Droplet stability and product quality in the Higee-assisted microemulsion process for preparing CaCO3 particles

Abstract A novel Higee (high-gravity)-assisted two-microemulsion process was used for preparing CaCO 3 ultrafine particles, aiming at an increase in droplet stability and product yield, along with a decrease of particle size. The microemulsion system of AOT/isooctane/aqueous solution was selected, and the reactant in each of the aqueous phases was CaCl 2 and NaCO 3 . In the first step, the individual reverse microemulsion of CaCl 2 and Na 2 CO 3 was prepared using a spinning disk, which generated high-gravity force to form the microemulsion. Then, the two microemulsions were mixed in a stirred vessel to yield CaCO 3 particles. The stability of CaCl 2 microemulsion, which was less stable than the Na 2 CO 3 microemulsion, and the properties of product particles, including particle size, habit, and morphology, so prepared were compared with that obtained from the conventional microemulsion process, in which a magnetic stirrer was used in the first step. In addition, the effects of R value (CaCl 2 /Na 2 CO 3 molar ratio after mixing), Cu 2+ impurities, and emulsion preparation mode on the product yield were investigated. All the three variables significantly influenced the product yield, especially for the Higee-assisted technique. The high-gravity equipment is a good tool for process intensification.