chem. Phys., 104, 10023–10029 (1996).
Curtiss, L.A., D.J. Frurip, and M. Blander, “Studies of Molecular Association in H2O and D2O Vapors by Measurement of Thermal Conductivity,” J. Chem. Phys., 71, 2703–2711 (1979).
Dacey, J.R. and M.J. Evans, “Volume Changes in Saran Charcoal Caused by the Adsorption of Water, Methanol, and Benzene Vapors,” Carbon, 9, 579–585 (1971).
De Keizer, A., T. Michalski, and G.H. Findenegg, “Fluids in Pores: Experimental and Computer Simulation Studies of Multilayer Adsorption, Pore Condensation, and Critical-Point Shifts,” Pure Appl. Chem., 63, 1495–1502 (1991).
Dubinin, M.M., E.D. Zaverina, and V.V. Serpinsky, “The Sorption of Water Vapour by Active Carbon,” J. Chem. Soc., 1955, 1760–1766 (1955).
Eisenberg, D. and W. Kauzman, The Structure and Properties of Water, p. 53, Oxford University Press, London, 1969.
Freeman, J.J., J.B. Tomlinson, K.S.W. Sing, and C.R. Theocharis, “Adsorption of Nitrogen and Water Vapour by Activated Nomex® Chars,” Carbon, 33, 195–799 (1995).
Fujie, K., S. Minagawa, T. Suzuki, and K. Kaneko, “NO/H2O Clathrate Formation in Sub-Nano Graphitic Slit Space,” Chem. Phys. Lett., 236, 427–430 (1995).
Fujiwara, Y., K. Nishikawa, T. Iijima, and K. Kaneko, “A Simulation Study of Small Angle X-Ray Scattering Behavior of Activated Carbon Fibers Adsorbing Water,” J. Chem. Soc. Faraday Trans., 87, 2763–2768 (1991).
Gregg, S.J. and K.S.W. Sing, Adsorption, Surface Area, and Porosity, chap. 3, Academic Press, London, 1982.
Hanzawa, Y., K. Kaneko, R.W. Pekala, and M.S. Dresselhaus, “Activated Carbon Aerogels,” Langmuir, 12, 6167–6169 (1996).
Hanzawa, Y., N. Yoshizawa, K. Kaneko, R.W. Pekala, and M.S. Dresselhaus, “Pore Structure Determination of Carbon Aerogels,” Adsorption, in press.
Iiyama, T., K. Nishikawa, T. Otowa, and K. Kaneko, “A Ordered Water Molecular Assembly in a Slit-Shaped Carbon Nanospace,” J. Phys. Chem., 99, 10075–10076 (1995).
Iiyama, T., K. Nishikawa, T. Otowa, T. Suzuki, and K. Kaneko, “Organized Molecular States in Carbon Micropores,” Fundamentals of Adsorption, M.D. LeVan (Ed.), pp. 401–408, Kluwer Academic Pub., MA, 1996a.
Iiyama, T., K. Nishikawa, T. Otowa, T. Suzuki, and K. Kaneko, “Molecular Assembly Structure of CCl4 in Graphitic Nanospaces,” J. Phys. Chem. B, 101, 3037–3042 (1997a).
Iiyama, T., T. Nishikawa, T. Suzuki, and K. Kaneko, “Study of Structure of Water Molecular Assembly in a Hydrophobic Nanospace at Low Temperature with in situ X-Ray Diffraction,” Chem. Phys. Lett., 274, 152–158 (1997b).
Iiyama, T., T. Suzuki, and K. Kaneko, “An Imperfect Packing of CCl4 Molecules Confined in a Graphitic Slit Nanospace,” Chem. Phys. Lett., 259, 37–40 (1996b).
Kaneko, K. and C. Ishii, “Superhigh Surface Area Determination of Microporous Solids,” Colloid Surf., 67, 203–212 (1992).
Kaneko, K., T. Katori, K. Shimizu, N. Shindo, and T. Maeda, “Changes in the Molecular Adsorption Properties of Pitch-Based Activated Carbon Fibers by Air Oxidation,” J. Chem. Soc. Faraday Trans., 88, 1305–1309 (1992).
Kaneko, K., N. Kosugi, and H. Kuroda, “Characterization of Iron Oxide Dispersed Activated Carbon Fibers with Water Adsorption and Fe K-Edge XANES and EXAFS,” J. Chem. Soc. Faraday Trans. I, 85, 869–881 (1989).
Kaneko, K., T. Suzuki, Y. Fujiwara, and K. Nishikawa, “Dynamic Micropore Structures of Micrographitic Carbons During Adsorption,” Characterization of Porous Solids II, F. Rodriguez-Reinoso, J. Rouquerol, K.S.W. Sing, and K.K. Unger (Eds.), pp. 389–398, Elsevier, Amsterdam, 1991.
MacClellan, A.L. and H.F. Harnsberger, “Cross-Section Areas of Molecules Adsorbed on Solid Surface,” J. Colloid Interface Sci., 23, 577–599 (1967).
McBain, J.W., J.L. Porter, and R.F. Sessions, “The Nature of the Sorption of Water by Charcoal,” J. Amer. Chem. Soc., 55, 2294–2304 (1933).
Müller, E.A., L.F. Rull, L.F. Vega, and K.E. Gubbins, “Adsorption of Water on Activated Carbons: A Molecular Simulation Study,” J. Phys. Chem., 100, 1189–1196 (1996).
Rigby, M., E.B. Smith, W.A. Wakeham, and G.C. Maitland, The Forces between Molecules, chap. 1, Oxford Sci. Pub., Oxford, 1986.
Rouquerol, J., D. Avnir, C.W. Fairbridge, D.H. Everett, J.H. Hynes, N. Pernicone, J.D.F. Ramsay, K.S.W. Sing, and K.K. Unger, “Recommendation for the Characterization of Porous Solids,” Pure Appl. Chem., 66, 1739–1758 (1994).
Setoyama, N., T. Suzuki, and K. Kaneko, “Simulation Study on Relationship between High Resolution α s-Plot and Pore Size Distribution for Activated Carbon,” Carbon, 36, 1459–1467 (1998).
Suzuki, T. and K. Kaneko, “The Structural Change of Graphitization-Controlled Microporous Carbon upon Adsorption of H2O and N2,” J. Chem. Soc. Faraday Trans., 88, 1305–1309 (1992).
Suzuki, T., K. Kaneko, and K.E. Gubbins, “Pore Width-Sensitive Filling Mechanism for CCl4 in a Graphitic Micropore by Computer Simulation,” Langmuir, 13, 2545–2549 (1997).
Wang, Z.-M. and K. Kaneko, “Dipole Oriented States of SO2 Confined in a Slit-Shaped Graphitic Subnanospace from Calorimetry,” J. Phys. Chem., 99, 16714–16721 (1995).
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Kaneko, K., Hanzawa, Y., Iiyama, T. et al. Cluster-Mediated Water Adsorption on Carbon Nanopores. Adsorption 5, 7–13 (1999). https://doi.org/10.1023/A:1026471819039
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DOI: https://doi.org/10.1023/A:1026471819039