Aa. Shugai et al., ELECTROPHORETIC MOTION OF 2 SPHERICAL-PARTICLES WITH THICK DOUBLE-LAYERS, Journal of colloid and interface science, 191(2), 1997, pp. 357-371
The electrophoretic mobilities of two interacting spheres are calculat
ed numerically for arbitrary values of the double-layer thickness. A g
eneral formula for the electrophoreric translational and angular veloc
ities of N interacting particles is derived for low-zeta-potential con
ditions. The present calculation complements the well-studied case of
thin double layers. The results are compared with recent reflection ca
lculations and are used to compute the O(empty set) contribution to th
e electrophoretic mobility of a suspension. Particle interactions can
be significant for values of the scaled particle radius kappa alpha le
ss than or equal to 10. At kappa alpha = 1 the O(empty set) contributi
on can increase by a factor of 2-3 over its thin-double-layer value. T
he precise values depend on the strength of the double-layer repulsion
s as determined by the particle size. Fluctuations in the electrophore
tic velocity are also calculated but would appear to be limited to abo
ut 10% of the mean velocity. The reflection results to order R-6, wher
e R is the particle separation, are in good agreement with the numeric
al results for the suspension mobility and fluctuations but higher ord
er reflections produce worse results. Although the effects of pair int
eractions are noticeable, the major result is that pair interactions e
ven for quite thick double layers are not large. (C) 1997 Academic Pre
ss.