Sedimentation of Microparticles in Highly Concentrated Non-Newtonian Emulsions

Abstract

From the perspective of many industrial products, it is important that no phase separation occurs over time, as this affects their quality. Therefore, every effort is made to maintain the stability of the systems by the addition of various stabilizers, but additional artificial ingredients often discourage consumers. However, there is another alternative possibility to maintain the stability of such systems by consciously controlling the parameters of liquids and solids, based on the knowledge of the mechanisms occurring between the components. This is of immeasurable importance also in cases where multicomponent systems need to be separated, which is particularly important in chemical engineering and environmental engineering. The paper presents an experimental study of the solids-sedimentation process in highly concentrated, stable emulsions that exhibit the properties of non-Newtonian liquids. A study based on turbidimetric techniques is presented in which the influence of both solids (average grain diameters 150–700 μm and concentration 0.2–0.4 g/mL) and emulsion parameters (concentration 60–70% and average droplet diameters of 8.24–15.72 μm) were taken into account. The occurring phenomena have been also explained. As a result, the dependence of system parameters on the intensity of the sedimentation process was determined. This can be of great practical importance in product design in the chemical, food, pharmaceutical, or even cosmetic industry.

Keywords

• microparticles
• sedimentation
• non-Newtonian emulsion
• highly concentrated emulsion
• emulsion stability