Electrostatic classifier

Specific advancements ia the chemical synthesis of coUoidal materials are noteworthy. Many types of genera ting devices have been used to produce coUoidal Hquid aerosols (qv) and emulsions (qv) (39—43) among them are atomizers and nebulizers of various designs (30,44—50). A unique feature of produciag Hquid or soHd coUoids via aerosol processes (Table 3) is that material with a relatively narrow size distribution can be routinely prepared. These monosized coUoids are often produced by relying on an electrostatic classifier to select desired particle sizes ia the final stage of aerosol production. 

E-C, evaporation-condensation N, nebulizer EC, electrostatic classifier VO, vibrating orifice SD, spinning disc FD, fluidized bed RB, rotating brush WDF, Wright dust feeder NBS, NBS dust generator. Values of parameters given are from specifications listed by TSI, Inc., and BGI, Inc. Stability data are from the references. A density of / g/m3 is assumed for the mass concentration values. 

Constant-ouput atomizer, tri-jet aerosol generator, electrostatic classifier, vibrating-orifice aerosol generator, fluidized-bed aerosol... 

The electrostatic classifier (Fig. 6.7) is used to measure particle size distributions in Hk size range from about 0.01 /im to 0.5 pm (Pui and Liu, 1988), The classifier is operated at atmospheric pressure to select narrow size ranges from a polydisperse aerosol. The concentration in each size range is measured usually with a conden.saiion particle counter, and in this way the particle size distribution can be determined. 

Design of electrostatic classifiers and precipitators is based on the principle that the electrostatic charge generated on a particle is proportional to the particle surface area. Furthermore, the behavior of particles in an electric field is controlled by the presence and amount of the electrostatic charge residing on the particle surfaces. 

Fissan, H.J., Helsper, C., Thielen, H.J., 1983. Determination of particle size distributions by means of an electrostatic classifier. J. Aerosol Sci. 14, 354-357. 

A differential mobility analyser (DMA) works on the same principle as the EAA, with some operational differences. In a DMA, an electrostatic classifier is used instead of a mobility analyser and aerosol particles can be sorted by size from 0.01 to 0.9 pm while suspended in air [124]. 

TSl Incorporated. (2000). Model 3080 Electrostatic Classifier Instruction Manual. pp. b-5. 

Knowledge of the spatial dimensions of a molecule is insufficient to imderstand the details of complex molecular interactions. In fact, molecular properties such as electrostatic potential, hydrophilic/lipophilic properties, and hydrogen bonding ability should be taken into account. These properties can be classified as scalar isosurfaces), vector field, and volumetric properties. 

Forces of Adsorption. Adsorption may be classified as chemisorption or physical adsorption, depending on the nature of the surface forces. In physical adsorption the forces are relatively weak, involving mainly van der Waals (induced dipole—induced dipole) interactions, supplemented in many cases by electrostatic contributions from field gradient—dipole or —quadmpole interactions. By contrast, in chemisorption there is significant electron transfer, equivalent to the formation of a chemical bond between the sorbate and the soHd surface. Such interactions are both stronger and more specific than the forces of physical adsorption and are obviously limited to monolayer coverage. The differences in the general features of physical and chemisorption systems (Table 1) can be understood on the basis of this difference in the nature of the surface forces. 

The intermolecular forces of adhesion and cohesion can be loosely classified into three categories (7) quantum mechanical forces, pure electrostatic... 

Electrostatic precipitator A filtering system for the removal of particles from an air stream by giving them an electrical charge. The charged particles are attracted to plates of opposite polarity onto which they adhere. The precipitators are classified as... 

Next, display electrostatic potential maps for acetUi chloroacetate, trichloroacetate, 2-chlorohutyrate a 4-chlorobutyrate anions. Compare potentials at the positi between the two oxygens. Classify the anions as havi large, intermediate or small charge in this region. 

In general, all electrostatic separator systems contain at least four components (i) a chargingdischarging mechanism (ii) an external electric field (iii) a nonelectrical particle trajectory device and (iv) feed and product collection systems. Depending primarily on the charging mechanism involved, the electrostatic separator systems are classified into three categories (i) free fall separators (ii) high tension separators and (iii) conduction separators. 

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