Kaneko

Department of Chemistry, Faculty of Science, Chiba University, 1-33 Yayoi, Inage, Chiba 263, Japan 

Recently activated carbons such as activated carbon fibers (ACFs) and superhigh surface area carbons have been developed. New activated carbons have more uniform micropore size distribution and greater surface area than traditional activated carbons. The carbon membranes for gas separation have been also developed lately[8]. The activation of the polyamide film leads to self-supported activated carbon film whose surface area is larger than 1100 m /g [9]. Thus various kinds of carbon adsorbents have been developed to find new applications. Scientific studies on activated carbon have been increasing according to development of these new carbon adsorbents with a special relevance to energy and environmental demands. In particular, controll of an adsorptive ability of activated carbon is requisite for new application. Consequently, basic principles for control of the micropore filling mechanism of activated carbons are shown here. 

The van der Waals equation describes the critical phenomena of vapour to supercritical gas or fluid. Below critical temperature Tc gas which coexists with the liquid phase is called a vapour. Vapor has own saturated vapour pressure Pq. Then we can use the relative pressure P/Pq for description of adsorption. Fundamentally, physical adsorption is valid for vapours [10]. As the molecule-surface interaction of physical adsorption is weak, a sufficient intermolecular interaction corresponding to heat of vapourization is necessary for predominant physical adsorption. Micropore filling is a physical adsorption enhanced by overlapping of the molecule-surface interaction potentials from opposite pore walls and the adsorptive force is the strongest in physical adsorption. Nevertheless, micropore filling is a predominant process only for vapour. 

However, we need a more physical basis on the concept of the saturated vapour pressure for the adsorptive of the supercritical gas. When we use the molecular statistical approach to description of adsorption for the supercritical gas, the saturated vapour pressure is not necessarily indispensable. The distinction between vapour and supercritical gas can be taken into account through the intermolecular and molecule surface interaction energies [12-15]. Nevertheless, it is better to discuss the micropore filling mechanisms for vapour and supercritical gas separately in order to obtain each physical picture. 

The interaction between an admolecule and a surface atom as a function (r) of the distance r between them can be expressed by the Lennard-Jones potential 

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Fig. XVII-31. (a) Nitrogen adsorption isotherms expressed as /-plots for various samples of a-FeOOH dispersed on carbon fibers, (h) Micropore size distributions as obtained by the MP method. [Reprinted with permission from K. Kaneko, Langmuir, 3, 357 (1987) (Ref. 231.) Copyright 1987, American Chemical Society.]...

Kaneko E Active matrix addressed displays Handbook of Liquid Crystals Vol 2A. Low Molecular Weight Liquid Crystals led D Demus, J Goodby, G W Gray, H-W Speiss and V Vill (New York Wiley-VCH)... 

Y. Yamamoto, H. Nakamura, R, Yoda. N. Kaneko. M. Mikawa. and S. Mizutani. KyorUsu Yakka Daigaku Kenkyu Nempo. 10, 56 (1965) Chem Abstr.. 66, 94939... 

T. Kaneko and co-eds.. Synthetic Production and Dtilicyation ofyimino yicids ]ohn. Wiley Sons, Inc., New York, 1974. 

E. Munekata, Y. Masui, T. Shiba, andT. Kaneko, Chem. Soc. Japan 46, 3187 (1973). 

Chloro-3-nitropyridine [5470-18-8] M 158.5, m 100-103°, 101-102°, 103-104° (sublimes), pK -2.6. Forms needles from H2O. Purified by continuous sublimation over a period of 2 weeks at 50-60°/0.1mm [Barlin J Chem Soc 2150 1964]. The N-oxide has m 99-100°(from CH2Cl2-Et20). [Taylor and Driscoll J Org Chem 25 1716 I960-, Ochiai and Kaneko Chem Pharm Bull Jpn 8 28 I960.]... 

Suzuki, T. and Kaneko, K., Structural change of activated carbon fibers with desorption by in situ x-ray diffraction. Carbon, 1988, 26(5), 744 745. 

Jaroniec, M., Gilpin, R. K., Kaneko, K. and Choma, J., Evaluation of energetic heterogeneity and microporosity of activated carbon fibers on the basis of gas adsorption isotherms, Langmuir, 1991, 7(1 1), 2719 2722. 

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