加压碳化体系对纳米碳酸钙粒度和分散性的影响

利用加压碳化体系制备粒径均一、高分散性纳米碳酸钙材料。考察氢氧化钙浓度、表面活性剂添加量、反应温度、CO2压力对制备纳米CaCO3粒子尺寸和分散程度的影响，采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、Zeta电位和傅立叶变换红外光谱(FT-IR)对制备的纳米碳酸钙粒子进行表征。结果表明，最优加压碳化反应条件是Ca(OH)2质量浓度为2%、表面活性剂添加量为3%(占碳酸钙理论产量的百分比)、反应温度为40℃、CO2压力为6 MPa，所得立方形碳酸钙平均粒径为117 nm，晶型为方解石型碳酸钙。碳化反应加入表面活性剂十六烷基三甲基溴化铵(CTAB)使CaCO3表面形成的正电荷增大至+37.7 mV并高于标准值30 mV，表明制备的CaCO3产品具有良好的分散性且稳定。通过FT-IR和Zeta电位对CTAB改性前后CaCO3纳米粒子进行表征，探讨了CTAB对合成纳米CaCO3分散性的影响机理，为纳米碳酸钙制备提供了一种新的方法。

Effect of pressurized carbonization system on the particle size and dispersion of nano calcium carbonate

Nano calcium carbonate with uniform particle size and high dispersion was prepared by pressurized carbonization system. The effects of calcium hydroxide concentration, surfactant addition amount, reaction temperature and CO2 pressure on the size and dispersion degree of prepared nano CaCO3 particles were investigated. X-ray diffraction (XRD), scanning electron microscope (SEM), Zeta potential and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the prepared nano CaCO3 particles. The results showed that the optimum conditions for pressure carbonization are Ca(OH)2 mass concentration of 2%, surfactant dosage of 3% (percentage of theoretical production of calcium carbonate), reaction temperature of 40℃ and CO2 pressure of 6 MPa, the average particle size of the cubed calcium carbonate was 117 nm, and the crystal type was calcite calcium carbonate. The addition of surfactant cetyl trimethyl ammonium bromide (CTAB) to the carbonization reaction increased the positive charge formed on the surface of CaCO3 to +37.7 mV and higher than the standard value of 30 mV, indicating that the prepared CaCO3 product has good dispersibility and stability. FT-IR and Zeta potential were used to characterize CaCO3 nanoparticles before and after the modification of CTAB, and the influence mechanism of CTAB on the dispersion of synthetic CaCO3 nanoparticles was discussed, providing a new method for the preparation of nano CaCO3 .