在高剪切结晶器中合成文石型纳米碳酸钙
发布时间：2018-11-08 15:53
【摘要】：在高剪切结晶器中,以Ca(OH)_2-CO_2为反应物系,磷酸和聚丙烯酰胺(PAM)为复合添加剂,成功合成了文石型纳米碳酸钙。采用X射线衍射(XRD)和扫描电镜(SEM)表征了产物的晶体结构和形貌,探讨了高剪切结晶器转速和添加剂用量对碳酸钙晶型和粒径的影响。结果表明,在高剪切结晶器中制得的文石型纳米碳酸钙纯度为98.1%,平均直径为50nm;而且反应时间只是普通搅拌反应器的(1/6)~(1/3)。高剪切结晶器具有较好的微混合性能,在反应结晶过程中能有效调控结晶器内过饱和度分布等微环境,利于亚稳态的文石形成。磷酸和PAM复合添加剂对晶型和粒径的调控有重要的作用。磷酸与Ca(OH)_2反应生成了羟基磷灰石,其作为晶种诱导文石异相成核;PAM对粒径减小有重要作用,能够阻止晶体沿着径向生长,使亚稳态的文石在溶液里稳定存在,防止粒子间的团聚。
[Abstract]:Using Ca (OH) _ 2-CO_2 as reactant system, phosphoric acid and polyacrylamide (PAM) as composite additives, the aragonite nano-calcium carbonate was successfully synthesized in a high shear mould. The crystal structure and morphology of the product were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of the rotation speed of high shear mould and the amount of additives on the crystal shape and particle size of calcium carbonate were investigated. The results show that the purity of calcium carbonate is 98.1 and the average diameter is 50 nm, and the reaction time is only (1 / 6) ~ (1 / 3) of the conventional agitation reactor. The high shear mold has good micromixing performance and can effectively control the distribution of supersaturation in the mold during the reaction crystallization process, which is conducive to the formation of metastable aragonite. The compound additive of phosphoric acid and PAM plays an important role in the regulation of crystal shape and particle size. Hydroxyapatite was formed by the reaction of phosphoric acid with Ca (OH) _ 2. PAM plays an important role in the reduction of particle size and can prevent the crystal from growing along the radial direction and stabilize the metastable aragonite in the solution and prevent the agglomeration of the particles.
【作者单位】： 天津大学化工学院;
【分类号】：TB383.1;TQ132.32
本文编号：2318947
[Abstract]:Using Ca (OH) _ 2-CO_2 as reactant system, phosphoric acid and polyacrylamide (PAM) as composite additives, the aragonite nano-calcium carbonate was successfully synthesized in a high shear mould. The crystal structure and morphology of the product were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of the rotation speed of high shear mould and the amount of additives on the crystal shape and particle size of calcium carbonate were investigated. The results show that the purity of calcium carbonate is 98.1 and the average diameter is 50 nm, and the reaction time is only (1 / 6) ~ (1 / 3) of the conventional agitation reactor. The high shear mold has good micromixing performance and can effectively control the distribution of supersaturation in the mold during the reaction crystallization process, which is conducive to the formation of metastable aragonite. The compound additive of phosphoric acid and PAM plays an important role in the regulation of crystal shape and particle size. Hydroxyapatite was formed by the reaction of phosphoric acid with Ca (OH) _ 2. PAM plays an important role in the reduction of particle size and can prevent the crystal from growing along the radial direction and stabilize the metastable aragonite in the solution and prevent the agglomeration of the particles.
【作者单位】： 天津大学化工学院;
【分类号】：TB383.1;TQ132.32
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