Electrostatic separation charging mechanisms

Electrostatic-Separation Machines The first electrostatic machines to be used commercially employed the principle of contact elec trification. These were free-fall devices incorporating large vertical plates between which an electrostatic field was maintained. Tribo-elec tric separation (contact charging) has experienced an increase in apphcations due to advances in mechanical self-cleaning and electrical design as well as the development of efficient precharging techniques. 

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. 

Charging by contact electrification is an active mechanism whenever dissimilar particles make and break contact with each other, or whenever they slide over a chute or an electrode. This charging mechanism is most frequently used to charge selectively and obtain an electrostatic separation of two species of dielectric materials as realized in a free fall electrostatic separator. 

Presently, there is no direct proof for such a mechanism in pure imidazole (e.g., by NMR) however, the observation that the ratio of the proton diffusion and conduction rates virtually coincide with the Boltzmann factor (i.e., exp(— E e)/ kT)), where is the electrostatic separation energy of two unit charges in a continuum of dielectric constant e) is a strong indication. 

The central theme that the apoprotein facilitates the scission of the O—O bond is based on the established mechanisms of peroxide heterolysis 165). By invoking concerted proton transfer (s) in the transition state, such schemes illustrate that oxygen-oxygen heterolysis need not be attended by an electrostatically unfavorable charge separation. In addition, they offer some rationale for the observed high entropy of activation in the primary H202-catalase reaction (—25 cal mole" deg ) 166). This should be the case in a rigid lattice of interactions implied in Eq. (20) and formulas (VII) and (VIII). 

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