Preparation and in-situ surface modification of CaCO3 nanoparticles with calcium stearate in a microreaction system

Nano-sized calcium carbonate , as a multifunctional material, is widely used in various industrial fields. The morphology, particle size, surface property of CaCO 3 particles have great impact on the application effect. This study presents an energy-saving and efficient approach to controllably prepare CaCO 3 nanoparticles and conduct surface modification simultaneously. Ca(OH) 2 /CO 2 carbonation method was adopted to prepare CaCO 3 nanoparticles using a membrane dispersion microreactor in the presence of calcium stearate (CaSt 2 ) surfactant . The effects of gas and liquid flow rates , temperature and the dosage of surfactant were systematically investigated. The effect of surface modification was evaluated by contact angle and active ratio. The as-prepared hydrophobic CaCO 3 nanoparticles were of good dispersity, with an average particle size of 34 nm, a specific surface area of above 30 m 2 /g and a contact angle of 107.8°. In this work, the effect of surfactant on the carbonation reaction was greatly diminished by adding CaSt 2 surfactant to a portion of Ca(OH) 2 slurry. Additionally, the modification process was carried out without organic solvents and high temperature. As compared to post-modification method, the in-situ modification process is of significant practical importance because of high production efficiency, excellent process stability, and high product quality.