Velocities, migration

The term sgn z (it holds that sgn z = 1 for z 0 sgn z = -1 for z 0 and sgn z = 0 for z = 0) reflects the fact that particles with the positive charge are moving in the sense of the vector , while particles with the negative charge are moving the opposite direction. The proportionality constant in this equation (L(,) is called (actual) mobility, and represents the velocity that would be exhibited by the particle of the /-th component with the relative charge z in the electric field of unit intensity. 

Actual mobility, of any ionic form (component) of the /-th compound is, generally saying a complicated function of the distribution of all ions in the solution 

For the characterization of a particular component the limiting (absolute) mobility m.z) can be used that is defined as mobility of this component at a given temperature in a solution in which the concentration of all components approaches zero. It holds 

Besides the actual mobilities U/, and the limiting mobilities (t, ) of the /-th component with the relative charge z the magnitude (t/,)ef/ is also in use. This magnitude characterizes the mobility of the /-th eompound as a whole. 

If the /-th compound is a weak electrolyte, it takes part in the appropriate protolytic equilibria with the solvent, e.g., water. The total concentration c, of this compound is given by the sum c,. of all ionie forms (z 0) and the concentration c, 0 of the electroneutral molecules (z = 0) of this /-th compound. It holds that c, =, . The proportion of the /, z-th component in the /-th compound, expressed, 

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Particle diam., i Number of elementary electrical charges, Nq Particle migration velocity, u, ft/sec... 

Type of precipitator Type of dust Gas volume, cu ft/ min Average gas veloc- ity, ft/sec Collecting electrode area, sq ft Over-all collection efficiency, % Average particle migration velocity, ft/sec... 

Migration velocity The electrophoretic velocity of a charged particle in an electric field. 

Particle migration velocity The velocity at which a charged particle moves in a given direction in an electric field. 

A theoretical model whereby maximum peak capacity could be achieved by the use of 3-D planar chromatographic separation was proposed by Guiochon and coworkers (23-27). Unfortunately, until now, because of technical problems, this idea could not be realized in practice. Very recently, however, a special stationary phase, namely Empore silica TLC sheets, has now become available for realization of 3-D PC. This stationary phase, developed as a new separation medium for planar chromatography, contains silica entrapped in an inert matrix of polytetrafluoroethy-lene (PTFE) microfibrils. It has been established that the separating power is only ca. 60% of that of conventional TLC (28) this has been attributed to the very slow solvent migration velocity resulting from capillary action. 

Wandenings-geschwindigkeit, /. migration velocity. -sinn, m. direction of migration (of ions), -zahl,/. transport number. 

The relative displacement rates of the interfaces AIAB and ABIB in any particular system will, of course, depend on the relative migration velocities of all mobile participants across the barrier layer and reaction will continue while appropriate reactant constituents remain available. Such migrant entities travel by the most efficient route and therefore overall rates of such reactions are frequently sensitive to the concentration of imperfections in the product crystal lattice [1171]. One possible... 

This equation has been used for estimating migration velocities of radionuclides (e.g. 66). Here Pr is the density of the rock (kg/m3), p the density of water, e the fissure porosity, af the specific surface of fissures in the bedrock (m2/m3) and ap the specific surface of particles used in the Kd determinations (m2/m3). The distribution coefficient Kd represents ar. equilibrium value for the particular rock under the pertinent conditions. 

Solvents for reducing viscosity, which increase migration velocity... 

The separation of charged compounds is based on the differences in migration velocity (v) when the electric field is applied. Migration velocity is derived by dividing the length of the capillary from injection to detection (1) by the measured migration time (t) ... 

If solutions of two electrolytes are brought into contact there is, generally speaking, a potential difference between them, just as there is one at the interface mercury-electrolyte in the capillary electrometer. This potential difference has been shown by Nemst to depend on the differences in the concentrations and the migration velocities of the ions. Smith uses dilute solutions containing equivalent amounts of KI and KC1 the kation is thus the same in both solutions, and the migration velocities of the I and Cl ions are nearly equal, so that, according to Nemst s theory, there should be no potential difference or double layer at the interface. These... 

In order to influence a migration it is obvious that one can alter the charge of the compounds, the viscosity of the medium and the dynamic radius of the compounds. According to Eq. 17.5, the electrophoretic mobility is the proportionality factor in the linear relationship of the migration velocity and the electric field strength... 

From the migration velocity of a compound and the migration distance one can derive its migration time (tj). The migration distance (/) in CE is equal to the length of the capillary from the inlet (injection site) to the point of detection. 

The migration in CE is obviously influenced by both the effective and the electroosmotic mobility. Therefore, the proportionality factor in the relationship of the migration velocity and the electric field strength in such a case is called the apparent electrophoretic mobility (/iapp) and the migration velocity the apparent migration velocity (vapp). The /iapp is equal to the sum of /[Pg.587]

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