油酸在CaCl_2和Ca(OH)_2反应体系中对CaCO_3晶型和形貌的调控

Regulation of Oleic Acid on the Polymorphs and the Morphologies of CaCO_3 during CaCl_2 and Ca(OH)_2 Reaction System

分别在CaCl_2碳化体系中(以CaCl_2、CO_2、NH_3·H_2O和油酸为原料)和Ca(OH)_2碳化体系中(以Ca(OH)_2、CO_2和油酸为原料)采用微孔分散碳化法于室温下制备了微纳米CaCO_3,并采用XRD、TEM和SEM等表征手段重点研究了油酸对CaCO_3晶型和形貌的影响和调控。结果表明:在不添加油酸的CaCl_2反应体系中,反应初期生成方解石相,随着反应的进行,球霰石相的含量逐渐增加,而油酸的加入使得该体系整个碳化过程中产物均为球霰石相。另外,油酸的加入还可以加速反应过程,使得球形颗粒的形成时间缩短。而Ca(OH)_2反应体系中,整个碳化过程中产物均为方解石相,油酸的加入对晶体类型没有明显影响。

In the present work,micro-nano CaC0 3 was prepared at room temperature via microporous dispersion carbonation method from CaCl2 solution(CaCl2,C0 2,ammonia water and oleic acid as the raw materials)and Ca(OH)2 suspension(Ca(OH)2,C0 2 and oleic acid as raw materials),respectively.The influence and regulation of oleic acid on the polymorphs and morphologies of CaC0 3 were investigated by means of XRD,TEM and SEM.The results indicate that calcite is the major crystalline phase at the early carbonation stage of CaCl2 at absence of oleic acid and the content of vaterite increases as the reaction going on.While vaterite is the single crystalline phase during the whole carbonation of CaCl2 in the presence of oleic acid.Moreover,the addition of oleic acid can accelerate the carbonation process and shorten the formation time of spherical particles.However,calcite is the single phase during the whole carbonation of Ca(OH)2 and the addition of oleic acid cannot alter the crystalline phase.