title: Electroacoustic study of dispersions containing two types of colloidal particles.
abstract: The procedure of subtraction of electrolyte background electroacoustic signal, which is a standard feature in commercially available instruments, can be used to determine the ζ potentials of particular types of colloidal particles in multi-component dispersions. A preliminary study was carried out in a few two-component dispersions (dispersions containing two types of particles). One-component dispersion with the same mass fraction of component 1 and with the same solution composition as in the two-component dispersion of interest was prepared and the electroacoustic signal of that one-component dispersion was measured and saved as the "electrolyte background". Then, the signal of the two-component dispersion was measured, and the saved background signal was subtracted from the signal of the two-component dispersion, thus producing the ζ potential of component 2. An analogous procedure was carried out to determine the ζ potential of component 1. Two opposite types of behavior were observed in various two-component dispersions. In certain dispersions (e.g., titania-alumina in dilute solutions of 1-1 electrolytes at various pH), the behavior of the both types particles was independent, that is, their ζ potentials at certain pH in one- and two-component dispersions were equal. In other dispersions (e.g., silica-alumina at neutral pH), the apparent behavior of particles in one- and two-component dispersions was completely different. The observed difference indicates an interaction between the particles, e.g., formation of aggregates containing both types of particles, adsorption of products of dissolution or formation of new phases.
authors.affiliation: Lublin University of Technology, Lublin, Poland. mkosmuls@abo.fi
authors.forename: Marek
authors.initials: M
authors.lastname: Kosmulski