Interfacial surface area content

Figure 7. The specific interfacial surface area goes through a broad maximum as polystyrene content increases. (Reproduced firom ref. 18. Copyright 1988 American Chemical Society.)...

The catalyst particles are built of crystallites, the interior of which is extremely pure iron, whereas the surface layers have a high content of promoter atoms. The total crystallite surface area as will be discussed later, is some two to three times greater than that found by low-temperature surface area measurements by the BET-method. It is concluded that interfacial layers join the crystallites, and only where the distance between two crystallites is too great or their orientation too divergent is the interfacial layer split up into two separate surface layers, thus producing a rift network through the catalyst particles. It is through this rift network that the inner surface is reached by the reactants, and this inner surface is utilized as effectively as is the outer surface. 

Bentonite rocks have many uses in the chemical and oil industries and also in agriculture and environmental protection. The usefulness of bentonite for each of these applications is based on its interfacial properties. These properties are determined by geological origin, chemical and mineral composition (especially montmorillonite content), and particle size distribution, and they include the specific surface area (internal and external), cation-exchange capacity (CEC), acid-base properties of the edge sites, viscosity, swelling, water permeability, adsorption of different substances, and migration rate of soluble substances in bentonite clay. 

Standard nanosilica A-380 (specific surface area 5bet=378 m /g) was heated at 673 K for several hours before the measurements to remove organic adsorbates and residual HCl. Polar and weakly nonpolar deuterated (D) solvents, CDjCN, ( 03)280, and CDCI3 (Aldrich, qualification for NMR spectroscopy at content of main isotope of 99.5%), soluble or practically insoluble in water, were used in the deuterium form to avoid their contribution to the H NMR signal intensity of unfrozen interfacial water at T<273 K. Bidistilled water was used here. 

The objective of the present work is to determine the static adsorption of petroleum sulfonates from microemulsions on representative reservoir solids and to define the effect of microemulsion composition, specifically its relative oil and brine content, on sulfonate adsorption. It is also of interest to determine the effect of adsorption on the microemulsion oil and brine content because of the relationship between microemulsion composition and interfacial behavior. Consequently, the adsorption of a given petroleum sulfonate was determined from a series of microemulsions where each microemulsion contained different volume fractions of the same oil and brine. The difference in microemulsion composition within such a series was effected either by using a different cosurfactant in each microemulsion or by changing the total surfactant/cosurfactant concentration. The adsorbent was carefully reproduced in each experiment in terms of sand/clay composition and total surface area. All experiments within a series were therefore carried out at constant temperature, pressure, adsorbent composition and total surface area. 

The effect of rapid stirring (greater than 10 rpm) on interfacial systems is to increase the surface area of the interface, and consequently the reaction rate over ten thousand times. It is assumed that condensation is stopped when rapid stirring is halted. The modification of dextran is rapid with both yield and content approximately constant after fifteen seconds stirring time (Table 1). This is in agreement with a number of other... 

In the case of alumina nanofillers inside the silica matrix, the adhesion between particles and the matrix appears to be stronger. Therefore, there is low interfacial cracking and no increase in the fracture energy due to an increase in fracture surface area is observed. This situation leads to constant values of fracture energy in terms of nanofiller content. 

The conclusion that is independent of copolymer composition has very important ramifications. Morphological studies indicate that as the co-unit content increases the lamellar crystallites degrade and eventually become micellar in character. Concomitantly, spherulites become more poorly developed. Eventually, at sufficiently high comonomer content, they do not form at all. (18,19) Despite the loss of the lamellar-like crystallite structure the value of a n, or more properly the product of cTenCTun, remaius constant. These results demonstrate that it is not required, or necessary, to relate the chain conformation within the nucleus to that within the mature crystallite. The nucleus is an extremely small entity as compared to the crystallite. The value of a n only reflects the contribution between the junction of the ordered and disordered sequences, and perhaps a few units beyond the interfacial region of the nucleus. It is not dependent on the nominal copolymer composition. However, the structure of the interfacial region of a mature crystallite can be expected to be different since a relatively large surface area is involved. In this case... 

Very recently, ESR techniques have been employed to study the packing of surfactant molecules at the oil/water interface in w/o HIPEs [102,103], By including an amphiphilic ESR probe, which is adsorbed at the oil/water interfaces, it is possible to determine the microstructure of the oil phase from the distribution of amphiphiles between the films surrounding the droplets and the reverse micelles. It was found that most of the surfactant is located in the micelles, over a wide range of water fraction values. However, when the water content is very high (water droplets of the emulsion, to stabilise the large interfacial area created. 

The influence of gas density on the gas-liquid interfacial area could be related to the flow patterns and to the interpenetration between gas and liquid. It is probable that the gas-liquid interface results from two distinct mechanisms. The first one is based on the extent of the solid surface where liquid films could develop (wetting of particles), virtually controlled by fluid velocities and liquid properties. The second mechanism depends on the kinetic energy content of the gas phase. The more important the gas inertia, the more important is the contribution of fine gas bubbles penetrating liquid films. 

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