The importance of surface energy in the dispersion behaviour of talc particles in aqueous media

The dispersion of powders in liquids is an operation used in many industries, which depends on parameters involving both the process (stirring power, temperature and reactor geometry) and the material (the powder, the liquid and the powder/liquid interface). Even though dispersion operations have been the object of several investigations, the importance of the various parameters and especially the physicochemical properties is rarely treated. This paper presents an experimental study of the kinetics of talc dispersion in water based on prior determination of powder properties (particle size, density, surface area and surface free energy), which are used to calculate the different work functions involved in dispersion (adhesion, immersion and spreading). Experiments are presented using an optical fibre sensor to determine the dispersion kinetics of talc in water as a function of stirring power and powder concentration. These results are found to correlate with the energy calculated to be required to cross the liquid–gas interface.