The Effect of Molar Ratio Ca/Al on Synthesis of Aragonite Precipitated Calcium Carbonate

Effect of aluminum ion on synthesis of precipitated calcium carbonate by carbonation process was investigated with changing its amount of addition, mixing condition and reaction temperature. 0.2 mole Ca(OH)2 was added to 2L of 0.1M NaAlO2 aqueous solution, and then calcium carbonate was synthesized by blowing CO2 gas into the suspension. For Ca/Al>1(molar ratio), only calcite powder was precipitated, for Ca/Al=1, both calcite and aragonite were precipitated and for Ca/Al>l, the content of aragonite decreased. The raising of reaction temperature made the pH of the suspension lowered, and it resulted in progress of formation of aragonite phase at 80°C.