Abstract
Physical adsorption on microporous adsorbents such as silica gel and various forms of carbon has been described by many different theories, as: (1) capillary condensation, (2) multilayer adsorption, and (3) a combination of multilayer and capillary adsorption. Most of the nitrogen adsorption-desorption investigations at liquid nitrogen temperature of porous systems have found hysteresis in the relative pressure (p/p0) region of 0.5 to 1.0. This hysteresis has been attributed to the action of surface tension at a curved meniscus formed by capillary condensation. For some time it was believed that the effect of capillaries on adsorption was confined to the region of the hysteresis loop, but recent experimental evidence indicates that the presence of capillaries can influence adsorption not only in the high relative pressure region but also in the low relative pressure region. The purpose of this discussion is to present theoretical and experimental evidence of the effects of capillaries below the hysteresis loop for a series of carbon blacks and for a series of oxidized carbon blacks.
Published Version
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