Apparatus for Streaming Potential Measurements on Granular Filter Media

Abstract

This paper is intended to provide the necessary information to construct and properly operate a simple streaming potential apparatus capable of measuring the zeta potential of granular media. Through an understanding of the principles of the technique, such a device can readily be used in the study of a variety of granular materials including unstable and dynamic surfaces, as shown for surface coatings and even biofilm growth. The simplified mathematical theory of the streaming potential is herein explained, as well as operational factors and the general reasons for nonreproducible measurements such as electrode maintenance, electrode polarization, nonzero rest potentials, and sample equilibration. This specific apparatus design is intended for use with granular materials and has intentionally been developed in a simplistic fashion to encourage wider usage of the technique. The overall precision of this instrument was ±10% based on a 95% confidence interval. In addition, the accuracy of the device was found to be very good based on comparisons with literature values.