Study on Precipitation Process of Spherical Calcium Carbonate Controlled by Polyaspartic Acid

Using polyaspartic acid(PASP) as the organic template,the precipitation process of calcium carbonate in aqueous solution was examined by the carbonation method.The precipitated samples were characterized by FTIR,XRD,SEM and Granularity analyzer.Moreover,the form and growth process of crystal nucleus and morphology changes of precipitated calcium carbonate were analyzed according to the biomimetic mineralization theory.The results showed that crystal transformation of calcium carbonate from calcite to vaterite and its morphology changes from rhombic to sphere is produced in the presence of polyaspartic acid.The average size of precipitated particles has reduced 64.3%,and the distribution of particle size tends to narrow.The main reason was that the distance of both adjacent COO-was matched to that of both oxygen atoms in the 12 spatial configuration ligands of Ca2 +.The spherical particles with small crystal on its surface was formed via mesomorphic,thus crystal growth was inhibited because of polyaspartic acid adsorbed on the surface of particle.