Viscosity Control of Kaolinites Dispersion via Addition of Tannin and Ferric Chloride

Traditional recipes from around the world show that various organic additives can affect the properties of clay-based materials. Tannins, which are polyphenols derived from plants, have the ability to interact with clay particles in both attractive and repulsive ways due to their surface properties. The study investigates the effect of complex formation between tannin, clay, and metal ions on the apparent viscosity of mixtures. Rheological measurements were conducted on several slurry formulations based on kaolinites, ferric chloride, and three types of tannin representing the main typological families of polyphenols. The results indicate that the inclusion of tannins of any kind decreases the apparent viscosity of pastes across all pH ranges. However, the dispersing capacity of the substance is particularly effective at natural pH value between 3 and 5. The addition of iron can be used to neutralise the dispersant effect. Controlling the viscosity and the creation of tannin-iron bridges between the clays is a promising approach to stabilisation.