Enhancement of Mixing and Mass Transfer Performance with a Microstructure Minireactor for Controllable Preparation of CaCO 3 Nanoparticles

CO 2 /Ca(OH) 2 precipitation reaction was used to prepare CaCO 3 nanoparticles in this work. As a fast reaction system, nice mixing and a fast mass transfer rate of CO 2 are required to enhance supersaturation. To increase the mixing performance, a microstructure reactor, a membrane dispersion minireactor, which has microfiltration membranes as the dispersion media, was introduced and CaCO 3 nanoparticles with average diameters ranging from 34.3 to 110 nm were prepared. Several operating conditions were investigated for the purpose of controlling the particle size. In addition, a deep analysis on the mass transfer flux density of CO 2 was carried out and the particle size decreased with the increasing of the mass transfer flux density during the reaction. Compared with a membrane-free reactor, it was found that the mixing performance was significantly enhanced by the effect of the micropore membrane, and nanoparticles cannot be prepared without it.