Influence of cation exchange on electrokinetic and rheological properties of the oxidized graphite dispersions

Abstract

Abstract In this study we describe the relations between surface hydrophilicity, stability, electrokinetical and rheological behavior of the aqueous oxidized graphite (OG) dispersions, saturated by alkali and other metal cations. Ion exchange modification of OG by Li, Na, K, Rb, Cs, (CH3)4N, Ca, Cu, and Al chlorides has been carried out and the influence of the exchange-cation nature on the colloidal stability, electrosurface and rheological properties of the cation-substituted OG dispersions has been studied. The dependences of the optical density, critical coagulation concentration (ccc), ζ-potential, plastic viscosity and Bingham yield stress of OG dispersions on charge, radius and polarizability of exchangeable cations, on enthalpy and entropy of their hydration have been obtained. The most important correlations between the rheological, electrosurface and hydrophilic characteristics of the ion-exchanged OG have been found from them. The latters shed light on the structure of the electrical double and hydrate boundary layers and their role in the mechanism of the stabilization and structure formation of the graphite-containing dispersions.