Improving the productivity and purity of vaterite produced via a refined bubbling method

The bubbling method has been refined to produce vaterite with both high productivity and purity for its promising applications. This involves: a) adding an adequate amount of ammonia water to achieve maximum precipitation of Ca 2+ , b) refining CO 2 bubble sizes into microns by a designed gas disperser, and c) using optimal final pH condition and CO 2 flow rate to obtain vaterite with both high productivity and purity. In addition, the conservation of vaterite was also investigated by exposing vaterite to two moist environments. The results show that 95.1 % pure vaterite can be produced with 88.8 % yield at a final pH value of 8.6 and CO 2 flow rate of 11 l min −1 . The corresponding vaterite particles mostly have a hollow structure. The conservation of vaterite is very sensitive to moisture, and it transforms into calcite gradually depending on the moisture content.