Classification of Particles Dispersed by Bead Milling with Electrophoresis

Abstract

The purpose of the present study is to develop a new particle classification technique and apparatus to replace centrifugal separation method, where continuous operation for classification is impossible because of the deposition of the coarse particles on the wall of the separator. In our recent research, it was clear that the zeta potential of the silica particles dispersed by a bead mill had size dependency. Hence, the particles were classified using an electrical field flow fractionation (EFFF) system under the condition that the zeta potential of the smaller particles was more negative than that of larger particles. Previous EFFF apparatus utilized horizontal field flow; however, the apparatus designed in this study had vertical field flow and cylindrical channel with length of 350 mm and radius width of 6 mm to reduce the running cost and operation time for classification of particles. About the classification performance of this apparatus, it was found that the silica particles with the size from 50 nm to 400 nm were classified using a low applied voltage. This method prevented deposition of particles on the wall of the apparatus and allowed continuous operation. Results of theoretical calculations supported qualitatively the experimental results obtained in this research.

Keywords

• zeta potential
• classification
• electrophoresis
• efff