Synthesis of aragonite by the carbonation process

The conditions necessary for synthesizing aragonite by the carbonation process were investigated. Aragonite formation was found to have no relation to the pH value, the mole ratio of MgCl2/Ca(OH)(2), or the magnesium/calciurn ion concentration in a solution. The synthesis of aragonite requires a concentration of magnesium ions in the appropriate range (similar to0.1-0.26 mol/L) and a concentration of calcium ions below a certain range (less than similar to0.16-0.25 mol/L). An excess of calcium ions or magnesium ions favors calcite formation. Needlelike aragonite with a large aspect ratio was successfully synthesized in the present study.