Sonochemical Formation of CaCO3Nanoparticles with Controlled Particle Size Distribution

The effect of operating parameters such as flow rate of CO2 and concentration of Ca(OH)2 on the particle size distribution, crystallite size, and induction period of nano calcium carbonate synthesis in a sonochemical carbonization process has been investigated. Synthesis of calcium carbonate was carried out by bubbling CO2 gas (40, 50, 60 L/h) through Ca(OH)2 slurry (4%, 5%, 6% by weight). Particle size was determined using a dynamic light scattering technique. It was found that average crystallite size was between 45 and 36 nm for 40 to 60 L/h at 4% concentration of Ca(OH)2 slurry, which was maintained constant. This indicates that ultrasound imparts the shear stress on the gas–solid interface that leads to a decrease in particle size. As the concentration of Ca(OH)2 increased from 4% to 6% (by weight), crystallite size was found to be increased from 45 to 72 nm. The pH and conductivity, induction time, and particle size distribution (PSD) data also indicate that an appropriate combination of slurry concentration and CO2 flow rate and direct cavitation can produce nanosize particles of CaCO3.