Removal of Submicron Silica Particles from tert-Amyl Alcohol by Dielectric/Electric Packed Bed Filtration

Abstract

A packed bed with an applied electric field is used to remove submicron and nanometer particles from a nonconducting or slightly conducting solution. Several studies have shown that the application of an electric field to a packed bed significantly increases the performance of the filtration. To enhance the electric-field filtration efficiency, it is desired that the packing materials have a higher dielectric constant than the solution so that the electric-field lines will be diverted into the packing materials.

In the present studies, a dc voltage of 0 to 8 kV/cm is applied to a packed bed (2.5-cm diameter and 3.0-cm length) filled with 1-mm-diameter glass beads. The filtration medium contains submicrometer or nanometer SiO₂ particles dispersed in tert-amyl alcohol. Two particle sizes are investigated: the average particle sizes are about 300 nm and 50 nm, respectively.

Visible light spectrophotometry is used to estimate the amount of SiO₂ particles in the effluent. The experimental results are presented as a series of breakthrough curves. The effect of the applied electric field on the breakthrough curve on two different particle sizes is presented. Depending on the applied electric field and the conductivity of the system, heating of the packed bed may occur. The operating current and temperature of the packed bed are also presented.