Surface area, of particles

X = ratio of surface area of particle to surface area of a sphere with diameter D,... 

There are two widely used methods for the determination of the specific surface area of particles. One is based on permeability and the other on gas adsorption. 

External surface area of particles per unit volume of reactor = 1200 m2/m3. 

An equivalent diameter de for flow through the bed can be defined as four times the cross-sectional flow area divided by the appropriate flow perimeter. For a random packing, this is equal to four times the volume occupied by the fluid divided by the surface area of particles in contact with the fluid. 

These relations can be spread to the systems of particles of one form, but of various sizes, D. The specific surface area of such PS is equal to the sum of surface areas of particles related to the entire mass. At known particle size distribution (PSD), v(D), one has... 

Surfactants have been explored widely for their effects on drug absorption, in particular using experimental animals (Gibaldi and Feldman, 1970 Gibaldi, 1976). Surfactants alter dissolution rates (of lipid materials), surface areas of particles and droplets, and membrane characteristics, all of which affect absorption. 

The calculation of free volumes and free surface areas requires an efficient way of extending the cavity algorithm. To calculate the free volume of a particle i, the particle and its associated exclusion sphere are effectively removed from a snapshot of the particle configuration. The volume and surface area of the cavity that is produced in the absence of particle i are equal to the free volume and free surface area of particle i, respectively. 

In a recent comprehensive study, Chhabra, Agarwal, and Sinha(27) have found that the most satisfactory characteristic linear dimension to use is the diameter of the sphere of equal volume and that the most relevant characteristic shape is the sphericity, (surface area of particle / surface area of sphere of equal volume). The limitation of this whole... 

R Drag force per unit surface area of particles N/m2 ML- T-2... 

One advantage of sol-gel processing over surface modification is to create the inorganic oxide support in situ. Hence, without the limitation of the surface area of particles, more organic groups can be incorporated, even though their accessibility is not warranted. Another advantage is the possibility to... 

External surface area of particles per unit volume of reactor 1200 m-1 Mass transfer coefficient, liquid to particles 0.10 x 10"3 m/s Volume mass transfer coefficient, gas to liquid (basis unit volume of reactor) (ki.a) = 0.02 s l... 

Despite many years of interest in the phase distribution of POPs, few predictive models are available. A Langmuir-type relationship, which Junge (1977) first proposed and Pankow (1987) later reviewed and critically evaluated, is the most popular model for estimating adsorption onto aerosols. The Junge-Pankow equation relates the fraction of particulate POPs (c >) to the saturation liquid-phase vapor pressure of the compound ( P Pa) and the surface area of particles per unit volume of air (8, cm2 aerosol / cm3 air). 

Effects of Size, Shape, and Surface Area of Particles... 

The surface area of particles is related to particles size, as discussed previously. The surface area of powders affects the drug dissolution rate, powder flow, cohesiveness, and adsorption. Furthermore, the surface area of solid materials may also... 

British Standard Specifications BS 410 [13] adopts a primary size of 75 pm (200-mesh) with a fourth root of two progression in size and suggest that alternate sieves should normally be used for an analysis (i.e. a root two progression of sizes). Thus, the specific surface area of particles on consecutive sieves is in a 2 1 progression. BS 1796 describes the methods to be used in sieving with woven wire and perforated plate sieves [14],... 

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