ChaDter 2
Electrical properties of interfaces
Nomenclature
a
ai
cfi
Ci
e
E
ES
F
i
IS
k
n,, R
no
ni
nio
NS
L
r
R
T
U
4
ve43
X
Xi
Y
Yo
zi
Y
6
AP
V
X
z
radius of sphere
activity of ion i
capacitance of Stem layer
molar concentration of ion i
electron charge
electric field strength
streaming potential
Faraday constant
current
streaming current
Boltzmann constant
local number concentrations of cations and anions
number concentration of ions in bulk solution
local number concentration of ion i
number concentration of ion i in bulk solution
surface density of adsorption sites
total charge on sphere
flow rate
radial distance from centre of sphere
gas constant
absolute temperature
electrophoretic mobility
specific adsorption potential of ion i
velocity
electro-osmotic velocity
distance from surface
mole fraction of counterions in solution
= ze$/kT
= ze$dkT
valence of ions in symmetrical (2-2) electrolyte.
valence of ion i (including sign of charge)
=Kx
= tanh (yiJ4)
thickness of Stem layer
pressure Merence
I O Particle Deposition and Aggregation
permittivity
zeta potential
Debye-Huckel parameter, eqn (2.7)
specific conductivity of solution
surface conductivity
viscosity
volume charge density in solution
charge density in the Stem layer
surface charge density
diffuse layer charge per unit area of surface
electrical potential
surface potential
2.1 INTRODUCTION
Many of the important properties of colloidal systems are determined directly or
indirectly by the interaction forces between particles. These colloidal forces
consist of several components, principally the electrical double layer, van der
Waals, Bom, hydration and steric forces, which act over relatively short distances
and are greatly dependent on the surface properties of particles or collectors.
Consequently, a detailed understanding of the solid-liquid interfacial region is
important in any attempt to model and simulate aggregation and deposition
phenomena. The nature of