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

A novel Higee (high-gravity)-assisted two-microemulsion process was used for preparing CaCO3 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 CaCl2 and NaCO3. In the first step, the individual reverse microemulsion of CaCl2 and Na2CO3 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 CaCO3 particles. The stability of CaCl2 microemulsion, which was less stable than the Na2CO3 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 (CaCl2/Na2CO3 molar ratio after mixing), Cu2+ 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.

► A novel Higee (high-gravity)-assisted two-microemulsion process was adopted to synthesize CaCO3 particles.
► The individual reverse microemulsion of CaCl2 and Na2CO3 was prepared using a spinning disk before mixing.
► The stability of the microemulsion increased using the high-gravity force.
► The product yield for the Higee-assisted system was higher than that for the stirrer-prepared system.