R.W. O'Brien

The dynamic mobility of nonspherical particles

Abstract This paper is concerned with the electrophoretic mobility of particles in alternating electric fields. We refer to this mobility as the “dynamic mobility,” to distinguish it from the standard electrophoretic mobility, which is defined for static fields. This dynamic mobility can now be measured at frequencies up to 1 MHz with the aid of electroacoustic devices. In this paper we present formulae for calculating the dynamic mobility of spheroidal particles with thin double layers. With the aid of these formulae it should be possible to obtain information on particle charge, size, and shape from electroacoustic measurements on dilute suspensions.

The electrophoretic mobility of a porous aggregate

Abstract This work predicts the dependence of electrophoretic mobility on zeta potential for a porous aggregate. The analysis of the electrophoretic motion of a porous spherical aggregate differs from the classical analysis of a solid dielectric sphere in two important aspects: the sphere can not be assumed impermeable if there is electroosmotic flow within the aggregate, and the sphere cannot be considered nonconducting if conducting fluid is entrained in the aggregates pore spaces. Both of these effects are considered for the low zeta potential case by applying the unit cell model to the aggregate interior. The results show that at high and low electrolyte concentrations the mobility of the aggregate will be significantly higher and lower, respectively, than it would be for a solid dielectric sphere.