Surface area factor

Most of the adsorbents used in the adsorption process are also useful to catalysis, because they can act as solid catalysts or their supports. The basic function of catalyst supports, usually porous adsorbents, is to keep the catalytically active phase in a highly dispersed state. It is obvious that the methods of preparation and characterization of adsorbents and catalysts are very similar or identical. The physical structure of catalysts is investigated by means of both adsorption methods and various instrumental techniques derived for estimating their porosity and surface area. Factors such as surface area, distribution of pore volumes, pore sizes, stability, and mechanical properties of materials used are also very important in both processes—adsorption and catalysis. Activated carbons, silica, and alumina species as well as natural amorphous aluminosilicates and zeolites are widely used as either catalyst supports or heterogeneous catalysts. From the above, the following conclusions can be easily drawn (Dabrowski, 2001) ... 

In order to quantify the level of exfoliation, a surface area factor (SAF) has been proposed, which is the sum of the numerical products of A and B, as defined above. 

Table 9 Calculated values of number of platelets per stack and surface area factor as obtained from HRTEM image analysis...

Fig. 39 Plots showing the effect of surface area factor on the extent of property improvement. Symbols represent experimental values, and the lines are their apparent fitting. Encircled data points are taken from unpublished research work on NR latex-based NA nanocomposites. Vertical dotted line indicates the critical point...

Table 11.2 Adsorption of Nonionic Nitroaromatic Compounds (NACs) to Aluminosilicate Clays (a) Surface Area Factors,/saf, for Different Clays Expressing Maximum Sorption Sites Relative to Kaolinite, and (b) KNAC EDA Values (L- mol 1 sites) Measured for Several NACs on K+-Kaolinite Allowing Estimates of KNACd Values Due to Electron Donor-Acceptor Interactions (Eq. 11-20) ...

Adsorption to the K+-covered siloxane surfaces of the clay, illite, can be estimated using Eq. 11-20. A tnt.eda is 300,000 L mol-1 and the surface area factor, /saf, for illite is 6 (Table 11.2). Since the ground water contains so much calcium relative to potassium (30 1), only a very small fraction of the cation exchange sites on the illite are covered with weakly hydrated potassium ions you assume/K+clay is about 0.01. Thus, you estimate ... 

Sieve size (pm) Mean sieve size (dj Mass fraction residing on sieve iSurface area factor (cm2 cm-3)... 

Table 9.7 Carbon fluxes from deep-sea sediments (below 1000 m water depth) in 10 mol yr estimated by using different parameters. Global estimations of regional data compilations are made by multiplication with surface area factors.

The radial variable r is dimensionalized to isolate the Damkohler number in the mass balance. It is important to emphasize that dimensional analysis on the radial coordinate must be performed after implementing the canonical transformation from Ca to iJia- If the surface area factors of and 1/r are written in terms of as defined by equation (13-9), prior to introducing the canonical transformation given by equation (13-4), then the mass transfer problem external to the spherical interface retains variable coefficients. If diffusion and chemical reaction are considered inside the gas bubble, then the order in which the canonical transformation and dimensional analysis are performed is unimportant. Hence,... 

For the determination of the surface area of the total aggregate, SA, the procedure provided by the Asphalt Institute may be used (Asphalt Institute MS-2). The procedure utilises the aggregate grading and the surface area factors per sieve size (see Table 5.15). The calculations consist of multiplying the total percentage passing through a sieve by the surface... 

Table 5.10 Surface area factors and example of calculation of surface area...

It must be noted that the surface area factors shown in Table 5.10 are applicable only to the listed sieves, which should be used during sieving. 

The surface area factors have been determined assuming that the aggregate specific gravity is 2650. When the aggregate used has a significantly different specific gravity, the result of the surface area of the total aggregate mix should be multiplied by a correction factor a (= 2650/SGJ. 

There are two main issues in an ultrafiltration process productivity and selectivity. Productivity is quantified in terms of the permeate flux, this being defined as the permeation rate per unit membrane surface area. Factors that affect permeate flux are solute type, solute concentration, membrane type, solution pH, solution ionic strength, apphed pressure (also called the transmembrane pressure), and the hydrodynamic conditions on the feed side. The volumetric permeate flux, which is the volume of permeate collected per unit time per unit membrane area is given by the following generalized equation, based on a resistance model ... 

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