以白云石为原料氨碱法制备球霰石及其生成机理研究

Study on preparation of vaterite from dolomite by ammonia-alkali method and its mechanism

采用仿Solvay氨碱法,以白云石为起始原料,在碱性环境下制备出高球霰石含量的碳酸钙。XRD和SEM表征结果显示,碳化温度为20~40℃时的产品为球霰石;40~60℃时的产品为方解石;60~90℃时的产品为文石。球霰石的高倍SEM发现产品有许多微孔结构,对产品进行比表面积测定为32.653 m^(2)/g,孔径为2.972 nm,为生物分子的装载提供了良好的空间。对球霰石的形成机理分析表明,NH_(4)^(+)-NH3缓冲体系不仅可以增加碳酸钙的过饱和度,还可以改善溶液环境,为球霰石的生长提供了一个良好的溶液环境,溶液中微量的Mg^(2+)起到了促进完好晶型形成的作用。

Calcium carbonate with high content of vaterite was prepared by imitating Solvay ammonia-alkali method with dolomite as starting material in alkaline environment.The results of XRD and SEM showed that the product with carbonization temperature of 20~40℃was vaterite,40~60℃was calcite and 60~90℃was aragonite.The high magnification SEM of vaterite showed that the product had many microporous structures.The specific surface area of the product was determined to be 32.653 m^(2)/g and the pore size was 2.972 nm.It provides a good space for the loading of biomolecules.The analysis of the formation mechanism of vaterite showed that the NH_(4)^(+)-NH3 buffer system could not only increase the supersaturation of calcium carbonate in the solution,but also improve the solution environment and provide a good solution environment for the growth of vaterite.The trace amount of Mg^(2+)in the solution played a role in promoting the formation of intact crystal forms.