Volume of voids

In applying Eq. XVI-13 to an actual porous bed, r is taken to be proportional to the volume of void space Ale, where e is die porosity, divided by the amount of surface alternatively, then,... 

Diatomaceous Silica Filter aids of diatomaceous silica have a dry bulk density of 128 to 320 kg/m (8 to 20 Ib/fU), contain paiiicies mostly smaller than 50 [Lm, and produce a cake with porosity in the range of 0.9 (volume of voids/total filter-cake volume). The high porosity (compared with a porosity of 0.38 for randomly packed uniform spheres and 0.2 to 0.3 for a typical filter cake) is indicative of its filter-aid ability Different methods of processing the crude diatomite result in a series of filter aids having a wide range of permeability. 

Volume of voids + volume of solids, i.e. total bed volume)... 

Reciprocal order of the adsorption Peclet number per unit volume of voids Fractional saturation, volume of liquid Time... 

Henry s Law constant for the equilibrium is KH = (Vc/Vg)((t/to) — 1). Vc and Vg are the volumes of condensed and vapor phases in the column (i.e. for gas-liquid chromatography, Vc is the volume of the liquid film on the supported packing or open tubular wall, and Vg the volume of void space, respectively). If the column is in the linear range (small loading) the resolution is,... 

The volume occupied by the solid plus the volume of voids when divided into the powder mass yields the bulk density. Therefore, when powder is poured into a graduated container, the bulk density is the mass divided by the volume of the powder bed. 

Volume of voids per total surface area Exit age distribution... 

Figure 1. General diagram of the shrinkage curve and its derivatives. On the horizontal axis is the moisture ratio (volume of water per unit volume of solids, dimensionless). On the vertical axis is, for the solid line (the shrinkage curve), the void ratio (volume of voids per unit volume of solids, dimensionless), and, for the broken line, the value of the slope of the shrinkage curve (dimensionless), and, for the dotted line, the absolute value of the curvature of the shrinkage curve (dimensionless). The following values were used for the parameters k. = 2, k. = 1.6, n = 1.6, and e = 1.9.

Case Face angles Volume of unit-cell Volume of void Porosity (percent) Remarks... 

Most solids of high surface area are to some extent porous. The texture of such materials is defined by the detailed geometry of the void and pore space. Porosity, , is a concept related to texture and refers to the pore space in a material. An open pore is a cavity or channel communicating with the surface of a particle, as opposed to a closed pore. Void is the space or interstice between particles. In the context of adsorption and fluid penetration powder porosity is the ratio of the volume of voids plus the volume of open pores to the total volume occupied by the powder. Similarly, particle porosity is the ratio of the volume of open pores to the total volume of the particle. It should be noted that these definitions place the emphasis on the accessibility of pore space to the adsorptive. 

Total porosity Ratio of volume of voids and pores (open and closed) to volume occupied by solid... 

Most adsorption data were collected by volumetric method until microbalance of high sensitivity appeared few years ago. It can hardly say which method is superior to the other, and both methods need the value of the skeleton volume of sample adsorbent. This volume has to be subtracted from the whole volume of the sample container to obtain the volume of void space, which is used for the calculation of the amount adsorbed. The skeleton volume of sample adsorbent was directly used in the calculation of buoyancy correction in gravimetric method. This volume was usually determined by helium assuming the amount of helium adsorbed was negligible. If, however, helium adsorption cannot be omitted, error would yield in the skeleton volume and, finally, in the calculated amount adsorbed. However, the effect of helium adsorption would be much less for volumetric method if the skeleton volume is considerably less than the volume of void space, but the volume of void space cannot affect buoyancy correction. In this respect, helium adsorption would result in less consequence on volumetric method especially when the skeleton volume was determined at room temperature and pressures less than IS MPa. The skeleton volume (or density) was taken for a parameter in modeling process in some gravimetric measurements. However, the true value of skeleton volume (or density) can hardly be more reliable basing on a fitted parameter than on a measured value. Therefore, one method of measurement cannot expel the other up to now, and the consequence of helium adsorption in the measured amount adsorbed should be estimated appropriately. 

From the definition (9) it follows that theoretically both parameters G and U are equivalent, as might be expected for the probabilities of two contrary events (substance — void). Since the values G and U are mutually complementary to unity, it is possible to formulate for porous systems a rule of reciprocals If there is a porous system where the volume of voids is and the volume of solid matter V, an exchange of these parameters (V becoming V ) would yield a new porous... 

The volume of voids is the porosity, and the volume of solids is (1 - ). If the specific surface area, that is, the surface area of unit volume of solids, is 5o, the total surface presented by unit volume of the bed is 5o(l - e). Therefore, Eq. (18) applies. 

Similar to particle size, the porosity of an ion-exchanger particle plays an important role in the exchanger s capacity. Porosity can be defined as a ratio (usually expressed as a percentage) of volume of voids to total volume of the resin. The porosity of conventional resins ranges from 20% to 55% (4-8). 

In order to calculate the porosity, it is necessary to determine the volume of void space within a known volume of porous material. The sensitivity of NMR... 

The void ratio of a soil, e, is defined as the quotient of the volume of voids divided by the volume of solids in a soil mass ... 

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