Charge on a particle

The subscript k identifies the different species present, charges on a particle of species k,... 

Electrostatic Interaction. Similarly charged particles repel one another. The charges on a particle surface may be due to hydrolysis of surface groups or adsorption of ions from solution. The surface charge density can be converted to an effective surface potential, /, when the potential is <30 mV, using the foUowing equation, where -Np represents the Faraday constant and Ai the gas law constant. 

The magnitude of charge on a particle can be expressed in any one of several ways total charge (Jp), surface charge density (i pj), specific particle surface gradient or field (Sps charge-to-mass ratio (J c), or specific particle potential (Eps). These are related by the following identities ... 

What is the relation between the zeta potential and the charge on a particle How is this relation determined ... 

The electrical conductivity a is defined as the electrical current density or the amount of charges passing through a unit cross-sectional area per second in an electrical field with strength E of 1 V/m. The electrical conductivity can be determined from the particle number concentration n, the charge on a particle q, and the mobility of a particle p by... 

The precipitation process requires (1) a method of providing an electrical charge on a particle, (2) a means of establishing and maintaining an electrical field, and (3) a method of removing the particle from the precipitator. 

For colloidal particles with at>h Eq. 8.22 reduces to z/zion = h la. Since the charge on a particle, zion, is proportional to its surface area, 4ira2 (if the particle is a sphere), z is proportional to radius a. Friction coefficient /is also proportional to a as shown by Stokes law, Eq. 4.42. Thus mobility... 

A simple theory for diffusion charging was first proposed by White (1963). He considered that ions diffuse in a gas in accordance with the postulates of kinetic theory except that when an ion strikes a particle, it stays, thus accumulating charge. However, this accumulation of charge on the particle produces an electric field which tends to prevent additional ions from reaching the particle. Thus in White s theory the rate of accumulation of charge on a particle decreases as the charge on the particle increases. 

DLS instruments can be used to measure the size of particle aggregates in water, as described previously. DLS can also measure the movement of nanoparticles in an electric field to determine the zeta potential, which provides information about the surface charge on a particle. The zeta potential will affect the distribution of the nanoparticles in solution and influence surface reactive properties. The zeta potential can be calculated using the Henry equation ... 

Surface charge on a particle results in an unequal distribution of ions in the polar medium in the vicinity of the surface. Ions of opposite charge (counterions) are attracted to the surface, and ions of like charges (coions) are repelled away from the surface. This unequal distribution gives rise to a potential across the interface. The exact distribution of the counterions in the solution surrounding the charged surface is very important, since it determines the potential decay into the bulk from the charged surface. Electrostatic attraction, thermal motion and forces other than electrostatic (specific adsorption) influence the counterions in the vicinity of the surface. 

The electric charge on a particle may be positive or negative, and is measured in coulombs. Thus the charge on an electron is... 

Type of charge on a particle could be determined by the measurement of Zeta potential [9] or a titration curve. According to Fajan s rule [10], the ions forming a crystalline phase should be adsorbed prior to other ions. For the system studied in this paper, the sol particles produced must carry positive charge to make it stably adsorb the cationic surfactant. In order to elucidate the effect... 

Assuming Stokes f formula the magnitude of the charge on a particle of known diameter may be calculated from its velocity. This... 

Example 6-3 The charge on a particle in a flow situation is dependent on the number of collisions it receives as it passes through a pipe. If the initial charge on a particle is zero, determine the behavior of the charge on the particle as the number of collisions varies. Consider the case of no charge leakage for a 50-/im-diameter coal particle in a gas-solid flow of a loading of 1.5 in a 0.0254-m-diameter pipe. The contact potential is 1 V. The gas velocity in the pipe is 30.5 m/sec. 

Generally the charge on a particle of radius Tp developed in an electrical field of strength E via the phenomenon of field charging is given as (Flagan and Seinfeld, 1988)... 

A charged particle is acted upon by an electrostatic force near charged surfaces or other charged particles. The force acts remotely through air or vacuum and does not require the flow of current. The charge on a particle can be negative or positive, depending on whether the particle has an excess or deficiency, respectively, of electrons. In this section, we review the basic principles of electrostatics and the system of units used to express electrostatic quantities. 

From thousands of measurements, Millikan found that the value of the charge on a particle was always a whole-number multiple (e, 2e, 3e, etc.) of a fundamental unit of charge the elementary charge, or the charge of an electron, e. 

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