Grains, surface charge

Surface roughness of grains Pore-diameter size and size distribution Surface charge of grains... 

Typical operating temperatures are 200 °C to 400 °C. If oxygen is present, it is ionosorbed on the surface as O" or O ". A layer of negative charges builds up at the grain surface and leads to a depletion of the conduction band at the surface. 

Electrostatic Separation and Electrostatic Concentration. The principle of this opera-tiah.is based on the fact that, if one or more of the materials in a granular mixture can receive a surface charge on or just before entering an electrostatic field, the grains of... 

After pH adjustment, the water enters a precipitation/coprecipitation tank, where chemical reagents (such as iron or aluminum salts) are carefully added to form the precipitates. The resulting precipitates are often colloidal or are otherwise too fine grained to readily settle out of solution. They may also have repulsive surface charges that prevent them from agglomerating and settling. As shown in Figure 7.1,... 

Adsorption of the admixture on the hydrating cement grains could decrease flocculation in at least three ways (D44). The first is an increase in the magnitude of the ( -potential if all the particles carry a surface charge of the same sign and sufficient magnitude, they will repel each other. The second is an increase in solid- liquid affinity if the particles are more strongly attracted to the liquid than to each other, they will tend to disperse. The third is steric hindrance the oriented adsorption of a non-ionic polymer can weaken the attraction between solid particles. 

In the first place, these are nonlinear effects in the grain screening. Simple estimates evidence that the magnitude of the ratio cp)/k (T (where e is the electron charge, is the potential, k >, and T are the Boltzmann constant and the temperature, respectively), which determines the significance of nonlinear effects, is, near the grain surface, on the order of 10 in real experiments on dusty plasmas and charged colloidal suspensions. This means that the linear approximation may fail in this case. 

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