Adsorbent inner surface area

Porous-layer- open tubular (PLOT) and support-coated open tubular (SCOT) columns are prepared by extending the inner surface area of the capillary tube. A layer of particles can be deposited on the surface or the column wall can be chemically treated to create a porous adsorbent layer. Obviously some of the wall-modified open tubular columns discussed in section 2.3.3 could be... 

The surface of an adsorbent is not smooth but shows a roughness of molecular or higher dimensions. Many catalysts used in practice are deliberately prepared to contain a great number of capillaries of submicro-scopic dimensions. There are many places on the highly developed inner surface areas of such microporous adsorbents where the adsorbed molecules come into direct contact with many more atoms of the adsorbent than would be possible if the surface were an ideally smooth plane. Such places where an increased number of atoms of the adsorbent are in direct contact with the adsorbed molecules form active places or active spots for van der Waals adsorption (28-30). 

Figures 6 a/b On the left ordinate the relative amount of adsorbed water per inner surface area at 30% relative humidity vi. density is given on the right ordinate the frequency of maximal loss for the RF aerogels with R/C 1500 and 800, respectively are displayed.

Precipitation of the growing polymer from the initial solution of styrene and DVB in an inert diluent during crosshnking copolymerization results in the formation of a two-phase heterogeneous network, in which one phase is presented hy the highly crosshnked and rigid polymer, while the rejected diluent forms another phase. After removing the diluent, permanent voids remain in the copolymer beads. The total pore volume, and the inner surface area, S, are the major characteristics of the porous structure these are intimately related to pore size and pore size distribution. These parameters determine the practical apphcation frelds of the polymeric adsorbent resins therefore, a precise quantitative characterization of resin porosity becomes an important task. 

The adsorption capacity (adsorptive power, loading) of an adsorbent resulting from the size and the structure of its inner surface area for a defined component is normally represented as a function of the component concentration c in the carrier gas for the equilibrium conditions at constant temperature. This is known as the adsorption isotherm x = f (c )x. There are variety of approaches proceeding from different model assumptions for the quantitative description of adsorption isotherms (Table 22.1.3) which are discussed in detail in the literature. ... 

Without sonication, Pt particles adsorb primarily on the external surface of SBA-15 and at the mesopore openings. Sonication promotes homogeneous inclusion and deposition of Pt nanoparticles on the inner surface of the support mesopores, because ca. 90% of the total surface area is from the inner pore walls. Heat treatment... 

The experiment was carried out in a reaction cell shown in Fig. 3.3 with inner walls covered by a zinc oxide film having thickness 10 pm [20]. The surface area of the measuring film on the quartz plate was about 1/445 of the total film area on the wall of the vessel. The results of direct experimental measurements obtained when the adsorbent temperature was -196 C and temperature of pyrolysis filament (emitter of H-atoms) 1000°C and 1100°C, are shown on Fig. 3.4. One can see a satisfactory linear dependence between parameters A r (the change in film conductivity) and APh2 (reduction of hydrogen pressure due to adsorption of H-atoms), i.e. relations... 

Figure 5.14 Hydrogen molecule on the surface of a SWNT (5,5). The van der Waals interaction between H2 and the curved surface of the nanotube is weaker on the outer surface and stronger on the inner surface. Furthermore, the specific surface area of the adsorbate layer (Rads) is larger than that of the nanotube (Rnt)-...

Examination of powdered materials with an electron microscope can generally disclose the presence of surface imperfections and pores. However, those imperfections or irregularities smaller than the microscope s resolving power will remain hidden. Also hidden is the internal structure of the pores, their inner shape and dimensions, their volume and volume distribution as well as their contribution to the surface area. However, by enveloping each particle of a powder sample in an adsorbed film, the method of gas adsorption can probe the surface irregularities and pore interiors even at the atomic level. In this manner a very powerful method is available which can generate detailed information about the morphology of surfaces. 

The adsorption capacity of carbon materials is not related in a simple manner to their surface area and porosity. The adsorption capacity will depend on the accessibility of the organic molecules to the inner surface of the adsorbent, which depends on their size. Thus, under appropriate experimental conditions, small molecules (e.g., phenol) can access micropores, natural organic matter (NOM) can access mesopores, and bacteria can access macropores. 

The filter can consist of up to three elements. The outer element is a particulate filter, often made of glass fibre paper, pleated to increase surface area. The inner element is a vapour adsorbent, usually activated granular charcoal. The third element comprises various chemicals impregnated on to the charcoal, such as copper, chromium, silver and triethylenediamine (TEDA), to react with volatile chemical agents such as hydrogen cyanide and cyanogen chloride that are poorly adsorbed. 

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