The study is concerned with addressing
hydrodynamic dispersion of an electroneutral non-adsorbed
solute being transported by electroosmotic flow through a
slit channel formed by walls with different zeta potentials.
The analysis is conducted in terms of the plate height
which, using the Van Deemter equation, can be expressed
through the cross-sectional mean flow velocity, the solute
molecular diffusion coefficient and a length scale param-
eter having meaning of the minimum achievable plate
heig...

The study is concerned with addressing
hydrodynamic dispersion of an electroneutral non-adsorbed
solute being transported by electroosmotic flow through a
slit channel formed by walls with different zeta potentials.
The analysis is conducted in terms of the plate height
which, using the Van Deemter equation, can be expressed
through the cross-sectional mean flow velocity, the solute
molecular diffusion coefficient and a length scale param-
eter having meaning of the minimum achievable plate
height and depending on the velocity distribution within
the channel cross-section. The minimum plate height is
determined by substituting distribution of electroosmotic
velocity into the preliminary derived integral expression
that is valid for any given velocity distribution within a slit
channel cross-section. The electroosmotic velocity distri-
bution within the slit channel cross-section is obtained by
solving one-dimensional version of the Stokes equation
accounting for electric force exerted on the local equilib-
rium electric space charge. The major obtained result is an
analytical expression which represents the minimum plate
height normalized by half of channel width as a function
of two dimensionless parameters, namely, half of channel width normalized by the Debye length, and the ratio of the
wall zeta potentials. The obtained result reveals a sub-
stantial increase in the minimum plate height compared
with the case of equal wall zeta potentials. Different lim-
iting cases of the obtained relationships are analyzed and
possible applications are discussed.
The study is concerned with addressing hydrodynamic dispersion of an electroneutral non-adsorbed solute being transported by electroosmotic flow through a slit channel formed by walls with different zeta potentials. The analysis is conducted in terms of the plate height which, using the Van Deemter equation, can be expressed through the cross-sectional mean flow velocity, the solute molecular diffusion coefficient and a length scale parameter having meaning of the minimum achievable plate height and depending on the velocity distribution within the channel cross-section. The minimum plate height is determined by substituting distribution of electroosmotic velocity into the preliminary derived integral expression that is valid for any given velocity distribution within a slit channel cross-section. The electroosmotic velocity distribution within the slit channel cross-section is obtained by solving one-dimensional version of the Stokes equation accounting for electric force exerted on the local equilibrium electric space charge. The major obtained result is an analytical expression which represents the minimum plate height normalized by half of channel width as a function of two dimensionless parameters, namely, half of channel width normalized by the Debye length, and the ratio of the wall zeta potentials. The obtained result reveals a substantial increase in the minimum plate height compared with the case of equal wall zeta potentials. Different limiting cases of the obtained relationships are analyzed and possible applications are discussed

Citació

Zholkovskij, E.; Masliyah, J.; Yaroshchuk, A. Broadening of neutral analyte band in electroosmotic flow through slit channel with different zeta potentials of the walls. "Microfluidics and nanofluidics", Juliol 2013, vol. 15, núm. 1, p. 35-47.