Flocculation and Dispersion of Fine Particles in Non-Polar Organic Solvent

Abstract

The dispersion of fine particles in organic solvent is an important process in paint industry, cosmetic industry and so on.Fine particles in non-polar organic solvent such as cyclohexane, if they. are not aerophilic, settle rapidly by flocculation. Then, the following two methods have been applied to stabilize such a suspension ;(1) The organic compounds, soluble in the solvent, are added directly to the suspension, as the dispersing agents.(2) The organic compounds, soluble in water, are added to the aqueous suspension. The fine particles, being adsorbed by the agents on the surface, are filtrated and dried. Then, they are dispersed in organic solvent. This process is sometimes called the FLUSHING PROCESS.The latter method, on which few systematic studies are undertaken, has been recently developed. The flushing process is applied upon the fine particles of α-ferric oxide. It is found that the particles coated with the monomolecular layer of oleate through the pretreatment in the aqueous suspension are very stable in cyclohexane.The mechanism of the dispersion above remarked is explained in connection with the adsorption behavior of sodium oleate upon the fine particles of α-ferric oxide.